Series comparison

-[Qemu-devel] [PULL 0/8] Block patches
+[PULL v2 00/28] Block patches
-The following changes since commit 812b835fb4d23dd108b2f9802158472d50b73579:
+The following changes since commit ac793156f650ae2d77834932d72224175ee69086:
-  Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-05-07' into staging (2019-05-09 16:31:12 +0100)
+  Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20201020-1' into staging (2020-10-20 21:11:35 +0100)
 are available in the Git repository at:
-  https://github.com/stefanha/qemu.git tags/block-pull-request
+  https://gitlab.com/stefanha/qemu.git tags/block-pull-request
-for you to fetch changes up to e84125761f78919fe63616d9888ea45e72dc956f:
+for you to fetch changes up to 32a3fd65e7e3551337fd26bfc0e2f899d70c028c:
-  docs: add Security chapter to the documentation (2019-05-10 10:53:52 +0100)
+  iotests: add commit top->base cases to 274 (2020-10-22 09:55:39 +0100)
 ----------------------------------------------------------------
 Pull request
+v2:
+ * Fix format string issues on 32-bit hosts [Peter]
+ * Fix qemu-nbd.c CONFIG_POSIX ifdef issue [Eric]
+ * Fix missing eventfd.h header on macOS [Peter]
+ * Drop unreliable vhost-user-blk test (will send a new patch when ready) [Peter]
+This pull request contains the vhost-user-blk server by Coiby Xu along with my
+additions, block/nvme.c alignment and hardware error statistics by Philippe
+Mathieu-Daudé, and bdrv_co_block_status_above() fixes by Vladimir
+Sementsov-Ogievskiy.
 ----------------------------------------------------------------
-Andrey Shinkevich (1):
+Coiby Xu (6):
-  block/io.c: fix for the allocation failure
+  libvhost-user: Allow vu_message_read to be replaced
   libvhost-user: remove watch for kick_fd when de-initialize vu-dev
   util/vhost-user-server: generic vhost user server
   block: move logical block size check function to a common utility
     function
   block/export: vhost-user block device backend server
   MAINTAINERS: Add vhost-user block device backend server maintainer
-Jules Irenge (3):
+Philippe Mathieu-Daudé (1):
-  util/readline: add a space to fix errors by checkpatch tool
+  block/nvme: Add driver statistics for access alignment and hw errors
   util: readline: replace tab indent by four spaces to fix checkpatch
     errors
   util/readline: Add braces to fix checkpatch errors
-Nikita Alekseev (1):
+Stefan Hajnoczi (16):
-  block: Add coroutine_fn to bdrv_check_co_entry
+  util/vhost-user-server: s/fileds/fields/ typo fix
   util/vhost-user-server: drop unnecessary QOM cast
   util/vhost-user-server: drop unnecessary watch deletion
   block/export: consolidate request structs into VuBlockReq
   util/vhost-user-server: drop unused DevicePanicNotifier
   util/vhost-user-server: fix memory leak in vu_message_read()
   util/vhost-user-server: check EOF when reading payload
   util/vhost-user-server: rework vu_client_trip() coroutine lifecycle
   block/export: report flush errors
   block/export: convert vhost-user-blk server to block export API
   util/vhost-user-server: move header to include/
   util/vhost-user-server: use static library in meson.build
   qemu-storage-daemon: avoid compiling blockdev_ss twice
   block: move block exports to libblockdev
   block/export: add iothread and fixed-iothread options
   block/export: add vhost-user-blk multi-queue support
-Paolo Bonzini (1):
+Vladimir Sementsov-Ogievskiy (5):
-  aio-posix: ensure poll mode is left when aio_notify is called
+  block/io: fix bdrv_co_block_status_above
   block/io: bdrv_common_block_status_above: support include_base
   block/io: bdrv_common_block_status_above: support bs == base
   block/io: fix bdrv_is_allocated_above
   iotests: add commit top->base cases to 274
-Stefan Hajnoczi (2):
+ MAINTAINERS                                |   9 +
-  docs: add Secure Coding Practices to developer docs
+ qapi/block-core.json                       |  24 +-
-  docs: add Security chapter to the documentation
+ qapi/block-export.json                     |  36 +-
+ block/coroutines.h                         |   2 +
- Makefile                               |   2 +-
+ block/export/vhost-user-blk-server.h       |  19 +
- block.c                                |   2 +-
+ contrib/libvhost-user/libvhost-user.h      |  21 +
- block/io.c                             |   2 +-
+ include/qemu/vhost-user-server.h           |  65 +++
- util/aio-posix.c                       |  12 +-
+ util/block-helpers.h                       |  19 +
- util/readline.c                        | 174 ++++++++++++++-----------
+ block/export/export.c                      |  37 +-
- docs/devel/index.rst                   |   1 +
+ block/export/vhost-user-blk-server.c       | 431 ++++++++++++++++++++
- docs/devel/secure-coding-practices.rst | 106 +++++++++++++++
+ block/io.c                                 | 132 +++---
- docs/security.texi                     | 131 +++++++++++++++++++
+ block/nvme.c                               |  27 ++
- qemu-doc.texi                          |   3 +
+ block/qcow2.c                              |  16 +-
-files changed, 347 insertions(+), 86 deletions(-)
+ contrib/libvhost-user/libvhost-user-glib.c |   2 +-
- create mode 100644 docs/devel/secure-coding-practices.rst
+ contrib/libvhost-user/libvhost-user.c      |  15 +-
- create mode 100644 docs/security.texi
+ hw/core/qdev-properties-system.c           |  31 +-
  nbd/server.c                               |   2 -
  qemu-nbd.c                                 |  21 +-
  softmmu/vl.c                               |   4 +
  stubs/blk-exp-close-all.c                  |   7 +
  tests/vhost-user-bridge.c                  |   2 +
  tools/virtiofsd/fuse_virtio.c              |   4 +-
  util/block-helpers.c                       |  46 +++
  util/vhost-user-server.c                   | 446 +++++++++++++++++++++
  block/export/meson.build                   |   3 +-
  contrib/libvhost-user/meson.build          |   1 +
  meson.build                                |  22 +-
  nbd/meson.build                            |   2 +
  storage-daemon/meson.build                 |   3 +-
  stubs/meson.build                          |   1 +
  tests/qemu-iotests/274                     |  20 +
  tests/qemu-iotests/274.out                 |  68 ++++
  util/meson.build                           |   4 +
 files changed, 1420 insertions(+), 122 deletions(-)
  create mode 100644 block/export/vhost-user-blk-server.h
  create mode 100644 include/qemu/vhost-user-server.h
  create mode 100644 util/block-helpers.h
  create mode 100644 block/export/vhost-user-blk-server.c
  create mode 100644 stubs/blk-exp-close-all.c
  create mode 100644 util/block-helpers.c
  create mode 100644 util/vhost-user-server.c
 --
-.21.0
+.26.2

-New patch
+[PULL v2 01/28] block/nvme: Add driver statistics for access alignment and hw errors
+From: Philippe Mathieu-Daudé <philmd@redhat.com>
+Keep statistics of some hardware errors, and number of
+aligned/unaligned I/O accesses.
+QMP example booting a full RHEL 8.3 aarch64 guest:
+{ "execute": "query-blockstats" }
+{
+    "return": [
+        {
+            "device": "",
+            "node-name": "drive0",
+            "stats": {
+                "flush_total_time_ns": 6026948,
+                "wr_highest_offset": 3383991230464,
+                "wr_total_time_ns": 807450995,
+                "failed_wr_operations": 0,
+                "failed_rd_operations": 0,
+                "wr_merged": 3,
+                "wr_bytes": 50133504,
+                "failed_unmap_operations": 0,
+                "failed_flush_operations": 0,
+                "account_invalid": false,
+                "rd_total_time_ns": 1846979900,
+                "flush_operations": 130,
+                "wr_operations": 659,
+                "rd_merged": 1192,
+                "rd_bytes": 218244096,
+                "account_failed": false,
+                "idle_time_ns": 2678641497,
+                "rd_operations": 7406,
+            },
+            "driver-specific": {
+                "driver": "nvme",
+                "completion-errors": 0,
+                "unaligned-accesses": 2959,
+                "aligned-accesses": 4477
+            },
+            "qdev": "/machine/peripheral-anon/device[0]/virtio-backend"
+        }
+    ]
+}
+Suggested-by: Stefan Hajnoczi <stefanha@gmail.com>
+Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
+Acked-by: Markus Armbruster <armbru@redhat.com>
+Message-id: 20201001162939.1567915-1-philmd@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ qapi/block-core.json | 24 +++++++++++++++++++++++-
+ block/nvme.c         | 27 +++++++++++++++++++++++++++
+files changed, 50 insertions(+), 1 deletion(-)
+diff --git a/qapi/block-core.json b/qapi/block-core.json
+index XXXXXXX..XXXXXXX 100644
+--- a/qapi/block-core.json
++++ b/qapi/block-core.json
+@@ -XXX,XX +XXX,XX @@
+       'discard-nb-failed': 'uint64',
+       'discard-bytes-ok': 'uint64' } }
++##
++# @BlockStatsSpecificNvme:
++#
++# NVMe driver statistics
++#
++# @completion-errors: The number of completion errors.
++#
++# @aligned-accesses: The number of aligned accesses performed by
++#                    the driver.
++#
++# @unaligned-accesses: The number of unaligned accesses performed by
++#                      the driver.
++#
++# Since: 5.2
++##
++{ 'struct': 'BlockStatsSpecificNvme',
++  'data': {
++      'completion-errors': 'uint64',
++      'aligned-accesses': 'uint64',
++      'unaligned-accesses': 'uint64' } }
++
+ ##
+ # @BlockStatsSpecific:
+ #
+@@ -XXX,XX +XXX,XX @@
+   'discriminator': 'driver',
+   'data': {
+       'file': 'BlockStatsSpecificFile',
+-      'host_device': 'BlockStatsSpecificFile' } }
++      'host_device': 'BlockStatsSpecificFile',
++      'nvme': 'BlockStatsSpecificNvme' } }
+ ##
+ # @BlockStats:
+diff --git a/block/nvme.c b/block/nvme.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/nvme.c
++++ b/block/nvme.c
+@@ -XXX,XX +XXX,XX @@ struct BDRVNVMeState {
+     /* PCI address (required for nvme_refresh_filename()) */
+     char *device;
++
++    struct {
++        uint64_t completion_errors;
++        uint64_t aligned_accesses;
++        uint64_t unaligned_accesses;
++    } stats;
+ };
+ #define NVME_BLOCK_OPT_DEVICE "device"
+@@ -XXX,XX +XXX,XX @@ static bool nvme_process_completion(NVMeQueuePair *q)
+             break;
+         }
+         ret = nvme_translate_error(c);
++        if (ret) {
++            s->stats.completion_errors++;
++        }
+         q->cq.head = (q->cq.head + 1) % NVME_QUEUE_SIZE;
+         if (!q->cq.head) {
+             q->cq_phase = !q->cq_phase;
+@@ -XXX,XX +XXX,XX @@ static int nvme_co_prw(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+     assert(QEMU_IS_ALIGNED(bytes, s->page_size));
+     assert(bytes <= s->max_transfer);
+     if (nvme_qiov_aligned(bs, qiov)) {
++        s->stats.aligned_accesses++;
+         return nvme_co_prw_aligned(bs, offset, bytes, qiov, is_write, flags);
+     }
++    s->stats.unaligned_accesses++;
+     trace_nvme_prw_buffered(s, offset, bytes, qiov->niov, is_write);
+     buf = qemu_try_memalign(s->page_size, bytes);
+@@ -XXX,XX +XXX,XX @@ static void nvme_unregister_buf(BlockDriverState *bs, void *host)
+     qemu_vfio_dma_unmap(s->vfio, host);
+ }
++static BlockStatsSpecific *nvme_get_specific_stats(BlockDriverState *bs)
++{
++    BlockStatsSpecific *stats = g_new(BlockStatsSpecific, 1);
++    BDRVNVMeState *s = bs->opaque;
++
++    stats->driver = BLOCKDEV_DRIVER_NVME;
++    stats->u.nvme = (BlockStatsSpecificNvme) {
++        .completion_errors = s->stats.completion_errors,
++        .aligned_accesses = s->stats.aligned_accesses,
++        .unaligned_accesses = s->stats.unaligned_accesses,
++    };
++
++    return stats;
++}
++
+ static const char *const nvme_strong_runtime_opts[] = {
+     NVME_BLOCK_OPT_DEVICE,
+     NVME_BLOCK_OPT_NAMESPACE,
+@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_nvme = {
+     .bdrv_refresh_filename    = nvme_refresh_filename,
+     .bdrv_refresh_limits      = nvme_refresh_limits,
+     .strong_runtime_opts      = nvme_strong_runtime_opts,
++    .bdrv_get_specific_stats  = nvme_get_specific_stats,
+     .bdrv_detach_aio_context  = nvme_detach_aio_context,
+     .bdrv_attach_aio_context  = nvme_attach_aio_context,
+--
+.26.2

-New patch
+[PULL v2 02/28] libvhost-user: Allow vu_message_read to be replaced
+From: Coiby Xu <coiby.xu@gmail.com>
+Allow vu_message_read to be replaced by one which will make use of the
+QIOChannel functions. Thus reading vhost-user message won't stall the
+guest. For slave channel, we still use the default vu_message_read.
+Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
+Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200918080912.321299-2-coiby.xu@gmail.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ contrib/libvhost-user/libvhost-user.h      | 21 +++++++++++++++++++++
+ contrib/libvhost-user/libvhost-user-glib.c |  2 +-
+ contrib/libvhost-user/libvhost-user.c      | 14 +++++++-------
+ tests/vhost-user-bridge.c                  |  2 ++
+ tools/virtiofsd/fuse_virtio.c              |  4 ++--
+files changed, 33 insertions(+), 10 deletions(-)
+diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
+index XXXXXXX..XXXXXXX 100644
+--- a/contrib/libvhost-user/libvhost-user.h
++++ b/contrib/libvhost-user/libvhost-user.h
+@@ -XXX,XX +XXX,XX @@
+  */
+ #define VHOST_USER_MAX_RAM_SLOTS 32
++#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
++
+ typedef enum VhostSetConfigType {
+     VHOST_SET_CONFIG_TYPE_MASTER = 0,
+     VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
+@@ -XXX,XX +XXX,XX @@ typedef uint64_t (*vu_get_features_cb) (VuDev *dev);
+ typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
+ typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
+                                   int *do_reply);
++typedef bool (*vu_read_msg_cb) (VuDev *dev, int sock, VhostUserMsg *vmsg);
+ typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
+ typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
+ typedef int (*vu_get_config_cb) (VuDev *dev, uint8_t *config, uint32_t len);
+@@ -XXX,XX +XXX,XX @@ struct VuDev {
+     bool broken;
+     uint16_t max_queues;
++    /* @read_msg: custom method to read vhost-user message
++     *
++     * Read data from vhost_user socket fd and fill up
++     * the passed VhostUserMsg *vmsg struct.
++     *
++     * If reading fails, it should close the received set of file
++     * descriptors as socket message's auxiliary data.
++     *
++     * For the details, please refer to vu_message_read in libvhost-user.c
++     * which will be used by default if not custom method is provided when
++     * calling vu_init
++     *
++     * Returns: true if vhost-user message successfully received,
++     *          otherwise return false.
++     *
++     */
++    vu_read_msg_cb read_msg;
+     /* @set_watch: add or update the given fd to the watch set,
+      * call cb when condition is met */
+     vu_set_watch_cb set_watch;
+@@ -XXX,XX +XXX,XX @@ bool vu_init(VuDev *dev,
+              uint16_t max_queues,
+              int socket,
+              vu_panic_cb panic,
++             vu_read_msg_cb read_msg,
+              vu_set_watch_cb set_watch,
+              vu_remove_watch_cb remove_watch,
+              const VuDevIface *iface);
+diff --git a/contrib/libvhost-user/libvhost-user-glib.c b/contrib/libvhost-user/libvhost-user-glib.c
+index XXXXXXX..XXXXXXX 100644
+--- a/contrib/libvhost-user/libvhost-user-glib.c
++++ b/contrib/libvhost-user/libvhost-user-glib.c
+@@ -XXX,XX +XXX,XX @@ vug_init(VugDev *dev, uint16_t max_queues, int socket,
+     g_assert(dev);
+     g_assert(iface);
+-    if (!vu_init(&dev->parent, max_queues, socket, panic, set_watch,
++    if (!vu_init(&dev->parent, max_queues, socket, panic, NULL, set_watch,
+                  remove_watch, iface)) {
+         return false;
+     }
+diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
+index XXXXXXX..XXXXXXX 100644
+--- a/contrib/libvhost-user/libvhost-user.c
++++ b/contrib/libvhost-user/libvhost-user.c
+@@ -XXX,XX +XXX,XX @@
+ /* The version of inflight buffer */
+ #define INFLIGHT_VERSION 1
+-#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
+-
+ /* The version of the protocol we support */
+ #define VHOST_USER_VERSION 1
+ #define LIBVHOST_USER_DEBUG 0
+@@ -XXX,XX +XXX,XX @@ have_userfault(void)
+ }
+ static bool
+-vu_message_read(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
++vu_message_read_default(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
+ {
+     char control[CMSG_SPACE(VHOST_MEMORY_BASELINE_NREGIONS * sizeof(int))] = {};
+     struct iovec iov = {
+@@ -XXX,XX +XXX,XX @@ vu_process_message_reply(VuDev *dev, const VhostUserMsg *vmsg)
+         goto out;
+     }
+-    if (!vu_message_read(dev, dev->slave_fd, &msg_reply)) {
++    if (!vu_message_read_default(dev, dev->slave_fd, &msg_reply)) {
+         goto out;
+     }
+@@ -XXX,XX +XXX,XX @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg)
+     /* Wait for QEMU to confirm that it's registered the handler for the
+      * faults.
+      */
+-    if (!vu_message_read(dev, dev->sock, vmsg) ||
++    if (!dev->read_msg(dev, dev->sock, vmsg) ||
+         vmsg->size != sizeof(vmsg->payload.u64) ||
+         vmsg->payload.u64 != 0) {
+         vu_panic(dev, "failed to receive valid ack for postcopy set-mem-table");
+@@ -XXX,XX +XXX,XX @@ vu_dispatch(VuDev *dev)
+     int reply_requested;
+     bool need_reply, success = false;
+-    if (!vu_message_read(dev, dev->sock, &vmsg)) {
++    if (!dev->read_msg(dev, dev->sock, &vmsg)) {
+         goto end;
+     }
+@@ -XXX,XX +XXX,XX @@ vu_init(VuDev *dev,
+         uint16_t max_queues,
+         int socket,
+         vu_panic_cb panic,
++        vu_read_msg_cb read_msg,
+         vu_set_watch_cb set_watch,
+         vu_remove_watch_cb remove_watch,
+         const VuDevIface *iface)
+@@ -XXX,XX +XXX,XX @@ vu_init(VuDev *dev,
+     dev->sock = socket;
+     dev->panic = panic;
++    dev->read_msg = read_msg ? read_msg : vu_message_read_default;
+     dev->set_watch = set_watch;
+     dev->remove_watch = remove_watch;
+     dev->iface = iface;
+@@ -XXX,XX +XXX,XX @@ static void _vu_queue_notify(VuDev *dev, VuVirtq *vq, bool sync)
+         vu_message_write(dev, dev->slave_fd, &vmsg);
+         if (ack) {
+-            vu_message_read(dev, dev->slave_fd, &vmsg);
++            vu_message_read_default(dev, dev->slave_fd, &vmsg);
+         }
+         return;
+     }
+diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
+index XXXXXXX..XXXXXXX 100644
+--- a/tests/vhost-user-bridge.c
++++ b/tests/vhost-user-bridge.c
+@@ -XXX,XX +XXX,XX @@ vubr_accept_cb(int sock, void *ctx)
+                  VHOST_USER_BRIDGE_MAX_QUEUES,
+                  conn_fd,
+                  vubr_panic,
++                 NULL,
+                  vubr_set_watch,
+                  vubr_remove_watch,
+                  &vuiface)) {
+@@ -XXX,XX +XXX,XX @@ vubr_new(const char *path, bool client)
+                      VHOST_USER_BRIDGE_MAX_QUEUES,
+                      dev->sock,
+                      vubr_panic,
++                     NULL,
+                      vubr_set_watch,
+                      vubr_remove_watch,
+                      &vuiface)) {
+diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
+index XXXXXXX..XXXXXXX 100644
+--- a/tools/virtiofsd/fuse_virtio.c
++++ b/tools/virtiofsd/fuse_virtio.c
+@@ -XXX,XX +XXX,XX @@ int virtio_session_mount(struct fuse_session *se)
+     se->vu_socketfd = data_sock;
+     se->virtio_dev->se = se;
+     pthread_rwlock_init(&se->virtio_dev->vu_dispatch_rwlock, NULL);
+-    vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, fv_set_watch,
+-            fv_remove_watch, &fv_iface);
++    vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, NULL,
++            fv_set_watch, fv_remove_watch, &fv_iface);
+     return 0;
+ }
+--
+.26.2

-New patch
+[PULL v2 03/28] libvhost-user: remove watch for kick_fd when de-initialize vu-dev
+From: Coiby Xu <coiby.xu@gmail.com>
+When the client is running in gdb and quit command is run in gdb,
+QEMU will still dispatch the event which will cause segment fault in
+the callback function.
+Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
+Message-id: 20200918080912.321299-3-coiby.xu@gmail.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ contrib/libvhost-user/libvhost-user.c | 1 +
+file changed, 1 insertion(+)
+diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
+index XXXXXXX..XXXXXXX 100644
+--- a/contrib/libvhost-user/libvhost-user.c
++++ b/contrib/libvhost-user/libvhost-user.c
+@@ -XXX,XX +XXX,XX @@ vu_deinit(VuDev *dev)
+         }
+         if (vq->kick_fd != -1) {
++            dev->remove_watch(dev, vq->kick_fd);
+             close(vq->kick_fd);
+             vq->kick_fd = -1;
+         }
+--
+.26.2

-New patch
+[PULL v2 04/28] util/vhost-user-server: generic vhost user server
+From: Coiby Xu <coiby.xu@gmail.com>
+Sharing QEMU devices via vhost-user protocol.
+Only one vhost-user client can connect to the server one time.
+Suggested-by: Kevin Wolf <kwolf@redhat.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
+Message-id: 20200918080912.321299-4-coiby.xu@gmail.com
+[Fixed size_t %lu -> %zu format string compiler error.
+--Stefan]
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ util/vhost-user-server.h |  65 ++++++
+ util/vhost-user-server.c | 428 +++++++++++++++++++++++++++++++++++++++
+ util/meson.build         |   1 +
+files changed, 494 insertions(+)
+ create mode 100644 util/vhost-user-server.h
+ create mode 100644 util/vhost-user-server.c
+diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
+new file mode 100644
+index XXXXXXX..XXXXXXX
+--- /dev/null
++++ b/util/vhost-user-server.h
+@@ -XXX,XX +XXX,XX @@
++/*
++ * Sharing QEMU devices via vhost-user protocol
++ *
++ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
++ * Copyright (c) 2020 Red Hat, Inc.
++ *
++ * This work is licensed under the terms of the GNU GPL, version 2 or
++ * later.  See the COPYING file in the top-level directory.
++ */
++
++#ifndef VHOST_USER_SERVER_H
++#define VHOST_USER_SERVER_H
++
++#include "contrib/libvhost-user/libvhost-user.h"
++#include "io/channel-socket.h"
++#include "io/channel-file.h"
++#include "io/net-listener.h"
++#include "qemu/error-report.h"
++#include "qapi/error.h"
++#include "standard-headers/linux/virtio_blk.h"
++
++typedef struct VuFdWatch {
++    VuDev *vu_dev;
++    int fd; /*kick fd*/
++    void *pvt;
++    vu_watch_cb cb;
++    bool processing;
++    QTAILQ_ENTRY(VuFdWatch) next;
++} VuFdWatch;
++
++typedef struct VuServer VuServer;
++typedef void DevicePanicNotifierFn(VuServer *server);
++
++struct VuServer {
++    QIONetListener *listener;
++    AioContext *ctx;
++    DevicePanicNotifierFn *device_panic_notifier;
++    int max_queues;
++    const VuDevIface *vu_iface;
++    VuDev vu_dev;
++    QIOChannel *ioc; /* The I/O channel with the client */
++    QIOChannelSocket *sioc; /* The underlying data channel with the client */
++    /* IOChannel for fd provided via VHOST_USER_SET_SLAVE_REQ_FD */
++    QIOChannel *ioc_slave;
++    QIOChannelSocket *sioc_slave;
++    Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
++    QTAILQ_HEAD(, VuFdWatch) vu_fd_watches;
++    /* restart coroutine co_trip if AIOContext is changed */
++    bool aio_context_changed;
++    bool processing_msg;
++};
++
++bool vhost_user_server_start(VuServer *server,
++                             SocketAddress *unix_socket,
++                             AioContext *ctx,
++                             uint16_t max_queues,
++                             DevicePanicNotifierFn *device_panic_notifier,
++                             const VuDevIface *vu_iface,
++                             Error **errp);
++
++void vhost_user_server_stop(VuServer *server);
++
++void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx);
++
++#endif /* VHOST_USER_SERVER_H */
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+new file mode 100644
+index XXXXXXX..XXXXXXX
+--- /dev/null
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@
++/*
++ * Sharing QEMU devices via vhost-user protocol
++ *
++ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
++ * Copyright (c) 2020 Red Hat, Inc.
++ *
++ * This work is licensed under the terms of the GNU GPL, version 2 or
++ * later.  See the COPYING file in the top-level directory.
++ */
++#include "qemu/osdep.h"
++#include "qemu/main-loop.h"
++#include "vhost-user-server.h"
++
++static void vmsg_close_fds(VhostUserMsg *vmsg)
++{
++    int i;
++    for (i = 0; i < vmsg->fd_num; i++) {
++        close(vmsg->fds[i]);
++    }
++}
++
++static void vmsg_unblock_fds(VhostUserMsg *vmsg)
++{
++    int i;
++    for (i = 0; i < vmsg->fd_num; i++) {
++        qemu_set_nonblock(vmsg->fds[i]);
++    }
++}
++
++static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
++                      gpointer opaque);
++
++static void close_client(VuServer *server)
++{
++    /*
++     * Before closing the client
++     *
++     * 1. Let vu_client_trip stop processing new vhost-user msg
++     *
++     * 2. remove kick_handler
++     *
++     * 3. wait for the kick handler to be finished
++     *
++     * 4. wait for the current vhost-user msg to be finished processing
++     */
++
++    QIOChannelSocket *sioc = server->sioc;
++    /* When this is set vu_client_trip will stop new processing vhost-user message */
++    server->sioc = NULL;
++
++    VuFdWatch *vu_fd_watch, *next;
++    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
++        aio_set_fd_handler(server->ioc->ctx, vu_fd_watch->fd, true, NULL,
++                           NULL, NULL, NULL);
++    }
++
++    while (!QTAILQ_EMPTY(&server->vu_fd_watches)) {
++        QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
++            if (!vu_fd_watch->processing) {
++                QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
++                g_free(vu_fd_watch);
++            }
++        }
++    }
++
++    while (server->processing_msg) {
++        if (server->ioc->read_coroutine) {
++            server->ioc->read_coroutine = NULL;
++            qio_channel_set_aio_fd_handler(server->ioc, server->ioc->ctx, NULL,
++                                           NULL, server->ioc);
++            server->processing_msg = false;
++        }
++    }
++
++    vu_deinit(&server->vu_dev);
++    object_unref(OBJECT(sioc));
++    object_unref(OBJECT(server->ioc));
++}
++
++static void panic_cb(VuDev *vu_dev, const char *buf)
++{
++    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
++
++    /* avoid while loop in close_client */
++    server->processing_msg = false;
++
++    if (buf) {
++        error_report("vu_panic: %s", buf);
++    }
++
++    if (server->sioc) {
++        close_client(server);
++    }
++
++    if (server->device_panic_notifier) {
++        server->device_panic_notifier(server);
++    }
++
++    /*
++     * Set the callback function for network listener so another
++     * vhost-user client can connect to this server
++     */
++    qio_net_listener_set_client_func(server->listener,
++                                     vu_accept,
++                                     server,
++                                     NULL);
++}
++
++static bool coroutine_fn
++vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
++{
++    struct iovec iov = {
++        .iov_base = (char *)vmsg,
++        .iov_len = VHOST_USER_HDR_SIZE,
++    };
++    int rc, read_bytes = 0;
++    Error *local_err = NULL;
++    /*
++     * Store fds/nfds returned from qio_channel_readv_full into
++     * temporary variables.
++     *
++     * VhostUserMsg is a packed structure, gcc will complain about passing
++     * pointer to a packed structure member if we pass &VhostUserMsg.fd_num
++     * and &VhostUserMsg.fds directly when calling qio_channel_readv_full,
++     * thus two temporary variables nfds and fds are used here.
++     */
++    size_t nfds = 0, nfds_t = 0;
++    const size_t max_fds = G_N_ELEMENTS(vmsg->fds);
++    int *fds_t = NULL;
++    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
++    QIOChannel *ioc = server->ioc;
++
++    if (!ioc) {
++        error_report_err(local_err);
++        goto fail;
++    }
++
++    assert(qemu_in_coroutine());
++    do {
++        /*
++         * qio_channel_readv_full may have short reads, keeping calling it
++         * until getting VHOST_USER_HDR_SIZE or 0 bytes in total
++         */
++        rc = qio_channel_readv_full(ioc, &iov, 1, &fds_t, &nfds_t, &local_err);
++        if (rc < 0) {
++            if (rc == QIO_CHANNEL_ERR_BLOCK) {
++                qio_channel_yield(ioc, G_IO_IN);
++                continue;
++            } else {
++                error_report_err(local_err);
++                return false;
++            }
++        }
++        read_bytes += rc;
++        if (nfds_t > 0) {
++            if (nfds + nfds_t > max_fds) {
++                error_report("A maximum of %zu fds are allowed, "
++                             "however got %zu fds now",
++                             max_fds, nfds + nfds_t);
++                goto fail;
++            }
++            memcpy(vmsg->fds + nfds, fds_t,
++                   nfds_t *sizeof(vmsg->fds[0]));
++            nfds += nfds_t;
++            g_free(fds_t);
++        }
++        if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
++            break;
++        }
++        iov.iov_base = (char *)vmsg + read_bytes;
++        iov.iov_len = VHOST_USER_HDR_SIZE - read_bytes;
++    } while (true);
++
++    vmsg->fd_num = nfds;
++    /* qio_channel_readv_full will make socket fds blocking, unblock them */
++    vmsg_unblock_fds(vmsg);
++    if (vmsg->size > sizeof(vmsg->payload)) {
++        error_report("Error: too big message request: %d, "
++                     "size: vmsg->size: %u, "
++                     "while sizeof(vmsg->payload) = %zu",
++                     vmsg->request, vmsg->size, sizeof(vmsg->payload));
++        goto fail;
++    }
++
++    struct iovec iov_payload = {
++        .iov_base = (char *)&vmsg->payload,
++        .iov_len = vmsg->size,
++    };
++    if (vmsg->size) {
++        rc = qio_channel_readv_all_eof(ioc, &iov_payload, 1, &local_err);
++        if (rc == -1) {
++            error_report_err(local_err);
++            goto fail;
++        }
++    }
++
++    return true;
++
++fail:
++    vmsg_close_fds(vmsg);
++
++    return false;
++}
++
++
++static void vu_client_start(VuServer *server);
++static coroutine_fn void vu_client_trip(void *opaque)
++{
++    VuServer *server = opaque;
++
++    while (!server->aio_context_changed && server->sioc) {
++        server->processing_msg = true;
++        vu_dispatch(&server->vu_dev);
++        server->processing_msg = false;
++    }
++
++    if (server->aio_context_changed && server->sioc) {
++        server->aio_context_changed = false;
++        vu_client_start(server);
++    }
++}
++
++static void vu_client_start(VuServer *server)
++{
++    server->co_trip = qemu_coroutine_create(vu_client_trip, server);
++    aio_co_enter(server->ctx, server->co_trip);
++}
++
++/*
++ * a wrapper for vu_kick_cb
++ *
++ * since aio_dispatch can only pass one user data pointer to the
++ * callback function, pack VuDev and pvt into a struct. Then unpack it
++ * and pass them to vu_kick_cb
++ */
++static void kick_handler(void *opaque)
++{
++    VuFdWatch *vu_fd_watch = opaque;
++    vu_fd_watch->processing = true;
++    vu_fd_watch->cb(vu_fd_watch->vu_dev, 0, vu_fd_watch->pvt);
++    vu_fd_watch->processing = false;
++}
++
++
++static VuFdWatch *find_vu_fd_watch(VuServer *server, int fd)
++{
++
++    VuFdWatch *vu_fd_watch, *next;
++    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
++        if (vu_fd_watch->fd == fd) {
++            return vu_fd_watch;
++        }
++    }
++    return NULL;
++}
++
++static void
++set_watch(VuDev *vu_dev, int fd, int vu_evt,
++          vu_watch_cb cb, void *pvt)
++{
++
++    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
++    g_assert(vu_dev);
++    g_assert(fd >= 0);
++    g_assert(cb);
++
++    VuFdWatch *vu_fd_watch = find_vu_fd_watch(server, fd);
++
++    if (!vu_fd_watch) {
++        VuFdWatch *vu_fd_watch = g_new0(VuFdWatch, 1);
++
++        QTAILQ_INSERT_TAIL(&server->vu_fd_watches, vu_fd_watch, next);
++
++        vu_fd_watch->fd = fd;
++        vu_fd_watch->cb = cb;
++        qemu_set_nonblock(fd);
++        aio_set_fd_handler(server->ioc->ctx, fd, true, kick_handler,
++                           NULL, NULL, vu_fd_watch);
++        vu_fd_watch->vu_dev = vu_dev;
++        vu_fd_watch->pvt = pvt;
++    }
++}
++
++
++static void remove_watch(VuDev *vu_dev, int fd)
++{
++    VuServer *server;
++    g_assert(vu_dev);
++    g_assert(fd >= 0);
++
++    server = container_of(vu_dev, VuServer, vu_dev);
++
++    VuFdWatch *vu_fd_watch = find_vu_fd_watch(server, fd);
++
++    if (!vu_fd_watch) {
++        return;
++    }
++    aio_set_fd_handler(server->ioc->ctx, fd, true, NULL, NULL, NULL, NULL);
++
++    QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
++    g_free(vu_fd_watch);
++}
++
++
++static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
++                      gpointer opaque)
++{
++    VuServer *server = opaque;
++
++    if (server->sioc) {
++        warn_report("Only one vhost-user client is allowed to "
++                    "connect the server one time");
++        return;
++    }
++
++    if (!vu_init(&server->vu_dev, server->max_queues, sioc->fd, panic_cb,
++                 vu_message_read, set_watch, remove_watch, server->vu_iface)) {
++        error_report("Failed to initialize libvhost-user");
++        return;
++    }
++
++    /*
++     * Unset the callback function for network listener to make another
++     * vhost-user client keeping waiting until this client disconnects
++     */
++    qio_net_listener_set_client_func(server->listener,
++                                     NULL,
++                                     NULL,
++                                     NULL);
++    server->sioc = sioc;
++    /*
++     * Increase the object reference, so sioc will not freed by
++     * qio_net_listener_channel_func which will call object_unref(OBJECT(sioc))
++     */
++    object_ref(OBJECT(server->sioc));
++    qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
++    server->ioc = QIO_CHANNEL(sioc);
++    object_ref(OBJECT(server->ioc));
++    qio_channel_attach_aio_context(server->ioc, server->ctx);
++    qio_channel_set_blocking(QIO_CHANNEL(server->sioc), false, NULL);
++    vu_client_start(server);
++}
++
++
++void vhost_user_server_stop(VuServer *server)
++{
++    if (server->sioc) {
++        close_client(server);
++    }
++
++    if (server->listener) {
++        qio_net_listener_disconnect(server->listener);
++        object_unref(OBJECT(server->listener));
++    }
++
++}
++
++void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx)
++{
++    VuFdWatch *vu_fd_watch, *next;
++    void *opaque = NULL;
++    IOHandler *io_read = NULL;
++    bool attach;
++
++    server->ctx = ctx ? ctx : qemu_get_aio_context();
++
++    if (!server->sioc) {
++        /* not yet serving any client*/
++        return;
++    }
++
++    if (ctx) {
++        qio_channel_attach_aio_context(server->ioc, ctx);
++        server->aio_context_changed = true;
++        io_read = kick_handler;
++        attach = true;
++    } else {
++        qio_channel_detach_aio_context(server->ioc);
++        /* server->ioc->ctx keeps the old AioConext */
++        ctx = server->ioc->ctx;
++        attach = false;
++    }
++
++    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
++        if (vu_fd_watch->cb) {
++            opaque = attach ? vu_fd_watch : NULL;
++            aio_set_fd_handler(ctx, vu_fd_watch->fd, true,
++                               io_read, NULL, NULL,
++                               opaque);
++        }
++    }
++}
++
++
++bool vhost_user_server_start(VuServer *server,
++                             SocketAddress *socket_addr,
++                             AioContext *ctx,
++                             uint16_t max_queues,
++                             DevicePanicNotifierFn *device_panic_notifier,
++                             const VuDevIface *vu_iface,
++                             Error **errp)
++{
++    QIONetListener *listener = qio_net_listener_new();
++    if (qio_net_listener_open_sync(listener, socket_addr, 1,
++                                   errp) < 0) {
++        object_unref(OBJECT(listener));
++        return false;
++    }
++
++    /* zero out unspecified fileds */
++    *server = (VuServer) {
++        .listener              = listener,
++        .vu_iface              = vu_iface,
++        .max_queues            = max_queues,
++        .ctx                   = ctx,
++        .device_panic_notifier = device_panic_notifier,
++    };
++
++    qio_net_listener_set_name(server->listener, "vhost-user-backend-listener");
++
++    qio_net_listener_set_client_func(server->listener,
++                                     vu_accept,
++                                     server,
++                                     NULL);
++
++    QTAILQ_INIT(&server->vu_fd_watches);
++    return true;
++}
+diff --git a/util/meson.build b/util/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/util/meson.build
++++ b/util/meson.build
+@@ -XXX,XX +XXX,XX @@ if have_block
+   util_ss.add(files('main-loop.c'))
+   util_ss.add(files('nvdimm-utils.c'))
+   util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
++  util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
+   util_ss.add(files('qemu-coroutine-sleep.c'))
+   util_ss.add(files('qemu-co-shared-resource.c'))
+   util_ss.add(files('thread-pool.c', 'qemu-timer.c'))
+--
+.26.2

-[Qemu-devel] [PULL 7/8] docs: add Secure Coding Practices to developer docs
+[PULL v2 05/28] block: move logical block size check function to a common utility function
-At KVM Forum 2018 I gave a presentation on security in QEMU:
+From: Coiby Xu <coiby.xu@gmail.com>
 https://www.youtube.com/watch?v=YAdRf_hwxU8 (video)
 https://vmsplice.net/~stefan/stefanha-kvm-forum-2018.pdf (slides)
-This patch adds a guide to secure coding practices.  This document
+Move the constants from hw/core/qdev-properties.c to
-covers things that developers should know about security in QEMU.  It is
+util/block-helpers.h so that knowledge of the min/max values is
 just a starting point that we can expand on later.  I hope it will be
 useful as a resource for new contributors and will save code reviewers
 from explaining the same concepts many times.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
+Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
-Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
-Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
+Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
-Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
+Acked-by: Eduardo Habkost <ehabkost@redhat.com>
-Reviewed-by: Li Qiang <liq3ea@gmail.com>
+Message-id: 20200918080912.321299-5-coiby.xu@gmail.com
 Message-id: 20190509121820.16294-2-stefanha@redhat.com
 Message-Id: <20190509121820.16294-2-stefanha@redhat.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- docs/devel/index.rst                   |   1 +
+ util/block-helpers.h             | 19 +++++++++++++
- docs/devel/secure-coding-practices.rst | 106 +++++++++++++++++++++++++
+ hw/core/qdev-properties-system.c | 31 ++++-----------------
-files changed, 107 insertions(+)
+ util/block-helpers.c             | 46 ++++++++++++++++++++++++++++++++
- create mode 100644 docs/devel/secure-coding-practices.rst
+ util/meson.build                 |  1 +
 files changed, 71 insertions(+), 26 deletions(-)
  create mode 100644 util/block-helpers.h
  create mode 100644 util/block-helpers.c
-diff --git a/docs/devel/index.rst b/docs/devel/index.rst
+diff --git a/util/block-helpers.h b/util/block-helpers.h
 index XXXXXXX..XXXXXXX 100644
 --- a/docs/devel/index.rst
 +++ b/docs/devel/index.rst
@@ -XXX,XX +XXX,XX @@ Contents:
     stable-process
     testing
     decodetree
 +   secure-coding-practices
 diff --git a/docs/devel/secure-coding-practices.rst b/docs/devel/secure-coding-practices.rst
 new file mode 100644
 index XXXXXXX..XXXXXXX
 --- /dev/null
-+++ b/docs/devel/secure-coding-practices.rst
++++ b/util/block-helpers.h
 @@ -XXX,XX +XXX,XX @@
-+=======================
++#ifndef BLOCK_HELPERS_H
-+Secure Coding Practices
++#define BLOCK_HELPERS_H
 +=======================
 +This document covers topics that both developers and security researchers must
 +be aware of so that they can develop safe code and audit existing code
 +properly.
 +
-+Reporting Security Bugs
++#include "qemu/units.h"
 +-----------------------
 +For details on how to report security bugs or ask questions about potential
 +security bugs, see the `Security Process wiki page
 +<https://wiki.qemu.org/SecurityProcess>`_.
 +
-+General Secure C Coding Practices
++/* lower limit is sector size */
-+---------------------------------
++#define MIN_BLOCK_SIZE          INT64_C(512)
-+Most CVEs (security bugs) reported against QEMU are not specific to
++#define MIN_BLOCK_SIZE_STR      "512 B"
-+virtualization or emulation.  They are simply C programming bugs.  Therefore
++/*
-+it's critical to be aware of common classes of security bugs.
++ * upper limit is arbitrary, 2 MiB looks sufficient for all sensible uses, and
 + * matches qcow2 cluster size limit
 + */
 +#define MAX_BLOCK_SIZE          (2 * MiB)
 +#define MAX_BLOCK_SIZE_STR      "2 MiB"
 +
-+There is a wide selection of resources available covering secure C coding.  For
++void check_block_size(const char *id, const char *name, int64_t value,
-+example, the `CERT C Coding Standard
++                      Error **errp);
 +<https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard>`_
 +covers the most important classes of security bugs.
 +
-+Instead of describing them in detail here, only the names of the most important
++#endif /* BLOCK_HELPERS_H */
-+classes of security bugs are mentioned:
+diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
 index XXXXXXX..XXXXXXX 100644
 --- a/hw/core/qdev-properties-system.c
 +++ b/hw/core/qdev-properties-system.c
@@ -XXX,XX +XXX,XX @@
  #include "sysemu/blockdev.h"
  #include "net/net.h"
  #include "hw/pci/pci.h"
 +#include "util/block-helpers.h"
  static bool check_prop_still_unset(DeviceState *dev, const char *name,
                                     const void *old_val, const char *new_val,
@@ -XXX,XX +XXX,XX @@ const PropertyInfo qdev_prop_losttickpolicy = {
  /* --- blocksize --- */
 -/* lower limit is sector size */
 -#define MIN_BLOCK_SIZE          512
 -#define MIN_BLOCK_SIZE_STR      "512 B"
 -/*
 - * upper limit is arbitrary, 2 MiB looks sufficient for all sensible uses, and
 - * matches qcow2 cluster size limit
 - */
 -#define MAX_BLOCK_SIZE          (2 * MiB)
 -#define MAX_BLOCK_SIZE_STR      "2 MiB"
 -
  static void set_blocksize(Object *obj, Visitor *v, const char *name,
                            void *opaque, Error **errp)
  {
@@ -XXX,XX +XXX,XX @@ static void set_blocksize(Object *obj, Visitor *v, const char *name,
      Property *prop = opaque;
      uint32_t *ptr = qdev_get_prop_ptr(dev, prop);
      uint64_t value;
 +    Error *local_err = NULL;
      if (dev->realized) {
          qdev_prop_set_after_realize(dev, name, errp);
@@ -XXX,XX +XXX,XX @@ static void set_blocksize(Object *obj, Visitor *v, const char *name,
      if (!visit_type_size(v, name, &value, errp)) {
          return;
      }
 -    /* value of 0 means "unset" */
 -    if (value && (value < MIN_BLOCK_SIZE || value > MAX_BLOCK_SIZE)) {
 -        error_setg(errp,
 -                   "Property %s.%s doesn't take value %" PRIu64
 -                   " (minimum: " MIN_BLOCK_SIZE_STR
 -                   ", maximum: " MAX_BLOCK_SIZE_STR ")",
 -                   dev->id ? : "", name, value);
 +    check_block_size(dev->id ? : "", name, value, &local_err);
 +    if (local_err) {
 +        error_propagate(errp, local_err);
          return;
      }
 -
 -    /* We rely on power-of-2 blocksizes for bitmasks */
 -    if ((value & (value - 1)) != 0) {
 -        error_setg(errp,
 -                  "Property %s.%s doesn't take value '%" PRId64 "', "
 -                  "it's not a power of 2", dev->id ?: "", name, (int64_t)value);
 -        return;
 -    }
 -
      *ptr = value;
  }
 diff --git a/util/block-helpers.c b/util/block-helpers.c
 new file mode 100644
 index XXXXXXX..XXXXXXX
 --- /dev/null
 +++ b/util/block-helpers.c
@@ -XXX,XX +XXX,XX @@
 +/*
 + * Block utility functions
 + *
 + * Copyright IBM, Corp. 2011
 + * Copyright (c) 2020 Coiby Xu <coiby.xu@gmail.com>
 + *
 + * This work is licensed under the terms of the GNU GPL, version 2 or later.
 + * See the COPYING file in the top-level directory.
 + */
 +
-+* Buffer overflows
++#include "qemu/osdep.h"
-+* Use-after-free and double-free
++#include "qapi/error.h"
-+* Integer overflows
++#include "qapi/qmp/qerror.h"
-+* Format string vulnerabilities
++#include "block-helpers.h"
 +
-+Some of these classes of bugs can be detected by analyzers.  Static analysis is
++/**
-+performed regularly by Coverity and the most obvious of these bugs are even
++ * check_block_size:
-+reported by compilers.  Dynamic analysis is possible with valgrind, tsan, and
++ * @id: The unique ID of the object
-+asan.
++ * @name: The name of the property being validated
 + * @value: The block size in bytes
 + * @errp: A pointer to an area to store an error
 + *
 + * This function checks that the block size meets the following conditions:
 + * 1. At least MIN_BLOCK_SIZE
 + * 2. No larger than MAX_BLOCK_SIZE
 + * 3. A power of 2
 + */
 +void check_block_size(const char *id, const char *name, int64_t value,
 +                      Error **errp)
 +{
 +    /* value of 0 means "unset" */
 +    if (value && (value < MIN_BLOCK_SIZE || value > MAX_BLOCK_SIZE)) {
 +        error_setg(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
 +                   id, name, value, MIN_BLOCK_SIZE, MAX_BLOCK_SIZE);
 +        return;
 +    }
 +
-+Input Validation
++    /* We rely on power-of-2 blocksizes for bitmasks */
-+----------------
++    if ((value & (value - 1)) != 0) {
-+Inputs from the guest or external sources (e.g. network, files) cannot be
++        error_setg(errp,
-+trusted and may be invalid.  Inputs must be checked before using them in a way
++                   "Property %s.%s doesn't take value '%" PRId64
-+that could crash the program, expose host memory to the guest, or otherwise be
++                   "', it's not a power of 2",
-+exploitable by an attacker.
++                   id, name, value);
-+
++        return;
-+The most sensitive attack surface is device emulation.  All hardware register
++    }
-+accesses and data read from guest memory must be validated.  A typical example
++}
-+is a device that contains multiple units that are selectable by the guest via
+diff --git a/util/meson.build b/util/meson.build
-+an index register::
+index XXXXXXX..XXXXXXX 100644
-+
+--- a/util/meson.build
-+  typedef struct {
++++ b/util/meson.build
-+      ProcessingUnit unit[2];
+@@ -XXX,XX +XXX,XX @@ if have_block
-+      ...
+   util_ss.add(files('nvdimm-utils.c'))
-+  } MyDeviceState;
+   util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
-+
+   util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
-+  static void mydev_writel(void *opaque, uint32_t addr, uint32_t val)
++  util_ss.add(files('block-helpers.c'))
-+  {
+   util_ss.add(files('qemu-coroutine-sleep.c'))
-+      MyDeviceState *mydev = opaque;
+   util_ss.add(files('qemu-co-shared-resource.c'))
-+      ProcessingUnit *unit;
+   util_ss.add(files('thread-pool.c', 'qemu-timer.c'))
 +
 +      switch (addr) {
 +      case MYDEV_SELECT_UNIT:
 +          unit = &mydev->unit[val];   <-- this input wasn't validated!
 +          ...
 +      }
 +  }
 +
 +If ``val`` is not in range [0, 1] then an out-of-bounds memory access will take
 +place when ``unit`` is dereferenced.  The code must check that ``val`` is 0 or
 +1 and handle the case where it is invalid.
 +
 +Unexpected Device Accesses
 +--------------------------
 +The guest may access device registers in unusual orders or at unexpected
 +moments.  Device emulation code must not assume that the guest follows the
 +typical "theory of operation" presented in driver writer manuals.  The guest
 +may make nonsense accesses to device registers such as starting operations
 +before the device has been fully initialized.
 +
 +A related issue is that device emulation code must be prepared for unexpected
 +device register accesses while asynchronous operations are in progress.  A
 +well-behaved guest might wait for a completion interrupt before accessing
 +certain device registers.  Device emulation code must handle the case where the
 +guest overwrites registers or submits further requests before an ongoing
 +request completes.  Unexpected accesses must not cause memory corruption or
 +leaks in QEMU.
 +
 +Invalid device register accesses can be reported with
 +``qemu_log_mask(LOG_GUEST_ERROR, ...)``.  The ``-d guest_errors`` command-line
 +option enables these log messages.
 +
 +Live Migration
 +--------------
 +Device state can be saved to disk image files and shared with other users.
 +Live migration code must validate inputs when loading device state so an
 +attacker cannot gain control by crafting invalid device states.  Device state
 +is therefore considered untrusted even though it is typically generated by QEMU
 +itself.
 +
 +Guest Memory Access Races
 +-------------------------
 +Guests with multiple vCPUs may modify guest RAM while device emulation code is
 +running.  Device emulation code must copy in descriptors and other guest RAM
 +structures and only process the local copy.  This prevents
 +time-of-check-to-time-of-use (TOCTOU) race conditions that could cause QEMU to
 +crash when a vCPU thread modifies guest RAM while device emulation is
 +processing it.
 --
-.21.0
+.26.2

-New patch
+[PULL v2 06/28] block/export: vhost-user block device backend server
+From: Coiby Xu <coiby.xu@gmail.com>
+By making use of libvhost-user, block device drive can be shared to
+the connected vhost-user client. Only one client can connect to the
+server one time.
+Since vhost-user-server needs a block drive to be created first, delay
+the creation of this object.
+Suggested-by: Kevin Wolf <kwolf@redhat.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
+Message-id: 20200918080912.321299-6-coiby.xu@gmail.com
+[Shorten "vhost_user_blk_server" string to "vhost_user_blk" to avoid the
+following compiler warning:
+../block/export/vhost-user-blk-server.c:178:50: error: ‘%s’ directive output truncated writing 21 bytes into a region of size 20 [-Werror=format-truncation=]
+and fix "Invalid size %ld ..." ssize_t format string arguments for
+-bit hosts.
+--Stefan]
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ block/export/vhost-user-blk-server.h |  36 ++
+ block/export/vhost-user-blk-server.c | 661 +++++++++++++++++++++++++++
+ softmmu/vl.c                         |   4 +
+ block/meson.build                    |   1 +
+files changed, 702 insertions(+)
+ create mode 100644 block/export/vhost-user-blk-server.h
+ create mode 100644 block/export/vhost-user-blk-server.c
+diff --git a/block/export/vhost-user-blk-server.h b/block/export/vhost-user-blk-server.h
+new file mode 100644
+index XXXXXXX..XXXXXXX
+--- /dev/null
++++ b/block/export/vhost-user-blk-server.h
+@@ -XXX,XX +XXX,XX @@
++/*
++ * Sharing QEMU block devices via vhost-user protocal
++ *
++ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
++ * Copyright (c) 2020 Red Hat, Inc.
++ *
++ * This work is licensed under the terms of the GNU GPL, version 2 or
++ * later.  See the COPYING file in the top-level directory.
++ */
++
++#ifndef VHOST_USER_BLK_SERVER_H
++#define VHOST_USER_BLK_SERVER_H
++#include "util/vhost-user-server.h"
++
++typedef struct VuBlockDev VuBlockDev;
++#define TYPE_VHOST_USER_BLK_SERVER "vhost-user-blk-server"
++#define VHOST_USER_BLK_SERVER(obj) \
++   OBJECT_CHECK(VuBlockDev, obj, TYPE_VHOST_USER_BLK_SERVER)
++
++/* vhost user block device */
++struct VuBlockDev {
++    Object parent_obj;
++    char *node_name;
++    SocketAddress *addr;
++    AioContext *ctx;
++    VuServer vu_server;
++    bool running;
++    uint32_t blk_size;
++    BlockBackend *backend;
++    QIOChannelSocket *sioc;
++    QTAILQ_ENTRY(VuBlockDev) next;
++    struct virtio_blk_config blkcfg;
++    bool writable;
++};
++
++#endif /* VHOST_USER_BLK_SERVER_H */
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+new file mode 100644
+index XXXXXXX..XXXXXXX
+--- /dev/null
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@
++/*
++ * Sharing QEMU block devices via vhost-user protocal
++ *
++ * Parts of the code based on nbd/server.c.
++ *
++ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
++ * Copyright (c) 2020 Red Hat, Inc.
++ *
++ * This work is licensed under the terms of the GNU GPL, version 2 or
++ * later.  See the COPYING file in the top-level directory.
++ */
++#include "qemu/osdep.h"
++#include "block/block.h"
++#include "vhost-user-blk-server.h"
++#include "qapi/error.h"
++#include "qom/object_interfaces.h"
++#include "sysemu/block-backend.h"
++#include "util/block-helpers.h"
++
++enum {
++    VHOST_USER_BLK_MAX_QUEUES = 1,
++};
++struct virtio_blk_inhdr {
++    unsigned char status;
++};
++
++typedef struct VuBlockReq {
++    VuVirtqElement *elem;
++    int64_t sector_num;
++    size_t size;
++    struct virtio_blk_inhdr *in;
++    struct virtio_blk_outhdr out;
++    VuServer *server;
++    struct VuVirtq *vq;
++} VuBlockReq;
++
++static void vu_block_req_complete(VuBlockReq *req)
++{
++    VuDev *vu_dev = &req->server->vu_dev;
++
++    /* IO size with 1 extra status byte */
++    vu_queue_push(vu_dev, req->vq, req->elem, req->size + 1);
++    vu_queue_notify(vu_dev, req->vq);
++
++    if (req->elem) {
++        free(req->elem);
++    }
++
++    g_free(req);
++}
++
++static VuBlockDev *get_vu_block_device_by_server(VuServer *server)
++{
++    return container_of(server, VuBlockDev, vu_server);
++}
++
++static int coroutine_fn
++vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
++                              uint32_t iovcnt, uint32_t type)
++{
++    struct virtio_blk_discard_write_zeroes desc;
++    ssize_t size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc));
++    if (unlikely(size != sizeof(desc))) {
++        error_report("Invalid size %zd, expect %zu", size, sizeof(desc));
++        return -EINVAL;
++    }
++
++    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
++    uint64_t range[2] = { le64_to_cpu(desc.sector) << 9,
++                          le32_to_cpu(desc.num_sectors) << 9 };
++    if (type == VIRTIO_BLK_T_DISCARD) {
++        if (blk_co_pdiscard(vdev_blk->backend, range[0], range[1]) == 0) {
++            return 0;
++        }
++    } else if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
++        if (blk_co_pwrite_zeroes(vdev_blk->backend,
++                                 range[0], range[1], 0) == 0) {
++            return 0;
++        }
++    }
++
++    return -EINVAL;
++}
++
++static void coroutine_fn vu_block_flush(VuBlockReq *req)
++{
++    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
++    BlockBackend *backend = vdev_blk->backend;
++    blk_co_flush(backend);
++}
++
++struct req_data {
++    VuServer *server;
++    VuVirtq *vq;
++    VuVirtqElement *elem;
++};
++
++static void coroutine_fn vu_block_virtio_process_req(void *opaque)
++{
++    struct req_data *data = opaque;
++    VuServer *server = data->server;
++    VuVirtq *vq = data->vq;
++    VuVirtqElement *elem = data->elem;
++    uint32_t type;
++    VuBlockReq *req;
++
++    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
++    BlockBackend *backend = vdev_blk->backend;
++
++    struct iovec *in_iov = elem->in_sg;
++    struct iovec *out_iov = elem->out_sg;
++    unsigned in_num = elem->in_num;
++    unsigned out_num = elem->out_num;
++    /* refer to hw/block/virtio_blk.c */
++    if (elem->out_num < 1 || elem->in_num < 1) {
++        error_report("virtio-blk request missing headers");
++        free(elem);
++        return;
++    }
++
++    req = g_new0(VuBlockReq, 1);
++    req->server = server;
++    req->vq = vq;
++    req->elem = elem;
++
++    if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
++                            sizeof(req->out)) != sizeof(req->out))) {
++        error_report("virtio-blk request outhdr too short");
++        goto err;
++    }
++
++    iov_discard_front(&out_iov, &out_num, sizeof(req->out));
++
++    if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
++        error_report("virtio-blk request inhdr too short");
++        goto err;
++    }
++
++    /* We always touch the last byte, so just see how big in_iov is.  */
++    req->in = (void *)in_iov[in_num - 1].iov_base
++              + in_iov[in_num - 1].iov_len
++              - sizeof(struct virtio_blk_inhdr);
++    iov_discard_back(in_iov, &in_num, sizeof(struct virtio_blk_inhdr));
++
++    type = le32_to_cpu(req->out.type);
++    switch (type & ~VIRTIO_BLK_T_BARRIER) {
++    case VIRTIO_BLK_T_IN:
++    case VIRTIO_BLK_T_OUT: {
++        ssize_t ret = 0;
++        bool is_write = type & VIRTIO_BLK_T_OUT;
++        req->sector_num = le64_to_cpu(req->out.sector);
++
++        int64_t offset = req->sector_num * vdev_blk->blk_size;
++        QEMUIOVector qiov;
++        if (is_write) {
++            qemu_iovec_init_external(&qiov, out_iov, out_num);
++            ret = blk_co_pwritev(backend, offset, qiov.size,
++                                 &qiov, 0);
++        } else {
++            qemu_iovec_init_external(&qiov, in_iov, in_num);
++            ret = blk_co_preadv(backend, offset, qiov.size,
++                                &qiov, 0);
++        }
++        if (ret >= 0) {
++            req->in->status = VIRTIO_BLK_S_OK;
++        } else {
++            req->in->status = VIRTIO_BLK_S_IOERR;
++        }
++        break;
++    }
++    case VIRTIO_BLK_T_FLUSH:
++        vu_block_flush(req);
++        req->in->status = VIRTIO_BLK_S_OK;
++        break;
++    case VIRTIO_BLK_T_GET_ID: {
++        size_t size = MIN(iov_size(&elem->in_sg[0], in_num),
++                          VIRTIO_BLK_ID_BYTES);
++        snprintf(elem->in_sg[0].iov_base, size, "%s", "vhost_user_blk");
++        req->in->status = VIRTIO_BLK_S_OK;
++        req->size = elem->in_sg[0].iov_len;
++        break;
++    }
++    case VIRTIO_BLK_T_DISCARD:
++    case VIRTIO_BLK_T_WRITE_ZEROES: {
++        int rc;
++        rc = vu_block_discard_write_zeroes(req, &elem->out_sg[1],
++                                           out_num, type);
++        if (rc == 0) {
++            req->in->status = VIRTIO_BLK_S_OK;
++        } else {
++            req->in->status = VIRTIO_BLK_S_IOERR;
++        }
++        break;
++    }
++    default:
++        req->in->status = VIRTIO_BLK_S_UNSUPP;
++        break;
++    }
++
++    vu_block_req_complete(req);
++    return;
++
++err:
++    free(elem);
++    g_free(req);
++    return;
++}
++
++static void vu_block_process_vq(VuDev *vu_dev, int idx)
++{
++    VuServer *server;
++    VuVirtq *vq;
++    struct req_data *req_data;
++
++    server = container_of(vu_dev, VuServer, vu_dev);
++    assert(server);
++
++    vq = vu_get_queue(vu_dev, idx);
++    assert(vq);
++    VuVirtqElement *elem;
++    while (1) {
++        elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) +
++                                    sizeof(VuBlockReq));
++        if (elem) {
++            req_data = g_new0(struct req_data, 1);
++            req_data->server = server;
++            req_data->vq = vq;
++            req_data->elem = elem;
++            Coroutine *co = qemu_coroutine_create(vu_block_virtio_process_req,
++                                                  req_data);
++            aio_co_enter(server->ioc->ctx, co);
++        } else {
++            break;
++        }
++    }
++}
++
++static void vu_block_queue_set_started(VuDev *vu_dev, int idx, bool started)
++{
++    VuVirtq *vq;
++
++    assert(vu_dev);
++
++    vq = vu_get_queue(vu_dev, idx);
++    vu_set_queue_handler(vu_dev, vq, started ? vu_block_process_vq : NULL);
++}
++
++static uint64_t vu_block_get_features(VuDev *dev)
++{
++    uint64_t features;
++    VuServer *server = container_of(dev, VuServer, vu_dev);
++    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
++    features = 1ull << VIRTIO_BLK_F_SIZE_MAX |
++               1ull << VIRTIO_BLK_F_SEG_MAX |
++               1ull << VIRTIO_BLK_F_TOPOLOGY |
++               1ull << VIRTIO_BLK_F_BLK_SIZE |
++               1ull << VIRTIO_BLK_F_FLUSH |
++               1ull << VIRTIO_BLK_F_DISCARD |
++               1ull << VIRTIO_BLK_F_WRITE_ZEROES |
++               1ull << VIRTIO_BLK_F_CONFIG_WCE |
++               1ull << VIRTIO_F_VERSION_1 |
++               1ull << VIRTIO_RING_F_INDIRECT_DESC |
++               1ull << VIRTIO_RING_F_EVENT_IDX |
++               1ull << VHOST_USER_F_PROTOCOL_FEATURES;
++
++    if (!vdev_blk->writable) {
++        features |= 1ull << VIRTIO_BLK_F_RO;
++    }
++
++    return features;
++}
++
++static uint64_t vu_block_get_protocol_features(VuDev *dev)
++{
++    return 1ull << VHOST_USER_PROTOCOL_F_CONFIG |
++           1ull << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD;
++}
++
++static int
++vu_block_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
++{
++    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
++    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
++    memcpy(config, &vdev_blk->blkcfg, len);
++
++    return 0;
++}
++
++static int
++vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
++                    uint32_t offset, uint32_t size, uint32_t flags)
++{
++    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
++    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
++    uint8_t wce;
++
++    /* don't support live migration */
++    if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
++        return -EINVAL;
++    }
++
++    if (offset != offsetof(struct virtio_blk_config, wce) ||
++        size != 1) {
++        return -EINVAL;
++    }
++
++    wce = *data;
++    vdev_blk->blkcfg.wce = wce;
++    blk_set_enable_write_cache(vdev_blk->backend, wce);
++    return 0;
++}
++
++/*
++ * When the client disconnects, it sends a VHOST_USER_NONE request
++ * and vu_process_message will simple call exit which cause the VM
++ * to exit abruptly.
++ * To avoid this issue,  process VHOST_USER_NONE request ahead
++ * of vu_process_message.
++ *
++ */
++static int vu_block_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
++{
++    if (vmsg->request == VHOST_USER_NONE) {
++        dev->panic(dev, "disconnect");
++        return true;
++    }
++    return false;
++}
++
++static const VuDevIface vu_block_iface = {
++    .get_features          = vu_block_get_features,
++    .queue_set_started     = vu_block_queue_set_started,
++    .get_protocol_features = vu_block_get_protocol_features,
++    .get_config            = vu_block_get_config,
++    .set_config            = vu_block_set_config,
++    .process_msg           = vu_block_process_msg,
++};
++
++static void blk_aio_attached(AioContext *ctx, void *opaque)
++{
++    VuBlockDev *vub_dev = opaque;
++    aio_context_acquire(ctx);
++    vhost_user_server_set_aio_context(&vub_dev->vu_server, ctx);
++    aio_context_release(ctx);
++}
++
++static void blk_aio_detach(void *opaque)
++{
++    VuBlockDev *vub_dev = opaque;
++    AioContext *ctx = vub_dev->vu_server.ctx;
++    aio_context_acquire(ctx);
++    vhost_user_server_set_aio_context(&vub_dev->vu_server, NULL);
++    aio_context_release(ctx);
++}
++
++static void
++vu_block_initialize_config(BlockDriverState *bs,
++                           struct virtio_blk_config *config, uint32_t blk_size)
++{
++    config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
++    config->blk_size = blk_size;
++    config->size_max = 0;
++    config->seg_max = 128 - 2;
++    config->min_io_size = 1;
++    config->opt_io_size = 1;
++    config->num_queues = VHOST_USER_BLK_MAX_QUEUES;
++    config->max_discard_sectors = 32768;
++    config->max_discard_seg = 1;
++    config->discard_sector_alignment = config->blk_size >> 9;
++    config->max_write_zeroes_sectors = 32768;
++    config->max_write_zeroes_seg = 1;
++}
++
++static VuBlockDev *vu_block_init(VuBlockDev *vu_block_device, Error **errp)
++{
++
++    BlockBackend *blk;
++    Error *local_error = NULL;
++    const char *node_name = vu_block_device->node_name;
++    bool writable = vu_block_device->writable;
++    uint64_t perm = BLK_PERM_CONSISTENT_READ;
++    int ret;
++
++    AioContext *ctx;
++
++    BlockDriverState *bs = bdrv_lookup_bs(node_name, node_name, &local_error);
++
++    if (!bs) {
++        error_propagate(errp, local_error);
++        return NULL;
++    }
++
++    if (bdrv_is_read_only(bs)) {
++        writable = false;
++    }
++
++    if (writable) {
++        perm |= BLK_PERM_WRITE;
++    }
++
++    ctx = bdrv_get_aio_context(bs);
++    aio_context_acquire(ctx);
++    bdrv_invalidate_cache(bs, NULL);
++    aio_context_release(ctx);
++
++    /*
++     * Don't allow resize while the vhost user server is running,
++     * otherwise we don't care what happens with the node.
++     */
++    blk = blk_new(bdrv_get_aio_context(bs), perm,
++                  BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
++                  BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
++    ret = blk_insert_bs(blk, bs, errp);
++
++    if (ret < 0) {
++        goto fail;
++    }
++
++    blk_set_enable_write_cache(blk, false);
++
++    blk_set_allow_aio_context_change(blk, true);
++
++    vu_block_device->blkcfg.wce = 0;
++    vu_block_device->backend = blk;
++    if (!vu_block_device->blk_size) {
++        vu_block_device->blk_size = BDRV_SECTOR_SIZE;
++    }
++    vu_block_device->blkcfg.blk_size = vu_block_device->blk_size;
++    blk_set_guest_block_size(blk, vu_block_device->blk_size);
++    vu_block_initialize_config(bs, &vu_block_device->blkcfg,
++                                   vu_block_device->blk_size);
++    return vu_block_device;
++
++fail:
++    blk_unref(blk);
++    return NULL;
++}
++
++static void vu_block_deinit(VuBlockDev *vu_block_device)
++{
++    if (vu_block_device->backend) {
++        blk_remove_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
++                                        blk_aio_detach, vu_block_device);
++    }
++
++    blk_unref(vu_block_device->backend);
++}
++
++static void vhost_user_blk_server_stop(VuBlockDev *vu_block_device)
++{
++    vhost_user_server_stop(&vu_block_device->vu_server);
++    vu_block_deinit(vu_block_device);
++}
++
++static void vhost_user_blk_server_start(VuBlockDev *vu_block_device,
++                                        Error **errp)
++{
++    AioContext *ctx;
++    SocketAddress *addr = vu_block_device->addr;
++
++    if (!vu_block_init(vu_block_device, errp)) {
++        return;
++    }
++
++    ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));
++
++    if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx,
++                                 VHOST_USER_BLK_MAX_QUEUES,
++                                 NULL, &vu_block_iface,
++                                 errp)) {
++        goto error;
++    }
++
++    blk_add_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
++                                 blk_aio_detach, vu_block_device);
++    vu_block_device->running = true;
++    return;
++
++ error:
++    vu_block_deinit(vu_block_device);
++}
++
++static bool vu_prop_modifiable(VuBlockDev *vus, Error **errp)
++{
++    if (vus->running) {
++            error_setg(errp, "The property can't be modified "
++                       "while the server is running");
++            return false;
++    }
++    return true;
++}
++
++static void vu_set_node_name(Object *obj, const char *value, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++
++    if (!vu_prop_modifiable(vus, errp)) {
++        return;
++    }
++
++    if (vus->node_name) {
++        g_free(vus->node_name);
++    }
++
++    vus->node_name = g_strdup(value);
++}
++
++static char *vu_get_node_name(Object *obj, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++    return g_strdup(vus->node_name);
++}
++
++static void free_socket_addr(SocketAddress *addr)
++{
++        g_free(addr->u.q_unix.path);
++        g_free(addr);
++}
++
++static void vu_set_unix_socket(Object *obj, const char *value,
++                               Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++
++    if (!vu_prop_modifiable(vus, errp)) {
++        return;
++    }
++
++    if (vus->addr) {
++        free_socket_addr(vus->addr);
++    }
++
++    SocketAddress *addr = g_new0(SocketAddress, 1);
++    addr->type = SOCKET_ADDRESS_TYPE_UNIX;
++    addr->u.q_unix.path = g_strdup(value);
++    vus->addr = addr;
++}
++
++static char *vu_get_unix_socket(Object *obj, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++    return g_strdup(vus->addr->u.q_unix.path);
++}
++
++static bool vu_get_block_writable(Object *obj, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++    return vus->writable;
++}
++
++static void vu_set_block_writable(Object *obj, bool value, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++
++    if (!vu_prop_modifiable(vus, errp)) {
++            return;
++    }
++
++    vus->writable = value;
++}
++
++static void vu_get_blk_size(Object *obj, Visitor *v, const char *name,
++                            void *opaque, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++    uint32_t value = vus->blk_size;
++
++    visit_type_uint32(v, name, &value, errp);
++}
++
++static void vu_set_blk_size(Object *obj, Visitor *v, const char *name,
++                            void *opaque, Error **errp)
++{
++    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
++
++    Error *local_err = NULL;
++    uint32_t value;
++
++    if (!vu_prop_modifiable(vus, errp)) {
++            return;
++    }
++
++    visit_type_uint32(v, name, &value, &local_err);
++    if (local_err) {
++        goto out;
++    }
++
++    check_block_size(object_get_typename(obj), name, value, &local_err);
++    if (local_err) {
++        goto out;
++    }
++
++    vus->blk_size = value;
++
++out:
++    error_propagate(errp, local_err);
++}
++
++static void vhost_user_blk_server_instance_finalize(Object *obj)
++{
++    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
++
++    vhost_user_blk_server_stop(vub);
++
++    /*
++     * Unlike object_property_add_str, object_class_property_add_str
++     * doesn't have a release method. Thus manual memory freeing is
++     * needed.
++     */
++    free_socket_addr(vub->addr);
++    g_free(vub->node_name);
++}
++
++static void vhost_user_blk_server_complete(UserCreatable *obj, Error **errp)
++{
++    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
++
++    vhost_user_blk_server_start(vub, errp);
++}
++
++static void vhost_user_blk_server_class_init(ObjectClass *klass,
++                                             void *class_data)
++{
++    UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
++    ucc->complete = vhost_user_blk_server_complete;
++
++    object_class_property_add_bool(klass, "writable",
++                                   vu_get_block_writable,
++                                   vu_set_block_writable);
++
++    object_class_property_add_str(klass, "node-name",
++                                  vu_get_node_name,
++                                  vu_set_node_name);
++
++    object_class_property_add_str(klass, "unix-socket",
++                                  vu_get_unix_socket,
++                                  vu_set_unix_socket);
++
++    object_class_property_add(klass, "logical-block-size", "uint32",
++                              vu_get_blk_size, vu_set_blk_size,
++                              NULL, NULL);
++}
++
++static const TypeInfo vhost_user_blk_server_info = {
++    .name = TYPE_VHOST_USER_BLK_SERVER,
++    .parent = TYPE_OBJECT,
++    .instance_size = sizeof(VuBlockDev),
++    .instance_finalize = vhost_user_blk_server_instance_finalize,
++    .class_init = vhost_user_blk_server_class_init,
++    .interfaces = (InterfaceInfo[]) {
++        {TYPE_USER_CREATABLE},
++        {}
++    },
++};
++
++static void vhost_user_blk_server_register_types(void)
++{
++    type_register_static(&vhost_user_blk_server_info);
++}
++
++type_init(vhost_user_blk_server_register_types)
+diff --git a/softmmu/vl.c b/softmmu/vl.c
+index XXXXXXX..XXXXXXX 100644
+--- a/softmmu/vl.c
++++ b/softmmu/vl.c
+@@ -XXX,XX +XXX,XX @@ static bool object_create_initial(const char *type, QemuOpts *opts)
+     }
+ #endif
++    /* Reason: vhost-user-blk-server property "node-name" */
++    if (g_str_equal(type, "vhost-user-blk-server")) {
++        return false;
++    }
+     /*
+      * Reason: filter-* property "netdev" etc.
+      */
+diff --git a/block/meson.build b/block/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/block/meson.build
++++ b/block/meson.build
+@@ -XXX,XX +XXX,XX @@ block_ss.add(when: 'CONFIG_WIN32', if_true: files('file-win32.c', 'win32-aio.c')
+ block_ss.add(when: 'CONFIG_POSIX', if_true: [files('file-posix.c'), coref, iokit])
+ block_ss.add(when: 'CONFIG_LIBISCSI', if_true: files('iscsi-opts.c'))
+ block_ss.add(when: 'CONFIG_LINUX', if_true: files('nvme.c'))
++block_ss.add(when: 'CONFIG_LINUX', if_true: files('export/vhost-user-blk-server.c', '../contrib/libvhost-user/libvhost-user.c'))
+ block_ss.add(when: 'CONFIG_REPLICATION', if_true: files('replication.c'))
+ block_ss.add(when: 'CONFIG_SHEEPDOG', if_true: files('sheepdog.c'))
+ block_ss.add(when: ['CONFIG_LINUX_AIO', libaio], if_true: files('linux-aio.c'))
+--
+.26.2

-New patch
+[PULL v2 07/28] MAINTAINERS: Add vhost-user block device backend server maintainer
+From: Coiby Xu <coiby.xu@gmail.com>
+Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
+Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
+Message-id: 20200918080912.321299-8-coiby.xu@gmail.com
+[Removed reference to vhost-user-blk-test.c, it will be sent in a
+separate pull request.
+--Stefan]
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ MAINTAINERS | 7 +++++++
+file changed, 7 insertions(+)
+diff --git a/MAINTAINERS b/MAINTAINERS
+index XXXXXXX..XXXXXXX 100644
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -XXX,XX +XXX,XX @@ L: qemu-block@nongnu.org
+ S: Supported
+ F: tests/image-fuzzer/
++Vhost-user block device backend server
++M: Coiby Xu <Coiby.Xu@gmail.com>
++S: Maintained
++F: block/export/vhost-user-blk-server.c
++F: util/vhost-user-server.c
++F: tests/qtest/libqos/vhost-user-blk.c
++
+ Replication
+ M: Wen Congyang <wencongyang2@huawei.com>
+ M: Xie Changlong <xiechanglong.d@gmail.com>
+--
+.26.2

-New patch
+[PULL v2 08/28] util/vhost-user-server: s/fileds/fields/ typo fix
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-3-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ util/vhost-user-server.c | 2 +-
+file changed, 1 insertion(+), 1 deletion(-)
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.c
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+         return false;
+     }
+-    /* zero out unspecified fileds */
++    /* zero out unspecified fields */
+     *server = (VuServer) {
+         .listener              = listener,
+         .vu_iface              = vu_iface,
+--
+.26.2

-[Qemu-devel] [PULL 4/8] block: Add coroutine_fn to bdrv_check_co_entry
+[PULL v2 09/28] util/vhost-user-server: drop unnecessary QOM cast
-From: Nikita Alekseev <n.alekseev2104@gmail.com>
+We already have access to the value with the correct type (ioc and sioc
 are the same QIOChannel).
-bdrv_check_co_entry calls bdrv_co_check, which is a coroutine function.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Thus, it also needs to be marked as a coroutine.
+Message-id: 20200924151549.913737-4-stefanha@redhat.com
 Signed-off-by: Nikita Alekseev <n.alekseev2104@gmail.com>
 Message-id: 20190401093051.16488-1-n.alekseev2104@gmail.com
 Message-Id: <20190401093051.16488-1-n.alekseev2104@gmail.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- block.c | 2 +-
+ util/vhost-user-server.c | 2 +-
 file changed, 1 insertion(+), 1 deletion(-)
-diff --git a/block.c b/block.c
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
 index XXXXXXX..XXXXXXX 100644
---- a/block.c
+--- a/util/vhost-user-server.c
-+++ b/block.c
++++ b/util/vhost-user-server.c
-@@ -XXX,XX +XXX,XX @@ typedef struct CheckCo {
+@@ -XXX,XX +XXX,XX @@ static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
-     int ret;
+     server->ioc = QIO_CHANNEL(sioc);
- } CheckCo;
+     object_ref(OBJECT(server->ioc));
+     qio_channel_attach_aio_context(server->ioc, server->ctx);
--static void bdrv_check_co_entry(void *opaque)
+-    qio_channel_set_blocking(QIO_CHANNEL(server->sioc), false, NULL);
-+static void coroutine_fn bdrv_check_co_entry(void *opaque)
++    qio_channel_set_blocking(server->ioc, false, NULL);
- {
+     vu_client_start(server);
-     CheckCo *cco = opaque;
+ }
-     cco->ret = bdrv_co_check(cco->bs, cco->res, cco->fix);
 --
-.21.0
+.26.2

-New patch
+[PULL v2 10/28] util/vhost-user-server: drop unnecessary watch deletion
+Explicitly deleting watches is not necessary since libvhost-user calls
+remove_watch() during vu_deinit(). Add an assertion to check this
+though.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-5-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ util/vhost-user-server.c | 19 ++++---------------
+file changed, 4 insertions(+), 15 deletions(-)
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.c
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@ static void close_client(VuServer *server)
+     /* When this is set vu_client_trip will stop new processing vhost-user message */
+     server->sioc = NULL;
+-    VuFdWatch *vu_fd_watch, *next;
+-    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+-        aio_set_fd_handler(server->ioc->ctx, vu_fd_watch->fd, true, NULL,
+-                           NULL, NULL, NULL);
+-    }
+-
+-    while (!QTAILQ_EMPTY(&server->vu_fd_watches)) {
+-        QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+-            if (!vu_fd_watch->processing) {
+-                QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
+-                g_free(vu_fd_watch);
+-            }
+-        }
+-    }
+-
+     while (server->processing_msg) {
+         if (server->ioc->read_coroutine) {
+             server->ioc->read_coroutine = NULL;
+@@ -XXX,XX +XXX,XX @@ static void close_client(VuServer *server)
+     }
+     vu_deinit(&server->vu_dev);
++
++    /* vu_deinit() should have called remove_watch() */
++    assert(QTAILQ_EMPTY(&server->vu_fd_watches));
++
+     object_unref(OBJECT(sioc));
+     object_unref(OBJECT(server->ioc));
+ }
+--
+.26.2

-[Qemu-devel] [PULL 2/8] util: readline: replace tab indent by four spaces to fix checkpatch errors
+[PULL v2 11/28] block/export: consolidate request structs into VuBlockReq
-From: Jules Irenge <jbi.octave@gmail.com>
+Only one struct is needed per request. Drop req_data and the separate
 VuBlockReq instance. Instead let vu_queue_pop() allocate everything at
 once.
-Replace tab indent by four spaces to fix errors issued by checkpatch.pl tool
+This fixes the req_data memory leak in vu_block_virtio_process_req().
 "ERROR: code indent should never use tabs" within "util/readline.c" file.
-Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Reviewed-by: Thomas Huth <thuth@redhat.com>
+Message-id: 20200924151549.913737-6-stefanha@redhat.com
 Message-id: 20190401024406.10819-3-jbi.octave@gmail.com
 Message-Id: <20190401024406.10819-3-jbi.octave@gmail.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- util/readline.c | 98 ++++++++++++++++++++++++-------------------------
+ block/export/vhost-user-blk-server.c | 68 +++++++++-------------------
-file changed, 49 insertions(+), 49 deletions(-)
+file changed, 21 insertions(+), 47 deletions(-)
-diff --git a/util/readline.c b/util/readline.c
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
 index XXXXXXX..XXXXXXX 100644
---- a/util/readline.c
+--- a/block/export/vhost-user-blk-server.c
-+++ b/util/readline.c
++++ b/block/export/vhost-user-blk-server.c
-@@ -XXX,XX +XXX,XX @@ static void readline_up_char(ReadLineState *rs)
+@@ -XXX,XX +XXX,XX @@ struct virtio_blk_inhdr {
-     int idx;
+ };
-     if (rs->hist_entry == 0)
+ typedef struct VuBlockReq {
--    return;
+-    VuVirtqElement *elem;
-+        return;
++    VuVirtqElement elem;
-     if (rs->hist_entry == -1) {
+     int64_t sector_num;
--    /* Find latest entry */
+     size_t size;
--    for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
+     struct virtio_blk_inhdr *in;
--        if (rs->history[idx] == NULL)
+@@ -XXX,XX +XXX,XX @@ static void vu_block_req_complete(VuBlockReq *req)
--        break;
+     VuDev *vu_dev = &req->server->vu_dev;
--    }
--    rs->hist_entry = idx;
+     /* IO size with 1 extra status byte */
-+        /* Find latest entry */
+-    vu_queue_push(vu_dev, req->vq, req->elem, req->size + 1);
-+        for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
++    vu_queue_push(vu_dev, req->vq, &req->elem, req->size + 1);
-+            if (rs->history[idx] == NULL)
+     vu_queue_notify(vu_dev, req->vq);
-+                break;
-+        }
+-    if (req->elem) {
-+        rs->hist_entry = idx;
+-        free(req->elem);
 -    }
 -
 -    g_free(req);
 +    free(req);
  }
  static VuBlockDev *get_vu_block_device_by_server(VuServer *server)
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_flush(VuBlockReq *req)
      blk_co_flush(backend);
  }
 -struct req_data {
 -    VuServer *server;
 -    VuVirtq *vq;
 -    VuVirtqElement *elem;
 -};
 -
  static void coroutine_fn vu_block_virtio_process_req(void *opaque)
  {
 -    struct req_data *data = opaque;
 -    VuServer *server = data->server;
 -    VuVirtq *vq = data->vq;
 -    VuVirtqElement *elem = data->elem;
 +    VuBlockReq *req = opaque;
 +    VuServer *server = req->server;
 +    VuVirtqElement *elem = &req->elem;
      uint32_t type;
 -    VuBlockReq *req;
      VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
      BlockBackend *backend = vdev_blk->backend;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
      struct iovec *out_iov = elem->out_sg;
      unsigned in_num = elem->in_num;
      unsigned out_num = elem->out_num;
 +
      /* refer to hw/block/virtio_blk.c */
      if (elem->out_num < 1 || elem->in_num < 1) {
          error_report("virtio-blk request missing headers");
 -        free(elem);
 -        return;
 +        goto err;
      }
-     rs->hist_entry--;
-     if (rs->hist_entry >= 0) {
+-    req = g_new0(VuBlockReq, 1);
--    pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
+-    req->server = server;
-+        pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
+-    req->vq = vq;
-                 rs->history[rs->hist_entry]);
+-    req->elem = elem;
--    rs->cmd_buf_index = rs->cmd_buf_size = strlen(rs->cmd_buf);
+-
-+        rs->cmd_buf_index = rs->cmd_buf_size = strlen(rs->cmd_buf);
+     if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
                              sizeof(req->out)) != sizeof(req->out))) {
          error_report("virtio-blk request outhdr too short");
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
  err:
      free(elem);
 -    g_free(req);
 -    return;
  }
  static void vu_block_process_vq(VuDev *vu_dev, int idx)
  {
 -    VuServer *server;
 -    VuVirtq *vq;
 -    struct req_data *req_data;
 +    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
 +    VuVirtq *vq = vu_get_queue(vu_dev, idx);
 -    server = container_of(vu_dev, VuServer, vu_dev);
 -    assert(server);
 -
 -    vq = vu_get_queue(vu_dev, idx);
 -    assert(vq);
 -    VuVirtqElement *elem;
      while (1) {
 -        elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) +
 -                                    sizeof(VuBlockReq));
 -        if (elem) {
 -            req_data = g_new0(struct req_data, 1);
 -            req_data->server = server;
 -            req_data->vq = vq;
 -            req_data->elem = elem;
 -            Coroutine *co = qemu_coroutine_create(vu_block_virtio_process_req,
 -                                                  req_data);
 -            aio_co_enter(server->ioc->ctx, co);
 -        } else {
 +        VuBlockReq *req;
 +
 +        req = vu_queue_pop(vu_dev, vq, sizeof(VuBlockReq));
 +        if (!req) {
              break;
          }
 +
 +        req->server = server;
 +        req->vq = vq;
 +
 +        Coroutine *co =
 +            qemu_coroutine_create(vu_block_virtio_process_req, req);
 +        qemu_coroutine_enter(co);
      }
  }
-@@ -XXX,XX +XXX,XX @@ static void readline_down_char(ReadLineState *rs)
-         return;
-     if (rs->hist_entry < READLINE_MAX_CMDS - 1 &&
-         rs->history[++rs->hist_entry] != NULL) {
--    pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
-+        pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
-                 rs->history[rs->hist_entry]);
-     } else {
-         rs->cmd_buf[0] = 0;
--    rs->hist_entry = -1;
-+        rs->hist_entry = -1;
-     }
-     rs->cmd_buf_index = rs->cmd_buf_size = strlen(rs->cmd_buf);
- }
-@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
-     int idx;
-     if (cmdline[0] == '\0')
--    return;
-+        return;
-     new_entry = NULL;
-     if (rs->hist_entry != -1) {
--    /* We were editing an existing history entry: replace it */
--    hist_entry = rs->history[rs->hist_entry];
--    idx = rs->hist_entry;
--    if (strcmp(hist_entry, cmdline) == 0) {
--        goto same_entry;
--    }
-+        /* We were editing an existing history entry: replace it */
-+        hist_entry = rs->history[rs->hist_entry];
-+        idx = rs->hist_entry;
-+        if (strcmp(hist_entry, cmdline) == 0) {
-+            goto same_entry;
-+        }
-     }
-     /* Search cmdline in history buffers */
-     for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
--    hist_entry = rs->history[idx];
--    if (hist_entry == NULL)
--        break;
--    if (strcmp(hist_entry, cmdline) == 0) {
--    same_entry:
--        new_entry = hist_entry;
--        /* Put this entry at the end of history */
--        memmove(&rs->history[idx], &rs->history[idx + 1],
--            (READLINE_MAX_CMDS - (idx + 1)) * sizeof(char *));
--        rs->history[READLINE_MAX_CMDS - 1] = NULL;
--        for (; idx < READLINE_MAX_CMDS; idx++) {
--        if (rs->history[idx] == NULL)
--            break;
--        }
--        break;
--    }
-+        hist_entry = rs->history[idx];
-+        if (hist_entry == NULL)
-+            break;
-+        if (strcmp(hist_entry, cmdline) == 0) {
-+        same_entry:
-+            new_entry = hist_entry;
-+            /* Put this entry at the end of history */
-+            memmove(&rs->history[idx], &rs->history[idx + 1],
-+                    (READLINE_MAX_CMDS - (idx + 1)) * sizeof(char *));
-+            rs->history[READLINE_MAX_CMDS - 1] = NULL;
-+            for (; idx < READLINE_MAX_CMDS; idx++) {
-+                if (rs->history[idx] == NULL)
-+                    break;
-+            }
-+            break;
-+        }
-     }
-     if (idx == READLINE_MAX_CMDS) {
--    /* Need to get one free slot */
-+        /* Need to get one free slot */
-         g_free(rs->history[0]);
--    memmove(rs->history, &rs->history[1],
--            (READLINE_MAX_CMDS - 1) * sizeof(char *));
--    rs->history[READLINE_MAX_CMDS - 1] = NULL;
--    idx = READLINE_MAX_CMDS - 1;
-+        memmove(rs->history, &rs->history[1],
-+                (READLINE_MAX_CMDS - 1) * sizeof(char *));
-+        rs->history[READLINE_MAX_CMDS - 1] = NULL;
-+        idx = READLINE_MAX_CMDS - 1;
-     }
-     if (new_entry == NULL)
-         new_entry = g_strdup(cmdline);
-@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
-         case 8:
-             readline_backspace(rs);
-             break;
--    case 155:
-+        case 155:
-             rs->esc_state = IS_CSI;
--        break;
-+            break;
-         default:
-             if (ch >= 32) {
-                 readline_insert_char(rs, ch);
-@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
-         break;
-     case IS_CSI:
-         switch (ch) {
--    case 'A':
--    case 'F':
--        readline_up_char(rs);
--        break;
--    case 'B':
--    case 'E':
--        readline_down_char(rs);
--        break;
-+        case 'A':
-+        case 'F':
-+            readline_up_char(rs);
-+            break;
-+        case 'B':
-+        case 'E':
-+            readline_down_char(rs);
-+            break;
-         case 'D':
-             readline_backward_char(rs);
-             break;
 --
-.21.0
+.26.2

-New patch
+[PULL v2 12/28] util/vhost-user-server: drop unused DevicePanicNotifier
+The device panic notifier callback is not used. Drop it.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-7-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ util/vhost-user-server.h             | 3 ---
+ block/export/vhost-user-blk-server.c | 3 +--
+ util/vhost-user-server.c             | 6 ------
+files changed, 1 insertion(+), 11 deletions(-)
+diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.h
++++ b/util/vhost-user-server.h
+@@ -XXX,XX +XXX,XX @@ typedef struct VuFdWatch {
+ } VuFdWatch;
+ typedef struct VuServer VuServer;
+-typedef void DevicePanicNotifierFn(VuServer *server);
+ struct VuServer {
+     QIONetListener *listener;
+     AioContext *ctx;
+-    DevicePanicNotifierFn *device_panic_notifier;
+     int max_queues;
+     const VuDevIface *vu_iface;
+     VuDev vu_dev;
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+                              SocketAddress *unix_socket,
+                              AioContext *ctx,
+                              uint16_t max_queues,
+-                             DevicePanicNotifierFn *device_panic_notifier,
+                              const VuDevIface *vu_iface,
+                              Error **errp);
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/vhost-user-blk-server.c
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@ static void vhost_user_blk_server_start(VuBlockDev *vu_block_device,
+     ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));
+     if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx,
+-                                 VHOST_USER_BLK_MAX_QUEUES,
+-                                 NULL, &vu_block_iface,
++                                 VHOST_USER_BLK_MAX_QUEUES, &vu_block_iface,
+                                  errp)) {
+         goto error;
+     }
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.c
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@ static void panic_cb(VuDev *vu_dev, const char *buf)
+         close_client(server);
+     }
+-    if (server->device_panic_notifier) {
+-        server->device_panic_notifier(server);
+-    }
+-
+     /*
+      * Set the callback function for network listener so another
+      * vhost-user client can connect to this server
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+                              SocketAddress *socket_addr,
+                              AioContext *ctx,
+                              uint16_t max_queues,
+-                             DevicePanicNotifierFn *device_panic_notifier,
+                              const VuDevIface *vu_iface,
+                              Error **errp)
+ {
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+         .vu_iface              = vu_iface,
+         .max_queues            = max_queues,
+         .ctx                   = ctx,
+-        .device_panic_notifier = device_panic_notifier,
+     };
+     qio_net_listener_set_name(server->listener, "vhost-user-backend-listener");
+--
+.26.2

-[Qemu-devel] [PULL 1/8] util/readline: add a space to fix errors by checkpatch tool
+[PULL v2 13/28] util/vhost-user-server: fix memory leak in vu_message_read()
-From: Jules Irenge <jbi.octave@gmail.com>
+fds[] is leaked when qio_channel_readv_full() fails.
-util/readline: add a space to fix errors reported by checkpatch.pl tool
+Use vmsg->fds[] instead of keeping a local fds[] array. Then we can
-"ERROR: space required before the open parenthesis"
+reuse goto fail to clean up fds. vmsg->fd_num must be zeroed before the
-"ERROR: space required after that ..."
+loop to make this safe.
 within "util/redline.c" file
-Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Reviewed-by: Thomas Huth <thuth@redhat.com>
+Message-id: 20200924151549.913737-8-stefanha@redhat.com
 Message-id: 20190401024406.10819-2-jbi.octave@gmail.com
 Message-Id: <20190401024406.10819-2-jbi.octave@gmail.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- util/readline.c | 34 +++++++++++++++++-----------------
+ util/vhost-user-server.c | 50 ++++++++++++++++++----------------------
-file changed, 17 insertions(+), 17 deletions(-)
+file changed, 23 insertions(+), 27 deletions(-)
-diff --git a/util/readline.c b/util/readline.c
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
 index XXXXXXX..XXXXXXX 100644
---- a/util/readline.c
+--- a/util/vhost-user-server.c
-+++ b/util/readline.c
++++ b/util/vhost-user-server.c
-@@ -XXX,XX +XXX,XX @@ static void readline_update(ReadLineState *rs)
+@@ -XXX,XX +XXX,XX @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
+     };
-     if (rs->cmd_buf_size != rs->last_cmd_buf_size ||
+     int rc, read_bytes = 0;
-         memcmp(rs->cmd_buf, rs->last_cmd_buf, rs->cmd_buf_size) != 0) {
+     Error *local_err = NULL;
--        for(i = 0; i < rs->last_cmd_buf_index; i++) {
+-    /*
-+        for (i = 0; i < rs->last_cmd_buf_index; i++) {
+-     * Store fds/nfds returned from qio_channel_readv_full into
-             rs->printf_func(rs->opaque, "\033[D");
+-     * temporary variables.
-         }
+-     *
-         rs->cmd_buf[rs->cmd_buf_size] = '\0';
+-     * VhostUserMsg is a packed structure, gcc will complain about passing
-         if (rs->read_password) {
+-     * pointer to a packed structure member if we pass &VhostUserMsg.fd_num
-             len = strlen(rs->cmd_buf);
+-     * and &VhostUserMsg.fds directly when calling qio_channel_readv_full,
--            for(i = 0; i < len; i++)
+-     * thus two temporary variables nfds and fds are used here.
-+            for (i = 0; i < len; i++)
+-     */
-                 rs->printf_func(rs->opaque, "*");
+-    size_t nfds = 0, nfds_t = 0;
-         } else {
+     const size_t max_fds = G_N_ELEMENTS(vmsg->fds);
-             rs->printf_func(rs->opaque, "%s", rs->cmd_buf);
+-    int *fds_t = NULL;
-@@ -XXX,XX +XXX,XX @@ static void readline_update(ReadLineState *rs)
+     VuServer *server = container_of(vu_dev, VuServer, vu_dev);
-     if (rs->cmd_buf_index != rs->last_cmd_buf_index) {
+     QIOChannel *ioc = server->ioc;
-         delta = rs->cmd_buf_index - rs->last_cmd_buf_index;
-         if (delta > 0) {
++    vmsg->fd_num = 0;
--            for(i = 0;i < delta; i++) {
+     if (!ioc) {
-+            for (i = 0; i < delta; i++) {
+         error_report_err(local_err);
-                 rs->printf_func(rs->opaque, "\033[C");
+         goto fail;
-             }
+@@ -XXX,XX +XXX,XX @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
-         } else {
-             delta = -delta;
+     assert(qemu_in_coroutine());
--            for(i = 0;i < delta; i++) {
+     do {
-+            for (i = 0; i < delta; i++) {
++        size_t nfds = 0;
-                 rs->printf_func(rs->opaque, "\033[D");
++        int *fds = NULL;
 +
          /*
           * qio_channel_readv_full may have short reads, keeping calling it
           * until getting VHOST_USER_HDR_SIZE or 0 bytes in total
           */
 -        rc = qio_channel_readv_full(ioc, &iov, 1, &fds_t, &nfds_t, &local_err);
 +        rc = qio_channel_readv_full(ioc, &iov, 1, &fds, &nfds, &local_err);
          if (rc < 0) {
              if (rc == QIO_CHANNEL_ERR_BLOCK) {
 +                assert(local_err == NULL);
                  qio_channel_yield(ioc, G_IO_IN);
                  continue;
              } else {
                  error_report_err(local_err);
 -                return false;
 +                goto fail;
              }
          }
-@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
+-        read_bytes += rc;
-         return;
+-        if (nfds_t > 0) {
-     if (rs->nb_completions == 1) {
+-            if (nfds + nfds_t > max_fds) {
-         len = strlen(rs->completions[0]);
++
--        for(i = rs->completion_index; i < len; i++) {
++        if (nfds > 0) {
-+        for (i = rs->completion_index; i < len; i++) {
++            if (vmsg->fd_num + nfds > max_fds) {
-             readline_insert_char(rs, rs->completions[0][i]);
+                 error_report("A maximum of %zu fds are allowed, "
                               "however got %zu fds now",
 -                             max_fds, nfds + nfds_t);
 +                             max_fds, vmsg->fd_num + nfds);
 +                g_free(fds);
                  goto fail;
              }
 -            memcpy(vmsg->fds + nfds, fds_t,
 -                   nfds_t *sizeof(vmsg->fds[0]));
 -            nfds += nfds_t;
 -            g_free(fds_t);
 +            memcpy(vmsg->fds + vmsg->fd_num, fds, nfds * sizeof(vmsg->fds[0]));
 +            vmsg->fd_num += nfds;
 +            g_free(fds);
          }
-         /* extra space for next argument. XXX: make it more generic */
+-        if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
-@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
+-            break;
-               completion_comp);
++
-         rs->printf_func(rs->opaque, "\n");
++        if (rc == 0) { /* socket closed */
-         max_width = 0;
++            goto fail;
 -        max_prefix = 0;
 -        for(i = 0; i < rs->nb_completions; i++) {
 +        max_prefix = 0;
 +        for (i = 0; i < rs->nb_completions; i++) {
              len = strlen(rs->completions[i]);
 -            if (i==0) {
 +            if (i == 0) {
                  max_prefix = len;
              } else {
                  if (len < max_prefix)
                      max_prefix = len;
 -                for(j=0; j<max_prefix; j++) {
 +                for (j = 0; j < max_prefix; j++) {
                      if (rs->completions[i][j] != rs->completions[0][j])
                          max_prefix = j;
                  }
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
              if (len > max_width)
                  max_width = len;
          }
--        if (max_prefix > 0)
+-        iov.iov_base = (char *)vmsg + read_bytes;
--            for(i = rs->completion_index; i < max_prefix; i++) {
+-        iov.iov_len = VHOST_USER_HDR_SIZE - read_bytes;
-+        if (max_prefix > 0)
+-    } while (true);
-+            for (i = rs->completion_index; i < max_prefix; i++) {
-                 readline_insert_char(rs, rs->completions[0][i]);
+-    vmsg->fd_num = nfds;
-             }
++        iov.iov_base += rc;
-         max_width += 2;
++        iov.iov_len -= rc;
-@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
++        read_bytes += rc;
-             max_width = 80;
++    } while (read_bytes != VHOST_USER_HDR_SIZE);
-         nb_cols = 80 / max_width;
++
-         j = 0;
+     /* qio_channel_readv_full will make socket fds blocking, unblock them */
--        for(i = 0; i < rs->nb_completions; i++) {
+     vmsg_unblock_fds(vmsg);
-+        for (i = 0; i < rs->nb_completions; i++) {
+     if (vmsg->size > sizeof(vmsg->payload)) {
              rs->printf_func(rs->opaque, "%-*s", max_width, rs->completions[i]);
              if (++j == nb_cols || i == (rs->nb_completions - 1)) {
                  rs->printf_func(rs->opaque, "\n");
@@ -XXX,XX +XXX,XX @@ static void readline_clear_screen(ReadLineState *rs)
  /* return true if command handled */
  void readline_handle_byte(ReadLineState *rs, int ch)
  {
 -    switch(rs->esc_state) {
 +    switch (rs->esc_state) {
      case IS_NORM:
 -        switch(ch) {
 +        switch (ch) {
          case 1:
              readline_bol(rs);
              break;
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
          }
          break;
      case IS_CSI:
 -        switch(ch) {
 +        switch (ch) {
      case 'A':
      case 'F':
          readline_up_char(rs);
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
              rs->esc_param = rs->esc_param * 10 + (ch - '0');
              goto the_end;
          case '~':
 -            switch(rs->esc_param) {
 +            switch (rs->esc_param) {
              case 1:
                  readline_bol(rs);
                  break;
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
      the_end:
          break;
      case IS_SS3:
 -        switch(ch) {
 +        switch (ch) {
          case 'F':
              readline_eol(rs);
              break;
 --
-.21.0
+.26.2

-New patch
+[PULL v2 14/28] util/vhost-user-server: check EOF when reading payload
+Unexpected EOF is an error that must be reported.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-9-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ util/vhost-user-server.c | 6 ++++--
+file changed, 4 insertions(+), 2 deletions(-)
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.c
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
+     };
+     if (vmsg->size) {
+         rc = qio_channel_readv_all_eof(ioc, &iov_payload, 1, &local_err);
+-        if (rc == -1) {
+-            error_report_err(local_err);
++        if (rc != 1) {
++            if (local_err) {
++                error_report_err(local_err);
++            }
+             goto fail;
+         }
+     }
+--
+.26.2

-New patch
+[PULL v2 15/28] util/vhost-user-server: rework vu_client_trip() coroutine lifecycle
+The vu_client_trip() coroutine is leaked during AioContext switching. It
+is also unsafe to destroy the vu_dev in panic_cb() since its callers
+still access it in some cases.
+Rework the lifecycle to solve these safety issues.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-10-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ util/vhost-user-server.h             |  29 ++--
+ block/export/vhost-user-blk-server.c |   9 +-
+ util/vhost-user-server.c             | 245 +++++++++++++++------------
+files changed, 155 insertions(+), 128 deletions(-)
+diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.h
++++ b/util/vhost-user-server.h
+@@ -XXX,XX +XXX,XX @@
+ #include "qapi/error.h"
+ #include "standard-headers/linux/virtio_blk.h"
++/* A kick fd that we monitor on behalf of libvhost-user */
+ typedef struct VuFdWatch {
+     VuDev *vu_dev;
+     int fd; /*kick fd*/
+     void *pvt;
+     vu_watch_cb cb;
+-    bool processing;
+     QTAILQ_ENTRY(VuFdWatch) next;
+ } VuFdWatch;
+-typedef struct VuServer VuServer;
+-
+-struct VuServer {
++/**
++ * VuServer:
++ * A vhost-user server instance with user-defined VuDevIface callbacks.
++ * Vhost-user device backends can be implemented using VuServer. VuDevIface
++ * callbacks and virtqueue kicks run in the given AioContext.
++ */
++typedef struct {
+     QIONetListener *listener;
++    QEMUBH *restart_listener_bh;
+     AioContext *ctx;
+     int max_queues;
+     const VuDevIface *vu_iface;
++
++    /* Protected by ctx lock */
+     VuDev vu_dev;
+     QIOChannel *ioc; /* The I/O channel with the client */
+     QIOChannelSocket *sioc; /* The underlying data channel with the client */
+-    /* IOChannel for fd provided via VHOST_USER_SET_SLAVE_REQ_FD */
+-    QIOChannel *ioc_slave;
+-    QIOChannelSocket *sioc_slave;
+-    Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
+     QTAILQ_HEAD(, VuFdWatch) vu_fd_watches;
+-    /* restart coroutine co_trip if AIOContext is changed */
+-    bool aio_context_changed;
+-    bool processing_msg;
+-};
++
++    Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
++} VuServer;
+ bool vhost_user_server_start(VuServer *server,
+                              SocketAddress *unix_socket,
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+ void vhost_user_server_stop(VuServer *server);
+-void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx);
++void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx);
++void vhost_user_server_detach_aio_context(VuServer *server);
+ #endif /* VHOST_USER_SERVER_H */
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/vhost-user-blk-server.c
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@ static const VuDevIface vu_block_iface = {
+ static void blk_aio_attached(AioContext *ctx, void *opaque)
+ {
+     VuBlockDev *vub_dev = opaque;
+-    aio_context_acquire(ctx);
+-    vhost_user_server_set_aio_context(&vub_dev->vu_server, ctx);
+-    aio_context_release(ctx);
++    vhost_user_server_attach_aio_context(&vub_dev->vu_server, ctx);
+ }
+ static void blk_aio_detach(void *opaque)
+ {
+     VuBlockDev *vub_dev = opaque;
+-    AioContext *ctx = vub_dev->vu_server.ctx;
+-    aio_context_acquire(ctx);
+-    vhost_user_server_set_aio_context(&vub_dev->vu_server, NULL);
+-    aio_context_release(ctx);
++    vhost_user_server_detach_aio_context(&vub_dev->vu_server);
+ }
+ static void
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.c
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@
+  */
+ #include "qemu/osdep.h"
+ #include "qemu/main-loop.h"
++#include "block/aio-wait.h"
+ #include "vhost-user-server.h"
++/*
++ * Theory of operation:
++ *
++ * VuServer is started and stopped by vhost_user_server_start() and
++ * vhost_user_server_stop() from the main loop thread. Starting the server
++ * opens a vhost-user UNIX domain socket and listens for incoming connections.
++ * Only one connection is allowed at a time.
++ *
++ * The connection is handled by the vu_client_trip() coroutine in the
++ * VuServer->ctx AioContext. The coroutine consists of a vu_dispatch() loop
++ * where libvhost-user calls vu_message_read() to receive the next vhost-user
++ * protocol messages over the UNIX domain socket.
++ *
++ * When virtqueues are set up libvhost-user calls set_watch() to monitor kick
++ * fds. These fds are also handled in the VuServer->ctx AioContext.
++ *
++ * Both vu_client_trip() and kick fd monitoring can be stopped by shutting down
++ * the socket connection. Shutting down the socket connection causes
++ * vu_message_read() to fail since no more data can be received from the socket.
++ * After vu_dispatch() fails, vu_client_trip() calls vu_deinit() to stop
++ * libvhost-user before terminating the coroutine. vu_deinit() calls
++ * remove_watch() to stop monitoring kick fds and this stops virtqueue
++ * processing.
++ *
++ * When vu_client_trip() has finished cleaning up it schedules a BH in the main
++ * loop thread to accept the next client connection.
++ *
++ * When libvhost-user detects an error it calls panic_cb() and sets the
++ * dev->broken flag. Both vu_client_trip() and kick fd processing stop when
++ * the dev->broken flag is set.
++ *
++ * It is possible to switch AioContexts using
++ * vhost_user_server_detach_aio_context() and
++ * vhost_user_server_attach_aio_context(). They stop monitoring fds in the old
++ * AioContext and resume monitoring in the new AioContext. The vu_client_trip()
++ * coroutine remains in a yielded state during the switch. This is made
++ * possible by QIOChannel's support for spurious coroutine re-entry in
++ * qio_channel_yield(). The coroutine will restart I/O when re-entered from the
++ * new AioContext.
++ */
++
+ static void vmsg_close_fds(VhostUserMsg *vmsg)
+ {
+     int i;
+@@ -XXX,XX +XXX,XX @@ static void vmsg_unblock_fds(VhostUserMsg *vmsg)
+     }
+ }
+-static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+-                      gpointer opaque);
+-
+-static void close_client(VuServer *server)
+-{
+-    /*
+-     * Before closing the client
+-     *
+-     * 1. Let vu_client_trip stop processing new vhost-user msg
+-     *
+-     * 2. remove kick_handler
+-     *
+-     * 3. wait for the kick handler to be finished
+-     *
+-     * 4. wait for the current vhost-user msg to be finished processing
+-     */
+-
+-    QIOChannelSocket *sioc = server->sioc;
+-    /* When this is set vu_client_trip will stop new processing vhost-user message */
+-    server->sioc = NULL;
+-
+-    while (server->processing_msg) {
+-        if (server->ioc->read_coroutine) {
+-            server->ioc->read_coroutine = NULL;
+-            qio_channel_set_aio_fd_handler(server->ioc, server->ioc->ctx, NULL,
+-                                           NULL, server->ioc);
+-            server->processing_msg = false;
+-        }
+-    }
+-
+-    vu_deinit(&server->vu_dev);
+-
+-    /* vu_deinit() should have called remove_watch() */
+-    assert(QTAILQ_EMPTY(&server->vu_fd_watches));
+-
+-    object_unref(OBJECT(sioc));
+-    object_unref(OBJECT(server->ioc));
+-}
+-
+ static void panic_cb(VuDev *vu_dev, const char *buf)
+ {
+-    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+-
+-    /* avoid while loop in close_client */
+-    server->processing_msg = false;
+-
+-    if (buf) {
+-        error_report("vu_panic: %s", buf);
+-    }
+-
+-    if (server->sioc) {
+-        close_client(server);
+-    }
+-
+-    /*
+-     * Set the callback function for network listener so another
+-     * vhost-user client can connect to this server
+-     */
+-    qio_net_listener_set_client_func(server->listener,
+-                                     vu_accept,
+-                                     server,
+-                                     NULL);
++    error_report("vu_panic: %s", buf);
+ }
+ static bool coroutine_fn
+@@ -XXX,XX +XXX,XX @@ fail:
+     return false;
+ }
+-
+-static void vu_client_start(VuServer *server);
+ static coroutine_fn void vu_client_trip(void *opaque)
+ {
+     VuServer *server = opaque;
++    VuDev *vu_dev = &server->vu_dev;
+-    while (!server->aio_context_changed && server->sioc) {
+-        server->processing_msg = true;
+-        vu_dispatch(&server->vu_dev);
+-        server->processing_msg = false;
++    while (!vu_dev->broken && vu_dispatch(vu_dev)) {
++        /* Keep running */
+     }
+-    if (server->aio_context_changed && server->sioc) {
+-        server->aio_context_changed = false;
+-        vu_client_start(server);
+-    }
+-}
++    vu_deinit(vu_dev);
++
++    /* vu_deinit() should have called remove_watch() */
++    assert(QTAILQ_EMPTY(&server->vu_fd_watches));
++
++    object_unref(OBJECT(server->sioc));
++    server->sioc = NULL;
+-static void vu_client_start(VuServer *server)
+-{
+-    server->co_trip = qemu_coroutine_create(vu_client_trip, server);
+-    aio_co_enter(server->ctx, server->co_trip);
++    object_unref(OBJECT(server->ioc));
++    server->ioc = NULL;
++
++    server->co_trip = NULL;
++    if (server->restart_listener_bh) {
++        qemu_bh_schedule(server->restart_listener_bh);
++    }
++    aio_wait_kick();
+ }
+ /*
+@@ -XXX,XX +XXX,XX @@ static void vu_client_start(VuServer *server)
+ static void kick_handler(void *opaque)
+ {
+     VuFdWatch *vu_fd_watch = opaque;
+-    vu_fd_watch->processing = true;
+-    vu_fd_watch->cb(vu_fd_watch->vu_dev, 0, vu_fd_watch->pvt);
+-    vu_fd_watch->processing = false;
++    VuDev *vu_dev = vu_fd_watch->vu_dev;
++
++    vu_fd_watch->cb(vu_dev, 0, vu_fd_watch->pvt);
++
++    /* Stop vu_client_trip() if an error occurred in vu_fd_watch->cb() */
++    if (vu_dev->broken) {
++        VuServer *server = container_of(vu_dev, VuServer, vu_dev);
++
++        qio_channel_shutdown(server->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
++    }
+ }
+-
+ static VuFdWatch *find_vu_fd_watch(VuServer *server, int fd)
+ {
+@@ -XXX,XX +XXX,XX @@ static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+     qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
+     server->ioc = QIO_CHANNEL(sioc);
+     object_ref(OBJECT(server->ioc));
+-    qio_channel_attach_aio_context(server->ioc, server->ctx);
++
++    /* TODO vu_message_write() spins if non-blocking! */
+     qio_channel_set_blocking(server->ioc, false, NULL);
+-    vu_client_start(server);
++
++    server->co_trip = qemu_coroutine_create(vu_client_trip, server);
++
++    aio_context_acquire(server->ctx);
++    vhost_user_server_attach_aio_context(server, server->ctx);
++    aio_context_release(server->ctx);
+ }
+-
+ void vhost_user_server_stop(VuServer *server)
+ {
++    aio_context_acquire(server->ctx);
++
++    qemu_bh_delete(server->restart_listener_bh);
++    server->restart_listener_bh = NULL;
++
+     if (server->sioc) {
+-        close_client(server);
++        VuFdWatch *vu_fd_watch;
++
++        QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
++            aio_set_fd_handler(server->ctx, vu_fd_watch->fd, true,
++                               NULL, NULL, NULL, vu_fd_watch);
++        }
++
++        qio_channel_shutdown(server->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
++
++        AIO_WAIT_WHILE(server->ctx, server->co_trip);
+     }
++    aio_context_release(server->ctx);
++
+     if (server->listener) {
+         qio_net_listener_disconnect(server->listener);
+         object_unref(OBJECT(server->listener));
+     }
++}
++
++/*
++ * Allow the next client to connect to the server. Called from a BH in the main
++ * loop.
++ */
++static void restart_listener_bh(void *opaque)
++{
++    VuServer *server = opaque;
++    qio_net_listener_set_client_func(server->listener, vu_accept, server,
++                                     NULL);
+ }
+-void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx)
++/* Called with ctx acquired */
++void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx)
+ {
+-    VuFdWatch *vu_fd_watch, *next;
+-    void *opaque = NULL;
+-    IOHandler *io_read = NULL;
+-    bool attach;
++    VuFdWatch *vu_fd_watch;
+-    server->ctx = ctx ? ctx : qemu_get_aio_context();
++    server->ctx = ctx;
+     if (!server->sioc) {
+-        /* not yet serving any client*/
+         return;
+     }
+-    if (ctx) {
+-        qio_channel_attach_aio_context(server->ioc, ctx);
+-        server->aio_context_changed = true;
+-        io_read = kick_handler;
+-        attach = true;
+-    } else {
++    qio_channel_attach_aio_context(server->ioc, ctx);
++
++    QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
++        aio_set_fd_handler(ctx, vu_fd_watch->fd, true, kick_handler, NULL,
++                           NULL, vu_fd_watch);
++    }
++
++    aio_co_schedule(ctx, server->co_trip);
++}
++
++/* Called with server->ctx acquired */
++void vhost_user_server_detach_aio_context(VuServer *server)
++{
++    if (server->sioc) {
++        VuFdWatch *vu_fd_watch;
++
++        QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
++            aio_set_fd_handler(server->ctx, vu_fd_watch->fd, true,
++                               NULL, NULL, NULL, vu_fd_watch);
++        }
++
+         qio_channel_detach_aio_context(server->ioc);
+-        /* server->ioc->ctx keeps the old AioConext */
+-        ctx = server->ioc->ctx;
+-        attach = false;
+     }
+-    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+-        if (vu_fd_watch->cb) {
+-            opaque = attach ? vu_fd_watch : NULL;
+-            aio_set_fd_handler(ctx, vu_fd_watch->fd, true,
+-                               io_read, NULL, NULL,
+-                               opaque);
+-        }
+-    }
++    server->ctx = NULL;
+ }
+-
+ bool vhost_user_server_start(VuServer *server,
+                              SocketAddress *socket_addr,
+                              AioContext *ctx,
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+                              const VuDevIface *vu_iface,
+                              Error **errp)
+ {
++    QEMUBH *bh;
+     QIONetListener *listener = qio_net_listener_new();
+     if (qio_net_listener_open_sync(listener, socket_addr, 1,
+                                    errp) < 0) {
+@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
+         return false;
+     }
++    bh = qemu_bh_new(restart_listener_bh, server);
++
+     /* zero out unspecified fields */
+     *server = (VuServer) {
+         .listener              = listener,
++        .restart_listener_bh   = bh,
+         .vu_iface              = vu_iface,
+         .max_queues            = max_queues,
+         .ctx                   = ctx,
+--
+.26.2

-New patch
+[PULL v2 16/28] block/export: report flush errors
+Propagate the flush return value since errors are possible.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-11-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ block/export/vhost-user-blk-server.c | 11 +++++++----
+file changed, 7 insertions(+), 4 deletions(-)
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/vhost-user-blk-server.c
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@ vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
+     return -EINVAL;
+ }
+-static void coroutine_fn vu_block_flush(VuBlockReq *req)
++static int coroutine_fn vu_block_flush(VuBlockReq *req)
+ {
+     VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
+     BlockBackend *backend = vdev_blk->backend;
+-    blk_co_flush(backend);
++    return blk_co_flush(backend);
+ }
+ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
+@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
+         break;
+     }
+     case VIRTIO_BLK_T_FLUSH:
+-        vu_block_flush(req);
+-        req->in->status = VIRTIO_BLK_S_OK;
++        if (vu_block_flush(req) == 0) {
++            req->in->status = VIRTIO_BLK_S_OK;
++        } else {
++            req->in->status = VIRTIO_BLK_S_IOERR;
++        }
+         break;
+     case VIRTIO_BLK_T_GET_ID: {
+         size_t size = MIN(iov_size(&elem->in_sg[0], in_num),
+--
+.26.2

-New patch
+[PULL v2 17/28] block/export: convert vhost-user-blk server to block export API
+Use the new QAPI block exports API instead of defining our own QOM
 objects.
 This is a large change because the lifecycle of VuBlockDev needs to
 follow BlockExportDriver. QOM properties are replaced by QAPI options
 objects.
 VuBlockDev is renamed VuBlkExport and contains a BlockExport field.
 Several fields can be dropped since BlockExport already has equivalents.
 The file names and meson build integration will be adjusted in a future
 patch. libvhost-user should probably be built as a static library that
 is linked into QEMU instead of as a .c file that results in duplicate
 compilation.
 The new command-line syntax is:
   $ qemu-storage-daemon \
       --blockdev file,node-name=drive0,filename=test.img \
       --export vhost-user-blk,node-name=drive0,id=export0,unix-socket=/tmp/vhost-user-blk.sock
 Note that unix-socket is optional because we may wish to accept chardevs
 too in the future.
 Markus noted that supported address families are not explicit in the
 QAPI schema. It is unlikely that support for more address families will
 be added since file descriptor passing is required and few address
 families support it. If a new address family needs to be added, then the
 QAPI 'features' syntax can be used to advertize them.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 Acked-by: Markus Armbruster <armbru@redhat.com>
 Message-id: 20200924151549.913737-12-stefanha@redhat.com
 [Skip test on big-endian host architectures because this device doesn't
 support them yet (as already mentioned in a code comment).
 --Stefan]
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
  qapi/block-export.json               |  21 +-
  block/export/vhost-user-blk-server.h |  23 +-
  block/export/export.c                |   6 +
  block/export/vhost-user-blk-server.c | 452 +++++++--------------------
  util/vhost-user-server.c             |  10 +-
  block/export/meson.build             |   1 +
  block/meson.build                    |   1 -
 files changed, 156 insertions(+), 358 deletions(-)
 diff --git a/qapi/block-export.json b/qapi/block-export.json
 index XXXXXXX..XXXXXXX 100644
 --- a/qapi/block-export.json
 +++ b/qapi/block-export.json
@@ -XXX,XX +XXX,XX @@
    'data': { '*name': 'str', '*description': 'str',
              '*bitmap': 'str' } }
 +##
 +# @BlockExportOptionsVhostUserBlk:
 +#
 +# A vhost-user-blk block export.
 +#
 +# @addr: The vhost-user socket on which to listen. Both 'unix' and 'fd'
 +#        SocketAddress types are supported. Passed fds must be UNIX domain
 +#        sockets.
 +# @logical-block-size: Logical block size in bytes. Defaults to 512 bytes.
 +#
 +# Since: 5.2
 +##
 +{ 'struct': 'BlockExportOptionsVhostUserBlk',
 +  'data': { 'addr': 'SocketAddress', '*logical-block-size': 'size' } }
 +
  ##
  # @NbdServerAddOptions:
  #
@@ -XXX,XX +XXX,XX @@
  # An enumeration of block export types
  #
  # @nbd: NBD export
 +# @vhost-user-blk: vhost-user-blk export (since 5.2)
  #
  # Since: 4.2
  ##
  { 'enum': 'BlockExportType',
 -  'data': [ 'nbd' ] }
 +  'data': [ 'nbd', 'vhost-user-blk' ] }
  ##
  # @BlockExportOptions:
@@ -XXX,XX +XXX,XX @@
              '*writethrough': 'bool' },
    'discriminator': 'type',
    'data': {
 -      'nbd': 'BlockExportOptionsNbd'
 +      'nbd': 'BlockExportOptionsNbd',
 +      'vhost-user-blk': 'BlockExportOptionsVhostUserBlk'
     } }
  ##
 diff --git a/block/export/vhost-user-blk-server.h b/block/export/vhost-user-blk-server.h
 index XXXXXXX..XXXXXXX 100644
 --- a/block/export/vhost-user-blk-server.h
 +++ b/block/export/vhost-user-blk-server.h
@@ -XXX,XX +XXX,XX @@
  #ifndef VHOST_USER_BLK_SERVER_H
  #define VHOST_USER_BLK_SERVER_H
 -#include "util/vhost-user-server.h"
 -typedef struct VuBlockDev VuBlockDev;
 -#define TYPE_VHOST_USER_BLK_SERVER "vhost-user-blk-server"
 -#define VHOST_USER_BLK_SERVER(obj) \
 -   OBJECT_CHECK(VuBlockDev, obj, TYPE_VHOST_USER_BLK_SERVER)
 +#include "block/export.h"
 -/* vhost user block device */
 -struct VuBlockDev {
 -    Object parent_obj;
 -    char *node_name;
 -    SocketAddress *addr;
 -    AioContext *ctx;
 -    VuServer vu_server;
 -    bool running;
 -    uint32_t blk_size;
 -    BlockBackend *backend;
 -    QIOChannelSocket *sioc;
 -    QTAILQ_ENTRY(VuBlockDev) next;
 -    struct virtio_blk_config blkcfg;
 -    bool writable;
 -};
 +/* For block/export/export.c */
 +extern const BlockExportDriver blk_exp_vhost_user_blk;
  #endif /* VHOST_USER_BLK_SERVER_H */
 diff --git a/block/export/export.c b/block/export/export.c
 index XXXXXXX..XXXXXXX 100644
 --- a/block/export/export.c
 +++ b/block/export/export.c
@@ -XXX,XX +XXX,XX @@
  #include "sysemu/block-backend.h"
  #include "block/export.h"
  #include "block/nbd.h"
 +#if CONFIG_LINUX
 +#include "block/export/vhost-user-blk-server.h"
 +#endif
  #include "qapi/error.h"
  #include "qapi/qapi-commands-block-export.h"
  #include "qapi/qapi-events-block-export.h"
@@ -XXX,XX +XXX,XX @@
  static const BlockExportDriver *blk_exp_drivers[] = {
      &blk_exp_nbd,
 +#if CONFIG_LINUX
 +    &blk_exp_vhost_user_blk,
 +#endif
  };
  /* Only accessed from the main thread */
 diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
 index XXXXXXX..XXXXXXX 100644
 --- a/block/export/vhost-user-blk-server.c
 +++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@
   */
  #include "qemu/osdep.h"
  #include "block/block.h"
 +#include "contrib/libvhost-user/libvhost-user.h"
 +#include "standard-headers/linux/virtio_blk.h"
 +#include "util/vhost-user-server.h"
  #include "vhost-user-blk-server.h"
  #include "qapi/error.h"
  #include "qom/object_interfaces.h"
@@ -XXX,XX +XXX,XX @@ struct virtio_blk_inhdr {
      unsigned char status;
  };
 -typedef struct VuBlockReq {
 +typedef struct VuBlkReq {
      VuVirtqElement elem;
      int64_t sector_num;
      size_t size;
@@ -XXX,XX +XXX,XX @@ typedef struct VuBlockReq {
      struct virtio_blk_outhdr out;
      VuServer *server;
      struct VuVirtq *vq;
 -} VuBlockReq;
 +} VuBlkReq;
 -static void vu_block_req_complete(VuBlockReq *req)
 +/* vhost user block device */
 +typedef struct {
 +    BlockExport export;
 +    VuServer vu_server;
 +    uint32_t blk_size;
 +    QIOChannelSocket *sioc;
 +    struct virtio_blk_config blkcfg;
 +    bool writable;
 +} VuBlkExport;
 +
 +static void vu_blk_req_complete(VuBlkReq *req)
  {
      VuDev *vu_dev = &req->server->vu_dev;
@@ -XXX,XX +XXX,XX @@ static void vu_block_req_complete(VuBlockReq *req)
      free(req);
  }
 -static VuBlockDev *get_vu_block_device_by_server(VuServer *server)
 -{
 -    return container_of(server, VuBlockDev, vu_server);
 -}
 -
  static int coroutine_fn
 -vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
 -                              uint32_t iovcnt, uint32_t type)
 +vu_blk_discard_write_zeroes(BlockBackend *blk, struct iovec *iov,
 +                            uint32_t iovcnt, uint32_t type)
  {
      struct virtio_blk_discard_write_zeroes desc;
      ssize_t size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc));
@@ -XXX,XX +XXX,XX @@ vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
          return -EINVAL;
      }
 -    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
      uint64_t range[2] = { le64_to_cpu(desc.sector) << 9,
                            le32_to_cpu(desc.num_sectors) << 9 };
      if (type == VIRTIO_BLK_T_DISCARD) {
 -        if (blk_co_pdiscard(vdev_blk->backend, range[0], range[1]) == 0) {
 +        if (blk_co_pdiscard(blk, range[0], range[1]) == 0) {
              return 0;
          }
      } else if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
 -        if (blk_co_pwrite_zeroes(vdev_blk->backend,
 -                                 range[0], range[1], 0) == 0) {
 +        if (blk_co_pwrite_zeroes(blk, range[0], range[1], 0) == 0) {
              return 0;
          }
      }
@@ -XXX,XX +XXX,XX @@ vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
      return -EINVAL;
  }
 -static int coroutine_fn vu_block_flush(VuBlockReq *req)
 +static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
  {
 -    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
 -    BlockBackend *backend = vdev_blk->backend;
 -    return blk_co_flush(backend);
 -}
 -
 -static void coroutine_fn vu_block_virtio_process_req(void *opaque)
 -{
 -    VuBlockReq *req = opaque;
 +    VuBlkReq *req = opaque;
      VuServer *server = req->server;
      VuVirtqElement *elem = &req->elem;
      uint32_t type;
 -    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
 -    BlockBackend *backend = vdev_blk->backend;
 +    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
 +    BlockBackend *blk = vexp->export.blk;
      struct iovec *in_iov = elem->in_sg;
      struct iovec *out_iov = elem->out_sg;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
          bool is_write = type & VIRTIO_BLK_T_OUT;
          req->sector_num = le64_to_cpu(req->out.sector);
 -        int64_t offset = req->sector_num * vdev_blk->blk_size;
 +        if (is_write && !vexp->writable) {
 +            req->in->status = VIRTIO_BLK_S_IOERR;
 +            break;
 +        }
 +
 +        int64_t offset = req->sector_num * vexp->blk_size;
          QEMUIOVector qiov;
          if (is_write) {
              qemu_iovec_init_external(&qiov, out_iov, out_num);
 -            ret = blk_co_pwritev(backend, offset, qiov.size,
 -                                 &qiov, 0);
 +            ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0);
          } else {
              qemu_iovec_init_external(&qiov, in_iov, in_num);
 -            ret = blk_co_preadv(backend, offset, qiov.size,
 -                                &qiov, 0);
 +            ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0);
          }
          if (ret >= 0) {
              req->in->status = VIRTIO_BLK_S_OK;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
          break;
      }
      case VIRTIO_BLK_T_FLUSH:
 -        if (vu_block_flush(req) == 0) {
 +        if (blk_co_flush(blk) == 0) {
              req->in->status = VIRTIO_BLK_S_OK;
          } else {
              req->in->status = VIRTIO_BLK_S_IOERR;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
      case VIRTIO_BLK_T_DISCARD:
      case VIRTIO_BLK_T_WRITE_ZEROES: {
          int rc;
 -        rc = vu_block_discard_write_zeroes(req, &elem->out_sg[1],
 -                                           out_num, type);
 +
 +        if (!vexp->writable) {
 +            req->in->status = VIRTIO_BLK_S_IOERR;
 +            break;
 +        }
 +
 +        rc = vu_blk_discard_write_zeroes(blk, &elem->out_sg[1], out_num, type);
          if (rc == 0) {
              req->in->status = VIRTIO_BLK_S_OK;
          } else {
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
          break;
      }
 -    vu_block_req_complete(req);
 +    vu_blk_req_complete(req);
      return;
  err:
 -    free(elem);
 +    free(req);
  }
 -static void vu_block_process_vq(VuDev *vu_dev, int idx)
 +static void vu_blk_process_vq(VuDev *vu_dev, int idx)
  {
      VuServer *server = container_of(vu_dev, VuServer, vu_dev);
      VuVirtq *vq = vu_get_queue(vu_dev, idx);
      while (1) {
 -        VuBlockReq *req;
 +        VuBlkReq *req;
 -        req = vu_queue_pop(vu_dev, vq, sizeof(VuBlockReq));
 +        req = vu_queue_pop(vu_dev, vq, sizeof(VuBlkReq));
          if (!req) {
              break;
          }
@@ -XXX,XX +XXX,XX @@ static void vu_block_process_vq(VuDev *vu_dev, int idx)
          req->vq = vq;
          Coroutine *co =
 -            qemu_coroutine_create(vu_block_virtio_process_req, req);
 +            qemu_coroutine_create(vu_blk_virtio_process_req, req);
          qemu_coroutine_enter(co);
      }
  }
 -static void vu_block_queue_set_started(VuDev *vu_dev, int idx, bool started)
 +static void vu_blk_queue_set_started(VuDev *vu_dev, int idx, bool started)
  {
      VuVirtq *vq;
      assert(vu_dev);
      vq = vu_get_queue(vu_dev, idx);
 -    vu_set_queue_handler(vu_dev, vq, started ? vu_block_process_vq : NULL);
 +    vu_set_queue_handler(vu_dev, vq, started ? vu_blk_process_vq : NULL);
  }
 -static uint64_t vu_block_get_features(VuDev *dev)
 +static uint64_t vu_blk_get_features(VuDev *dev)
  {
      uint64_t features;
      VuServer *server = container_of(dev, VuServer, vu_dev);
 -    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
 +    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
      features = 1ull << VIRTIO_BLK_F_SIZE_MAX |
 ull << VIRTIO_BLK_F_SEG_MAX |
 ull << VIRTIO_BLK_F_TOPOLOGY |
@@ -XXX,XX +XXX,XX @@ static uint64_t vu_block_get_features(VuDev *dev)
 ull << VIRTIO_RING_F_EVENT_IDX |
 ull << VHOST_USER_F_PROTOCOL_FEATURES;
 -    if (!vdev_blk->writable) {
 +    if (!vexp->writable) {
          features |= 1ull << VIRTIO_BLK_F_RO;
      }
      return features;
  }
 -static uint64_t vu_block_get_protocol_features(VuDev *dev)
 +static uint64_t vu_blk_get_protocol_features(VuDev *dev)
  {
      return 1ull << VHOST_USER_PROTOCOL_F_CONFIG |
 ull << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD;
  }
  static int
 -vu_block_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
 +vu_blk_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
  {
 +    /* TODO blkcfg must be little-endian for VIRTIO 1.0 */
      VuServer *server = container_of(vu_dev, VuServer, vu_dev);
 -    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
 -    memcpy(config, &vdev_blk->blkcfg, len);
 -
 +    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
 +    memcpy(config, &vexp->blkcfg, len);
      return 0;
  }
  static int
 -vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
 +vu_blk_set_config(VuDev *vu_dev, const uint8_t *data,
                      uint32_t offset, uint32_t size, uint32_t flags)
  {
      VuServer *server = container_of(vu_dev, VuServer, vu_dev);
 -    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
 +    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
      uint8_t wce;
      /* don't support live migration */
@@ -XXX,XX +XXX,XX @@ vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
      }
      wce = *data;
 -    vdev_blk->blkcfg.wce = wce;
 -    blk_set_enable_write_cache(vdev_blk->backend, wce);
 +    vexp->blkcfg.wce = wce;
 +    blk_set_enable_write_cache(vexp->export.blk, wce);
      return 0;
  }
@@ -XXX,XX +XXX,XX @@ vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
   * of vu_process_message.
   *
   */
 -static int vu_block_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
 +static int vu_blk_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
  {
      if (vmsg->request == VHOST_USER_NONE) {
          dev->panic(dev, "disconnect");
@@ -XXX,XX +XXX,XX @@ static int vu_block_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
      return false;
  }
 -static const VuDevIface vu_block_iface = {
 -    .get_features          = vu_block_get_features,
 -    .queue_set_started     = vu_block_queue_set_started,
 -    .get_protocol_features = vu_block_get_protocol_features,
 -    .get_config            = vu_block_get_config,
 -    .set_config            = vu_block_set_config,
 -    .process_msg           = vu_block_process_msg,
 +static const VuDevIface vu_blk_iface = {
 +    .get_features          = vu_blk_get_features,
 +    .queue_set_started     = vu_blk_queue_set_started,
 +    .get_protocol_features = vu_blk_get_protocol_features,
 +    .get_config            = vu_blk_get_config,
 +    .set_config            = vu_blk_set_config,
 +    .process_msg           = vu_blk_process_msg,
  };
  static void blk_aio_attached(AioContext *ctx, void *opaque)
  {
 -    VuBlockDev *vub_dev = opaque;
 -    vhost_user_server_attach_aio_context(&vub_dev->vu_server, ctx);
 +    VuBlkExport *vexp = opaque;
 +    vhost_user_server_attach_aio_context(&vexp->vu_server, ctx);
  }
  static void blk_aio_detach(void *opaque)
  {
 -    VuBlockDev *vub_dev = opaque;
 -    vhost_user_server_detach_aio_context(&vub_dev->vu_server);
 +    VuBlkExport *vexp = opaque;
 +    vhost_user_server_detach_aio_context(&vexp->vu_server);
  }
  static void
 -vu_block_initialize_config(BlockDriverState *bs,
 +vu_blk_initialize_config(BlockDriverState *bs,
                             struct virtio_blk_config *config, uint32_t blk_size)
  {
      config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
@@ -XXX,XX +XXX,XX @@ vu_block_initialize_config(BlockDriverState *bs,
      config->max_write_zeroes_seg = 1;
  }
 -static VuBlockDev *vu_block_init(VuBlockDev *vu_block_device, Error **errp)
 +static void vu_blk_exp_request_shutdown(BlockExport *exp)
  {
 +    VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
 -    BlockBackend *blk;
 -    Error *local_error = NULL;
 -    const char *node_name = vu_block_device->node_name;
 -    bool writable = vu_block_device->writable;
 -    uint64_t perm = BLK_PERM_CONSISTENT_READ;
 -    int ret;
 -
 -    AioContext *ctx;
 -
 -    BlockDriverState *bs = bdrv_lookup_bs(node_name, node_name, &local_error);
 -
 -    if (!bs) {
 -        error_propagate(errp, local_error);
 -        return NULL;
 -    }
 -
 -    if (bdrv_is_read_only(bs)) {
 -        writable = false;
 -    }
 -
 -    if (writable) {
 -        perm |= BLK_PERM_WRITE;
 -    }
 -
 -    ctx = bdrv_get_aio_context(bs);
 -    aio_context_acquire(ctx);
 -    bdrv_invalidate_cache(bs, NULL);
 -    aio_context_release(ctx);
 -
 -    /*
 -     * Don't allow resize while the vhost user server is running,
 -     * otherwise we don't care what happens with the node.
 -     */
 -    blk = blk_new(bdrv_get_aio_context(bs), perm,
 -                  BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
 -                  BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
 -    ret = blk_insert_bs(blk, bs, errp);
 -
 -    if (ret < 0) {
 -        goto fail;
 -    }
 -
 -    blk_set_enable_write_cache(blk, false);
 -
 -    blk_set_allow_aio_context_change(blk, true);
 -
 -    vu_block_device->blkcfg.wce = 0;
 -    vu_block_device->backend = blk;
 -    if (!vu_block_device->blk_size) {
 -        vu_block_device->blk_size = BDRV_SECTOR_SIZE;
 -    }
 -    vu_block_device->blkcfg.blk_size = vu_block_device->blk_size;
 -    blk_set_guest_block_size(blk, vu_block_device->blk_size);
 -    vu_block_initialize_config(bs, &vu_block_device->blkcfg,
 -                                   vu_block_device->blk_size);
 -    return vu_block_device;
 -
 -fail:
 -    blk_unref(blk);
 -    return NULL;
 -}
 -
 -static void vu_block_deinit(VuBlockDev *vu_block_device)
 -{
 -    if (vu_block_device->backend) {
 -        blk_remove_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
 -                                        blk_aio_detach, vu_block_device);
 -    }
 -
 -    blk_unref(vu_block_device->backend);
 -}
 -
 -static void vhost_user_blk_server_stop(VuBlockDev *vu_block_device)
 -{
 -    vhost_user_server_stop(&vu_block_device->vu_server);
 -    vu_block_deinit(vu_block_device);
 -}
 -
 -static void vhost_user_blk_server_start(VuBlockDev *vu_block_device,
 -                                        Error **errp)
 -{
 -    AioContext *ctx;
 -    SocketAddress *addr = vu_block_device->addr;
 -
 -    if (!vu_block_init(vu_block_device, errp)) {
 -        return;
 -    }
 -
 -    ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));
 -
 -    if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx,
 -                                 VHOST_USER_BLK_MAX_QUEUES, &vu_block_iface,
 -                                 errp)) {
 -        goto error;
 -    }
 -
 -    blk_add_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
 -                                 blk_aio_detach, vu_block_device);
 -    vu_block_device->running = true;
 -    return;
 -
 - error:
 -    vu_block_deinit(vu_block_device);
 -}
 -
 -static bool vu_prop_modifiable(VuBlockDev *vus, Error **errp)
 -{
 -    if (vus->running) {
 -            error_setg(errp, "The property can't be modified "
 -                       "while the server is running");
 -            return false;
 -    }
 -    return true;
 -}
 -
 -static void vu_set_node_name(Object *obj, const char *value, Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -
 -    if (!vu_prop_modifiable(vus, errp)) {
 -        return;
 -    }
 -
 -    if (vus->node_name) {
 -        g_free(vus->node_name);
 -    }
 -
 -    vus->node_name = g_strdup(value);
 -}
 -
 -static char *vu_get_node_name(Object *obj, Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -    return g_strdup(vus->node_name);
 -}
 -
 -static void free_socket_addr(SocketAddress *addr)
 -{
 -        g_free(addr->u.q_unix.path);
 -        g_free(addr);
 -}
 -
 -static void vu_set_unix_socket(Object *obj, const char *value,
 -                               Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -
 -    if (!vu_prop_modifiable(vus, errp)) {
 -        return;
 -    }
 -
 -    if (vus->addr) {
 -        free_socket_addr(vus->addr);
 -    }
 -
 -    SocketAddress *addr = g_new0(SocketAddress, 1);
 -    addr->type = SOCKET_ADDRESS_TYPE_UNIX;
 -    addr->u.q_unix.path = g_strdup(value);
 -    vus->addr = addr;
 +    vhost_user_server_stop(&vexp->vu_server);
  }
 -static char *vu_get_unix_socket(Object *obj, Error **errp)
 +static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
 +                             Error **errp)
  {
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -    return g_strdup(vus->addr->u.q_unix.path);
 -}
 -
 -static bool vu_get_block_writable(Object *obj, Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -    return vus->writable;
 -}
 -
 -static void vu_set_block_writable(Object *obj, bool value, Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -
 -    if (!vu_prop_modifiable(vus, errp)) {
 -            return;
 -    }
 -
 -    vus->writable = value;
 -}
 -
 -static void vu_get_blk_size(Object *obj, Visitor *v, const char *name,
 -                            void *opaque, Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -    uint32_t value = vus->blk_size;
 -
 -    visit_type_uint32(v, name, &value, errp);
 -}
 -
 -static void vu_set_blk_size(Object *obj, Visitor *v, const char *name,
 -                            void *opaque, Error **errp)
 -{
 -    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
 -
 +    VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
 +    BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk;
      Error *local_err = NULL;
 -    uint32_t value;
 +    uint64_t logical_block_size;
 -    if (!vu_prop_modifiable(vus, errp)) {
 -            return;
 -    }
 +    vexp->writable = opts->writable;
 +    vexp->blkcfg.wce = 0;
 -    visit_type_uint32(v, name, &value, &local_err);
 -    if (local_err) {
 -        goto out;
 +    if (vu_opts->has_logical_block_size) {
 +        logical_block_size = vu_opts->logical_block_size;
 +    } else {
 +        logical_block_size = BDRV_SECTOR_SIZE;
      }
 -
 -    check_block_size(object_get_typename(obj), name, value, &local_err);
 +    check_block_size(exp->id, "logical-block-size", logical_block_size,
 +                     &local_err);
      if (local_err) {
 -        goto out;
 +        error_propagate(errp, local_err);
 +        return -EINVAL;
 +    }
 +    vexp->blk_size = logical_block_size;
 +    blk_set_guest_block_size(exp->blk, logical_block_size);
 +    vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
 +                               logical_block_size);
 +
 +    blk_set_allow_aio_context_change(exp->blk, true);
 +    blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
 +                                 vexp);
 +
 +    if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx,
 +                                 VHOST_USER_BLK_MAX_QUEUES, &vu_blk_iface,
 +                                 errp)) {
 +        blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
 +                                        blk_aio_detach, vexp);
 +        return -EADDRNOTAVAIL;
      }
 -    vus->blk_size = value;
 -
 -out:
 -    error_propagate(errp, local_err);
 -}
 -
 -static void vhost_user_blk_server_instance_finalize(Object *obj)
 -{
 -    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
 -
 -    vhost_user_blk_server_stop(vub);
 -
 -    /*
 -     * Unlike object_property_add_str, object_class_property_add_str
 -     * doesn't have a release method. Thus manual memory freeing is
 -     * needed.
 -     */
 -    free_socket_addr(vub->addr);
 -    g_free(vub->node_name);
 -}
 -
 -static void vhost_user_blk_server_complete(UserCreatable *obj, Error **errp)
 -{
 -    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
 -
 -    vhost_user_blk_server_start(vub, errp);
 +    return 0;
  }
 -static void vhost_user_blk_server_class_init(ObjectClass *klass,
 -                                             void *class_data)
 +static void vu_blk_exp_delete(BlockExport *exp)
  {
 -    UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 -    ucc->complete = vhost_user_blk_server_complete;
 -
 -    object_class_property_add_bool(klass, "writable",
 -                                   vu_get_block_writable,
 -                                   vu_set_block_writable);
 -
 -    object_class_property_add_str(klass, "node-name",
 -                                  vu_get_node_name,
 -                                  vu_set_node_name);
 -
 -    object_class_property_add_str(klass, "unix-socket",
 -                                  vu_get_unix_socket,
 -                                  vu_set_unix_socket);
 +    VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
 -    object_class_property_add(klass, "logical-block-size", "uint32",
 -                              vu_get_blk_size, vu_set_blk_size,
 -                              NULL, NULL);
 +    blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
 +                                    vexp);
  }
 -static const TypeInfo vhost_user_blk_server_info = {
 -    .name = TYPE_VHOST_USER_BLK_SERVER,
 -    .parent = TYPE_OBJECT,
 -    .instance_size = sizeof(VuBlockDev),
 -    .instance_finalize = vhost_user_blk_server_instance_finalize,
 -    .class_init = vhost_user_blk_server_class_init,
 -    .interfaces = (InterfaceInfo[]) {
 -        {TYPE_USER_CREATABLE},
 -        {}
 -    },
 +const BlockExportDriver blk_exp_vhost_user_blk = {
 +    .type               = BLOCK_EXPORT_TYPE_VHOST_USER_BLK,
 +    .instance_size      = sizeof(VuBlkExport),
 +    .create             = vu_blk_exp_create,
 +    .delete             = vu_blk_exp_delete,
 +    .request_shutdown   = vu_blk_exp_request_shutdown,
  };
 -
 -static void vhost_user_blk_server_register_types(void)
 -{
 -    type_register_static(&vhost_user_blk_server_info);
 -}
 -
 -type_init(vhost_user_blk_server_register_types)
 diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
 index XXXXXXX..XXXXXXX 100644
 --- a/util/vhost-user-server.c
 +++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
                               Error **errp)
  {
      QEMUBH *bh;
 -    QIONetListener *listener = qio_net_listener_new();
 +    QIONetListener *listener;
 +
 +    if (socket_addr->type != SOCKET_ADDRESS_TYPE_UNIX &&
 +        socket_addr->type != SOCKET_ADDRESS_TYPE_FD) {
 +        error_setg(errp, "Only socket address types 'unix' and 'fd' are supported");
 +        return false;
 +    }
 +
 +    listener = qio_net_listener_new();
      if (qio_net_listener_open_sync(listener, socket_addr, 1,
                                     errp) < 0) {
          object_unref(OBJECT(listener));
 diff --git a/block/export/meson.build b/block/export/meson.build
 index XXXXXXX..XXXXXXX 100644
 --- a/block/export/meson.build
 +++ b/block/export/meson.build
@@ -1 +1,2 @@
  block_ss.add(files('export.c'))
 +block_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-blk-server.c', '../../contrib/libvhost-user/libvhost-user.c'))
 diff --git a/block/meson.build b/block/meson.build
 index XXXXXXX..XXXXXXX 100644
 --- a/block/meson.build
 +++ b/block/meson.build
@@ -XXX,XX +XXX,XX @@ block_ss.add(when: 'CONFIG_WIN32', if_true: files('file-win32.c', 'win32-aio.c')
  block_ss.add(when: 'CONFIG_POSIX', if_true: [files('file-posix.c'), coref, iokit])
  block_ss.add(when: 'CONFIG_LIBISCSI', if_true: files('iscsi-opts.c'))
  block_ss.add(when: 'CONFIG_LINUX', if_true: files('nvme.c'))
 -block_ss.add(when: 'CONFIG_LINUX', if_true: files('export/vhost-user-blk-server.c', '../contrib/libvhost-user/libvhost-user.c'))
  block_ss.add(when: 'CONFIG_REPLICATION', if_true: files('replication.c'))
  block_ss.add(when: 'CONFIG_SHEEPDOG', if_true: files('sheepdog.c'))
  block_ss.add(when: ['CONFIG_LINUX_AIO', libaio], if_true: files('linux-aio.c'))
 --
 .26.2

-New patch
+[PULL v2 18/28] util/vhost-user-server: move header to include/
+Headers used by other subsystems are located in include/. Also add the
+vhost-user-server and vhost-user-blk-server headers to MAINTAINERS.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-13-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ MAINTAINERS                                | 4 +++-
+ {util => include/qemu}/vhost-user-server.h | 0
+ block/export/vhost-user-blk-server.c       | 2 +-
+ util/vhost-user-server.c                   | 2 +-
+files changed, 5 insertions(+), 3 deletions(-)
+ rename {util => include/qemu}/vhost-user-server.h (100%)
+diff --git a/MAINTAINERS b/MAINTAINERS
+index XXXXXXX..XXXXXXX 100644
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -XXX,XX +XXX,XX @@ Vhost-user block device backend server
+ M: Coiby Xu <Coiby.Xu@gmail.com>
+ S: Maintained
+ F: block/export/vhost-user-blk-server.c
+-F: util/vhost-user-server.c
++F: block/export/vhost-user-blk-server.h
++F: include/qemu/vhost-user-server.h
+ F: tests/qtest/libqos/vhost-user-blk.c
++F: util/vhost-user-server.c
+ Replication
+ M: Wen Congyang <wencongyang2@huawei.com>
+diff --git a/util/vhost-user-server.h b/include/qemu/vhost-user-server.h
+similarity index 100%
+rename from util/vhost-user-server.h
+rename to include/qemu/vhost-user-server.h
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/vhost-user-blk-server.c
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@
+ #include "block/block.h"
+ #include "contrib/libvhost-user/libvhost-user.h"
+ #include "standard-headers/linux/virtio_blk.h"
+-#include "util/vhost-user-server.h"
++#include "qemu/vhost-user-server.h"
+ #include "vhost-user-blk-server.h"
+ #include "qapi/error.h"
+ #include "qom/object_interfaces.h"
+diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/vhost-user-server.c
++++ b/util/vhost-user-server.c
+@@ -XXX,XX +XXX,XX @@
+  */
+ #include "qemu/osdep.h"
+ #include "qemu/main-loop.h"
++#include "qemu/vhost-user-server.h"
+ #include "block/aio-wait.h"
+-#include "vhost-user-server.h"
+ /*
+  * Theory of operation:
+--
+.26.2

-New patch
+[PULL v2 19/28] util/vhost-user-server: use static library in meson.build
+Don't compile contrib/libvhost-user/libvhost-user.c again. Instead build
+the static library once and then reuse it throughout QEMU.
+Also switch from CONFIG_LINUX to CONFIG_VHOST_USER, which is what the
+vhost-user tools (vhost-user-gpu, etc) do.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200924151549.913737-14-stefanha@redhat.com
+[Added CONFIG_LINUX again because libvhost-user doesn't build on macOS.
+--Stefan]
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ block/export/export.c             | 8 ++++----
+ block/export/meson.build          | 2 +-
+ contrib/libvhost-user/meson.build | 1 +
+ meson.build                       | 6 +++++-
+ util/meson.build                  | 4 +++-
+files changed, 14 insertions(+), 7 deletions(-)
+diff --git a/block/export/export.c b/block/export/export.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/export.c
++++ b/block/export/export.c
+@@ -XXX,XX +XXX,XX @@
+ #include "sysemu/block-backend.h"
+ #include "block/export.h"
+ #include "block/nbd.h"
+-#if CONFIG_LINUX
+-#include "block/export/vhost-user-blk-server.h"
+-#endif
+ #include "qapi/error.h"
+ #include "qapi/qapi-commands-block-export.h"
+ #include "qapi/qapi-events-block-export.h"
+ #include "qemu/id.h"
++#ifdef CONFIG_VHOST_USER
++#include "vhost-user-blk-server.h"
++#endif
+ static const BlockExportDriver *blk_exp_drivers[] = {
+     &blk_exp_nbd,
+-#if CONFIG_LINUX
++#ifdef CONFIG_VHOST_USER
+     &blk_exp_vhost_user_blk,
+ #endif
+ };
+diff --git a/block/export/meson.build b/block/export/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/meson.build
++++ b/block/export/meson.build
+@@ -XXX,XX +XXX,XX @@
+ block_ss.add(files('export.c'))
+-block_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-blk-server.c', '../../contrib/libvhost-user/libvhost-user.c'))
++block_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: files('vhost-user-blk-server.c'))
+diff --git a/contrib/libvhost-user/meson.build b/contrib/libvhost-user/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/contrib/libvhost-user/meson.build
++++ b/contrib/libvhost-user/meson.build
+@@ -XXX,XX +XXX,XX @@
+ libvhost_user = static_library('vhost-user',
+                                files('libvhost-user.c', 'libvhost-user-glib.c'),
+                                build_by_default: false)
++vhost_user = declare_dependency(link_with: libvhost_user)
+diff --git a/meson.build b/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/meson.build
++++ b/meson.build
+@@ -XXX,XX +XXX,XX @@ trace_events_subdirs += [
+   'util',
+ ]
++vhost_user = not_found
++if 'CONFIG_VHOST_USER' in config_host
++  subdir('contrib/libvhost-user')
++endif
++
+ subdir('qapi')
+ subdir('qobject')
+ subdir('stubs')
+@@ -XXX,XX +XXX,XX @@ if have_tools
+              install: true)
+   if 'CONFIG_VHOST_USER' in config_host
+-    subdir('contrib/libvhost-user')
+     subdir('contrib/vhost-user-blk')
+     subdir('contrib/vhost-user-gpu')
+     subdir('contrib/vhost-user-input')
+diff --git a/util/meson.build b/util/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/util/meson.build
++++ b/util/meson.build
+@@ -XXX,XX +XXX,XX @@ if have_block
+   util_ss.add(files('main-loop.c'))
+   util_ss.add(files('nvdimm-utils.c'))
+   util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
+-  util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
++  util_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: [
++    files('vhost-user-server.c'), vhost_user
++  ])
+   util_ss.add(files('block-helpers.c'))
+   util_ss.add(files('qemu-coroutine-sleep.c'))
+   util_ss.add(files('qemu-co-shared-resource.c'))
+--
+.26.2

-New patch
+[PULL v2 20/28] qemu-storage-daemon: avoid compiling blockdev_ss twice
+Introduce libblkdev.fa to avoid recompiling blockdev_ss twice.
+Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
+Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200929125516.186715-3-stefanha@redhat.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ meson.build                | 12 ++++++++++--
+ storage-daemon/meson.build |  3 +--
+files changed, 11 insertions(+), 4 deletions(-)
+diff --git a/meson.build b/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/meson.build
++++ b/meson.build
+@@ -XXX,XX +XXX,XX @@ blockdev_ss.add(files(
+ # os-win32.c does not
+ blockdev_ss.add(when: 'CONFIG_POSIX', if_true: files('os-posix.c'))
+ softmmu_ss.add(when: 'CONFIG_WIN32', if_true: [files('os-win32.c')])
+-softmmu_ss.add_all(blockdev_ss)
+ common_ss.add(files('cpus-common.c'))
+@@ -XXX,XX +XXX,XX @@ block = declare_dependency(link_whole: [libblock],
+                            link_args: '@block.syms',
+                            dependencies: [crypto, io])
++blockdev_ss = blockdev_ss.apply(config_host, strict: false)
++libblockdev = static_library('blockdev', blockdev_ss.sources() + genh,
++                             dependencies: blockdev_ss.dependencies(),
++                             name_suffix: 'fa',
++                             build_by_default: false)
++
++blockdev = declare_dependency(link_whole: [libblockdev],
++                              dependencies: [block])
++
+ qmp_ss = qmp_ss.apply(config_host, strict: false)
+ libqmp = static_library('qmp', qmp_ss.sources() + genh,
+                         dependencies: qmp_ss.dependencies(),
+@@ -XXX,XX +XXX,XX @@ foreach m : block_mods + softmmu_mods
+                 install_dir: config_host['qemu_moddir'])
+ endforeach
+-softmmu_ss.add(authz, block, chardev, crypto, io, qmp)
++softmmu_ss.add(authz, blockdev, chardev, crypto, io, qmp)
+ common_ss.add(qom, qemuutil)
+ common_ss.add_all(when: 'CONFIG_SOFTMMU', if_true: [softmmu_ss])
+diff --git a/storage-daemon/meson.build b/storage-daemon/meson.build
+index XXXXXXX..XXXXXXX 100644
+--- a/storage-daemon/meson.build
++++ b/storage-daemon/meson.build
+@@ -XXX,XX +XXX,XX @@
+ qsd_ss = ss.source_set()
+ qsd_ss.add(files('qemu-storage-daemon.c'))
+-qsd_ss.add(block, chardev, qmp, qom, qemuutil)
+-qsd_ss.add_all(blockdev_ss)
++qsd_ss.add(blockdev, chardev, qmp, qom, qemuutil)
+ subdir('qapi')
+--
+.26.2

-[Qemu-devel] [PULL 8/8] docs: add Security chapter to the documentation
+[PULL v2 21/28] block: move block exports to libblockdev
-This new chapter in the QEMU documentation covers the security
+Block exports are used by softmmu, qemu-storage-daemon, and qemu-nbd.
-requirements that QEMU is designed to meet and principles for securely
+They are not used by other programs and are not otherwise needed in
-deploying QEMU.
+libblock.
-It is just a starting point that can be extended in the future with more
+Undo the recent move of blockdev-nbd.c from blockdev_ss into block_ss.
-information.
+Since bdrv_close_all() (libblock) calls blk_exp_close_all()
 (libblockdev) a stub function is required..
 Make qemu-nbd.c use signal handling utility functions instead of
 duplicating the code. This helps because os-posix.c is in libblockdev
 and it depends on a qemu_system_killed() symbol that qemu-nbd.c lacks.
 Once we use the signal handling utility functions we also end up
 providing the necessary symbol.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
+Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
-Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
+Reviewed-by: Eric Blake <eblake@redhat.com>
-Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
+Message-id: 20200929125516.186715-4-stefanha@redhat.com
-Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
+[Fixed s/ndb/nbd/ typo in commit description as suggested by Eric Blake
-Reviewed-by: Li Qiang <liq3ea@gmail.com>
+--Stefan]
 Message-id: 20190509121820.16294-3-stefanha@redhat.com
 Message-Id: <20190509121820.16294-3-stefanha@redhat.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- Makefile           |   2 +-
+ qemu-nbd.c                | 21 ++++++++-------------
- docs/security.texi | 131 +++++++++++++++++++++++++++++++++++++++++++++
+ stubs/blk-exp-close-all.c |  7 +++++++
- qemu-doc.texi      |   3 ++
+ block/export/meson.build  |  4 ++--
-files changed, 135 insertions(+), 1 deletion(-)
+ meson.build               |  4 ++--
- create mode 100644 docs/security.texi
+ nbd/meson.build           |  2 ++
  stubs/meson.build         |  1 +
 files changed, 22 insertions(+), 17 deletions(-)
  create mode 100644 stubs/blk-exp-close-all.c
-diff --git a/Makefile b/Makefile
+diff --git a/qemu-nbd.c b/qemu-nbd.c
 index XXXXXXX..XXXXXXX 100644
---- a/Makefile
+--- a/qemu-nbd.c
-+++ b/Makefile
++++ b/qemu-nbd.c
-@@ -XXX,XX +XXX,XX @@ qemu-doc.html qemu-doc.info qemu-doc.pdf qemu-doc.txt: \
+@@ -XXX,XX +XXX,XX @@
-     qemu-img.texi qemu-nbd.texi qemu-options.texi qemu-option-trace.texi \
+ #include "qapi/error.h"
-     qemu-deprecated.texi qemu-monitor.texi qemu-img-cmds.texi qemu-ga.texi \
+ #include "qemu/cutils.h"
-     qemu-monitor-info.texi docs/qemu-block-drivers.texi \
+ #include "sysemu/block-backend.h"
--    docs/qemu-cpu-models.texi
++#include "sysemu/runstate.h" /* for qemu_system_killed() prototype */
-+    docs/qemu-cpu-models.texi docs/security.texi
+ #include "block/block_int.h"
+ #include "block/nbd.h"
- docs/interop/qemu-ga-ref.dvi docs/interop/qemu-ga-ref.html \
+ #include "qemu/main-loop.h"
-     docs/interop/qemu-ga-ref.info docs/interop/qemu-ga-ref.pdf \
+@@ -XXX,XX +XXX,XX @@ QEMU_COPYRIGHT "\n"
-diff --git a/docs/security.texi b/docs/security.texi
+ }
  #ifdef CONFIG_POSIX
 -static void termsig_handler(int signum)
 +/*
 + * The client thread uses SIGTERM to interrupt the server.  A signal
 + * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 + */
 +void qemu_system_killed(int signum, pid_t pid)
  {
      qatomic_cmpxchg(&state, RUNNING, TERMINATE);
      qemu_notify_event();
@@ -XXX,XX +XXX,XX @@ int main(int argc, char **argv)
      BlockExportOptions *export_opts;
  #ifdef CONFIG_POSIX
 -    /*
 -     * Exit gracefully on various signals, which includes SIGTERM used
 -     * by 'qemu-nbd -v -c'.
 -     */
 -    struct sigaction sa_sigterm;
 -    memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 -    sa_sigterm.sa_handler = termsig_handler;
 -    sigaction(SIGTERM, &sa_sigterm, NULL);
 -    sigaction(SIGINT, &sa_sigterm, NULL);
 -    sigaction(SIGHUP, &sa_sigterm, NULL);
 -
 -    signal(SIGPIPE, SIG_IGN);
 +    os_setup_early_signal_handling();
 +    os_setup_signal_handling();
  #endif
      socket_init();
 diff --git a/stubs/blk-exp-close-all.c b/stubs/blk-exp-close-all.c
 new file mode 100644
 index XXXXXXX..XXXXXXX
 --- /dev/null
-+++ b/docs/security.texi
++++ b/stubs/blk-exp-close-all.c
 @@ -XXX,XX +XXX,XX @@
-+@node Security
++#include "qemu/osdep.h"
-+@chapter Security
++#include "block/export.h"
 +
-+@section Overview
++/* Only used in programs that support block exports (libblockdev.fa) */
-+
++void blk_exp_close_all(void)
-+This chapter explains the security requirements that QEMU is designed to meet
++{
-+and principles for securely deploying QEMU.
++}
-+
+diff --git a/block/export/meson.build b/block/export/meson.build
 +@section Security Requirements
 +
 +QEMU supports many different use cases, some of which have stricter security
 +requirements than others.  The community has agreed on the overall security
 +requirements that users may depend on.  These requirements define what is
 +considered supported from a security perspective.
 +
 +@subsection Virtualization Use Case
 +
 +The virtualization use case covers cloud and virtual private server (VPS)
 +hosting, as well as traditional data center and desktop virtualization.  These
 +use cases rely on hardware virtualization extensions to execute guest code
 +safely on the physical CPU at close-to-native speed.
 +
 +The following entities are untrusted, meaning that they may be buggy or
 +malicious:
 +
 +@itemize
 +@item Guest
 +@item User-facing interfaces (e.g. VNC, SPICE, WebSocket)
 +@item Network protocols (e.g. NBD, live migration)
 +@item User-supplied files (e.g. disk images, kernels, device trees)
 +@item Passthrough devices (e.g. PCI, USB)
 +@end itemize
 +
 +Bugs affecting these entities are evaluated on whether they can cause damage in
 +real-world use cases and treated as security bugs if this is the case.
 +
 +@subsection Non-virtualization Use Case
 +
 +The non-virtualization use case covers emulation using the Tiny Code Generator
 +(TCG).  In principle the TCG and device emulation code used in conjunction with
 +the non-virtualization use case should meet the same security requirements as
 +the virtualization use case.  However, for historical reasons much of the
 +non-virtualization use case code was not written with these security
 +requirements in mind.
 +
 +Bugs affecting the non-virtualization use case are not considered security
 +bugs at this time.  Users with non-virtualization use cases must not rely on
 +QEMU to provide guest isolation or any security guarantees.
 +
 +@section Architecture
 +
 +This section describes the design principles that ensure the security
 +requirements are met.
 +
 +@subsection Guest Isolation
 +
 +Guest isolation is the confinement of guest code to the virtual machine.  When
 +guest code gains control of execution on the host this is called escaping the
 +virtual machine.  Isolation also includes resource limits such as throttling of
 +CPU, memory, disk, or network.  Guests must be unable to exceed their resource
 +limits.
 +
 +QEMU presents an attack surface to the guest in the form of emulated devices.
 +The guest must not be able to gain control of QEMU.  Bugs in emulated devices
 +could allow malicious guests to gain code execution in QEMU.  At this point the
 +guest has escaped the virtual machine and is able to act in the context of the
 +QEMU process on the host.
 +
 +Guests often interact with other guests and share resources with them.  A
 +malicious guest must not gain control of other guests or access their data.
 +Disk image files and network traffic must be protected from other guests unless
 +explicitly shared between them by the user.
 +
 +@subsection Principle of Least Privilege
 +
 +The principle of least privilege states that each component only has access to
 +the privileges necessary for its function.  In the case of QEMU this means that
 +each process only has access to resources belonging to the guest.
 +
 +The QEMU process should not have access to any resources that are inaccessible
 +to the guest.  This way the guest does not gain anything by escaping into the
 +QEMU process since it already has access to those same resources from within
 +the guest.
 +
 +Following the principle of least privilege immediately fulfills guest isolation
 +requirements.  For example, guest A only has access to its own disk image file
 +@code{a.img} and not guest B's disk image file @code{b.img}.
 +
 +In reality certain resources are inaccessible to the guest but must be
 +available to QEMU to perform its function.  For example, host system calls are
 +necessary for QEMU but are not exposed to guests.  A guest that escapes into
 +the QEMU process can then begin invoking host system calls.
 +
 +New features must be designed to follow the principle of least privilege.
 +Should this not be possible for technical reasons, the security risk must be
 +clearly documented so users are aware of the trade-off of enabling the feature.
 +
 +@subsection Isolation mechanisms
 +
 +Several isolation mechanisms are available to realize this architecture of
 +guest isolation and the principle of least privilege.  With the exception of
 +Linux seccomp, these mechanisms are all deployed by management tools that
 +launch QEMU, such as libvirt.  They are also platform-specific so they are only
 +described briefly for Linux here.
 +
 +The fundamental isolation mechanism is that QEMU processes must run as
 +unprivileged users.  Sometimes it seems more convenient to launch QEMU as
 +root to give it access to host devices (e.g. @code{/dev/net/tun}) but this poses a
 +huge security risk.  File descriptor passing can be used to give an otherwise
 +unprivileged QEMU process access to host devices without running QEMU as root.
 +It is also possible to launch QEMU as a non-root user and configure UNIX groups
 +for access to @code{/dev/kvm}, @code{/dev/net/tun}, and other device nodes.
 +Some Linux distros already ship with UNIX groups for these devices by default.
 +
 +@itemize
 +@item SELinux and AppArmor make it possible to confine processes beyond the
 +traditional UNIX process and file permissions model.  They restrict the QEMU
 +process from accessing processes and files on the host system that are not
 +needed by QEMU.
 +
 +@item Resource limits and cgroup controllers provide throughput and utilization
 +limits on key resources such as CPU time, memory, and I/O bandwidth.
 +
 +@item Linux namespaces can be used to make process, file system, and other system
 +resources unavailable to QEMU.  A namespaced QEMU process is restricted to only
 +those resources that were granted to it.
 +
 +@item Linux seccomp is available via the QEMU @option{--sandbox} option.  It disables
 +system calls that are not needed by QEMU, thereby reducing the host kernel
 +attack surface.
 +@end itemize
 diff --git a/qemu-doc.texi b/qemu-doc.texi
 index XXXXXXX..XXXXXXX 100644
---- a/qemu-doc.texi
+--- a/block/export/meson.build
-+++ b/qemu-doc.texi
++++ b/block/export/meson.build
 @@ -XXX,XX +XXX,XX @@
- * QEMU Guest Agent::
+-block_ss.add(files('export.c'))
- * QEMU User space emulator::
+-block_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: files('vhost-user-blk-server.c'))
- * System requirements::
++blockdev_ss.add(files('export.c'))
-+* Security::
++blockdev_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: files('vhost-user-blk-server.c'))
- * Implementation notes::
+diff --git a/meson.build b/meson.build
- * Deprecated features::
+index XXXXXXX..XXXXXXX 100644
- * Supported build platforms::
+--- a/meson.build
-@@ -XXX,XX +XXX,XX @@ added with Linux 4.5 which is supported by the major distros. And even
++++ b/meson.build
- if RHEL7 has kernel 3.10, KVM there has the required functionality there
+@@ -XXX,XX +XXX,XX @@ subdir('dump')
- to make it close to a 4.5 or newer kernel.
+ block_ss.add(files(
-+@include docs/security.texi
+   'block.c',
-+
+-  'blockdev-nbd.c',
- @include qemu-tech.texi
+   'blockjob.c',
+   'job.c',
- @include qemu-deprecated.texi
+   'qemu-io-cmds.c',
@@ -XXX,XX +XXX,XX @@ subdir('block')
  blockdev_ss.add(files(
    'blockdev.c',
 +  'blockdev-nbd.c',
    'iothread.c',
    'job-qmp.c',
  ))
@@ -XXX,XX +XXX,XX @@ if have_tools
    qemu_io = executable('qemu-io', files('qemu-io.c'),
               dependencies: [block, qemuutil], install: true)
    qemu_nbd = executable('qemu-nbd', files('qemu-nbd.c'),
 -               dependencies: [block, qemuutil], install: true)
 +               dependencies: [blockdev, qemuutil], install: true)
    subdir('storage-daemon')
    subdir('contrib/rdmacm-mux')
 diff --git a/nbd/meson.build b/nbd/meson.build
 index XXXXXXX..XXXXXXX 100644
 --- a/nbd/meson.build
 +++ b/nbd/meson.build
@@ -XXX,XX +XXX,XX @@
  block_ss.add(files(
    'client.c',
    'common.c',
 +))
 +blockdev_ss.add(files(
    'server.c',
  ))
 diff --git a/stubs/meson.build b/stubs/meson.build
 index XXXXXXX..XXXXXXX 100644
 --- a/stubs/meson.build
 +++ b/stubs/meson.build
@@ -XXX,XX +XXX,XX @@
  stub_ss.add(files('arch_type.c'))
  stub_ss.add(files('bdrv-next-monitor-owned.c'))
  stub_ss.add(files('blk-commit-all.c'))
 +stub_ss.add(files('blk-exp-close-all.c'))
  stub_ss.add(files('blockdev-close-all-bdrv-states.c'))
  stub_ss.add(files('change-state-handler.c'))
  stub_ss.add(files('cmos.c'))
 --
-.21.0
+.26.2

-New patch
+[PULL v2 22/28] block/export: add iothread and fixed-iothread options
+Make it possible to specify the iothread where the export will run. By
+default the block node can be moved to other AioContexts later and the
+export will follow. The fixed-iothread option forces strict behavior
+that prevents changing AioContext while the export is active. See the
+QAPI docs for details.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-id: 20200929125516.186715-5-stefanha@redhat.com
+[Fix stray '#' character in block-export.json and add missing "(since:
+.2)" as suggested by Eric Blake.
+--Stefan]
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ qapi/block-export.json               | 11 ++++++++++
+ block/export/export.c                | 31 +++++++++++++++++++++++++++-
+ block/export/vhost-user-blk-server.c |  5 ++++-
+ nbd/server.c                         |  2 --
+files changed, 45 insertions(+), 4 deletions(-)
+diff --git a/qapi/block-export.json b/qapi/block-export.json
+index XXXXXXX..XXXXXXX 100644
+--- a/qapi/block-export.json
++++ b/qapi/block-export.json
+@@ -XXX,XX +XXX,XX @@
+ #                export before completion is signalled. (since: 5.2;
+ #                default: false)
+ #
++# @iothread: The name of the iothread object where the export will run. The
++#            default is to use the thread currently associated with the
++#            block node. (since: 5.2)
++#
++# @fixed-iothread: True prevents the block node from being moved to another
++#                  thread while the export is active. If true and @iothread is
++#                  given, export creation fails if the block node cannot be
++#                  moved to the iothread. The default is false. (since: 5.2)
++#
+ # Since: 4.2
+ ##
+ { 'union': 'BlockExportOptions',
+   'base': { 'type': 'BlockExportType',
+             'id': 'str',
++        '*fixed-iothread': 'bool',
++        '*iothread': 'str',
+             'node-name': 'str',
+             '*writable': 'bool',
+             '*writethrough': 'bool' },
+diff --git a/block/export/export.c b/block/export/export.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/export.c
++++ b/block/export/export.c
+@@ -XXX,XX +XXX,XX @@
+ #include "block/block.h"
+ #include "sysemu/block-backend.h"
++#include "sysemu/iothread.h"
+ #include "block/export.h"
+ #include "block/nbd.h"
+ #include "qapi/error.h"
+@@ -XXX,XX +XXX,XX @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
+ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
+ {
++    bool fixed_iothread = export->has_fixed_iothread && export->fixed_iothread;
+     const BlockExportDriver *drv;
+     BlockExport *exp = NULL;
+     BlockDriverState *bs;
+-    BlockBackend *blk;
++    BlockBackend *blk = NULL;
+     AioContext *ctx;
+     uint64_t perm;
+     int ret;
+@@ -XXX,XX +XXX,XX @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
+     ctx = bdrv_get_aio_context(bs);
+     aio_context_acquire(ctx);
++    if (export->has_iothread) {
++        IOThread *iothread;
++        AioContext *new_ctx;
++
++        iothread = iothread_by_id(export->iothread);
++        if (!iothread) {
++            error_setg(errp, "iothread \"%s\" not found", export->iothread);
++            goto fail;
++        }
++
++        new_ctx = iothread_get_aio_context(iothread);
++
++        ret = bdrv_try_set_aio_context(bs, new_ctx, errp);
++        if (ret == 0) {
++            aio_context_release(ctx);
++            aio_context_acquire(new_ctx);
++            ctx = new_ctx;
++        } else if (fixed_iothread) {
++            goto fail;
++        }
++    }
++
+     /*
+      * Block exports are used for non-shared storage migration. Make sure
+      * that BDRV_O_INACTIVE is cleared and the image is ready for write
+@@ -XXX,XX +XXX,XX @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
+     }
+     blk = blk_new(ctx, perm, BLK_PERM_ALL);
++
++    if (!fixed_iothread) {
++        blk_set_allow_aio_context_change(blk, true);
++    }
++
+     ret = blk_insert_bs(blk, bs, errp);
+     if (ret < 0) {
+         goto fail;
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/vhost-user-blk-server.c
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@ static const VuDevIface vu_blk_iface = {
+ static void blk_aio_attached(AioContext *ctx, void *opaque)
+ {
+     VuBlkExport *vexp = opaque;
++
++    vexp->export.ctx = ctx;
+     vhost_user_server_attach_aio_context(&vexp->vu_server, ctx);
+ }
+ static void blk_aio_detach(void *opaque)
+ {
+     VuBlkExport *vexp = opaque;
++
+     vhost_user_server_detach_aio_context(&vexp->vu_server);
++    vexp->export.ctx = NULL;
+ }
+ static void
+@@ -XXX,XX +XXX,XX @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
+     vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
+                                logical_block_size);
+-    blk_set_allow_aio_context_change(exp->blk, true);
+     blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
+                                  vexp);
+diff --git a/nbd/server.c b/nbd/server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/nbd/server.c
++++ b/nbd/server.c
+@@ -XXX,XX +XXX,XX @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
+         return ret;
+     }
+-    blk_set_allow_aio_context_change(blk, true);
+-
+     QTAILQ_INIT(&exp->clients);
+     exp->name = g_strdup(arg->name);
+     exp->description = g_strdup(arg->description);
+--
+.26.2

-New patch
+[PULL v2 23/28] block/export: add vhost-user-blk multi-queue support
+Allow the number of queues to be configured using --export
+vhost-user-blk,num-queues=N. This setting should match the QEMU --device
+vhost-user-blk-pci,num-queues=N setting but QEMU vhost-user-blk.c lowers
+its own value if the vhost-user-blk backend offers fewer queues than
+QEMU.
+The vhost-user-blk-server.c code is already capable of multi-queue. All
+virtqueue processing runs in the same AioContext. No new locking is
+needed.
+Add the num-queues=N option and set the VIRTIO_BLK_F_MQ feature bit.
+Note that the feature bit only announces the presence of the num_queues
+configuration space field. It does not promise that there is more than 1
+virtqueue, so we can set it unconditionally.
+I tested multi-queue by running a random read fio test with numjobs=4 on
+an -smp 4 guest. After the benchmark finished the guest /proc/interrupts
+file showed activity on all 4 virtio-blk MSI-X. The /sys/block/vda/mq/
+directory shows that Linux blk-mq has 4 queues configured.
+An automated test is included in the next commit.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Acked-by: Markus Armbruster <armbru@redhat.com>
+Message-id: 20201001144604.559733-2-stefanha@redhat.com
+[Fixed accidental tab characters as suggested by Markus Armbruster
+--Stefan]
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ qapi/block-export.json               | 10 +++++++---
+ block/export/vhost-user-blk-server.c | 24 ++++++++++++++++++------
+files changed, 25 insertions(+), 9 deletions(-)
+diff --git a/qapi/block-export.json b/qapi/block-export.json
+index XXXXXXX..XXXXXXX 100644
+--- a/qapi/block-export.json
++++ b/qapi/block-export.json
+@@ -XXX,XX +XXX,XX @@
+ #        SocketAddress types are supported. Passed fds must be UNIX domain
+ #        sockets.
+ # @logical-block-size: Logical block size in bytes. Defaults to 512 bytes.
++# @num-queues: Number of request virtqueues. Must be greater than 0. Defaults
++#              to 1.
+ #
+ # Since: 5.2
+ ##
+ { 'struct': 'BlockExportOptionsVhostUserBlk',
+-  'data': { 'addr': 'SocketAddress', '*logical-block-size': 'size' } }
++  'data': { 'addr': 'SocketAddress',
++        '*logical-block-size': 'size',
++            '*num-queues': 'uint16'} }
+ ##
+ # @NbdServerAddOptions:
+@@ -XXX,XX +XXX,XX @@
+ { 'union': 'BlockExportOptions',
+   'base': { 'type': 'BlockExportType',
+             'id': 'str',
+-        '*fixed-iothread': 'bool',
+-        '*iothread': 'str',
++            '*fixed-iothread': 'bool',
++            '*iothread': 'str',
+             'node-name': 'str',
+             '*writable': 'bool',
+             '*writethrough': 'bool' },
+diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/export/vhost-user-blk-server.c
++++ b/block/export/vhost-user-blk-server.c
+@@ -XXX,XX +XXX,XX @@
+ #include "util/block-helpers.h"
+ enum {
+-    VHOST_USER_BLK_MAX_QUEUES = 1,
++    VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1,
+ };
+ struct virtio_blk_inhdr {
+     unsigned char status;
+@@ -XXX,XX +XXX,XX @@ static uint64_t vu_blk_get_features(VuDev *dev)
+ull << VIRTIO_BLK_F_DISCARD |
+ull << VIRTIO_BLK_F_WRITE_ZEROES |
+ull << VIRTIO_BLK_F_CONFIG_WCE |
++               1ull << VIRTIO_BLK_F_MQ |
+ull << VIRTIO_F_VERSION_1 |
+ull << VIRTIO_RING_F_INDIRECT_DESC |
+ull << VIRTIO_RING_F_EVENT_IDX |
+@@ -XXX,XX +XXX,XX @@ static void blk_aio_detach(void *opaque)
+ static void
+ vu_blk_initialize_config(BlockDriverState *bs,
+-                           struct virtio_blk_config *config, uint32_t blk_size)
++                         struct virtio_blk_config *config,
++                         uint32_t blk_size,
++                         uint16_t num_queues)
+ {
+     config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+     config->blk_size = blk_size;
+@@ -XXX,XX +XXX,XX @@ vu_blk_initialize_config(BlockDriverState *bs,
+     config->seg_max = 128 - 2;
+     config->min_io_size = 1;
+     config->opt_io_size = 1;
+-    config->num_queues = VHOST_USER_BLK_MAX_QUEUES;
++    config->num_queues = num_queues;
+     config->max_discard_sectors = 32768;
+     config->max_discard_seg = 1;
+     config->discard_sector_alignment = config->blk_size >> 9;
+@@ -XXX,XX +XXX,XX @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
+     BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk;
+     Error *local_err = NULL;
+     uint64_t logical_block_size;
++    uint16_t num_queues = VHOST_USER_BLK_NUM_QUEUES_DEFAULT;
+     vexp->writable = opts->writable;
+     vexp->blkcfg.wce = 0;
+@@ -XXX,XX +XXX,XX @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
+     }
+     vexp->blk_size = logical_block_size;
+     blk_set_guest_block_size(exp->blk, logical_block_size);
++
++    if (vu_opts->has_num_queues) {
++        num_queues = vu_opts->num_queues;
++    }
++    if (num_queues == 0) {
++        error_setg(errp, "num-queues must be greater than 0");
++        return -EINVAL;
++    }
++
+     vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
+-                               logical_block_size);
++                             logical_block_size, num_queues);
+     blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
+                                  vexp);
+     if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx,
+-                                 VHOST_USER_BLK_MAX_QUEUES, &vu_blk_iface,
+-                                 errp)) {
++                                 num_queues, &vu_blk_iface, errp)) {
+         blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
+                                         blk_aio_detach, vexp);
+         return -EADDRNOTAVAIL;
+--
+.26.2

-[Qemu-devel] [PULL 3/8] util/readline: Add braces to fix checkpatch errors
+[PULL v2 24/28] block/io: fix bdrv_co_block_status_above
-From: Jules Irenge <jbi.octave@gmail.com>
+From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
-Add braces to fix errors issued by checkpatch.pl tool
+bdrv_co_block_status_above has several design problems with handling
-"ERROR: braces {} are necessary for all arms of this statement"
+short backing files:
 Within "util/readline.c" file
 Message-Id: <20190330112142.14082-1-jbi.octave@gmail.com>
+. With want_zeros=true, it may return ret with BDRV_BLOCK_ZERO but
+without BDRV_BLOCK_ALLOCATED flag, when actually short backing file
+which produces these after-EOF zeros is inside requested backing
+sequence.
+. With want_zero=false, it may return pnum=0 prior to actual EOF,
+because of EOF of short backing file.
+Fix these things, making logic about short backing files clearer.
+With fixed bdrv_block_status_above we also have to improve is_zero in
+qcow2 code, otherwise iotest 154 will fail, because with this patch we
+stop to merge zeros of different types (produced by fully unallocated
+in the whole backing chain regions vs produced by short backing files).
+Note also, that this patch leaves for another day the general problem
+around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
+vs go-to-backing.
+Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+Reviewed-by: Alberto Garcia <berto@igalia.com>
+Reviewed-by: Eric Blake <eblake@redhat.com>
+Message-id: 20200924194003.22080-2-vsementsov@virtuozzo.com
+[Fix s/comes/come/ as suggested by Eric Blake
+--Stefan]
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- util/readline.c | 50 ++++++++++++++++++++++++++++++++-----------------
+ block/io.c    | 68 ++++++++++++++++++++++++++++++++++++++++-----------
-file changed, 33 insertions(+), 17 deletions(-)
+ block/qcow2.c | 16 ++++++++++--
 files changed, 68 insertions(+), 16 deletions(-)
-diff --git a/util/readline.c b/util/readline.c
+diff --git a/block/io.c b/block/io.c
 index XXXXXXX..XXXXXXX 100644
---- a/util/readline.c
+--- a/block/io.c
-+++ b/util/readline.c
++++ b/block/io.c
-@@ -XXX,XX +XXX,XX @@ static void readline_update(ReadLineState *rs)
+@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
-         rs->cmd_buf[rs->cmd_buf_size] = '\0';
+                                   int64_t *map,
-         if (rs->read_password) {
+                                   BlockDriverState **file)
-             len = strlen(rs->cmd_buf);
+ {
--            for (i = 0; i < len; i++)
++    int ret;
-+            for (i = 0; i < len; i++) {
+     BlockDriverState *p;
-                 rs->printf_func(rs->opaque, "*");
+-    int ret = 0;
 -    bool first = true;
 +    int64_t eof = 0;
      assert(bs != base);
 -    for (p = bs; p != base; p = bdrv_filter_or_cow_bs(p)) {
 +
 +    ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
 +    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED) {
 +        return ret;
 +    }
 +
 +    if (ret & BDRV_BLOCK_EOF) {
 +        eof = offset + *pnum;
 +    }
 +
 +    assert(*pnum <= bytes);
 +    bytes = *pnum;
 +
 +    for (p = bdrv_filter_or_cow_bs(bs); p != base;
 +         p = bdrv_filter_or_cow_bs(p))
 +    {
          ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
                                     file);
          if (ret < 0) {
 -            break;
 +            return ret;
          }
 -        if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) {
 +        if (*pnum == 0) {
              /*
 -             * Reading beyond the end of the file continues to read
 -             * zeroes, but we can only widen the result to the
 -             * unallocated length we learned from an earlier
 -             * iteration.
 +             * The top layer deferred to this layer, and because this layer is
 +             * short, any zeroes that we synthesize beyond EOF behave as if they
 +             * were allocated at this layer.
 +             *
 +             * We don't include BDRV_BLOCK_EOF into ret, as upper layer may be
 +             * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see
 +             * below.
               */
 +            assert(ret & BDRV_BLOCK_EOF);
              *pnum = bytes;
 +            if (file) {
 +                *file = p;
 +            }
-         } else {
++            ret = BDRV_BLOCK_ZERO | BDRV_BLOCK_ALLOCATED;
-             rs->printf_func(rs->opaque, "%s", rs->cmd_buf);
++            break;
          }
-@@ -XXX,XX +XXX,XX @@ static void readline_up_char(ReadLineState *rs)
+-        if (ret & (BDRV_BLOCK_ZERO | BDRV_BLOCK_DATA)) {
- {
++        if (ret & BDRV_BLOCK_ALLOCATED) {
-     int idx;
++            /*
++             * We've found the node and the status, we must break.
--    if (rs->hist_entry == 0)
++             *
-+    if (rs->hist_entry == 0) {
++             * Drop BDRV_BLOCK_EOF, as it's not for upper layer, which may be
-         return;
++             * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see
-+    }
++             * below.
-     if (rs->hist_entry == -1) {
++             */
-         /* Find latest entry */
++            ret &= ~BDRV_BLOCK_EOF;
          for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
 -            if (rs->history[idx] == NULL)
 +            if (rs->history[idx] == NULL) {
                  break;
 +            }
          }
          rs->hist_entry = idx;
      }
@@ -XXX,XX +XXX,XX @@ static void readline_up_char(ReadLineState *rs)
  static void readline_down_char(ReadLineState *rs)
  {
 -    if (rs->hist_entry == -1)
 +    if (rs->hist_entry == -1) {
          return;
 +    }
      if (rs->hist_entry < READLINE_MAX_CMDS - 1 &&
          rs->history[++rs->hist_entry] != NULL) {
          pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
      char *hist_entry, *new_entry;
      int idx;
 -    if (cmdline[0] == '\0')
 +    if (cmdline[0] == '\0') {
          return;
 +    }
      new_entry = NULL;
      if (rs->hist_entry != -1) {
          /* We were editing an existing history entry: replace it */
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
      /* Search cmdline in history buffers */
      for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
          hist_entry = rs->history[idx];
 -        if (hist_entry == NULL)
 +        if (hist_entry == NULL) {
              break;
 +        }
          if (strcmp(hist_entry, cmdline) == 0) {
          same_entry:
              new_entry = hist_entry;
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
                      (READLINE_MAX_CMDS - (idx + 1)) * sizeof(char *));
              rs->history[READLINE_MAX_CMDS - 1] = NULL;
              for (; idx < READLINE_MAX_CMDS; idx++) {
 -                if (rs->history[idx] == NULL)
 +                if (rs->history[idx] == NULL) {
                      break;
 +                }
              }
              break;
          }
-@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
+-        /* [offset, pnum] unallocated on this layer, which could be only
-         rs->history[READLINE_MAX_CMDS - 1] = NULL;
+-         * the first part of [offset, bytes].  */
-         idx = READLINE_MAX_CMDS - 1;
+-        bytes = MIN(bytes, *pnum);
 -        first = false;
 +
 +        /*
 +         * OK, [offset, offset + *pnum) region is unallocated on this layer,
 +         * let's continue the diving.
 +         */
 +        assert(*pnum <= bytes);
 +        bytes = *pnum;
 +    }
 +
 +    if (offset + *pnum == eof) {
 +        ret |= BDRV_BLOCK_EOF;
      }
--    if (new_entry == NULL)
++
-+    if (new_entry == NULL) {
+     return ret;
          new_entry = g_strdup(cmdline);
 +    }
      rs->history[idx] = new_entry;
      rs->hist_entry = -1;
  }
-@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
-     g_free(cmdline);
+diff --git a/block/qcow2.c b/block/qcow2.c
+index XXXXXXX..XXXXXXX 100644
-     /* no completion found */
+--- a/block/qcow2.c
--    if (rs->nb_completions <= 0)
++++ b/block/qcow2.c
-+    if (rs->nb_completions <= 0) {
+@@ -XXX,XX +XXX,XX @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
-         return;
+     if (!bytes) {
-+    }
+         return true;
-     if (rs->nb_completions == 1) {
+     }
-         len = strlen(rs->completions[0]);
+-    res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
-         for (i = rs->completion_index; i < len; i++) {
+-    return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes;
-             readline_insert_char(rs, rs->completions[0][i]);
++
-         }
++    /*
-         /* extra space for next argument. XXX: make it more generic */
++     * bdrv_block_status_above doesn't merge different types of zeros, for
--        if (len > 0 && rs->completions[0][len - 1] != '/')
++     * example, zeros which come from the region which is unallocated in
-+        if (len > 0 && rs->completions[0][len - 1] != '/') {
++     * the whole backing chain, and zeros which come because of a short
-             readline_insert_char(rs, ' ');
++     * backing file. So, we need a loop.
-+        }
++     */
-     } else {
++    do {
-         qsort(rs->completions, rs->nb_completions, sizeof(char *),
++        res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
-               completion_comp);
++        offset += nr;
-@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
++        bytes -= nr;
-             if (i == 0) {
++    } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes);
-                 max_prefix = len;
++
-             } else {
++    return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0;
 -                if (len < max_prefix)
 +                if (len < max_prefix) {
                      max_prefix = len;
 +                }
                  for (j = 0; j < max_prefix; j++) {
 -                    if (rs->completions[i][j] != rs->completions[0][j])
 +                    if (rs->completions[i][j] != rs->completions[0][j]) {
                          max_prefix = j;
 +                    }
                  }
              }
 -            if (len > max_width)
 +            if (len > max_width) {
                  max_width = len;
 +            }
          }
          if (max_prefix > 0)
              for (i = rs->completion_index; i < max_prefix; i++) {
                  readline_insert_char(rs, rs->completions[0][i]);
              }
          max_width += 2;
 -        if (max_width < 10)
 +        if (max_width < 10) {
              max_width = 10;
 -        else if (max_width > 80)
 +        } else if (max_width > 80) {
              max_width = 80;
 +        }
          nb_cols = 80 / max_width;
          j = 0;
          for (i = 0; i < rs->nb_completions; i++) {
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
          case 10:
          case 13:
              rs->cmd_buf[rs->cmd_buf_size] = '\0';
 -            if (!rs->read_password)
 +            if (!rs->read_password) {
                  readline_hist_add(rs, rs->cmd_buf);
 +            }
              rs->printf_func(rs->opaque, "\n");
              rs->cmd_buf_index = 0;
              rs->cmd_buf_size = 0;
@@ -XXX,XX +XXX,XX @@ void readline_restart(ReadLineState *rs)
  const char *readline_get_history(ReadLineState *rs, unsigned int index)
  {
 -    if (index >= READLINE_MAX_CMDS)
 +    if (index >= READLINE_MAX_CMDS) {
          return NULL;
 +    }
      return rs->history[index];
  }
+ static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs,
 --
-.21.0
+.26.2

-New patch
+[PULL v2 25/28] block/io: bdrv_common_block_status_above: support include_base
+From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+In order to reuse bdrv_common_block_status_above in
+bdrv_is_allocated_above, let's support include_base parameter.
+Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+Reviewed-by: Alberto Garcia <berto@igalia.com>
+Reviewed-by: Eric Blake <eblake@redhat.com>
+Message-id: 20200924194003.22080-3-vsementsov@virtuozzo.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ block/coroutines.h |  2 ++
+ block/io.c         | 21 ++++++++++++++-------
+files changed, 16 insertions(+), 7 deletions(-)
+diff --git a/block/coroutines.h b/block/coroutines.h
+index XXXXXXX..XXXXXXX 100644
+--- a/block/coroutines.h
++++ b/block/coroutines.h
+@@ -XXX,XX +XXX,XX @@ bdrv_pwritev(BdrvChild *child, int64_t offset, unsigned int bytes,
+ int coroutine_fn
+ bdrv_co_common_block_status_above(BlockDriverState *bs,
+                                   BlockDriverState *base,
++                                  bool include_base,
+                                   bool want_zero,
+                                   int64_t offset,
+                                   int64_t bytes,
+@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
+ int generated_co_wrapper
+ bdrv_common_block_status_above(BlockDriverState *bs,
+                                BlockDriverState *base,
++                               bool include_base,
+                                bool want_zero,
+                                int64_t offset,
+                                int64_t bytes,
+diff --git a/block/io.c b/block/io.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/io.c
++++ b/block/io.c
+@@ -XXX,XX +XXX,XX @@ early_out:
+ int coroutine_fn
+ bdrv_co_common_block_status_above(BlockDriverState *bs,
+                                   BlockDriverState *base,
++                                  bool include_base,
+                                   bool want_zero,
+                                   int64_t offset,
+                                   int64_t bytes,
+@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
+     BlockDriverState *p;
+     int64_t eof = 0;
+-    assert(bs != base);
++    assert(include_base || bs != base);
++    assert(!include_base || base); /* Can't include NULL base */
+     ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
+-    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED) {
++    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
+         return ret;
+     }
+@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
+     assert(*pnum <= bytes);
+     bytes = *pnum;
+-    for (p = bdrv_filter_or_cow_bs(bs); p != base;
++    for (p = bdrv_filter_or_cow_bs(bs); include_base || p != base;
+          p = bdrv_filter_or_cow_bs(p))
+     {
+         ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
+@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
+             break;
+         }
++        if (p == base) {
++            assert(include_base);
++            break;
++        }
++
+         /*
+          * OK, [offset, offset + *pnum) region is unallocated on this layer,
+          * let's continue the diving.
+@@ -XXX,XX +XXX,XX @@ int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
+                             int64_t offset, int64_t bytes, int64_t *pnum,
+                             int64_t *map, BlockDriverState **file)
+ {
+-    return bdrv_common_block_status_above(bs, base, true, offset, bytes,
++    return bdrv_common_block_status_above(bs, base, false, true, offset, bytes,
+                                           pnum, map, file);
+ }
+@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
+     int ret;
+     int64_t dummy;
+-    ret = bdrv_common_block_status_above(bs, bdrv_filter_or_cow_bs(bs), false,
+-                                         offset, bytes, pnum ? pnum : &dummy,
+-                                         NULL, NULL);
++    ret = bdrv_common_block_status_above(bs, bs, true, false, offset,
++                                         bytes, pnum ? pnum : &dummy, NULL,
++                                         NULL);
+     if (ret < 0) {
+         return ret;
+     }
+--
+.26.2

-New patch
+[PULL v2 26/28] block/io: bdrv_common_block_status_above: support bs == base
+From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+We are going to reuse bdrv_common_block_status_above in
+bdrv_is_allocated_above. bdrv_is_allocated_above may be called with
+include_base == false and still bs == base (for ex. from img_rebase()).
+So, support this corner case.
+Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Reviewed-by: Eric Blake <eblake@redhat.com>
+Reviewed-by: Alberto Garcia <berto@igalia.com>
+Message-id: 20200924194003.22080-4-vsementsov@virtuozzo.com
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+---
+ block/io.c | 6 +++++-
+file changed, 5 insertions(+), 1 deletion(-)
+diff --git a/block/io.c b/block/io.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/io.c
++++ b/block/io.c
+@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
+     BlockDriverState *p;
+     int64_t eof = 0;
+-    assert(include_base || bs != base);
+     assert(!include_base || base); /* Can't include NULL base */
++    if (!include_base && bs == base) {
++        *pnum = bytes;
++        return 0;
++    }
++
+     ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
+     if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
+         return ret;
+--
+.26.2

-[Qemu-devel] [PULL 5/8] block/io.c: fix for the allocation failure
+[PULL v2 27/28] block/io: fix bdrv_is_allocated_above
-From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
+From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
-On a file system used by the customer, fallocate() returns an error
+bdrv_is_allocated_above wrongly handles short backing files: it reports
-if the block is not properly aligned. So, bdrv_co_pwrite_zeroes()
+after-EOF space as UNALLOCATED which is wrong, as on read the data is
-fails. We can handle that case the same way as it is done for the
+generated on the level of short backing file (if all overlays have
-unsupported cases, namely, call to bdrv_driver_pwritev() that writes
+unallocated areas at that place).
 zeroes to an image for the unaligned chunk of the block.
-Suggested-by: Denis V. Lunev <den@openvz.org>
+Reusing bdrv_common_block_status_above fixes the issue and unifies code
-Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
+path.
-Reviewed-by: John Snow <jsnow@redhat.com>
-Message-id: 1554474244-553661-1-git-send-email-andrey.shinkevich@virtuozzo.com
+Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
-Message-Id: <1554474244-553661-1-git-send-email-andrey.shinkevich@virtuozzo.com>
+Reviewed-by: Eric Blake <eblake@redhat.com>
 Reviewed-by: Alberto Garcia <berto@igalia.com>
 Message-id: 20200924194003.22080-5-vsementsov@virtuozzo.com
 [Fix s/has/have/ as suggested by Eric Blake. Fix s/area/areas/.
 --Stefan]
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- block/io.c | 2 +-
+ block/io.c | 43 +++++--------------------------------------
-file changed, 1 insertion(+), 1 deletion(-)
+file changed, 5 insertions(+), 38 deletions(-)
 diff --git a/block/io.c b/block/io.c
 index XXXXXXX..XXXXXXX 100644
 --- a/block/io.c
 +++ b/block/io.c
-@@ -XXX,XX +XXX,XX @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
+@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
-             assert(!bs->supported_zero_flags);
+  * at 'offset + *pnum' may return the same allocation status (in other
-         }
+  * words, the result is not necessarily the maximum possible range);
+  * but 'pnum' will only be 0 when end of file is reached.
--        if (ret == -ENOTSUP && !(flags & BDRV_REQ_NO_FALLBACK)) {
+- *
-+        if (ret < 0 && !(flags & BDRV_REQ_NO_FALLBACK)) {
+  */
-             /* Fall back to bounce buffer if write zeroes is unsupported */
+ int bdrv_is_allocated_above(BlockDriverState *top,
-             BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
+                             BlockDriverState *base,
+                             bool include_base, int64_t offset,
                              int64_t bytes, int64_t *pnum)
  {
 -    BlockDriverState *intermediate;
 -    int ret;
 -    int64_t n = bytes;
 -
 -    assert(base || !include_base);
 -
 -    intermediate = top;
 -    while (include_base || intermediate != base) {
 -        int64_t pnum_inter;
 -        int64_t size_inter;
 -
 -        assert(intermediate);
 -        ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter);
 -        if (ret < 0) {
 -            return ret;
 -        }
 -        if (ret) {
 -            *pnum = pnum_inter;
 -            return 1;
 -        }
 -
 -        size_inter = bdrv_getlength(intermediate);
 -        if (size_inter < 0) {
 -            return size_inter;
 -        }
 -        if (n > pnum_inter &&
 -            (intermediate == top || offset + pnum_inter < size_inter)) {
 -            n = pnum_inter;
 -        }
 -
 -        if (intermediate == base) {
 -            break;
 -        }
 -
 -        intermediate = bdrv_filter_or_cow_bs(intermediate);
 +    int ret = bdrv_common_block_status_above(top, base, include_base, false,
 +                                             offset, bytes, pnum, NULL, NULL);
 +    if (ret < 0) {
 +        return ret;
      }
 -    *pnum = n;
 -    return 0;
 +    return !!(ret & BDRV_BLOCK_ALLOCATED);
  }
  int coroutine_fn
 --
-.21.0
+.26.2

-[Qemu-devel] [PULL 6/8] aio-posix: ensure poll mode is left when aio_notify is called
+[PULL v2 28/28] iotests: add commit top->base cases to 274
-From: Paolo Bonzini <pbonzini@redhat.com>
+From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
-With aio=thread, adaptive polling makes latency worse rather than
+These cases are fixed by previous patches around block_status and
-better, because it delays the execution of the ThreadPool's
+is_allocated.
 completion bottom half.
-event_notifier_poll() does run while polling, detecting that
+Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
-a bottom half was scheduled by a worker thread, but because
+Reviewed-by: Eric Blake <eblake@redhat.com>
-ctx->notifier is explicitly ignored in run_poll_handlers_once(),
+Reviewed-by: Alberto Garcia <berto@igalia.com>
-scheduling the BH does not count as making progress and
+Message-id: 20200924194003.22080-6-vsementsov@virtuozzo.com
 run_poll_handlers() keeps running.  Fix this by recomputing
 the deadline after *timeout could have changed.
 With this change, ThreadPool still cannot participate in polling
 but at least it does not suffer from extra latency.
 Reported-by: Sergio Lopez <slp@redhat.com>
 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
 Message-id: 20190409122823.12416-1-pbonzini@redhat.com
 Cc: Stefan Hajnoczi <stefanha@gmail.com>
 Cc: Kevin Wolf <kwolf@redhat.com>
 Cc: qemu-block@nongnu.org
 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
 Message-Id: <1553692145-86728-1-git-send-email-pbonzini@redhat.com>
 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
 Message-Id: <20190409122823.12416-1-pbonzini@redhat.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- util/aio-posix.c | 12 ++++++++----
+ tests/qemu-iotests/274     | 20 +++++++++++
-file changed, 8 insertions(+), 4 deletions(-)
+ tests/qemu-iotests/274.out | 68 ++++++++++++++++++++++++++++++++++++++
 files changed, 88 insertions(+)
-diff --git a/util/aio-posix.c b/util/aio-posix.c
+diff --git a/tests/qemu-iotests/274 b/tests/qemu-iotests/274
 index XXXXXXX..XXXXXXX 100755
 --- a/tests/qemu-iotests/274
 +++ b/tests/qemu-iotests/274
@@ -XXX,XX +XXX,XX @@ with iotests.FilePath('base') as base, \
      iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, mid)
      iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), mid)
 +    iotests.log('=== Testing qemu-img commit (top -> base) ===')
 +
 +    create_chain()
 +    iotests.qemu_img_log('commit', '-b', base, top)
 +    iotests.img_info_log(base)
 +    iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, base)
 +    iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), base)
 +
 +    iotests.log('=== Testing QMP active commit (top -> base) ===')
 +
 +    create_chain()
 +    with create_vm() as vm:
 +        vm.launch()
 +        vm.qmp_log('block-commit', device='top', base_node='base',
 +                   job_id='job0', auto_dismiss=False)
 +        vm.run_job('job0', wait=5)
 +
 +    iotests.img_info_log(mid)
 +    iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, base)
 +    iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), base)
      iotests.log('== Resize tests ==')
 diff --git a/tests/qemu-iotests/274.out b/tests/qemu-iotests/274.out
 index XXXXXXX..XXXXXXX 100644
---- a/util/aio-posix.c
+--- a/tests/qemu-iotests/274.out
-+++ b/util/aio-posix.c
++++ b/tests/qemu-iotests/274.out
-@@ -XXX,XX +XXX,XX @@ static bool run_poll_handlers_once(AioContext *ctx, int64_t *timeout)
+@@ -XXX,XX +XXX,XX @@ read 1048576/1048576 bytes at offset 0
-         if (!node->deleted && node->io_poll &&
+ read 1048576/1048576 bytes at offset 1048576
-             aio_node_check(ctx, node->is_external) &&
+MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-             node->io_poll(node->opaque)) {
-+            /*
++=== Testing qemu-img commit (top -> base) ===
-+             * Polling was successful, exit try_poll_mode immediately
++Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 lazy_refcounts=off refcount_bits=16
-+             * to adjust the next polling time.
++
-+             */
++Formatting 'TEST_DIR/PID-mid', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 backing_file=TEST_DIR/PID-base backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
-             *timeout = 0;
++
-             if (node->opaque != &ctx->notifier) {
++Formatting 'TEST_DIR/PID-top', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 backing_file=TEST_DIR/PID-mid backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
-                 progress = true;
++
-@@ -XXX,XX +XXX,XX @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
++wrote 2097152/2097152 bytes at offset 0
-     do {
++2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-         progress = run_poll_handlers_once(ctx, timeout);
++
-         elapsed_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start_time;
++Image committed.
--    } while (!progress && elapsed_time < max_ns
++
--             && !atomic_read(&ctx->poll_disable_cnt));
++image: TEST_IMG
-+        max_ns = qemu_soonest_timeout(*timeout, max_ns);
++file format: IMGFMT
-+        assert(!(max_ns && progress));
++virtual size: 2 MiB (2097152 bytes)
-+    } while (elapsed_time < max_ns && !atomic_read(&ctx->poll_disable_cnt));
++cluster_size: 65536
++Format specific information:
-     /* If time has passed with no successful polling, adjust *timeout to
++    compat: 1.1
-      * keep the same ending time.
++    compression type: zlib
-@@ -XXX,XX +XXX,XX @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
++    lazy refcounts: false
-  */
++    refcount bits: 16
- static bool try_poll_mode(AioContext *ctx, int64_t *timeout)
++    corrupt: false
- {
++    extended l2: false
--    /* See qemu_soonest_timeout() uint64_t hack */
++
--    int64_t max_ns = MIN((uint64_t)*timeout, (uint64_t)ctx->poll_ns);
++read 1048576/1048576 bytes at offset 0
-+    int64_t max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
++1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
++
-     if (max_ns && !atomic_read(&ctx->poll_disable_cnt)) {
++read 1048576/1048576 bytes at offset 1048576
-         poll_set_started(ctx, true);
++1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 +
 +=== Testing QMP active commit (top -> base) ===
 +Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 lazy_refcounts=off refcount_bits=16
 +
 +Formatting 'TEST_DIR/PID-mid', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 backing_file=TEST_DIR/PID-base backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
 +
 +Formatting 'TEST_DIR/PID-top', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 backing_file=TEST_DIR/PID-mid backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
 +
 +wrote 2097152/2097152 bytes at offset 0
 +2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 +
 +{"execute": "block-commit", "arguments": {"auto-dismiss": false, "base-node": "base", "device": "top", "job-id": "job0"}}
 +{"return": {}}
 +{"execute": "job-complete", "arguments": {"id": "job0"}}
 +{"return": {}}
 +{"data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_READY", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
 +{"data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
 +{"execute": "job-dismiss", "arguments": {"id": "job0"}}
 +{"return": {}}
 +image: TEST_IMG
 +file format: IMGFMT
 +virtual size: 1 MiB (1048576 bytes)
 +cluster_size: 65536
 +backing file: TEST_DIR/PID-base
 +backing file format: IMGFMT
 +Format specific information:
 +    compat: 1.1
 +    compression type: zlib
 +    lazy refcounts: false
 +    refcount bits: 16
 +    corrupt: false
 +    extended l2: false
 +
 +read 1048576/1048576 bytes at offset 0
 +1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 +
 +read 1048576/1048576 bytes at offset 1048576
 +1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 +
  == Resize tests ==
  === preallocation=off ===
  Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
 --
-.21.0
+.26.2

The following changes since commit 812b835fb4d23dd108b2f9802158472d50b73579:

Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-05-07' into staging (2019-05-09 16:31:12 +0100)

are available in the Git repository at:

https://github.com/stefanha/qemu.git tags/block-pull-request

for you to fetch changes up to e84125761f78919fe63616d9888ea45e72dc956f:

docs: add Security chapter to the documentation (2019-05-10 10:53:52 +0100)

----------------------------------------------------------------
Pull request

----------------------------------------------------------------

Andrey Shinkevich (1):
  block/io.c: fix for the allocation failure

Jules Irenge (3):
  util/readline: add a space to fix errors by checkpatch tool
  util: readline: replace tab indent by four spaces to fix checkpatch
    errors
  util/readline: Add braces to fix checkpatch errors

Nikita Alekseev (1):
  block: Add coroutine_fn to bdrv_check_co_entry

Paolo Bonzini (1):
  aio-posix: ensure poll mode is left when aio_notify is called

Stefan Hajnoczi (2):
  docs: add Secure Coding Practices to developer docs
  docs: add Security chapter to the documentation

-- 
2.21.0

From: Jules Irenge <jbi.octave@gmail.com>

util/readline: add a space to fix errors reported by checkpatch.pl tool
"ERROR: space required before the open parenthesis"
"ERROR: space required after that ..."
within "util/redline.c" file

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20190401024406.10819-2-jbi.octave@gmail.com
Message-Id: <20190401024406.10819-2-jbi.octave@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/readline.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/util/readline.c b/util/readline.c
index XXXXXXX..XXXXXXX 100644
--- a/util/readline.c
+++ b/util/readline.c
@@ -XXX,XX +XXX,XX @@ static void readline_update(ReadLineState *rs)
 
     if (rs->cmd_buf_size != rs->last_cmd_buf_size ||
         memcmp(rs->cmd_buf, rs->last_cmd_buf, rs->cmd_buf_size) != 0) {
-        for(i = 0; i < rs->last_cmd_buf_index; i++) {
+        for (i = 0; i < rs->last_cmd_buf_index; i++) {
             rs->printf_func(rs->opaque, "\033[D");
         }
         rs->cmd_buf[rs->cmd_buf_size] = '\0';
         if (rs->read_password) {
             len = strlen(rs->cmd_buf);
-            for(i = 0; i < len; i++)
+            for (i = 0; i < len; i++)
                 rs->printf_func(rs->opaque, "*");
         } else {
             rs->printf_func(rs->opaque, "%s", rs->cmd_buf);
@@ -XXX,XX +XXX,XX @@ static void readline_update(ReadLineState *rs)
     if (rs->cmd_buf_index != rs->last_cmd_buf_index) {
         delta = rs->cmd_buf_index - rs->last_cmd_buf_index;
         if (delta > 0) {
-            for(i = 0;i < delta; i++) {
+            for (i = 0; i < delta; i++) {
                 rs->printf_func(rs->opaque, "\033[C");
             }
         } else {
             delta = -delta;
-            for(i = 0;i < delta; i++) {
+            for (i = 0; i < delta; i++) {
                 rs->printf_func(rs->opaque, "\033[D");
             }
         }
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
         return;
     if (rs->nb_completions == 1) {
         len = strlen(rs->completions[0]);
-        for(i = rs->completion_index; i < len; i++) {
+        for (i = rs->completion_index; i < len; i++) {
             readline_insert_char(rs, rs->completions[0][i]);
         }
         /* extra space for next argument. XXX: make it more generic */
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
               completion_comp);
         rs->printf_func(rs->opaque, "\n");
         max_width = 0;
-        max_prefix = 0;	
-        for(i = 0; i < rs->nb_completions; i++) {
+        max_prefix = 0;
+        for (i = 0; i < rs->nb_completions; i++) {
             len = strlen(rs->completions[i]);
-            if (i==0) {
+            if (i == 0) {
                 max_prefix = len;
             } else {
                 if (len < max_prefix)
                     max_prefix = len;
-                for(j=0; j<max_prefix; j++) {
+                for (j = 0; j < max_prefix; j++) {
                     if (rs->completions[i][j] != rs->completions[0][j])
                         max_prefix = j;
                 }
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
             if (len > max_width)
                 max_width = len;
         }
-        if (max_prefix > 0) 
-            for(i = rs->completion_index; i < max_prefix; i++) {
+        if (max_prefix > 0)
+            for (i = rs->completion_index; i < max_prefix; i++) {
                 readline_insert_char(rs, rs->completions[0][i]);
             }
         max_width += 2;
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
             max_width = 80;
         nb_cols = 80 / max_width;
         j = 0;
-        for(i = 0; i < rs->nb_completions; i++) {
+        for (i = 0; i < rs->nb_completions; i++) {
             rs->printf_func(rs->opaque, "%-*s", max_width, rs->completions[i]);
             if (++j == nb_cols || i == (rs->nb_completions - 1)) {
                 rs->printf_func(rs->opaque, "\n");
@@ -XXX,XX +XXX,XX @@ static void readline_clear_screen(ReadLineState *rs)
 /* return true if command handled */
 void readline_handle_byte(ReadLineState *rs, int ch)
 {
-    switch(rs->esc_state) {
+    switch (rs->esc_state) {
     case IS_NORM:
-        switch(ch) {
+        switch (ch) {
         case 1:
             readline_bol(rs);
             break;
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
         }
         break;
     case IS_CSI:
-        switch(ch) {
+        switch (ch) {
 	case 'A':
 	case 'F':
 	    readline_up_char(rs);
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
             rs->esc_param = rs->esc_param * 10 + (ch - '0');
             goto the_end;
         case '~':
-            switch(rs->esc_param) {
+            switch (rs->esc_param) {
             case 1:
                 readline_bol(rs);
                 break;
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
     the_end:
         break;
     case IS_SS3:
-        switch(ch) {
+        switch (ch) {
         case 'F':
             readline_eol(rs);
             break;
-- 
2.21.0

From: Jules Irenge <jbi.octave@gmail.com>

Replace tab indent by four spaces to fix errors issued by checkpatch.pl tool
"ERROR: code indent should never use tabs" within "util/readline.c" file.

Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20190401024406.10819-3-jbi.octave@gmail.com
Message-Id: <20190401024406.10819-3-jbi.octave@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/readline.c | 98 ++++++++++++++++++++++++-------------------------
 1 file changed, 49 insertions(+), 49 deletions(-)

diff --git a/util/readline.c b/util/readline.c
index XXXXXXX..XXXXXXX 100644
--- a/util/readline.c
+++ b/util/readline.c
@@ -XXX,XX +XXX,XX @@ static void readline_up_char(ReadLineState *rs)
     int idx;
 
     if (rs->hist_entry == 0)
-	return;
+        return;
     if (rs->hist_entry == -1) {
-	/* Find latest entry */
-	for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
-	    if (rs->history[idx] == NULL)
-		break;
-	}
-	rs->hist_entry = idx;
+        /* Find latest entry */
+        for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
+            if (rs->history[idx] == NULL)
+                break;
+        }
+        rs->hist_entry = idx;
     }
     rs->hist_entry--;
     if (rs->hist_entry >= 0) {
-	pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
+        pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
                 rs->history[rs->hist_entry]);
-	rs->cmd_buf_index = rs->cmd_buf_size = strlen(rs->cmd_buf);
+        rs->cmd_buf_index = rs->cmd_buf_size = strlen(rs->cmd_buf);
     }
 }
 
@@ -XXX,XX +XXX,XX @@ static void readline_down_char(ReadLineState *rs)
         return;
     if (rs->hist_entry < READLINE_MAX_CMDS - 1 &&
         rs->history[++rs->hist_entry] != NULL) {
-	pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
+        pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
                 rs->history[rs->hist_entry]);
     } else {
         rs->cmd_buf[0] = 0;
-	rs->hist_entry = -1;
+        rs->hist_entry = -1;
     }
     rs->cmd_buf_index = rs->cmd_buf_size = strlen(rs->cmd_buf);
 }
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
     int idx;
 
     if (cmdline[0] == '\0')
-	return;
+        return;
     new_entry = NULL;
     if (rs->hist_entry != -1) {
-	/* We were editing an existing history entry: replace it */
-	hist_entry = rs->history[rs->hist_entry];
-	idx = rs->hist_entry;
-	if (strcmp(hist_entry, cmdline) == 0) {
-	    goto same_entry;
-	}
+        /* We were editing an existing history entry: replace it */
+        hist_entry = rs->history[rs->hist_entry];
+        idx = rs->hist_entry;
+        if (strcmp(hist_entry, cmdline) == 0) {
+            goto same_entry;
+        }
     }
     /* Search cmdline in history buffers */
     for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
-	hist_entry = rs->history[idx];
-	if (hist_entry == NULL)
-	    break;
-	if (strcmp(hist_entry, cmdline) == 0) {
-	same_entry:
-	    new_entry = hist_entry;
-	    /* Put this entry at the end of history */
-	    memmove(&rs->history[idx], &rs->history[idx + 1],
-		    (READLINE_MAX_CMDS - (idx + 1)) * sizeof(char *));
-	    rs->history[READLINE_MAX_CMDS - 1] = NULL;
-	    for (; idx < READLINE_MAX_CMDS; idx++) {
-		if (rs->history[idx] == NULL)
-		    break;
-	    }
-	    break;
-	}
+        hist_entry = rs->history[idx];
+        if (hist_entry == NULL)
+            break;
+        if (strcmp(hist_entry, cmdline) == 0) {
+        same_entry:
+            new_entry = hist_entry;
+            /* Put this entry at the end of history */
+            memmove(&rs->history[idx], &rs->history[idx + 1],
+                    (READLINE_MAX_CMDS - (idx + 1)) * sizeof(char *));
+            rs->history[READLINE_MAX_CMDS - 1] = NULL;
+            for (; idx < READLINE_MAX_CMDS; idx++) {
+                if (rs->history[idx] == NULL)
+                    break;
+            }
+            break;
+        }
     }
     if (idx == READLINE_MAX_CMDS) {
-	/* Need to get one free slot */
+        /* Need to get one free slot */
         g_free(rs->history[0]);
-	memmove(rs->history, &rs->history[1],
-	        (READLINE_MAX_CMDS - 1) * sizeof(char *));
-	rs->history[READLINE_MAX_CMDS - 1] = NULL;
-	idx = READLINE_MAX_CMDS - 1;
+        memmove(rs->history, &rs->history[1],
+                (READLINE_MAX_CMDS - 1) * sizeof(char *));
+        rs->history[READLINE_MAX_CMDS - 1] = NULL;
+        idx = READLINE_MAX_CMDS - 1;
     }
     if (new_entry == NULL)
         new_entry = g_strdup(cmdline);
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
         case 8:
             readline_backspace(rs);
             break;
-	case 155:
+        case 155:
             rs->esc_state = IS_CSI;
-	    break;
+            break;
         default:
             if (ch >= 32) {
                 readline_insert_char(rs, ch);
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
         break;
     case IS_CSI:
         switch (ch) {
-	case 'A':
-	case 'F':
-	    readline_up_char(rs);
-	    break;
-	case 'B':
-	case 'E':
-	    readline_down_char(rs);
-	    break;
+        case 'A':
+        case 'F':
+            readline_up_char(rs);
+            break;
+        case 'B':
+        case 'E':
+            readline_down_char(rs);
+            break;
         case 'D':
             readline_backward_char(rs);
             break;
-- 
2.21.0

From: Jules Irenge <jbi.octave@gmail.com>

Add braces to fix errors issued by checkpatch.pl tool
"ERROR: braces {} are necessary for all arms of this statement"
Within "util/readline.c" file
Message-Id: <20190330112142.14082-1-jbi.octave@gmail.com>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/readline.c | 50 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 33 insertions(+), 17 deletions(-)

diff --git a/util/readline.c b/util/readline.c
index XXXXXXX..XXXXXXX 100644
--- a/util/readline.c
+++ b/util/readline.c
@@ -XXX,XX +XXX,XX @@ static void readline_update(ReadLineState *rs)
         rs->cmd_buf[rs->cmd_buf_size] = '\0';
         if (rs->read_password) {
             len = strlen(rs->cmd_buf);
-            for (i = 0; i < len; i++)
+            for (i = 0; i < len; i++) {
                 rs->printf_func(rs->opaque, "*");
+            }
         } else {
             rs->printf_func(rs->opaque, "%s", rs->cmd_buf);
         }
@@ -XXX,XX +XXX,XX @@ static void readline_up_char(ReadLineState *rs)
 {
     int idx;
 
-    if (rs->hist_entry == 0)
+    if (rs->hist_entry == 0) {
         return;
+    }
     if (rs->hist_entry == -1) {
         /* Find latest entry */
         for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
-            if (rs->history[idx] == NULL)
+            if (rs->history[idx] == NULL) {
                 break;
+            }
         }
         rs->hist_entry = idx;
     }
@@ -XXX,XX +XXX,XX @@ static void readline_up_char(ReadLineState *rs)
 
 static void readline_down_char(ReadLineState *rs)
 {
-    if (rs->hist_entry == -1)
+    if (rs->hist_entry == -1) {
         return;
+    }
     if (rs->hist_entry < READLINE_MAX_CMDS - 1 &&
         rs->history[++rs->hist_entry] != NULL) {
         pstrcpy(rs->cmd_buf, sizeof(rs->cmd_buf),
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
     char *hist_entry, *new_entry;
     int idx;
 
-    if (cmdline[0] == '\0')
+    if (cmdline[0] == '\0') {
         return;
+    }
     new_entry = NULL;
     if (rs->hist_entry != -1) {
         /* We were editing an existing history entry: replace it */
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
     /* Search cmdline in history buffers */
     for (idx = 0; idx < READLINE_MAX_CMDS; idx++) {
         hist_entry = rs->history[idx];
-        if (hist_entry == NULL)
+        if (hist_entry == NULL) {
             break;
+        }
         if (strcmp(hist_entry, cmdline) == 0) {
         same_entry:
             new_entry = hist_entry;
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
                     (READLINE_MAX_CMDS - (idx + 1)) * sizeof(char *));
             rs->history[READLINE_MAX_CMDS - 1] = NULL;
             for (; idx < READLINE_MAX_CMDS; idx++) {
-                if (rs->history[idx] == NULL)
+                if (rs->history[idx] == NULL) {
                     break;
+                }
             }
             break;
         }
@@ -XXX,XX +XXX,XX @@ static void readline_hist_add(ReadLineState *rs, const char *cmdline)
         rs->history[READLINE_MAX_CMDS - 1] = NULL;
         idx = READLINE_MAX_CMDS - 1;
     }
-    if (new_entry == NULL)
+    if (new_entry == NULL) {
         new_entry = g_strdup(cmdline);
+    }
     rs->history[idx] = new_entry;
     rs->hist_entry = -1;
 }
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
     g_free(cmdline);
 
     /* no completion found */
-    if (rs->nb_completions <= 0)
+    if (rs->nb_completions <= 0) {
         return;
+    }
     if (rs->nb_completions == 1) {
         len = strlen(rs->completions[0]);
         for (i = rs->completion_index; i < len; i++) {
             readline_insert_char(rs, rs->completions[0][i]);
         }
         /* extra space for next argument. XXX: make it more generic */
-        if (len > 0 && rs->completions[0][len - 1] != '/')
+        if (len > 0 && rs->completions[0][len - 1] != '/') {
             readline_insert_char(rs, ' ');
+        }
     } else {
         qsort(rs->completions, rs->nb_completions, sizeof(char *),
               completion_comp);
@@ -XXX,XX +XXX,XX @@ static void readline_completion(ReadLineState *rs)
             if (i == 0) {
                 max_prefix = len;
             } else {
-                if (len < max_prefix)
+                if (len < max_prefix) {
                     max_prefix = len;
+                }
                 for (j = 0; j < max_prefix; j++) {
-                    if (rs->completions[i][j] != rs->completions[0][j])
+                    if (rs->completions[i][j] != rs->completions[0][j]) {
                         max_prefix = j;
+                    }
                 }
             }
-            if (len > max_width)
+            if (len > max_width) {
                 max_width = len;
+            }
         }
         if (max_prefix > 0)
             for (i = rs->completion_index; i < max_prefix; i++) {
                 readline_insert_char(rs, rs->completions[0][i]);
             }
         max_width += 2;
-        if (max_width < 10)
+        if (max_width < 10) {
             max_width = 10;
-        else if (max_width > 80)
+        } else if (max_width > 80) {
             max_width = 80;
+        }
         nb_cols = 80 / max_width;
         j = 0;
         for (i = 0; i < rs->nb_completions; i++) {
@@ -XXX,XX +XXX,XX @@ void readline_handle_byte(ReadLineState *rs, int ch)
         case 10:
         case 13:
             rs->cmd_buf[rs->cmd_buf_size] = '\0';
-            if (!rs->read_password)
+            if (!rs->read_password) {
                 readline_hist_add(rs, rs->cmd_buf);
+            }
             rs->printf_func(rs->opaque, "\n");
             rs->cmd_buf_index = 0;
             rs->cmd_buf_size = 0;
@@ -XXX,XX +XXX,XX @@ void readline_restart(ReadLineState *rs)
 
 const char *readline_get_history(ReadLineState *rs, unsigned int index)
 {
-    if (index >= READLINE_MAX_CMDS)
+    if (index >= READLINE_MAX_CMDS) {
         return NULL;
+    }
     return rs->history[index];
 }
 
-- 
2.21.0

From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>

On a file system used by the customer, fallocate() returns an error
if the block is not properly aligned. So, bdrv_co_pwrite_zeroes()
fails. We can handle that case the same way as it is done for the
unsupported cases, namely, call to bdrv_driver_pwritev() that writes
zeroes to an image for the unaligned chunk of the block.

Suggested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1554474244-553661-1-git-send-email-andrey.shinkevich@virtuozzo.com
Message-Id: <1554474244-553661-1-git-send-email-andrey.shinkevich@virtuozzo.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/io.c b/block/io.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io.c
+++ b/block/io.c
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
             assert(!bs->supported_zero_flags);
         }
 
-        if (ret == -ENOTSUP && !(flags & BDRV_REQ_NO_FALLBACK)) {
+        if (ret < 0 && !(flags & BDRV_REQ_NO_FALLBACK)) {
             /* Fall back to bounce buffer if write zeroes is unsupported */
             BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE;
 
-- 
2.21.0

From: Paolo Bonzini <pbonzini@redhat.com>

With aio=thread, adaptive polling makes latency worse rather than
better, because it delays the execution of the ThreadPool's
completion bottom half.

event_notifier_poll() does run while polling, detecting that
a bottom half was scheduled by a worker thread, but because
ctx->notifier is explicitly ignored in run_poll_handlers_once(),
scheduling the BH does not count as making progress and
run_poll_handlers() keeps running.  Fix this by recomputing
the deadline after *timeout could have changed.

With this change, ThreadPool still cannot participate in polling
but at least it does not suffer from extra latency.

Reported-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20190409122823.12416-1-pbonzini@redhat.com
Cc: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1553692145-86728-1-git-send-email-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20190409122823.12416-1-pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/aio-posix.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/util/aio-posix.c b/util/aio-posix.c
index XXXXXXX..XXXXXXX 100644
--- a/util/aio-posix.c
+++ b/util/aio-posix.c
@@ -XXX,XX +XXX,XX @@ static bool run_poll_handlers_once(AioContext *ctx, int64_t *timeout)
         if (!node->deleted && node->io_poll &&
             aio_node_check(ctx, node->is_external) &&
             node->io_poll(node->opaque)) {
+            /*
+             * Polling was successful, exit try_poll_mode immediately
+             * to adjust the next polling time.
+             */
             *timeout = 0;
             if (node->opaque != &ctx->notifier) {
                 progress = true;
@@ -XXX,XX +XXX,XX @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
     do {
         progress = run_poll_handlers_once(ctx, timeout);
         elapsed_time = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start_time;
-    } while (!progress && elapsed_time < max_ns
-             && !atomic_read(&ctx->poll_disable_cnt));
+        max_ns = qemu_soonest_timeout(*timeout, max_ns);
+        assert(!(max_ns && progress));
+    } while (elapsed_time < max_ns && !atomic_read(&ctx->poll_disable_cnt));
 
     /* If time has passed with no successful polling, adjust *timeout to
      * keep the same ending time.
@@ -XXX,XX +XXX,XX @@ static bool run_poll_handlers(AioContext *ctx, int64_t max_ns, int64_t *timeout)
  */
 static bool try_poll_mode(AioContext *ctx, int64_t *timeout)
 {
-    /* See qemu_soonest_timeout() uint64_t hack */
-    int64_t max_ns = MIN((uint64_t)*timeout, (uint64_t)ctx->poll_ns);
+    int64_t max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
 
     if (max_ns && !atomic_read(&ctx->poll_disable_cnt)) {
         poll_set_started(ctx, true);
-- 
2.21.0

At KVM Forum 2018 I gave a presentation on security in QEMU:
https://www.youtube.com/watch?v=YAdRf_hwxU8 (video)
https://vmsplice.net/~stefan/stefanha-kvm-forum-2018.pdf (slides)

This patch adds a guide to secure coding practices.  This document
covers things that developers should know about security in QEMU.  It is
just a starting point that we can expand on later.  I hope it will be
useful as a resource for new contributors and will save code reviewers
from explaining the same concepts many times.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-id: 20190509121820.16294-2-stefanha@redhat.com
Message-Id: <20190509121820.16294-2-stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 docs/devel/index.rst                   |   1 +
 docs/devel/secure-coding-practices.rst | 106 +++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 docs/devel/secure-coding-practices.rst

diff --git a/docs/devel/index.rst b/docs/devel/index.rst
index XXXXXXX..XXXXXXX 100644
--- a/docs/devel/index.rst
+++ b/docs/devel/index.rst
@@ -XXX,XX +XXX,XX @@ Contents:
    stable-process
    testing
    decodetree
+   secure-coding-practices
diff --git a/docs/devel/secure-coding-practices.rst b/docs/devel/secure-coding-practices.rst
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/docs/devel/secure-coding-practices.rst
@@ -XXX,XX +XXX,XX @@
+=======================
+Secure Coding Practices
+=======================
+This document covers topics that both developers and security researchers must
+be aware of so that they can develop safe code and audit existing code
+properly.
+
+Reporting Security Bugs
+-----------------------
+For details on how to report security bugs or ask questions about potential
+security bugs, see the `Security Process wiki page
+<https://wiki.qemu.org/SecurityProcess>`_.
+
+General Secure C Coding Practices
+---------------------------------
+Most CVEs (security bugs) reported against QEMU are not specific to
+virtualization or emulation.  They are simply C programming bugs.  Therefore
+it's critical to be aware of common classes of security bugs.
+
+There is a wide selection of resources available covering secure C coding.  For
+example, the `CERT C Coding Standard
+<https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard>`_
+covers the most important classes of security bugs.
+
+Instead of describing them in detail here, only the names of the most important
+classes of security bugs are mentioned:
+
+* Buffer overflows
+* Use-after-free and double-free
+* Integer overflows
+* Format string vulnerabilities
+
+Some of these classes of bugs can be detected by analyzers.  Static analysis is
+performed regularly by Coverity and the most obvious of these bugs are even
+reported by compilers.  Dynamic analysis is possible with valgrind, tsan, and
+asan.
+
+Input Validation
+----------------
+Inputs from the guest or external sources (e.g. network, files) cannot be
+trusted and may be invalid.  Inputs must be checked before using them in a way
+that could crash the program, expose host memory to the guest, or otherwise be
+exploitable by an attacker.
+
+The most sensitive attack surface is device emulation.  All hardware register
+accesses and data read from guest memory must be validated.  A typical example
+is a device that contains multiple units that are selectable by the guest via
+an index register::
+
+  typedef struct {
+      ProcessingUnit unit[2];
+      ...
+  } MyDeviceState;
+
+  static void mydev_writel(void *opaque, uint32_t addr, uint32_t val)
+  {
+      MyDeviceState *mydev = opaque;
+      ProcessingUnit *unit;
+
+      switch (addr) {
+      case MYDEV_SELECT_UNIT:
+          unit = &mydev->unit[val];   <-- this input wasn't validated!
+          ...
+      }
+  }
+
+If ``val`` is not in range [0, 1] then an out-of-bounds memory access will take
+place when ``unit`` is dereferenced.  The code must check that ``val`` is 0 or
+1 and handle the case where it is invalid.
+
+Unexpected Device Accesses
+--------------------------
+The guest may access device registers in unusual orders or at unexpected
+moments.  Device emulation code must not assume that the guest follows the
+typical "theory of operation" presented in driver writer manuals.  The guest
+may make nonsense accesses to device registers such as starting operations
+before the device has been fully initialized.
+
+A related issue is that device emulation code must be prepared for unexpected
+device register accesses while asynchronous operations are in progress.  A
+well-behaved guest might wait for a completion interrupt before accessing
+certain device registers.  Device emulation code must handle the case where the
+guest overwrites registers or submits further requests before an ongoing
+request completes.  Unexpected accesses must not cause memory corruption or
+leaks in QEMU.
+
+Invalid device register accesses can be reported with
+``qemu_log_mask(LOG_GUEST_ERROR, ...)``.  The ``-d guest_errors`` command-line
+option enables these log messages.
+
+Live Migration
+--------------
+Device state can be saved to disk image files and shared with other users.
+Live migration code must validate inputs when loading device state so an
+attacker cannot gain control by crafting invalid device states.  Device state
+is therefore considered untrusted even though it is typically generated by QEMU
+itself.
+
+Guest Memory Access Races
+-------------------------
+Guests with multiple vCPUs may modify guest RAM while device emulation code is
+running.  Device emulation code must copy in descriptors and other guest RAM
+structures and only process the local copy.  This prevents
+time-of-check-to-time-of-use (TOCTOU) race conditions that could cause QEMU to
+crash when a vCPU thread modifies guest RAM while device emulation is
+processing it.
-- 
2.21.0

This new chapter in the QEMU documentation covers the security
requirements that QEMU is designed to meet and principles for securely
deploying QEMU.

It is just a starting point that can be extended in the future with more
information.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-id: 20190509121820.16294-3-stefanha@redhat.com
Message-Id: <20190509121820.16294-3-stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 Makefile           |   2 +-
 docs/security.texi | 131 +++++++++++++++++++++++++++++++++++++++++++++
 qemu-doc.texi      |   3 ++
 3 files changed, 135 insertions(+), 1 deletion(-)
 create mode 100644 docs/security.texi

diff --git a/Makefile b/Makefile
index XXXXXXX..XXXXXXX 100644
--- a/Makefile
+++ b/Makefile
@@ -XXX,XX +XXX,XX @@ qemu-doc.html qemu-doc.info qemu-doc.pdf qemu-doc.txt: \
 	qemu-img.texi qemu-nbd.texi qemu-options.texi qemu-option-trace.texi \
 	qemu-deprecated.texi qemu-monitor.texi qemu-img-cmds.texi qemu-ga.texi \
 	qemu-monitor-info.texi docs/qemu-block-drivers.texi \
-	docs/qemu-cpu-models.texi
+	docs/qemu-cpu-models.texi docs/security.texi
 
 docs/interop/qemu-ga-ref.dvi docs/interop/qemu-ga-ref.html \
     docs/interop/qemu-ga-ref.info docs/interop/qemu-ga-ref.pdf \
diff --git a/docs/security.texi b/docs/security.texi
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/docs/security.texi
@@ -XXX,XX +XXX,XX @@
+@node Security
+@chapter Security
+
+@section Overview
+
+This chapter explains the security requirements that QEMU is designed to meet
+and principles for securely deploying QEMU.
+
+@section Security Requirements
+
+QEMU supports many different use cases, some of which have stricter security
+requirements than others.  The community has agreed on the overall security
+requirements that users may depend on.  These requirements define what is
+considered supported from a security perspective.
+
+@subsection Virtualization Use Case
+
+The virtualization use case covers cloud and virtual private server (VPS)
+hosting, as well as traditional data center and desktop virtualization.  These
+use cases rely on hardware virtualization extensions to execute guest code
+safely on the physical CPU at close-to-native speed.
+
+The following entities are untrusted, meaning that they may be buggy or
+malicious:
+
+@itemize
+@item Guest
+@item User-facing interfaces (e.g. VNC, SPICE, WebSocket)
+@item Network protocols (e.g. NBD, live migration)
+@item User-supplied files (e.g. disk images, kernels, device trees)
+@item Passthrough devices (e.g. PCI, USB)
+@end itemize
+
+Bugs affecting these entities are evaluated on whether they can cause damage in
+real-world use cases and treated as security bugs if this is the case.
+
+@subsection Non-virtualization Use Case
+
+The non-virtualization use case covers emulation using the Tiny Code Generator
+(TCG).  In principle the TCG and device emulation code used in conjunction with
+the non-virtualization use case should meet the same security requirements as
+the virtualization use case.  However, for historical reasons much of the
+non-virtualization use case code was not written with these security
+requirements in mind.
+
+Bugs affecting the non-virtualization use case are not considered security
+bugs at this time.  Users with non-virtualization use cases must not rely on
+QEMU to provide guest isolation or any security guarantees.
+
+@section Architecture
+
+This section describes the design principles that ensure the security
+requirements are met.
+
+@subsection Guest Isolation
+
+Guest isolation is the confinement of guest code to the virtual machine.  When
+guest code gains control of execution on the host this is called escaping the
+virtual machine.  Isolation also includes resource limits such as throttling of
+CPU, memory, disk, or network.  Guests must be unable to exceed their resource
+limits.
+
+QEMU presents an attack surface to the guest in the form of emulated devices.
+The guest must not be able to gain control of QEMU.  Bugs in emulated devices
+could allow malicious guests to gain code execution in QEMU.  At this point the
+guest has escaped the virtual machine and is able to act in the context of the
+QEMU process on the host.
+
+Guests often interact with other guests and share resources with them.  A
+malicious guest must not gain control of other guests or access their data.
+Disk image files and network traffic must be protected from other guests unless
+explicitly shared between them by the user.
+
+@subsection Principle of Least Privilege
+
+The principle of least privilege states that each component only has access to
+the privileges necessary for its function.  In the case of QEMU this means that
+each process only has access to resources belonging to the guest.
+
+The QEMU process should not have access to any resources that are inaccessible
+to the guest.  This way the guest does not gain anything by escaping into the
+QEMU process since it already has access to those same resources from within
+the guest.
+
+Following the principle of least privilege immediately fulfills guest isolation
+requirements.  For example, guest A only has access to its own disk image file
+@code{a.img} and not guest B's disk image file @code{b.img}.
+
+In reality certain resources are inaccessible to the guest but must be
+available to QEMU to perform its function.  For example, host system calls are
+necessary for QEMU but are not exposed to guests.  A guest that escapes into
+the QEMU process can then begin invoking host system calls.
+
+New features must be designed to follow the principle of least privilege.
+Should this not be possible for technical reasons, the security risk must be
+clearly documented so users are aware of the trade-off of enabling the feature.
+
+@subsection Isolation mechanisms
+
+Several isolation mechanisms are available to realize this architecture of
+guest isolation and the principle of least privilege.  With the exception of
+Linux seccomp, these mechanisms are all deployed by management tools that
+launch QEMU, such as libvirt.  They are also platform-specific so they are only
+described briefly for Linux here.
+
+The fundamental isolation mechanism is that QEMU processes must run as
+unprivileged users.  Sometimes it seems more convenient to launch QEMU as
+root to give it access to host devices (e.g. @code{/dev/net/tun}) but this poses a
+huge security risk.  File descriptor passing can be used to give an otherwise
+unprivileged QEMU process access to host devices without running QEMU as root.
+It is also possible to launch QEMU as a non-root user and configure UNIX groups
+for access to @code{/dev/kvm}, @code{/dev/net/tun}, and other device nodes.
+Some Linux distros already ship with UNIX groups for these devices by default.
+
+@itemize
+@item SELinux and AppArmor make it possible to confine processes beyond the
+traditional UNIX process and file permissions model.  They restrict the QEMU
+process from accessing processes and files on the host system that are not
+needed by QEMU.
+
+@item Resource limits and cgroup controllers provide throughput and utilization
+limits on key resources such as CPU time, memory, and I/O bandwidth.
+
+@item Linux namespaces can be used to make process, file system, and other system
+resources unavailable to QEMU.  A namespaced QEMU process is restricted to only
+those resources that were granted to it.
+
+@item Linux seccomp is available via the QEMU @option{--sandbox} option.  It disables
+system calls that are not needed by QEMU, thereby reducing the host kernel
+attack surface.
+@end itemize
diff --git a/qemu-doc.texi b/qemu-doc.texi
index XXXXXXX..XXXXXXX 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -XXX,XX +XXX,XX @@
 * QEMU Guest Agent::
 * QEMU User space emulator::
 * System requirements::
+* Security::
 * Implementation notes::
 * Deprecated features::
 * Supported build platforms::
@@ -XXX,XX +XXX,XX @@ added with Linux 4.5 which is supported by the major distros. And even
 if RHEL7 has kernel 3.10, KVM there has the required functionality there
 to make it close to a 4.5 or newer kernel.
 
+@include docs/security.texi
+
 @include qemu-tech.texi
 
 @include qemu-deprecated.texi
-- 
2.21.0

The following changes since commit ac793156f650ae2d77834932d72224175ee69086:

Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20201020-1' into staging (2020-10-20 21:11:35 +0100)

are available in the Git repository at:

https://gitlab.com/stefanha/qemu.git tags/block-pull-request

for you to fetch changes up to 32a3fd65e7e3551337fd26bfc0e2f899d70c028c:

iotests: add commit top->base cases to 274 (2020-10-22 09:55:39 +0100)

----------------------------------------------------------------
Pull request

v2:
 * Fix format string issues on 32-bit hosts [Peter]
 * Fix qemu-nbd.c CONFIG_POSIX ifdef issue [Eric]
 * Fix missing eventfd.h header on macOS [Peter]
 * Drop unreliable vhost-user-blk test (will send a new patch when ready) [Peter]

This pull request contains the vhost-user-blk server by Coiby Xu along with my
additions, block/nvme.c alignment and hardware error statistics by Philippe
Mathieu-Daudé, and bdrv_co_block_status_above() fixes by Vladimir
Sementsov-Ogievskiy.

----------------------------------------------------------------

Coiby Xu (6):
  libvhost-user: Allow vu_message_read to be replaced
  libvhost-user: remove watch for kick_fd when de-initialize vu-dev
  util/vhost-user-server: generic vhost user server
  block: move logical block size check function to a common utility
    function
  block/export: vhost-user block device backend server
  MAINTAINERS: Add vhost-user block device backend server maintainer

Philippe Mathieu-Daudé (1):
  block/nvme: Add driver statistics for access alignment and hw errors

Stefan Hajnoczi (16):
  util/vhost-user-server: s/fileds/fields/ typo fix
  util/vhost-user-server: drop unnecessary QOM cast
  util/vhost-user-server: drop unnecessary watch deletion
  block/export: consolidate request structs into VuBlockReq
  util/vhost-user-server: drop unused DevicePanicNotifier
  util/vhost-user-server: fix memory leak in vu_message_read()
  util/vhost-user-server: check EOF when reading payload
  util/vhost-user-server: rework vu_client_trip() coroutine lifecycle
  block/export: report flush errors
  block/export: convert vhost-user-blk server to block export API
  util/vhost-user-server: move header to include/
  util/vhost-user-server: use static library in meson.build
  qemu-storage-daemon: avoid compiling blockdev_ss twice
  block: move block exports to libblockdev
  block/export: add iothread and fixed-iothread options
  block/export: add vhost-user-blk multi-queue support

Vladimir Sementsov-Ogievskiy (5):
  block/io: fix bdrv_co_block_status_above
  block/io: bdrv_common_block_status_above: support include_base
  block/io: bdrv_common_block_status_above: support bs == base
  block/io: fix bdrv_is_allocated_above
  iotests: add commit top->base cases to 274

-- 
2.26.2

From: Philippe Mathieu-Daudé <philmd@redhat.com>

Keep statistics of some hardware errors, and number of
aligned/unaligned I/O accesses.

QMP example booting a full RHEL 8.3 aarch64 guest:

{ "execute": "query-blockstats" }
{
    "return": [
        {
            "device": "",
            "node-name": "drive0",
            "stats": {
                "flush_total_time_ns": 6026948,
                "wr_highest_offset": 3383991230464,
                "wr_total_time_ns": 807450995,
                "failed_wr_operations": 0,
                "failed_rd_operations": 0,
                "wr_merged": 3,
                "wr_bytes": 50133504,
                "failed_unmap_operations": 0,
                "failed_flush_operations": 0,
                "account_invalid": false,
                "rd_total_time_ns": 1846979900,
                "flush_operations": 130,
                "wr_operations": 659,
                "rd_merged": 1192,
                "rd_bytes": 218244096,
                "account_failed": false,
                "idle_time_ns": 2678641497,
                "rd_operations": 7406,
            },
            "driver-specific": {
                "driver": "nvme",
                "completion-errors": 0,
                "unaligned-accesses": 2959,
                "aligned-accesses": 4477
            },
            "qdev": "/machine/peripheral-anon/device[0]/virtio-backend"
        }
    ]
}

Suggested-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20201001162939.1567915-1-philmd@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qapi/block-core.json | 24 +++++++++++++++++++++++-
 block/nvme.c         | 27 +++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index XXXXXXX..XXXXXXX 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -XXX,XX +XXX,XX @@
       'discard-nb-failed': 'uint64',
       'discard-bytes-ok': 'uint64' } }
 
+##
+# @BlockStatsSpecificNvme:
+#
+# NVMe driver statistics
+#
+# @completion-errors: The number of completion errors.
+#
+# @aligned-accesses: The number of aligned accesses performed by
+#                    the driver.
+#
+# @unaligned-accesses: The number of unaligned accesses performed by
+#                      the driver.
+#
+# Since: 5.2
+##
+{ 'struct': 'BlockStatsSpecificNvme',
+  'data': {
+      'completion-errors': 'uint64',
+      'aligned-accesses': 'uint64',
+      'unaligned-accesses': 'uint64' } }
+
 ##
 # @BlockStatsSpecific:
 #
@@ -XXX,XX +XXX,XX @@
   'discriminator': 'driver',
   'data': {
       'file': 'BlockStatsSpecificFile',
-      'host_device': 'BlockStatsSpecificFile' } }
+      'host_device': 'BlockStatsSpecificFile',
+      'nvme': 'BlockStatsSpecificNvme' } }
 
 ##
 # @BlockStats:
diff --git a/block/nvme.c b/block/nvme.c
index XXXXXXX..XXXXXXX 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -XXX,XX +XXX,XX @@ struct BDRVNVMeState {
 
     /* PCI address (required for nvme_refresh_filename()) */
     char *device;
+
+    struct {
+        uint64_t completion_errors;
+        uint64_t aligned_accesses;
+        uint64_t unaligned_accesses;
+    } stats;
 };
 
 #define NVME_BLOCK_OPT_DEVICE "device"
@@ -XXX,XX +XXX,XX @@ static bool nvme_process_completion(NVMeQueuePair *q)
             break;
         }
         ret = nvme_translate_error(c);
+        if (ret) {
+            s->stats.completion_errors++;
+        }
         q->cq.head = (q->cq.head + 1) % NVME_QUEUE_SIZE;
         if (!q->cq.head) {
             q->cq_phase = !q->cq_phase;
@@ -XXX,XX +XXX,XX @@ static int nvme_co_prw(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
     assert(QEMU_IS_ALIGNED(bytes, s->page_size));
     assert(bytes <= s->max_transfer);
     if (nvme_qiov_aligned(bs, qiov)) {
+        s->stats.aligned_accesses++;
         return nvme_co_prw_aligned(bs, offset, bytes, qiov, is_write, flags);
     }
+    s->stats.unaligned_accesses++;
     trace_nvme_prw_buffered(s, offset, bytes, qiov->niov, is_write);
     buf = qemu_try_memalign(s->page_size, bytes);
 
@@ -XXX,XX +XXX,XX @@ static void nvme_unregister_buf(BlockDriverState *bs, void *host)
     qemu_vfio_dma_unmap(s->vfio, host);
 }
 
+static BlockStatsSpecific *nvme_get_specific_stats(BlockDriverState *bs)
+{
+    BlockStatsSpecific *stats = g_new(BlockStatsSpecific, 1);
+    BDRVNVMeState *s = bs->opaque;
+
+    stats->driver = BLOCKDEV_DRIVER_NVME;
+    stats->u.nvme = (BlockStatsSpecificNvme) {
+        .completion_errors = s->stats.completion_errors,
+        .aligned_accesses = s->stats.aligned_accesses,
+        .unaligned_accesses = s->stats.unaligned_accesses,
+    };
+
+    return stats;
+}
+
 static const char *const nvme_strong_runtime_opts[] = {
     NVME_BLOCK_OPT_DEVICE,
     NVME_BLOCK_OPT_NAMESPACE,
@@ -XXX,XX +XXX,XX @@ static BlockDriver bdrv_nvme = {
     .bdrv_refresh_filename    = nvme_refresh_filename,
     .bdrv_refresh_limits      = nvme_refresh_limits,
     .strong_runtime_opts      = nvme_strong_runtime_opts,
+    .bdrv_get_specific_stats  = nvme_get_specific_stats,
 
     .bdrv_detach_aio_context  = nvme_detach_aio_context,
     .bdrv_attach_aio_context  = nvme_attach_aio_context,
-- 
2.26.2

From: Coiby Xu <coiby.xu@gmail.com>

Allow vu_message_read to be replaced by one which will make use of the
QIOChannel functions. Thus reading vhost-user message won't stall the
guest. For slave channel, we still use the default vu_message_read.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200918080912.321299-2-coiby.xu@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 contrib/libvhost-user/libvhost-user.h      | 21 +++++++++++++++++++++
 contrib/libvhost-user/libvhost-user-glib.c |  2 +-
 contrib/libvhost-user/libvhost-user.c      | 14 +++++++-------
 tests/vhost-user-bridge.c                  |  2 ++
 tools/virtiofsd/fuse_virtio.c              |  4 ++--
 5 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index XXXXXXX..XXXXXXX 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -XXX,XX +XXX,XX @@
  */
 #define VHOST_USER_MAX_RAM_SLOTS 32
 
+#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
+
 typedef enum VhostSetConfigType {
     VHOST_SET_CONFIG_TYPE_MASTER = 0,
     VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
@@ -XXX,XX +XXX,XX @@ typedef uint64_t (*vu_get_features_cb) (VuDev *dev);
 typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
 typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
                                   int *do_reply);
+typedef bool (*vu_read_msg_cb) (VuDev *dev, int sock, VhostUserMsg *vmsg);
 typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
 typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
 typedef int (*vu_get_config_cb) (VuDev *dev, uint8_t *config, uint32_t len);
@@ -XXX,XX +XXX,XX @@ struct VuDev {
     bool broken;
     uint16_t max_queues;
 
+    /* @read_msg: custom method to read vhost-user message
+     *
+     * Read data from vhost_user socket fd and fill up
+     * the passed VhostUserMsg *vmsg struct.
+     *
+     * If reading fails, it should close the received set of file
+     * descriptors as socket message's auxiliary data.
+     *
+     * For the details, please refer to vu_message_read in libvhost-user.c
+     * which will be used by default if not custom method is provided when
+     * calling vu_init
+     *
+     * Returns: true if vhost-user message successfully received,
+     *          otherwise return false.
+     *
+     */
+    vu_read_msg_cb read_msg;
     /* @set_watch: add or update the given fd to the watch set,
      * call cb when condition is met */
     vu_set_watch_cb set_watch;
@@ -XXX,XX +XXX,XX @@ bool vu_init(VuDev *dev,
              uint16_t max_queues,
              int socket,
              vu_panic_cb panic,
+             vu_read_msg_cb read_msg,
              vu_set_watch_cb set_watch,
              vu_remove_watch_cb remove_watch,
              const VuDevIface *iface);
diff --git a/contrib/libvhost-user/libvhost-user-glib.c b/contrib/libvhost-user/libvhost-user-glib.c
index XXXXXXX..XXXXXXX 100644
--- a/contrib/libvhost-user/libvhost-user-glib.c
+++ b/contrib/libvhost-user/libvhost-user-glib.c
@@ -XXX,XX +XXX,XX @@ vug_init(VugDev *dev, uint16_t max_queues, int socket,
     g_assert(dev);
     g_assert(iface);
 
-    if (!vu_init(&dev->parent, max_queues, socket, panic, set_watch,
+    if (!vu_init(&dev->parent, max_queues, socket, panic, NULL, set_watch,
                  remove_watch, iface)) {
         return false;
     }
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index XXXXXXX..XXXXXXX 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -XXX,XX +XXX,XX @@
 /* The version of inflight buffer */
 #define INFLIGHT_VERSION 1
 
-#define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
-
 /* The version of the protocol we support */
 #define VHOST_USER_VERSION 1
 #define LIBVHOST_USER_DEBUG 0
@@ -XXX,XX +XXX,XX @@ have_userfault(void)
 }
 
 static bool
-vu_message_read(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
+vu_message_read_default(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
 {
     char control[CMSG_SPACE(VHOST_MEMORY_BASELINE_NREGIONS * sizeof(int))] = {};
     struct iovec iov = {
@@ -XXX,XX +XXX,XX @@ vu_process_message_reply(VuDev *dev, const VhostUserMsg *vmsg)
         goto out;
     }
 
-    if (!vu_message_read(dev, dev->slave_fd, &msg_reply)) {
+    if (!vu_message_read_default(dev, dev->slave_fd, &msg_reply)) {
         goto out;
     }
 
@@ -XXX,XX +XXX,XX @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg *vmsg)
     /* Wait for QEMU to confirm that it's registered the handler for the
      * faults.
      */
-    if (!vu_message_read(dev, dev->sock, vmsg) ||
+    if (!dev->read_msg(dev, dev->sock, vmsg) ||
         vmsg->size != sizeof(vmsg->payload.u64) ||
         vmsg->payload.u64 != 0) {
         vu_panic(dev, "failed to receive valid ack for postcopy set-mem-table");
@@ -XXX,XX +XXX,XX @@ vu_dispatch(VuDev *dev)
     int reply_requested;
     bool need_reply, success = false;
 
-    if (!vu_message_read(dev, dev->sock, &vmsg)) {
+    if (!dev->read_msg(dev, dev->sock, &vmsg)) {
         goto end;
     }
 
@@ -XXX,XX +XXX,XX @@ vu_init(VuDev *dev,
         uint16_t max_queues,
         int socket,
         vu_panic_cb panic,
+        vu_read_msg_cb read_msg,
         vu_set_watch_cb set_watch,
         vu_remove_watch_cb remove_watch,
         const VuDevIface *iface)
@@ -XXX,XX +XXX,XX @@ vu_init(VuDev *dev,
 
     dev->sock = socket;
     dev->panic = panic;
+    dev->read_msg = read_msg ? read_msg : vu_message_read_default;
     dev->set_watch = set_watch;
     dev->remove_watch = remove_watch;
     dev->iface = iface;
@@ -XXX,XX +XXX,XX @@ static void _vu_queue_notify(VuDev *dev, VuVirtq *vq, bool sync)
 
         vu_message_write(dev, dev->slave_fd, &vmsg);
         if (ack) {
-            vu_message_read(dev, dev->slave_fd, &vmsg);
+            vu_message_read_default(dev, dev->slave_fd, &vmsg);
         }
         return;
     }
diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/vhost-user-bridge.c
+++ b/tests/vhost-user-bridge.c
@@ -XXX,XX +XXX,XX @@ vubr_accept_cb(int sock, void *ctx)
                  VHOST_USER_BRIDGE_MAX_QUEUES,
                  conn_fd,
                  vubr_panic,
+                 NULL,
                  vubr_set_watch,
                  vubr_remove_watch,
                  &vuiface)) {
@@ -XXX,XX +XXX,XX @@ vubr_new(const char *path, bool client)
                      VHOST_USER_BRIDGE_MAX_QUEUES,
                      dev->sock,
                      vubr_panic,
+                     NULL,
                      vubr_set_watch,
                      vubr_remove_watch,
                      &vuiface)) {
diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index XXXXXXX..XXXXXXX 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -XXX,XX +XXX,XX @@ int virtio_session_mount(struct fuse_session *se)
     se->vu_socketfd = data_sock;
     se->virtio_dev->se = se;
     pthread_rwlock_init(&se->virtio_dev->vu_dispatch_rwlock, NULL);
-    vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, fv_set_watch,
-            fv_remove_watch, &fv_iface);
+    vu_init(&se->virtio_dev->dev, 2, se->vu_socketfd, fv_panic, NULL,
+            fv_set_watch, fv_remove_watch, &fv_iface);
 
     return 0;
 }
-- 
2.26.2

From: Coiby Xu <coiby.xu@gmail.com>

Sharing QEMU devices via vhost-user protocol.

Only one vhost-user client can connect to the server one time.

diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/util/vhost-user-server.h
@@ -XXX,XX +XXX,XX @@
+/*
+ * Sharing QEMU devices via vhost-user protocol
+ *
+ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
+ * Copyright (c) 2020 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef VHOST_USER_SERVER_H
+#define VHOST_USER_SERVER_H
+
+#include "contrib/libvhost-user/libvhost-user.h"
+#include "io/channel-socket.h"
+#include "io/channel-file.h"
+#include "io/net-listener.h"
+#include "qemu/error-report.h"
+#include "qapi/error.h"
+#include "standard-headers/linux/virtio_blk.h"
+
+typedef struct VuFdWatch {
+    VuDev *vu_dev;
+    int fd; /*kick fd*/
+    void *pvt;
+    vu_watch_cb cb;
+    bool processing;
+    QTAILQ_ENTRY(VuFdWatch) next;
+} VuFdWatch;
+
+typedef struct VuServer VuServer;
+typedef void DevicePanicNotifierFn(VuServer *server);
+
+struct VuServer {
+    QIONetListener *listener;
+    AioContext *ctx;
+    DevicePanicNotifierFn *device_panic_notifier;
+    int max_queues;
+    const VuDevIface *vu_iface;
+    VuDev vu_dev;
+    QIOChannel *ioc; /* The I/O channel with the client */
+    QIOChannelSocket *sioc; /* The underlying data channel with the client */
+    /* IOChannel for fd provided via VHOST_USER_SET_SLAVE_REQ_FD */
+    QIOChannel *ioc_slave;
+    QIOChannelSocket *sioc_slave;
+    Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
+    QTAILQ_HEAD(, VuFdWatch) vu_fd_watches;
+    /* restart coroutine co_trip if AIOContext is changed */
+    bool aio_context_changed;
+    bool processing_msg;
+};
+
+bool vhost_user_server_start(VuServer *server,
+                             SocketAddress *unix_socket,
+                             AioContext *ctx,
+                             uint16_t max_queues,
+                             DevicePanicNotifierFn *device_panic_notifier,
+                             const VuDevIface *vu_iface,
+                             Error **errp);
+
+void vhost_user_server_stop(VuServer *server);
+
+void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx);
+
+#endif /* VHOST_USER_SERVER_H */
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@
+/*
+ * Sharing QEMU devices via vhost-user protocol
+ *
+ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
+ * Copyright (c) 2020 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
+#include "vhost-user-server.h"
+
+static void vmsg_close_fds(VhostUserMsg *vmsg)
+{
+    int i;
+    for (i = 0; i < vmsg->fd_num; i++) {
+        close(vmsg->fds[i]);
+    }
+}
+
+static void vmsg_unblock_fds(VhostUserMsg *vmsg)
+{
+    int i;
+    for (i = 0; i < vmsg->fd_num; i++) {
+        qemu_set_nonblock(vmsg->fds[i]);
+    }
+}
+
+static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+                      gpointer opaque);
+
+static void close_client(VuServer *server)
+{
+    /*
+     * Before closing the client
+     *
+     * 1. Let vu_client_trip stop processing new vhost-user msg
+     *
+     * 2. remove kick_handler
+     *
+     * 3. wait for the kick handler to be finished
+     *
+     * 4. wait for the current vhost-user msg to be finished processing
+     */
+
+    QIOChannelSocket *sioc = server->sioc;
+    /* When this is set vu_client_trip will stop new processing vhost-user message */
+    server->sioc = NULL;
+
+    VuFdWatch *vu_fd_watch, *next;
+    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+        aio_set_fd_handler(server->ioc->ctx, vu_fd_watch->fd, true, NULL,
+                           NULL, NULL, NULL);
+    }
+
+    while (!QTAILQ_EMPTY(&server->vu_fd_watches)) {
+        QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+            if (!vu_fd_watch->processing) {
+                QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
+                g_free(vu_fd_watch);
+            }
+        }
+    }
+
+    while (server->processing_msg) {
+        if (server->ioc->read_coroutine) {
+            server->ioc->read_coroutine = NULL;
+            qio_channel_set_aio_fd_handler(server->ioc, server->ioc->ctx, NULL,
+                                           NULL, server->ioc);
+            server->processing_msg = false;
+        }
+    }
+
+    vu_deinit(&server->vu_dev);
+    object_unref(OBJECT(sioc));
+    object_unref(OBJECT(server->ioc));
+}
+
+static void panic_cb(VuDev *vu_dev, const char *buf)
+{
+    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+
+    /* avoid while loop in close_client */
+    server->processing_msg = false;
+
+    if (buf) {
+        error_report("vu_panic: %s", buf);
+    }
+
+    if (server->sioc) {
+        close_client(server);
+    }
+
+    if (server->device_panic_notifier) {
+        server->device_panic_notifier(server);
+    }
+
+    /*
+     * Set the callback function for network listener so another
+     * vhost-user client can connect to this server
+     */
+    qio_net_listener_set_client_func(server->listener,
+                                     vu_accept,
+                                     server,
+                                     NULL);
+}
+
+static bool coroutine_fn
+vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
+{
+    struct iovec iov = {
+        .iov_base = (char *)vmsg,
+        .iov_len = VHOST_USER_HDR_SIZE,
+    };
+    int rc, read_bytes = 0;
+    Error *local_err = NULL;
+    /*
+     * Store fds/nfds returned from qio_channel_readv_full into
+     * temporary variables.
+     *
+     * VhostUserMsg is a packed structure, gcc will complain about passing
+     * pointer to a packed structure member if we pass &VhostUserMsg.fd_num
+     * and &VhostUserMsg.fds directly when calling qio_channel_readv_full,
+     * thus two temporary variables nfds and fds are used here.
+     */
+    size_t nfds = 0, nfds_t = 0;
+    const size_t max_fds = G_N_ELEMENTS(vmsg->fds);
+    int *fds_t = NULL;
+    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+    QIOChannel *ioc = server->ioc;
+
+    if (!ioc) {
+        error_report_err(local_err);
+        goto fail;
+    }
+
+    assert(qemu_in_coroutine());
+    do {
+        /*
+         * qio_channel_readv_full may have short reads, keeping calling it
+         * until getting VHOST_USER_HDR_SIZE or 0 bytes in total
+         */
+        rc = qio_channel_readv_full(ioc, &iov, 1, &fds_t, &nfds_t, &local_err);
+        if (rc < 0) {
+            if (rc == QIO_CHANNEL_ERR_BLOCK) {
+                qio_channel_yield(ioc, G_IO_IN);
+                continue;
+            } else {
+                error_report_err(local_err);
+                return false;
+            }
+        }
+        read_bytes += rc;
+        if (nfds_t > 0) {
+            if (nfds + nfds_t > max_fds) {
+                error_report("A maximum of %zu fds are allowed, "
+                             "however got %zu fds now",
+                             max_fds, nfds + nfds_t);
+                goto fail;
+            }
+            memcpy(vmsg->fds + nfds, fds_t,
+                   nfds_t *sizeof(vmsg->fds[0]));
+            nfds += nfds_t;
+            g_free(fds_t);
+        }
+        if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
+            break;
+        }
+        iov.iov_base = (char *)vmsg + read_bytes;
+        iov.iov_len = VHOST_USER_HDR_SIZE - read_bytes;
+    } while (true);
+
+    vmsg->fd_num = nfds;
+    /* qio_channel_readv_full will make socket fds blocking, unblock them */
+    vmsg_unblock_fds(vmsg);
+    if (vmsg->size > sizeof(vmsg->payload)) {
+        error_report("Error: too big message request: %d, "
+                     "size: vmsg->size: %u, "
+                     "while sizeof(vmsg->payload) = %zu",
+                     vmsg->request, vmsg->size, sizeof(vmsg->payload));
+        goto fail;
+    }
+
+    struct iovec iov_payload = {
+        .iov_base = (char *)&vmsg->payload,
+        .iov_len = vmsg->size,
+    };
+    if (vmsg->size) {
+        rc = qio_channel_readv_all_eof(ioc, &iov_payload, 1, &local_err);
+        if (rc == -1) {
+            error_report_err(local_err);
+            goto fail;
+        }
+    }
+
+    return true;
+
+fail:
+    vmsg_close_fds(vmsg);
+
+    return false;
+}
+
+
+static void vu_client_start(VuServer *server);
+static coroutine_fn void vu_client_trip(void *opaque)
+{
+    VuServer *server = opaque;
+
+    while (!server->aio_context_changed && server->sioc) {
+        server->processing_msg = true;
+        vu_dispatch(&server->vu_dev);
+        server->processing_msg = false;
+    }
+
+    if (server->aio_context_changed && server->sioc) {
+        server->aio_context_changed = false;
+        vu_client_start(server);
+    }
+}
+
+static void vu_client_start(VuServer *server)
+{
+    server->co_trip = qemu_coroutine_create(vu_client_trip, server);
+    aio_co_enter(server->ctx, server->co_trip);
+}
+
+/*
+ * a wrapper for vu_kick_cb
+ *
+ * since aio_dispatch can only pass one user data pointer to the
+ * callback function, pack VuDev and pvt into a struct. Then unpack it
+ * and pass them to vu_kick_cb
+ */
+static void kick_handler(void *opaque)
+{
+    VuFdWatch *vu_fd_watch = opaque;
+    vu_fd_watch->processing = true;
+    vu_fd_watch->cb(vu_fd_watch->vu_dev, 0, vu_fd_watch->pvt);
+    vu_fd_watch->processing = false;
+}
+
+
+static VuFdWatch *find_vu_fd_watch(VuServer *server, int fd)
+{
+
+    VuFdWatch *vu_fd_watch, *next;
+    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+        if (vu_fd_watch->fd == fd) {
+            return vu_fd_watch;
+        }
+    }
+    return NULL;
+}
+
+static void
+set_watch(VuDev *vu_dev, int fd, int vu_evt,
+          vu_watch_cb cb, void *pvt)
+{
+
+    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+    g_assert(vu_dev);
+    g_assert(fd >= 0);
+    g_assert(cb);
+
+    VuFdWatch *vu_fd_watch = find_vu_fd_watch(server, fd);
+
+    if (!vu_fd_watch) {
+        VuFdWatch *vu_fd_watch = g_new0(VuFdWatch, 1);
+
+        QTAILQ_INSERT_TAIL(&server->vu_fd_watches, vu_fd_watch, next);
+
+        vu_fd_watch->fd = fd;
+        vu_fd_watch->cb = cb;
+        qemu_set_nonblock(fd);
+        aio_set_fd_handler(server->ioc->ctx, fd, true, kick_handler,
+                           NULL, NULL, vu_fd_watch);
+        vu_fd_watch->vu_dev = vu_dev;
+        vu_fd_watch->pvt = pvt;
+    }
+}
+
+
+static void remove_watch(VuDev *vu_dev, int fd)
+{
+    VuServer *server;
+    g_assert(vu_dev);
+    g_assert(fd >= 0);
+
+    server = container_of(vu_dev, VuServer, vu_dev);
+
+    VuFdWatch *vu_fd_watch = find_vu_fd_watch(server, fd);
+
+    if (!vu_fd_watch) {
+        return;
+    }
+    aio_set_fd_handler(server->ioc->ctx, fd, true, NULL, NULL, NULL, NULL);
+
+    QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
+    g_free(vu_fd_watch);
+}
+
+
+static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
+                      gpointer opaque)
+{
+    VuServer *server = opaque;
+
+    if (server->sioc) {
+        warn_report("Only one vhost-user client is allowed to "
+                    "connect the server one time");
+        return;
+    }
+
+    if (!vu_init(&server->vu_dev, server->max_queues, sioc->fd, panic_cb,
+                 vu_message_read, set_watch, remove_watch, server->vu_iface)) {
+        error_report("Failed to initialize libvhost-user");
+        return;
+    }
+
+    /*
+     * Unset the callback function for network listener to make another
+     * vhost-user client keeping waiting until this client disconnects
+     */
+    qio_net_listener_set_client_func(server->listener,
+                                     NULL,
+                                     NULL,
+                                     NULL);
+    server->sioc = sioc;
+    /*
+     * Increase the object reference, so sioc will not freed by
+     * qio_net_listener_channel_func which will call object_unref(OBJECT(sioc))
+     */
+    object_ref(OBJECT(server->sioc));
+    qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
+    server->ioc = QIO_CHANNEL(sioc);
+    object_ref(OBJECT(server->ioc));
+    qio_channel_attach_aio_context(server->ioc, server->ctx);
+    qio_channel_set_blocking(QIO_CHANNEL(server->sioc), false, NULL);
+    vu_client_start(server);
+}
+
+
+void vhost_user_server_stop(VuServer *server)
+{
+    if (server->sioc) {
+        close_client(server);
+    }
+
+    if (server->listener) {
+        qio_net_listener_disconnect(server->listener);
+        object_unref(OBJECT(server->listener));
+    }
+
+}
+
+void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx)
+{
+    VuFdWatch *vu_fd_watch, *next;
+    void *opaque = NULL;
+    IOHandler *io_read = NULL;
+    bool attach;
+
+    server->ctx = ctx ? ctx : qemu_get_aio_context();
+
+    if (!server->sioc) {
+        /* not yet serving any client*/
+        return;
+    }
+
+    if (ctx) {
+        qio_channel_attach_aio_context(server->ioc, ctx);
+        server->aio_context_changed = true;
+        io_read = kick_handler;
+        attach = true;
+    } else {
+        qio_channel_detach_aio_context(server->ioc);
+        /* server->ioc->ctx keeps the old AioConext */
+        ctx = server->ioc->ctx;
+        attach = false;
+    }
+
+    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
+        if (vu_fd_watch->cb) {
+            opaque = attach ? vu_fd_watch : NULL;
+            aio_set_fd_handler(ctx, vu_fd_watch->fd, true,
+                               io_read, NULL, NULL,
+                               opaque);
+        }
+    }
+}
+
+
+bool vhost_user_server_start(VuServer *server,
+                             SocketAddress *socket_addr,
+                             AioContext *ctx,
+                             uint16_t max_queues,
+                             DevicePanicNotifierFn *device_panic_notifier,
+                             const VuDevIface *vu_iface,
+                             Error **errp)
+{
+    QIONetListener *listener = qio_net_listener_new();
+    if (qio_net_listener_open_sync(listener, socket_addr, 1,
+                                   errp) < 0) {
+        object_unref(OBJECT(listener));
+        return false;
+    }
+
+    /* zero out unspecified fileds */
+    *server = (VuServer) {
+        .listener              = listener,
+        .vu_iface              = vu_iface,
+        .max_queues            = max_queues,
+        .ctx                   = ctx,
+        .device_panic_notifier = device_panic_notifier,
+    };
+
+    qio_net_listener_set_name(server->listener, "vhost-user-backend-listener");
+
+    qio_net_listener_set_client_func(server->listener,
+                                     vu_accept,
+                                     server,
+                                     NULL);
+
+    QTAILQ_INIT(&server->vu_fd_watches);
+    return true;
+}
diff --git a/util/meson.build b/util/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -XXX,XX +XXX,XX @@ if have_block
   util_ss.add(files('main-loop.c'))
   util_ss.add(files('nvdimm-utils.c'))
   util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
+  util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
   util_ss.add(files('qemu-coroutine-sleep.c'))
   util_ss.add(files('qemu-co-shared-resource.c'))
   util_ss.add(files('thread-pool.c', 'qemu-timer.c'))
-- 
2.26.2

From: Coiby Xu <coiby.xu@gmail.com>

Move the constants from hw/core/qdev-properties.c to
util/block-helpers.h so that knowledge of the min/max values is

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Message-id: 20200918080912.321299-5-coiby.xu@gmail.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/block-helpers.h             | 19 +++++++++++++
 hw/core/qdev-properties-system.c | 31 ++++-----------------
 util/block-helpers.c             | 46 ++++++++++++++++++++++++++++++++
 util/meson.build                 |  1 +
 4 files changed, 71 insertions(+), 26 deletions(-)
 create mode 100644 util/block-helpers.h
 create mode 100644 util/block-helpers.c

diff --git a/util/block-helpers.h b/util/block-helpers.h
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/util/block-helpers.h
@@ -XXX,XX +XXX,XX @@
+#ifndef BLOCK_HELPERS_H
+#define BLOCK_HELPERS_H
+
+#include "qemu/units.h"
+
+/* lower limit is sector size */
+#define MIN_BLOCK_SIZE          INT64_C(512)
+#define MIN_BLOCK_SIZE_STR      "512 B"
+/*
+ * upper limit is arbitrary, 2 MiB looks sufficient for all sensible uses, and
+ * matches qcow2 cluster size limit
+ */
+#define MAX_BLOCK_SIZE          (2 * MiB)
+#define MAX_BLOCK_SIZE_STR      "2 MiB"
+
+void check_block_size(const char *id, const char *name, int64_t value,
+                      Error **errp);
+
+#endif /* BLOCK_HELPERS_H */
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -XXX,XX +XXX,XX @@
 #include "sysemu/blockdev.h"
 #include "net/net.h"
 #include "hw/pci/pci.h"
+#include "util/block-helpers.h"
 
 static bool check_prop_still_unset(DeviceState *dev, const char *name,
                                    const void *old_val, const char *new_val,
@@ -XXX,XX +XXX,XX @@ const PropertyInfo qdev_prop_losttickpolicy = {
 
 /* --- blocksize --- */
 
-/* lower limit is sector size */
-#define MIN_BLOCK_SIZE          512
-#define MIN_BLOCK_SIZE_STR      "512 B"
-/*
- * upper limit is arbitrary, 2 MiB looks sufficient for all sensible uses, and
- * matches qcow2 cluster size limit
- */
-#define MAX_BLOCK_SIZE          (2 * MiB)
-#define MAX_BLOCK_SIZE_STR      "2 MiB"
-
 static void set_blocksize(Object *obj, Visitor *v, const char *name,
                           void *opaque, Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ static void set_blocksize(Object *obj, Visitor *v, const char *name,
     Property *prop = opaque;
     uint32_t *ptr = qdev_get_prop_ptr(dev, prop);
     uint64_t value;
+    Error *local_err = NULL;
 
     if (dev->realized) {
         qdev_prop_set_after_realize(dev, name, errp);
@@ -XXX,XX +XXX,XX @@ static void set_blocksize(Object *obj, Visitor *v, const char *name,
     if (!visit_type_size(v, name, &value, errp)) {
         return;
     }
-    /* value of 0 means "unset" */
-    if (value && (value < MIN_BLOCK_SIZE || value > MAX_BLOCK_SIZE)) {
-        error_setg(errp,
-                   "Property %s.%s doesn't take value %" PRIu64
-                   " (minimum: " MIN_BLOCK_SIZE_STR
-                   ", maximum: " MAX_BLOCK_SIZE_STR ")",
-                   dev->id ? : "", name, value);
+    check_block_size(dev->id ? : "", name, value, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
         return;
     }
-
-    /* We rely on power-of-2 blocksizes for bitmasks */
-    if ((value & (value - 1)) != 0) {
-        error_setg(errp,
-                  "Property %s.%s doesn't take value '%" PRId64 "', "
-                  "it's not a power of 2", dev->id ?: "", name, (int64_t)value);
-        return;
-    }
-
     *ptr = value;
 }
 
diff --git a/util/block-helpers.c b/util/block-helpers.c
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/util/block-helpers.c
@@ -XXX,XX +XXX,XX @@
+/*
+ * Block utility functions
+ *
+ * Copyright IBM, Corp. 2011
+ * Copyright (c) 2020 Coiby Xu <coiby.xu@gmail.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qerror.h"
+#include "block-helpers.h"
+
+/**
+ * check_block_size:
+ * @id: The unique ID of the object
+ * @name: The name of the property being validated
+ * @value: The block size in bytes
+ * @errp: A pointer to an area to store an error
+ *
+ * This function checks that the block size meets the following conditions:
+ * 1. At least MIN_BLOCK_SIZE
+ * 2. No larger than MAX_BLOCK_SIZE
+ * 3. A power of 2
+ */
+void check_block_size(const char *id, const char *name, int64_t value,
+                      Error **errp)
+{
+    /* value of 0 means "unset" */
+    if (value && (value < MIN_BLOCK_SIZE || value > MAX_BLOCK_SIZE)) {
+        error_setg(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
+                   id, name, value, MIN_BLOCK_SIZE, MAX_BLOCK_SIZE);
+        return;
+    }
+
+    /* We rely on power-of-2 blocksizes for bitmasks */
+    if ((value & (value - 1)) != 0) {
+        error_setg(errp,
+                   "Property %s.%s doesn't take value '%" PRId64
+                   "', it's not a power of 2",
+                   id, name, value);
+        return;
+    }
+}
diff --git a/util/meson.build b/util/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -XXX,XX +XXX,XX @@ if have_block
   util_ss.add(files('nvdimm-utils.c'))
   util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
   util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
+  util_ss.add(files('block-helpers.c'))
   util_ss.add(files('qemu-coroutine-sleep.c'))
   util_ss.add(files('qemu-co-shared-resource.c'))
   util_ss.add(files('thread-pool.c', 'qemu-timer.c'))
-- 
2.26.2

From: Coiby Xu <coiby.xu@gmail.com>

By making use of libvhost-user, block device drive can be shared to
the connected vhost-user client. Only one client can connect to the
server one time.

Since vhost-user-server needs a block drive to be created first, delay
the creation of this object.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20200918080912.321299-6-coiby.xu@gmail.com
[Shorten "vhost_user_blk_server" string to "vhost_user_blk" to avoid the
following compiler warning:
../block/export/vhost-user-blk-server.c:178:50: error: ‘%s’ directive output truncated writing 21 bytes into a region of size 20 [-Werror=format-truncation=]
and fix "Invalid size %ld ..." ssize_t format string arguments for
32-bit hosts.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/export/vhost-user-blk-server.h |  36 ++
 block/export/vhost-user-blk-server.c | 661 +++++++++++++++++++++++++++
 softmmu/vl.c                         |   4 +
 block/meson.build                    |   1 +
 4 files changed, 702 insertions(+)
 create mode 100644 block/export/vhost-user-blk-server.h
 create mode 100644 block/export/vhost-user-blk-server.c

diff --git a/block/export/vhost-user-blk-server.h b/block/export/vhost-user-blk-server.h
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/block/export/vhost-user-blk-server.h
@@ -XXX,XX +XXX,XX @@
+/*
+ * Sharing QEMU block devices via vhost-user protocal
+ *
+ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
+ * Copyright (c) 2020 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#ifndef VHOST_USER_BLK_SERVER_H
+#define VHOST_USER_BLK_SERVER_H
+#include "util/vhost-user-server.h"
+
+typedef struct VuBlockDev VuBlockDev;
+#define TYPE_VHOST_USER_BLK_SERVER "vhost-user-blk-server"
+#define VHOST_USER_BLK_SERVER(obj) \
+   OBJECT_CHECK(VuBlockDev, obj, TYPE_VHOST_USER_BLK_SERVER)
+
+/* vhost user block device */
+struct VuBlockDev {
+    Object parent_obj;
+    char *node_name;
+    SocketAddress *addr;
+    AioContext *ctx;
+    VuServer vu_server;
+    bool running;
+    uint32_t blk_size;
+    BlockBackend *backend;
+    QIOChannelSocket *sioc;
+    QTAILQ_ENTRY(VuBlockDev) next;
+    struct virtio_blk_config blkcfg;
+    bool writable;
+};
+
+#endif /* VHOST_USER_BLK_SERVER_H */
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@
+/*
+ * Sharing QEMU block devices via vhost-user protocal
+ *
+ * Parts of the code based on nbd/server.c.
+ *
+ * Copyright (c) Coiby Xu <coiby.xu@gmail.com>.
+ * Copyright (c) 2020 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "block/block.h"
+#include "vhost-user-blk-server.h"
+#include "qapi/error.h"
+#include "qom/object_interfaces.h"
+#include "sysemu/block-backend.h"
+#include "util/block-helpers.h"
+
+enum {
+    VHOST_USER_BLK_MAX_QUEUES = 1,
+};
+struct virtio_blk_inhdr {
+    unsigned char status;
+};
+
+typedef struct VuBlockReq {
+    VuVirtqElement *elem;
+    int64_t sector_num;
+    size_t size;
+    struct virtio_blk_inhdr *in;
+    struct virtio_blk_outhdr out;
+    VuServer *server;
+    struct VuVirtq *vq;
+} VuBlockReq;
+
+static void vu_block_req_complete(VuBlockReq *req)
+{
+    VuDev *vu_dev = &req->server->vu_dev;
+
+    /* IO size with 1 extra status byte */
+    vu_queue_push(vu_dev, req->vq, req->elem, req->size + 1);
+    vu_queue_notify(vu_dev, req->vq);
+
+    if (req->elem) {
+        free(req->elem);
+    }
+
+    g_free(req);
+}
+
+static VuBlockDev *get_vu_block_device_by_server(VuServer *server)
+{
+    return container_of(server, VuBlockDev, vu_server);
+}
+
+static int coroutine_fn
+vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
+                              uint32_t iovcnt, uint32_t type)
+{
+    struct virtio_blk_discard_write_zeroes desc;
+    ssize_t size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc));
+    if (unlikely(size != sizeof(desc))) {
+        error_report("Invalid size %zd, expect %zu", size, sizeof(desc));
+        return -EINVAL;
+    }
+
+    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
+    uint64_t range[2] = { le64_to_cpu(desc.sector) << 9,
+                          le32_to_cpu(desc.num_sectors) << 9 };
+    if (type == VIRTIO_BLK_T_DISCARD) {
+        if (blk_co_pdiscard(vdev_blk->backend, range[0], range[1]) == 0) {
+            return 0;
+        }
+    } else if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
+        if (blk_co_pwrite_zeroes(vdev_blk->backend,
+                                 range[0], range[1], 0) == 0) {
+            return 0;
+        }
+    }
+
+    return -EINVAL;
+}
+
+static void coroutine_fn vu_block_flush(VuBlockReq *req)
+{
+    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
+    BlockBackend *backend = vdev_blk->backend;
+    blk_co_flush(backend);
+}
+
+struct req_data {
+    VuServer *server;
+    VuVirtq *vq;
+    VuVirtqElement *elem;
+};
+
+static void coroutine_fn vu_block_virtio_process_req(void *opaque)
+{
+    struct req_data *data = opaque;
+    VuServer *server = data->server;
+    VuVirtq *vq = data->vq;
+    VuVirtqElement *elem = data->elem;
+    uint32_t type;
+    VuBlockReq *req;
+
+    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
+    BlockBackend *backend = vdev_blk->backend;
+
+    struct iovec *in_iov = elem->in_sg;
+    struct iovec *out_iov = elem->out_sg;
+    unsigned in_num = elem->in_num;
+    unsigned out_num = elem->out_num;
+    /* refer to hw/block/virtio_blk.c */
+    if (elem->out_num < 1 || elem->in_num < 1) {
+        error_report("virtio-blk request missing headers");
+        free(elem);
+        return;
+    }
+
+    req = g_new0(VuBlockReq, 1);
+    req->server = server;
+    req->vq = vq;
+    req->elem = elem;
+
+    if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
+                            sizeof(req->out)) != sizeof(req->out))) {
+        error_report("virtio-blk request outhdr too short");
+        goto err;
+    }
+
+    iov_discard_front(&out_iov, &out_num, sizeof(req->out));
+
+    if (in_iov[in_num - 1].iov_len < sizeof(struct virtio_blk_inhdr)) {
+        error_report("virtio-blk request inhdr too short");
+        goto err;
+    }
+
+    /* We always touch the last byte, so just see how big in_iov is.  */
+    req->in = (void *)in_iov[in_num - 1].iov_base
+              + in_iov[in_num - 1].iov_len
+              - sizeof(struct virtio_blk_inhdr);
+    iov_discard_back(in_iov, &in_num, sizeof(struct virtio_blk_inhdr));
+
+    type = le32_to_cpu(req->out.type);
+    switch (type & ~VIRTIO_BLK_T_BARRIER) {
+    case VIRTIO_BLK_T_IN:
+    case VIRTIO_BLK_T_OUT: {
+        ssize_t ret = 0;
+        bool is_write = type & VIRTIO_BLK_T_OUT;
+        req->sector_num = le64_to_cpu(req->out.sector);
+
+        int64_t offset = req->sector_num * vdev_blk->blk_size;
+        QEMUIOVector qiov;
+        if (is_write) {
+            qemu_iovec_init_external(&qiov, out_iov, out_num);
+            ret = blk_co_pwritev(backend, offset, qiov.size,
+                                 &qiov, 0);
+        } else {
+            qemu_iovec_init_external(&qiov, in_iov, in_num);
+            ret = blk_co_preadv(backend, offset, qiov.size,
+                                &qiov, 0);
+        }
+        if (ret >= 0) {
+            req->in->status = VIRTIO_BLK_S_OK;
+        } else {
+            req->in->status = VIRTIO_BLK_S_IOERR;
+        }
+        break;
+    }
+    case VIRTIO_BLK_T_FLUSH:
+        vu_block_flush(req);
+        req->in->status = VIRTIO_BLK_S_OK;
+        break;
+    case VIRTIO_BLK_T_GET_ID: {
+        size_t size = MIN(iov_size(&elem->in_sg[0], in_num),
+                          VIRTIO_BLK_ID_BYTES);
+        snprintf(elem->in_sg[0].iov_base, size, "%s", "vhost_user_blk");
+        req->in->status = VIRTIO_BLK_S_OK;
+        req->size = elem->in_sg[0].iov_len;
+        break;
+    }
+    case VIRTIO_BLK_T_DISCARD:
+    case VIRTIO_BLK_T_WRITE_ZEROES: {
+        int rc;
+        rc = vu_block_discard_write_zeroes(req, &elem->out_sg[1],
+                                           out_num, type);
+        if (rc == 0) {
+            req->in->status = VIRTIO_BLK_S_OK;
+        } else {
+            req->in->status = VIRTIO_BLK_S_IOERR;
+        }
+        break;
+    }
+    default:
+        req->in->status = VIRTIO_BLK_S_UNSUPP;
+        break;
+    }
+
+    vu_block_req_complete(req);
+    return;
+
+err:
+    free(elem);
+    g_free(req);
+    return;
+}
+
+static void vu_block_process_vq(VuDev *vu_dev, int idx)
+{
+    VuServer *server;
+    VuVirtq *vq;
+    struct req_data *req_data;
+
+    server = container_of(vu_dev, VuServer, vu_dev);
+    assert(server);
+
+    vq = vu_get_queue(vu_dev, idx);
+    assert(vq);
+    VuVirtqElement *elem;
+    while (1) {
+        elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) +
+                                    sizeof(VuBlockReq));
+        if (elem) {
+            req_data = g_new0(struct req_data, 1);
+            req_data->server = server;
+            req_data->vq = vq;
+            req_data->elem = elem;
+            Coroutine *co = qemu_coroutine_create(vu_block_virtio_process_req,
+                                                  req_data);
+            aio_co_enter(server->ioc->ctx, co);
+        } else {
+            break;
+        }
+    }
+}
+
+static void vu_block_queue_set_started(VuDev *vu_dev, int idx, bool started)
+{
+    VuVirtq *vq;
+
+    assert(vu_dev);
+
+    vq = vu_get_queue(vu_dev, idx);
+    vu_set_queue_handler(vu_dev, vq, started ? vu_block_process_vq : NULL);
+}
+
+static uint64_t vu_block_get_features(VuDev *dev)
+{
+    uint64_t features;
+    VuServer *server = container_of(dev, VuServer, vu_dev);
+    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
+    features = 1ull << VIRTIO_BLK_F_SIZE_MAX |
+               1ull << VIRTIO_BLK_F_SEG_MAX |
+               1ull << VIRTIO_BLK_F_TOPOLOGY |
+               1ull << VIRTIO_BLK_F_BLK_SIZE |
+               1ull << VIRTIO_BLK_F_FLUSH |
+               1ull << VIRTIO_BLK_F_DISCARD |
+               1ull << VIRTIO_BLK_F_WRITE_ZEROES |
+               1ull << VIRTIO_BLK_F_CONFIG_WCE |
+               1ull << VIRTIO_F_VERSION_1 |
+               1ull << VIRTIO_RING_F_INDIRECT_DESC |
+               1ull << VIRTIO_RING_F_EVENT_IDX |
+               1ull << VHOST_USER_F_PROTOCOL_FEATURES;
+
+    if (!vdev_blk->writable) {
+        features |= 1ull << VIRTIO_BLK_F_RO;
+    }
+
+    return features;
+}
+
+static uint64_t vu_block_get_protocol_features(VuDev *dev)
+{
+    return 1ull << VHOST_USER_PROTOCOL_F_CONFIG |
+           1ull << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD;
+}
+
+static int
+vu_block_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
+{
+    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
+    memcpy(config, &vdev_blk->blkcfg, len);
+
+    return 0;
+}
+
+static int
+vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
+                    uint32_t offset, uint32_t size, uint32_t flags)
+{
+    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
+    uint8_t wce;
+
+    /* don't support live migration */
+    if (flags != VHOST_SET_CONFIG_TYPE_MASTER) {
+        return -EINVAL;
+    }
+
+    if (offset != offsetof(struct virtio_blk_config, wce) ||
+        size != 1) {
+        return -EINVAL;
+    }
+
+    wce = *data;
+    vdev_blk->blkcfg.wce = wce;
+    blk_set_enable_write_cache(vdev_blk->backend, wce);
+    return 0;
+}
+
+/*
+ * When the client disconnects, it sends a VHOST_USER_NONE request
+ * and vu_process_message will simple call exit which cause the VM
+ * to exit abruptly.
+ * To avoid this issue,  process VHOST_USER_NONE request ahead
+ * of vu_process_message.
+ *
+ */
+static int vu_block_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
+{
+    if (vmsg->request == VHOST_USER_NONE) {
+        dev->panic(dev, "disconnect");
+        return true;
+    }
+    return false;
+}
+
+static const VuDevIface vu_block_iface = {
+    .get_features          = vu_block_get_features,
+    .queue_set_started     = vu_block_queue_set_started,
+    .get_protocol_features = vu_block_get_protocol_features,
+    .get_config            = vu_block_get_config,
+    .set_config            = vu_block_set_config,
+    .process_msg           = vu_block_process_msg,
+};
+
+static void blk_aio_attached(AioContext *ctx, void *opaque)
+{
+    VuBlockDev *vub_dev = opaque;
+    aio_context_acquire(ctx);
+    vhost_user_server_set_aio_context(&vub_dev->vu_server, ctx);
+    aio_context_release(ctx);
+}
+
+static void blk_aio_detach(void *opaque)
+{
+    VuBlockDev *vub_dev = opaque;
+    AioContext *ctx = vub_dev->vu_server.ctx;
+    aio_context_acquire(ctx);
+    vhost_user_server_set_aio_context(&vub_dev->vu_server, NULL);
+    aio_context_release(ctx);
+}
+
+static void
+vu_block_initialize_config(BlockDriverState *bs,
+                           struct virtio_blk_config *config, uint32_t blk_size)
+{
+    config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+    config->blk_size = blk_size;
+    config->size_max = 0;
+    config->seg_max = 128 - 2;
+    config->min_io_size = 1;
+    config->opt_io_size = 1;
+    config->num_queues = VHOST_USER_BLK_MAX_QUEUES;
+    config->max_discard_sectors = 32768;
+    config->max_discard_seg = 1;
+    config->discard_sector_alignment = config->blk_size >> 9;
+    config->max_write_zeroes_sectors = 32768;
+    config->max_write_zeroes_seg = 1;
+}
+
+static VuBlockDev *vu_block_init(VuBlockDev *vu_block_device, Error **errp)
+{
+
+    BlockBackend *blk;
+    Error *local_error = NULL;
+    const char *node_name = vu_block_device->node_name;
+    bool writable = vu_block_device->writable;
+    uint64_t perm = BLK_PERM_CONSISTENT_READ;
+    int ret;
+
+    AioContext *ctx;
+
+    BlockDriverState *bs = bdrv_lookup_bs(node_name, node_name, &local_error);
+
+    if (!bs) {
+        error_propagate(errp, local_error);
+        return NULL;
+    }
+
+    if (bdrv_is_read_only(bs)) {
+        writable = false;
+    }
+
+    if (writable) {
+        perm |= BLK_PERM_WRITE;
+    }
+
+    ctx = bdrv_get_aio_context(bs);
+    aio_context_acquire(ctx);
+    bdrv_invalidate_cache(bs, NULL);
+    aio_context_release(ctx);
+
+    /*
+     * Don't allow resize while the vhost user server is running,
+     * otherwise we don't care what happens with the node.
+     */
+    blk = blk_new(bdrv_get_aio_context(bs), perm,
+                  BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
+                  BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
+    ret = blk_insert_bs(blk, bs, errp);
+
+    if (ret < 0) {
+        goto fail;
+    }
+
+    blk_set_enable_write_cache(blk, false);
+
+    blk_set_allow_aio_context_change(blk, true);
+
+    vu_block_device->blkcfg.wce = 0;
+    vu_block_device->backend = blk;
+    if (!vu_block_device->blk_size) {
+        vu_block_device->blk_size = BDRV_SECTOR_SIZE;
+    }
+    vu_block_device->blkcfg.blk_size = vu_block_device->blk_size;
+    blk_set_guest_block_size(blk, vu_block_device->blk_size);
+    vu_block_initialize_config(bs, &vu_block_device->blkcfg,
+                                   vu_block_device->blk_size);
+    return vu_block_device;
+
+fail:
+    blk_unref(blk);
+    return NULL;
+}
+
+static void vu_block_deinit(VuBlockDev *vu_block_device)
+{
+    if (vu_block_device->backend) {
+        blk_remove_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
+                                        blk_aio_detach, vu_block_device);
+    }
+
+    blk_unref(vu_block_device->backend);
+}
+
+static void vhost_user_blk_server_stop(VuBlockDev *vu_block_device)
+{
+    vhost_user_server_stop(&vu_block_device->vu_server);
+    vu_block_deinit(vu_block_device);
+}
+
+static void vhost_user_blk_server_start(VuBlockDev *vu_block_device,
+                                        Error **errp)
+{
+    AioContext *ctx;
+    SocketAddress *addr = vu_block_device->addr;
+
+    if (!vu_block_init(vu_block_device, errp)) {
+        return;
+    }
+
+    ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));
+
+    if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx,
+                                 VHOST_USER_BLK_MAX_QUEUES,
+                                 NULL, &vu_block_iface,
+                                 errp)) {
+        goto error;
+    }
+
+    blk_add_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
+                                 blk_aio_detach, vu_block_device);
+    vu_block_device->running = true;
+    return;
+
+ error:
+    vu_block_deinit(vu_block_device);
+}
+
+static bool vu_prop_modifiable(VuBlockDev *vus, Error **errp)
+{
+    if (vus->running) {
+            error_setg(errp, "The property can't be modified "
+                       "while the server is running");
+            return false;
+    }
+    return true;
+}
+
+static void vu_set_node_name(Object *obj, const char *value, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+
+    if (!vu_prop_modifiable(vus, errp)) {
+        return;
+    }
+
+    if (vus->node_name) {
+        g_free(vus->node_name);
+    }
+
+    vus->node_name = g_strdup(value);
+}
+
+static char *vu_get_node_name(Object *obj, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+    return g_strdup(vus->node_name);
+}
+
+static void free_socket_addr(SocketAddress *addr)
+{
+        g_free(addr->u.q_unix.path);
+        g_free(addr);
+}
+
+static void vu_set_unix_socket(Object *obj, const char *value,
+                               Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+
+    if (!vu_prop_modifiable(vus, errp)) {
+        return;
+    }
+
+    if (vus->addr) {
+        free_socket_addr(vus->addr);
+    }
+
+    SocketAddress *addr = g_new0(SocketAddress, 1);
+    addr->type = SOCKET_ADDRESS_TYPE_UNIX;
+    addr->u.q_unix.path = g_strdup(value);
+    vus->addr = addr;
+}
+
+static char *vu_get_unix_socket(Object *obj, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+    return g_strdup(vus->addr->u.q_unix.path);
+}
+
+static bool vu_get_block_writable(Object *obj, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+    return vus->writable;
+}
+
+static void vu_set_block_writable(Object *obj, bool value, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+
+    if (!vu_prop_modifiable(vus, errp)) {
+            return;
+    }
+
+    vus->writable = value;
+}
+
+static void vu_get_blk_size(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+    uint32_t value = vus->blk_size;
+
+    visit_type_uint32(v, name, &value, errp);
+}
+
+static void vu_set_blk_size(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
+{
+    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
+
+    Error *local_err = NULL;
+    uint32_t value;
+
+    if (!vu_prop_modifiable(vus, errp)) {
+            return;
+    }
+
+    visit_type_uint32(v, name, &value, &local_err);
+    if (local_err) {
+        goto out;
+    }
+
+    check_block_size(object_get_typename(obj), name, value, &local_err);
+    if (local_err) {
+        goto out;
+    }
+
+    vus->blk_size = value;
+
+out:
+    error_propagate(errp, local_err);
+}
+
+static void vhost_user_blk_server_instance_finalize(Object *obj)
+{
+    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
+
+    vhost_user_blk_server_stop(vub);
+
+    /*
+     * Unlike object_property_add_str, object_class_property_add_str
+     * doesn't have a release method. Thus manual memory freeing is
+     * needed.
+     */
+    free_socket_addr(vub->addr);
+    g_free(vub->node_name);
+}
+
+static void vhost_user_blk_server_complete(UserCreatable *obj, Error **errp)
+{
+    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
+
+    vhost_user_blk_server_start(vub, errp);
+}
+
+static void vhost_user_blk_server_class_init(ObjectClass *klass,
+                                             void *class_data)
+{
+    UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
+    ucc->complete = vhost_user_blk_server_complete;
+
+    object_class_property_add_bool(klass, "writable",
+                                   vu_get_block_writable,
+                                   vu_set_block_writable);
+
+    object_class_property_add_str(klass, "node-name",
+                                  vu_get_node_name,
+                                  vu_set_node_name);
+
+    object_class_property_add_str(klass, "unix-socket",
+                                  vu_get_unix_socket,
+                                  vu_set_unix_socket);
+
+    object_class_property_add(klass, "logical-block-size", "uint32",
+                              vu_get_blk_size, vu_set_blk_size,
+                              NULL, NULL);
+}
+
+static const TypeInfo vhost_user_blk_server_info = {
+    .name = TYPE_VHOST_USER_BLK_SERVER,
+    .parent = TYPE_OBJECT,
+    .instance_size = sizeof(VuBlockDev),
+    .instance_finalize = vhost_user_blk_server_instance_finalize,
+    .class_init = vhost_user_blk_server_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        {TYPE_USER_CREATABLE},
+        {}
+    },
+};
+
+static void vhost_user_blk_server_register_types(void)
+{
+    type_register_static(&vhost_user_blk_server_info);
+}
+
+type_init(vhost_user_blk_server_register_types)
diff --git a/softmmu/vl.c b/softmmu/vl.c
index XXXXXXX..XXXXXXX 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -XXX,XX +XXX,XX @@ static bool object_create_initial(const char *type, QemuOpts *opts)
     }
 #endif
 
+    /* Reason: vhost-user-blk-server property "node-name" */
+    if (g_str_equal(type, "vhost-user-blk-server")) {
+        return false;
+    }
     /*
      * Reason: filter-* property "netdev" etc.
      */
diff --git a/block/meson.build b/block/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/block/meson.build
+++ b/block/meson.build
@@ -XXX,XX +XXX,XX @@ block_ss.add(when: 'CONFIG_WIN32', if_true: files('file-win32.c', 'win32-aio.c')
 block_ss.add(when: 'CONFIG_POSIX', if_true: [files('file-posix.c'), coref, iokit])
 block_ss.add(when: 'CONFIG_LIBISCSI', if_true: files('iscsi-opts.c'))
 block_ss.add(when: 'CONFIG_LINUX', if_true: files('nvme.c'))
+block_ss.add(when: 'CONFIG_LINUX', if_true: files('export/vhost-user-blk-server.c', '../contrib/libvhost-user/libvhost-user.c'))
 block_ss.add(when: 'CONFIG_REPLICATION', if_true: files('replication.c'))
 block_ss.add(when: 'CONFIG_SHEEPDOG', if_true: files('sheepdog.c'))
 block_ss.add(when: ['CONFIG_LINUX_AIO', libaio], if_true: files('linux-aio.c'))
-- 
2.26.2

From: Coiby Xu <coiby.xu@gmail.com>

Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Coiby Xu <coiby.xu@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20200918080912.321299-8-coiby.xu@gmail.com
[Removed reference to vhost-user-blk-test.c, it will be sent in a
separate pull request.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 MAINTAINERS | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index XXXXXXX..XXXXXXX 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -XXX,XX +XXX,XX @@ L: qemu-block@nongnu.org
 S: Supported
 F: tests/image-fuzzer/
 
+Vhost-user block device backend server
+M: Coiby Xu <Coiby.Xu@gmail.com>
+S: Maintained
+F: block/export/vhost-user-blk-server.c
+F: util/vhost-user-server.c
+F: tests/qtest/libqos/vhost-user-blk.c
+
 Replication
 M: Wen Congyang <wencongyang2@huawei.com>
 M: Xie Changlong <xiechanglong.d@gmail.com>
-- 
2.26.2

Explicitly deleting watches is not necessary since libvhost-user calls
remove_watch() during vu_deinit(). Add an assertion to check this
though.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-5-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/vhost-user-server.c | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@ static void close_client(VuServer *server)
     /* When this is set vu_client_trip will stop new processing vhost-user message */
     server->sioc = NULL;
 
-    VuFdWatch *vu_fd_watch, *next;
-    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
-        aio_set_fd_handler(server->ioc->ctx, vu_fd_watch->fd, true, NULL,
-                           NULL, NULL, NULL);
-    }
-
-    while (!QTAILQ_EMPTY(&server->vu_fd_watches)) {
-        QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
-            if (!vu_fd_watch->processing) {
-                QTAILQ_REMOVE(&server->vu_fd_watches, vu_fd_watch, next);
-                g_free(vu_fd_watch);
-            }
-        }
-    }
-
     while (server->processing_msg) {
         if (server->ioc->read_coroutine) {
             server->ioc->read_coroutine = NULL;
@@ -XXX,XX +XXX,XX @@ static void close_client(VuServer *server)
     }
 
     vu_deinit(&server->vu_dev);
+
+    /* vu_deinit() should have called remove_watch() */
+    assert(QTAILQ_EMPTY(&server->vu_fd_watches));
+
     object_unref(OBJECT(sioc));
     object_unref(OBJECT(server->ioc));
 }
-- 
2.26.2

Only one struct is needed per request. Drop req_data and the separate
VuBlockReq instance. Instead let vu_queue_pop() allocate everything at
once.

This fixes the req_data memory leak in vu_block_virtio_process_req().

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-6-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/export/vhost-user-blk-server.c | 68 +++++++++-------------------
 1 file changed, 21 insertions(+), 47 deletions(-)

diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@ struct virtio_blk_inhdr {
 };
 
 typedef struct VuBlockReq {
-    VuVirtqElement *elem;
+    VuVirtqElement elem;
     int64_t sector_num;
     size_t size;
     struct virtio_blk_inhdr *in;
@@ -XXX,XX +XXX,XX @@ static void vu_block_req_complete(VuBlockReq *req)
     VuDev *vu_dev = &req->server->vu_dev;
 
     /* IO size with 1 extra status byte */
-    vu_queue_push(vu_dev, req->vq, req->elem, req->size + 1);
+    vu_queue_push(vu_dev, req->vq, &req->elem, req->size + 1);
     vu_queue_notify(vu_dev, req->vq);
 
-    if (req->elem) {
-        free(req->elem);
-    }
-
-    g_free(req);
+    free(req);
 }
 
 static VuBlockDev *get_vu_block_device_by_server(VuServer *server)
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_flush(VuBlockReq *req)
     blk_co_flush(backend);
 }
 
-struct req_data {
-    VuServer *server;
-    VuVirtq *vq;
-    VuVirtqElement *elem;
-};
-
 static void coroutine_fn vu_block_virtio_process_req(void *opaque)
 {
-    struct req_data *data = opaque;
-    VuServer *server = data->server;
-    VuVirtq *vq = data->vq;
-    VuVirtqElement *elem = data->elem;
+    VuBlockReq *req = opaque;
+    VuServer *server = req->server;
+    VuVirtqElement *elem = &req->elem;
     uint32_t type;
-    VuBlockReq *req;
 
     VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
     BlockBackend *backend = vdev_blk->backend;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
     struct iovec *out_iov = elem->out_sg;
     unsigned in_num = elem->in_num;
     unsigned out_num = elem->out_num;
+
     /* refer to hw/block/virtio_blk.c */
     if (elem->out_num < 1 || elem->in_num < 1) {
         error_report("virtio-blk request missing headers");
-        free(elem);
-        return;
+        goto err;
     }
 
-    req = g_new0(VuBlockReq, 1);
-    req->server = server;
-    req->vq = vq;
-    req->elem = elem;
-
     if (unlikely(iov_to_buf(out_iov, out_num, 0, &req->out,
                             sizeof(req->out)) != sizeof(req->out))) {
         error_report("virtio-blk request outhdr too short");
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
 
 err:
     free(elem);
-    g_free(req);
-    return;
 }
 
 static void vu_block_process_vq(VuDev *vu_dev, int idx)
 {
-    VuServer *server;
-    VuVirtq *vq;
-    struct req_data *req_data;
+    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+    VuVirtq *vq = vu_get_queue(vu_dev, idx);
 
-    server = container_of(vu_dev, VuServer, vu_dev);
-    assert(server);
-
-    vq = vu_get_queue(vu_dev, idx);
-    assert(vq);
-    VuVirtqElement *elem;
     while (1) {
-        elem = vu_queue_pop(vu_dev, vq, sizeof(VuVirtqElement) +
-                                    sizeof(VuBlockReq));
-        if (elem) {
-            req_data = g_new0(struct req_data, 1);
-            req_data->server = server;
-            req_data->vq = vq;
-            req_data->elem = elem;
-            Coroutine *co = qemu_coroutine_create(vu_block_virtio_process_req,
-                                                  req_data);
-            aio_co_enter(server->ioc->ctx, co);
-        } else {
+        VuBlockReq *req;
+
+        req = vu_queue_pop(vu_dev, vq, sizeof(VuBlockReq));
+        if (!req) {
             break;
         }
+
+        req->server = server;
+        req->vq = vq;
+
+        Coroutine *co =
+            qemu_coroutine_create(vu_block_virtio_process_req, req);
+        qemu_coroutine_enter(co);
     }
 }
 
-- 
2.26.2

The device panic notifier callback is not used. Drop it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-7-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/vhost-user-server.h             | 3 ---
 block/export/vhost-user-blk-server.c | 3 +--
 util/vhost-user-server.c             | 6 ------
 3 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.h
+++ b/util/vhost-user-server.h
@@ -XXX,XX +XXX,XX @@ typedef struct VuFdWatch {
 } VuFdWatch;
 
 typedef struct VuServer VuServer;
-typedef void DevicePanicNotifierFn(VuServer *server);
 
 struct VuServer {
     QIONetListener *listener;
     AioContext *ctx;
-    DevicePanicNotifierFn *device_panic_notifier;
     int max_queues;
     const VuDevIface *vu_iface;
     VuDev vu_dev;
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
                              SocketAddress *unix_socket,
                              AioContext *ctx,
                              uint16_t max_queues,
-                             DevicePanicNotifierFn *device_panic_notifier,
                              const VuDevIface *vu_iface,
                              Error **errp);
 
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@ static void vhost_user_blk_server_start(VuBlockDev *vu_block_device,
     ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));
 
     if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx,
-                                 VHOST_USER_BLK_MAX_QUEUES,
-                                 NULL, &vu_block_iface,
+                                 VHOST_USER_BLK_MAX_QUEUES, &vu_block_iface,
                                  errp)) {
         goto error;
     }
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@ static void panic_cb(VuDev *vu_dev, const char *buf)
         close_client(server);
     }
 
-    if (server->device_panic_notifier) {
-        server->device_panic_notifier(server);
-    }
-
     /*
      * Set the callback function for network listener so another
      * vhost-user client can connect to this server
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
                              SocketAddress *socket_addr,
                              AioContext *ctx,
                              uint16_t max_queues,
-                             DevicePanicNotifierFn *device_panic_notifier,
                              const VuDevIface *vu_iface,
                              Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
         .vu_iface              = vu_iface,
         .max_queues            = max_queues,
         .ctx                   = ctx,
-        .device_panic_notifier = device_panic_notifier,
     };
 
     qio_net_listener_set_name(server->listener, "vhost-user-backend-listener");
-- 
2.26.2

fds[] is leaked when qio_channel_readv_full() fails.

Use vmsg->fds[] instead of keeping a local fds[] array. Then we can
reuse goto fail to clean up fds. vmsg->fd_num must be zeroed before the
loop to make this safe.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-8-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/vhost-user-server.c | 50 ++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
     };
     int rc, read_bytes = 0;
     Error *local_err = NULL;
-    /*
-     * Store fds/nfds returned from qio_channel_readv_full into
-     * temporary variables.
-     *
-     * VhostUserMsg is a packed structure, gcc will complain about passing
-     * pointer to a packed structure member if we pass &VhostUserMsg.fd_num
-     * and &VhostUserMsg.fds directly when calling qio_channel_readv_full,
-     * thus two temporary variables nfds and fds are used here.
-     */
-    size_t nfds = 0, nfds_t = 0;
     const size_t max_fds = G_N_ELEMENTS(vmsg->fds);
-    int *fds_t = NULL;
     VuServer *server = container_of(vu_dev, VuServer, vu_dev);
     QIOChannel *ioc = server->ioc;
 
+    vmsg->fd_num = 0;
     if (!ioc) {
         error_report_err(local_err);
         goto fail;
@@ -XXX,XX +XXX,XX @@ vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
 
     assert(qemu_in_coroutine());
     do {
+        size_t nfds = 0;
+        int *fds = NULL;
+
         /*
          * qio_channel_readv_full may have short reads, keeping calling it
          * until getting VHOST_USER_HDR_SIZE or 0 bytes in total
          */
-        rc = qio_channel_readv_full(ioc, &iov, 1, &fds_t, &nfds_t, &local_err);
+        rc = qio_channel_readv_full(ioc, &iov, 1, &fds, &nfds, &local_err);
         if (rc < 0) {
             if (rc == QIO_CHANNEL_ERR_BLOCK) {
+                assert(local_err == NULL);
                 qio_channel_yield(ioc, G_IO_IN);
                 continue;
             } else {
                 error_report_err(local_err);
-                return false;
+                goto fail;
             }
         }
-        read_bytes += rc;
-        if (nfds_t > 0) {
-            if (nfds + nfds_t > max_fds) {
+
+        if (nfds > 0) {
+            if (vmsg->fd_num + nfds > max_fds) {
                 error_report("A maximum of %zu fds are allowed, "
                              "however got %zu fds now",
-                             max_fds, nfds + nfds_t);
+                             max_fds, vmsg->fd_num + nfds);
+                g_free(fds);
                 goto fail;
             }
-            memcpy(vmsg->fds + nfds, fds_t,
-                   nfds_t *sizeof(vmsg->fds[0]));
-            nfds += nfds_t;
-            g_free(fds_t);
+            memcpy(vmsg->fds + vmsg->fd_num, fds, nfds * sizeof(vmsg->fds[0]));
+            vmsg->fd_num += nfds;
+            g_free(fds);
         }
-        if (read_bytes == VHOST_USER_HDR_SIZE || rc == 0) {
-            break;
+
+        if (rc == 0) { /* socket closed */
+            goto fail;
         }
-        iov.iov_base = (char *)vmsg + read_bytes;
-        iov.iov_len = VHOST_USER_HDR_SIZE - read_bytes;
-    } while (true);
 
-    vmsg->fd_num = nfds;
+        iov.iov_base += rc;
+        iov.iov_len -= rc;
+        read_bytes += rc;
+    } while (read_bytes != VHOST_USER_HDR_SIZE);
+
     /* qio_channel_readv_full will make socket fds blocking, unblock them */
     vmsg_unblock_fds(vmsg);
     if (vmsg->size > sizeof(vmsg->payload)) {
-- 
2.26.2

The vu_client_trip() coroutine is leaked during AioContext switching. It
is also unsafe to destroy the vu_dev in panic_cb() since its callers
still access it in some cases.

Rework the lifecycle to solve these safety issues.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-10-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/vhost-user-server.h             |  29 ++--
 block/export/vhost-user-blk-server.c |   9 +-
 util/vhost-user-server.c             | 245 +++++++++++++++------------
 3 files changed, 155 insertions(+), 128 deletions(-)

diff --git a/util/vhost-user-server.h b/util/vhost-user-server.h
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.h
+++ b/util/vhost-user-server.h
@@ -XXX,XX +XXX,XX @@
 #include "qapi/error.h"
 #include "standard-headers/linux/virtio_blk.h"
 
+/* A kick fd that we monitor on behalf of libvhost-user */
 typedef struct VuFdWatch {
     VuDev *vu_dev;
     int fd; /*kick fd*/
     void *pvt;
     vu_watch_cb cb;
-    bool processing;
     QTAILQ_ENTRY(VuFdWatch) next;
 } VuFdWatch;
 
-typedef struct VuServer VuServer;
-
-struct VuServer {
+/**
+ * VuServer:
+ * A vhost-user server instance with user-defined VuDevIface callbacks.
+ * Vhost-user device backends can be implemented using VuServer. VuDevIface
+ * callbacks and virtqueue kicks run in the given AioContext.
+ */
+typedef struct {
     QIONetListener *listener;
+    QEMUBH *restart_listener_bh;
     AioContext *ctx;
     int max_queues;
     const VuDevIface *vu_iface;
+
+    /* Protected by ctx lock */
     VuDev vu_dev;
     QIOChannel *ioc; /* The I/O channel with the client */
     QIOChannelSocket *sioc; /* The underlying data channel with the client */
-    /* IOChannel for fd provided via VHOST_USER_SET_SLAVE_REQ_FD */
-    QIOChannel *ioc_slave;
-    QIOChannelSocket *sioc_slave;
-    Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
     QTAILQ_HEAD(, VuFdWatch) vu_fd_watches;
-    /* restart coroutine co_trip if AIOContext is changed */
-    bool aio_context_changed;
-    bool processing_msg;
-};
+
+    Coroutine *co_trip; /* coroutine for processing VhostUserMsg */
+} VuServer;
 
 bool vhost_user_server_start(VuServer *server,
                              SocketAddress *unix_socket,
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
 
 void vhost_user_server_stop(VuServer *server);
 
-void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx);
+void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx);
+void vhost_user_server_detach_aio_context(VuServer *server);
 
 #endif /* VHOST_USER_SERVER_H */
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@ static const VuDevIface vu_block_iface = {
 static void blk_aio_attached(AioContext *ctx, void *opaque)
 {
     VuBlockDev *vub_dev = opaque;
-    aio_context_acquire(ctx);
-    vhost_user_server_set_aio_context(&vub_dev->vu_server, ctx);
-    aio_context_release(ctx);
+    vhost_user_server_attach_aio_context(&vub_dev->vu_server, ctx);
 }
 
 static void blk_aio_detach(void *opaque)
 {
     VuBlockDev *vub_dev = opaque;
-    AioContext *ctx = vub_dev->vu_server.ctx;
-    aio_context_acquire(ctx);
-    vhost_user_server_set_aio_context(&vub_dev->vu_server, NULL);
-    aio_context_release(ctx);
+    vhost_user_server_detach_aio_context(&vub_dev->vu_server);
 }
 
 static void
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@
  */
 #include "qemu/osdep.h"
 #include "qemu/main-loop.h"
+#include "block/aio-wait.h"
 #include "vhost-user-server.h"
 
+/*
+ * Theory of operation:
+ *
+ * VuServer is started and stopped by vhost_user_server_start() and
+ * vhost_user_server_stop() from the main loop thread. Starting the server
+ * opens a vhost-user UNIX domain socket and listens for incoming connections.
+ * Only one connection is allowed at a time.
+ *
+ * The connection is handled by the vu_client_trip() coroutine in the
+ * VuServer->ctx AioContext. The coroutine consists of a vu_dispatch() loop
+ * where libvhost-user calls vu_message_read() to receive the next vhost-user
+ * protocol messages over the UNIX domain socket.
+ *
+ * When virtqueues are set up libvhost-user calls set_watch() to monitor kick
+ * fds. These fds are also handled in the VuServer->ctx AioContext.
+ *
+ * Both vu_client_trip() and kick fd monitoring can be stopped by shutting down
+ * the socket connection. Shutting down the socket connection causes
+ * vu_message_read() to fail since no more data can be received from the socket.
+ * After vu_dispatch() fails, vu_client_trip() calls vu_deinit() to stop
+ * libvhost-user before terminating the coroutine. vu_deinit() calls
+ * remove_watch() to stop monitoring kick fds and this stops virtqueue
+ * processing.
+ *
+ * When vu_client_trip() has finished cleaning up it schedules a BH in the main
+ * loop thread to accept the next client connection.
+ *
+ * When libvhost-user detects an error it calls panic_cb() and sets the
+ * dev->broken flag. Both vu_client_trip() and kick fd processing stop when
+ * the dev->broken flag is set.
+ *
+ * It is possible to switch AioContexts using
+ * vhost_user_server_detach_aio_context() and
+ * vhost_user_server_attach_aio_context(). They stop monitoring fds in the old
+ * AioContext and resume monitoring in the new AioContext. The vu_client_trip()
+ * coroutine remains in a yielded state during the switch. This is made
+ * possible by QIOChannel's support for spurious coroutine re-entry in
+ * qio_channel_yield(). The coroutine will restart I/O when re-entered from the
+ * new AioContext.
+ */
+
 static void vmsg_close_fds(VhostUserMsg *vmsg)
 {
     int i;
@@ -XXX,XX +XXX,XX @@ static void vmsg_unblock_fds(VhostUserMsg *vmsg)
     }
 }
 
-static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
-                      gpointer opaque);
-
-static void close_client(VuServer *server)
-{
-    /*
-     * Before closing the client
-     *
-     * 1. Let vu_client_trip stop processing new vhost-user msg
-     *
-     * 2. remove kick_handler
-     *
-     * 3. wait for the kick handler to be finished
-     *
-     * 4. wait for the current vhost-user msg to be finished processing
-     */
-
-    QIOChannelSocket *sioc = server->sioc;
-    /* When this is set vu_client_trip will stop new processing vhost-user message */
-    server->sioc = NULL;
-
-    while (server->processing_msg) {
-        if (server->ioc->read_coroutine) {
-            server->ioc->read_coroutine = NULL;
-            qio_channel_set_aio_fd_handler(server->ioc, server->ioc->ctx, NULL,
-                                           NULL, server->ioc);
-            server->processing_msg = false;
-        }
-    }
-
-    vu_deinit(&server->vu_dev);
-
-    /* vu_deinit() should have called remove_watch() */
-    assert(QTAILQ_EMPTY(&server->vu_fd_watches));
-
-    object_unref(OBJECT(sioc));
-    object_unref(OBJECT(server->ioc));
-}
-
 static void panic_cb(VuDev *vu_dev, const char *buf)
 {
-    VuServer *server = container_of(vu_dev, VuServer, vu_dev);
-
-    /* avoid while loop in close_client */
-    server->processing_msg = false;
-
-    if (buf) {
-        error_report("vu_panic: %s", buf);
-    }
-
-    if (server->sioc) {
-        close_client(server);
-    }
-
-    /*
-     * Set the callback function for network listener so another
-     * vhost-user client can connect to this server
-     */
-    qio_net_listener_set_client_func(server->listener,
-                                     vu_accept,
-                                     server,
-                                     NULL);
+    error_report("vu_panic: %s", buf);
 }
 
 static bool coroutine_fn
@@ -XXX,XX +XXX,XX @@ fail:
     return false;
 }
 
-
-static void vu_client_start(VuServer *server);
 static coroutine_fn void vu_client_trip(void *opaque)
 {
     VuServer *server = opaque;
+    VuDev *vu_dev = &server->vu_dev;
 
-    while (!server->aio_context_changed && server->sioc) {
-        server->processing_msg = true;
-        vu_dispatch(&server->vu_dev);
-        server->processing_msg = false;
+    while (!vu_dev->broken && vu_dispatch(vu_dev)) {
+        /* Keep running */
     }
 
-    if (server->aio_context_changed && server->sioc) {
-        server->aio_context_changed = false;
-        vu_client_start(server);
-    }
-}
+    vu_deinit(vu_dev);
+
+    /* vu_deinit() should have called remove_watch() */
+    assert(QTAILQ_EMPTY(&server->vu_fd_watches));
+
+    object_unref(OBJECT(server->sioc));
+    server->sioc = NULL;
 
-static void vu_client_start(VuServer *server)
-{
-    server->co_trip = qemu_coroutine_create(vu_client_trip, server);
-    aio_co_enter(server->ctx, server->co_trip);
+    object_unref(OBJECT(server->ioc));
+    server->ioc = NULL;
+
+    server->co_trip = NULL;
+    if (server->restart_listener_bh) {
+        qemu_bh_schedule(server->restart_listener_bh);
+    }
+    aio_wait_kick();
 }
 
 /*
@@ -XXX,XX +XXX,XX @@ static void vu_client_start(VuServer *server)
 static void kick_handler(void *opaque)
 {
     VuFdWatch *vu_fd_watch = opaque;
-    vu_fd_watch->processing = true;
-    vu_fd_watch->cb(vu_fd_watch->vu_dev, 0, vu_fd_watch->pvt);
-    vu_fd_watch->processing = false;
+    VuDev *vu_dev = vu_fd_watch->vu_dev;
+
+    vu_fd_watch->cb(vu_dev, 0, vu_fd_watch->pvt);
+
+    /* Stop vu_client_trip() if an error occurred in vu_fd_watch->cb() */
+    if (vu_dev->broken) {
+        VuServer *server = container_of(vu_dev, VuServer, vu_dev);
+
+        qio_channel_shutdown(server->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+    }
 }
 
-
 static VuFdWatch *find_vu_fd_watch(VuServer *server, int fd)
 {
 
@@ -XXX,XX +XXX,XX @@ static void vu_accept(QIONetListener *listener, QIOChannelSocket *sioc,
     qio_channel_set_name(QIO_CHANNEL(sioc), "vhost-user client");
     server->ioc = QIO_CHANNEL(sioc);
     object_ref(OBJECT(server->ioc));
-    qio_channel_attach_aio_context(server->ioc, server->ctx);
+
+    /* TODO vu_message_write() spins if non-blocking! */
     qio_channel_set_blocking(server->ioc, false, NULL);
-    vu_client_start(server);
+
+    server->co_trip = qemu_coroutine_create(vu_client_trip, server);
+
+    aio_context_acquire(server->ctx);
+    vhost_user_server_attach_aio_context(server, server->ctx);
+    aio_context_release(server->ctx);
 }
 
-
 void vhost_user_server_stop(VuServer *server)
 {
+    aio_context_acquire(server->ctx);
+
+    qemu_bh_delete(server->restart_listener_bh);
+    server->restart_listener_bh = NULL;
+
     if (server->sioc) {
-        close_client(server);
+        VuFdWatch *vu_fd_watch;
+
+        QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
+            aio_set_fd_handler(server->ctx, vu_fd_watch->fd, true,
+                               NULL, NULL, NULL, vu_fd_watch);
+        }
+
+        qio_channel_shutdown(server->ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+
+        AIO_WAIT_WHILE(server->ctx, server->co_trip);
     }
 
+    aio_context_release(server->ctx);
+
     if (server->listener) {
         qio_net_listener_disconnect(server->listener);
         object_unref(OBJECT(server->listener));
     }
+}
+
+/*
+ * Allow the next client to connect to the server. Called from a BH in the main
+ * loop.
+ */
+static void restart_listener_bh(void *opaque)
+{
+    VuServer *server = opaque;
 
+    qio_net_listener_set_client_func(server->listener, vu_accept, server,
+                                     NULL);
 }
 
-void vhost_user_server_set_aio_context(VuServer *server, AioContext *ctx)
+/* Called with ctx acquired */
+void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx)
 {
-    VuFdWatch *vu_fd_watch, *next;
-    void *opaque = NULL;
-    IOHandler *io_read = NULL;
-    bool attach;
+    VuFdWatch *vu_fd_watch;
 
-    server->ctx = ctx ? ctx : qemu_get_aio_context();
+    server->ctx = ctx;
 
     if (!server->sioc) {
-        /* not yet serving any client*/
         return;
     }
 
-    if (ctx) {
-        qio_channel_attach_aio_context(server->ioc, ctx);
-        server->aio_context_changed = true;
-        io_read = kick_handler;
-        attach = true;
-    } else {
+    qio_channel_attach_aio_context(server->ioc, ctx);
+
+    QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
+        aio_set_fd_handler(ctx, vu_fd_watch->fd, true, kick_handler, NULL,
+                           NULL, vu_fd_watch);
+    }
+
+    aio_co_schedule(ctx, server->co_trip);
+}
+
+/* Called with server->ctx acquired */
+void vhost_user_server_detach_aio_context(VuServer *server)
+{
+    if (server->sioc) {
+        VuFdWatch *vu_fd_watch;
+
+        QTAILQ_FOREACH(vu_fd_watch, &server->vu_fd_watches, next) {
+            aio_set_fd_handler(server->ctx, vu_fd_watch->fd, true,
+                               NULL, NULL, NULL, vu_fd_watch);
+        }
+
         qio_channel_detach_aio_context(server->ioc);
-        /* server->ioc->ctx keeps the old AioConext */
-        ctx = server->ioc->ctx;
-        attach = false;
     }
 
-    QTAILQ_FOREACH_SAFE(vu_fd_watch, &server->vu_fd_watches, next, next) {
-        if (vu_fd_watch->cb) {
-            opaque = attach ? vu_fd_watch : NULL;
-            aio_set_fd_handler(ctx, vu_fd_watch->fd, true,
-                               io_read, NULL, NULL,
-                               opaque);
-        }
-    }
+    server->ctx = NULL;
 }
 
-
 bool vhost_user_server_start(VuServer *server,
                              SocketAddress *socket_addr,
                              AioContext *ctx,
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
                              const VuDevIface *vu_iface,
                              Error **errp)
 {
+    QEMUBH *bh;
     QIONetListener *listener = qio_net_listener_new();
     if (qio_net_listener_open_sync(listener, socket_addr, 1,
                                    errp) < 0) {
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
         return false;
     }
 
+    bh = qemu_bh_new(restart_listener_bh, server);
+
     /* zero out unspecified fields */
     *server = (VuServer) {
         .listener              = listener,
+        .restart_listener_bh   = bh,
         .vu_iface              = vu_iface,
         .max_queues            = max_queues,
         .ctx                   = ctx,
-- 
2.26.2

Propagate the flush return value since errors are possible.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-11-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/export/vhost-user-blk-server.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Use the new QAPI block exports API instead of defining our own QOM
objects.

This is a large change because the lifecycle of VuBlockDev needs to
follow BlockExportDriver. QOM properties are replaced by QAPI options
objects.

VuBlockDev is renamed VuBlkExport and contains a BlockExport field.
Several fields can be dropped since BlockExport already has equivalents.

The file names and meson build integration will be adjusted in a future
patch. libvhost-user should probably be built as a static library that
is linked into QEMU instead of as a .c file that results in duplicate
compilation.

The new command-line syntax is:

$ qemu-storage-daemon \
      --blockdev file,node-name=drive0,filename=test.img \
      --export vhost-user-blk,node-name=drive0,id=export0,unix-socket=/tmp/vhost-user-blk.sock

Note that unix-socket is optional because we may wish to accept chardevs
too in the future.

Markus noted that supported address families are not explicit in the
QAPI schema. It is unlikely that support for more address families will
be added since file descriptor passing is required and few address
families support it. If a new address family needs to be added, then the
QAPI 'features' syntax can be used to advertize them.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20200924151549.913737-12-stefanha@redhat.com
[Skip test on big-endian host architectures because this device doesn't
support them yet (as already mentioned in a code comment).
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qapi/block-export.json               |  21 +-
 block/export/vhost-user-blk-server.h |  23 +-
 block/export/export.c                |   6 +
 block/export/vhost-user-blk-server.c | 452 +++++++--------------------
 util/vhost-user-server.c             |  10 +-
 block/export/meson.build             |   1 +
 block/meson.build                    |   1 -
 7 files changed, 156 insertions(+), 358 deletions(-)

diff --git a/qapi/block-export.json b/qapi/block-export.json
index XXXXXXX..XXXXXXX 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -XXX,XX +XXX,XX @@
   'data': { '*name': 'str', '*description': 'str',
             '*bitmap': 'str' } }
 
+##
+# @BlockExportOptionsVhostUserBlk:
+#
+# A vhost-user-blk block export.
+#
+# @addr: The vhost-user socket on which to listen. Both 'unix' and 'fd'
+#        SocketAddress types are supported. Passed fds must be UNIX domain
+#        sockets.
+# @logical-block-size: Logical block size in bytes. Defaults to 512 bytes.
+#
+# Since: 5.2
+##
+{ 'struct': 'BlockExportOptionsVhostUserBlk',
+  'data': { 'addr': 'SocketAddress', '*logical-block-size': 'size' } }
+
 ##
 # @NbdServerAddOptions:
 #
@@ -XXX,XX +XXX,XX @@
 # An enumeration of block export types
 #
 # @nbd: NBD export
+# @vhost-user-blk: vhost-user-blk export (since 5.2)
 #
 # Since: 4.2
 ##
 { 'enum': 'BlockExportType',
-  'data': [ 'nbd' ] }
+  'data': [ 'nbd', 'vhost-user-blk' ] }
 
 ##
 # @BlockExportOptions:
@@ -XXX,XX +XXX,XX @@
             '*writethrough': 'bool' },
   'discriminator': 'type',
   'data': {
-      'nbd': 'BlockExportOptionsNbd'
+      'nbd': 'BlockExportOptionsNbd',
+      'vhost-user-blk': 'BlockExportOptionsVhostUserBlk'
    } }
 
 ##
diff --git a/block/export/vhost-user-blk-server.h b/block/export/vhost-user-blk-server.h
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.h
+++ b/block/export/vhost-user-blk-server.h
@@ -XXX,XX +XXX,XX @@
 
 #ifndef VHOST_USER_BLK_SERVER_H
 #define VHOST_USER_BLK_SERVER_H
-#include "util/vhost-user-server.h"
 
-typedef struct VuBlockDev VuBlockDev;
-#define TYPE_VHOST_USER_BLK_SERVER "vhost-user-blk-server"
-#define VHOST_USER_BLK_SERVER(obj) \
-   OBJECT_CHECK(VuBlockDev, obj, TYPE_VHOST_USER_BLK_SERVER)
+#include "block/export.h"
 
-/* vhost user block device */
-struct VuBlockDev {
-    Object parent_obj;
-    char *node_name;
-    SocketAddress *addr;
-    AioContext *ctx;
-    VuServer vu_server;
-    bool running;
-    uint32_t blk_size;
-    BlockBackend *backend;
-    QIOChannelSocket *sioc;
-    QTAILQ_ENTRY(VuBlockDev) next;
-    struct virtio_blk_config blkcfg;
-    bool writable;
-};
+/* For block/export/export.c */
+extern const BlockExportDriver blk_exp_vhost_user_blk;
 
 #endif /* VHOST_USER_BLK_SERVER_H */
diff --git a/block/export/export.c b/block/export/export.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -XXX,XX +XXX,XX @@
 #include "sysemu/block-backend.h"
 #include "block/export.h"
 #include "block/nbd.h"
+#if CONFIG_LINUX
+#include "block/export/vhost-user-blk-server.h"
+#endif
 #include "qapi/error.h"
 #include "qapi/qapi-commands-block-export.h"
 #include "qapi/qapi-events-block-export.h"
@@ -XXX,XX +XXX,XX @@
 
 static const BlockExportDriver *blk_exp_drivers[] = {
     &blk_exp_nbd,
+#if CONFIG_LINUX
+    &blk_exp_vhost_user_blk,
+#endif
 };
 
 /* Only accessed from the main thread */
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@
  */
 #include "qemu/osdep.h"
 #include "block/block.h"
+#include "contrib/libvhost-user/libvhost-user.h"
+#include "standard-headers/linux/virtio_blk.h"
+#include "util/vhost-user-server.h"
 #include "vhost-user-blk-server.h"
 #include "qapi/error.h"
 #include "qom/object_interfaces.h"
@@ -XXX,XX +XXX,XX @@ struct virtio_blk_inhdr {
     unsigned char status;
 };
 
-typedef struct VuBlockReq {
+typedef struct VuBlkReq {
     VuVirtqElement elem;
     int64_t sector_num;
     size_t size;
@@ -XXX,XX +XXX,XX @@ typedef struct VuBlockReq {
     struct virtio_blk_outhdr out;
     VuServer *server;
     struct VuVirtq *vq;
-} VuBlockReq;
+} VuBlkReq;
 
-static void vu_block_req_complete(VuBlockReq *req)
+/* vhost user block device */
+typedef struct {
+    BlockExport export;
+    VuServer vu_server;
+    uint32_t blk_size;
+    QIOChannelSocket *sioc;
+    struct virtio_blk_config blkcfg;
+    bool writable;
+} VuBlkExport;
+
+static void vu_blk_req_complete(VuBlkReq *req)
 {
     VuDev *vu_dev = &req->server->vu_dev;
 
@@ -XXX,XX +XXX,XX @@ static void vu_block_req_complete(VuBlockReq *req)
     free(req);
 }
 
-static VuBlockDev *get_vu_block_device_by_server(VuServer *server)
-{
-    return container_of(server, VuBlockDev, vu_server);
-}
-
 static int coroutine_fn
-vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
-                              uint32_t iovcnt, uint32_t type)
+vu_blk_discard_write_zeroes(BlockBackend *blk, struct iovec *iov,
+                            uint32_t iovcnt, uint32_t type)
 {
     struct virtio_blk_discard_write_zeroes desc;
     ssize_t size = iov_to_buf(iov, iovcnt, 0, &desc, sizeof(desc));
@@ -XXX,XX +XXX,XX @@ vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
         return -EINVAL;
     }
 
-    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
     uint64_t range[2] = { le64_to_cpu(desc.sector) << 9,
                           le32_to_cpu(desc.num_sectors) << 9 };
     if (type == VIRTIO_BLK_T_DISCARD) {
-        if (blk_co_pdiscard(vdev_blk->backend, range[0], range[1]) == 0) {
+        if (blk_co_pdiscard(blk, range[0], range[1]) == 0) {
             return 0;
         }
     } else if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
-        if (blk_co_pwrite_zeroes(vdev_blk->backend,
-                                 range[0], range[1], 0) == 0) {
+        if (blk_co_pwrite_zeroes(blk, range[0], range[1], 0) == 0) {
             return 0;
         }
     }
@@ -XXX,XX +XXX,XX @@ vu_block_discard_write_zeroes(VuBlockReq *req, struct iovec *iov,
     return -EINVAL;
 }
 
-static int coroutine_fn vu_block_flush(VuBlockReq *req)
+static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
 {
-    VuBlockDev *vdev_blk = get_vu_block_device_by_server(req->server);
-    BlockBackend *backend = vdev_blk->backend;
-    return blk_co_flush(backend);
-}
-
-static void coroutine_fn vu_block_virtio_process_req(void *opaque)
-{
-    VuBlockReq *req = opaque;
+    VuBlkReq *req = opaque;
     VuServer *server = req->server;
     VuVirtqElement *elem = &req->elem;
     uint32_t type;
 
-    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
-    BlockBackend *backend = vdev_blk->backend;
+    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
+    BlockBackend *blk = vexp->export.blk;
 
     struct iovec *in_iov = elem->in_sg;
     struct iovec *out_iov = elem->out_sg;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
         bool is_write = type & VIRTIO_BLK_T_OUT;
         req->sector_num = le64_to_cpu(req->out.sector);
 
-        int64_t offset = req->sector_num * vdev_blk->blk_size;
+        if (is_write && !vexp->writable) {
+            req->in->status = VIRTIO_BLK_S_IOERR;
+            break;
+        }
+
+        int64_t offset = req->sector_num * vexp->blk_size;
         QEMUIOVector qiov;
         if (is_write) {
             qemu_iovec_init_external(&qiov, out_iov, out_num);
-            ret = blk_co_pwritev(backend, offset, qiov.size,
-                                 &qiov, 0);
+            ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0);
         } else {
             qemu_iovec_init_external(&qiov, in_iov, in_num);
-            ret = blk_co_preadv(backend, offset, qiov.size,
-                                &qiov, 0);
+            ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0);
         }
         if (ret >= 0) {
             req->in->status = VIRTIO_BLK_S_OK;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
         break;
     }
     case VIRTIO_BLK_T_FLUSH:
-        if (vu_block_flush(req) == 0) {
+        if (blk_co_flush(blk) == 0) {
             req->in->status = VIRTIO_BLK_S_OK;
         } else {
             req->in->status = VIRTIO_BLK_S_IOERR;
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
     case VIRTIO_BLK_T_DISCARD:
     case VIRTIO_BLK_T_WRITE_ZEROES: {
         int rc;
-        rc = vu_block_discard_write_zeroes(req, &elem->out_sg[1],
-                                           out_num, type);
+
+        if (!vexp->writable) {
+            req->in->status = VIRTIO_BLK_S_IOERR;
+            break;
+        }
+
+        rc = vu_blk_discard_write_zeroes(blk, &elem->out_sg[1], out_num, type);
         if (rc == 0) {
             req->in->status = VIRTIO_BLK_S_OK;
         } else {
@@ -XXX,XX +XXX,XX @@ static void coroutine_fn vu_block_virtio_process_req(void *opaque)
         break;
     }
 
-    vu_block_req_complete(req);
+    vu_blk_req_complete(req);
     return;
 
 err:
-    free(elem);
+    free(req);
 }
 
-static void vu_block_process_vq(VuDev *vu_dev, int idx)
+static void vu_blk_process_vq(VuDev *vu_dev, int idx)
 {
     VuServer *server = container_of(vu_dev, VuServer, vu_dev);
     VuVirtq *vq = vu_get_queue(vu_dev, idx);
 
     while (1) {
-        VuBlockReq *req;
+        VuBlkReq *req;
 
-        req = vu_queue_pop(vu_dev, vq, sizeof(VuBlockReq));
+        req = vu_queue_pop(vu_dev, vq, sizeof(VuBlkReq));
         if (!req) {
             break;
         }
@@ -XXX,XX +XXX,XX @@ static void vu_block_process_vq(VuDev *vu_dev, int idx)
         req->vq = vq;
 
         Coroutine *co =
-            qemu_coroutine_create(vu_block_virtio_process_req, req);
+            qemu_coroutine_create(vu_blk_virtio_process_req, req);
         qemu_coroutine_enter(co);
     }
 }
 
-static void vu_block_queue_set_started(VuDev *vu_dev, int idx, bool started)
+static void vu_blk_queue_set_started(VuDev *vu_dev, int idx, bool started)
 {
     VuVirtq *vq;
 
     assert(vu_dev);
 
     vq = vu_get_queue(vu_dev, idx);
-    vu_set_queue_handler(vu_dev, vq, started ? vu_block_process_vq : NULL);
+    vu_set_queue_handler(vu_dev, vq, started ? vu_blk_process_vq : NULL);
 }
 
-static uint64_t vu_block_get_features(VuDev *dev)
+static uint64_t vu_blk_get_features(VuDev *dev)
 {
     uint64_t features;
     VuServer *server = container_of(dev, VuServer, vu_dev);
-    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
+    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
     features = 1ull << VIRTIO_BLK_F_SIZE_MAX |
                1ull << VIRTIO_BLK_F_SEG_MAX |
                1ull << VIRTIO_BLK_F_TOPOLOGY |
@@ -XXX,XX +XXX,XX @@ static uint64_t vu_block_get_features(VuDev *dev)
                1ull << VIRTIO_RING_F_EVENT_IDX |
                1ull << VHOST_USER_F_PROTOCOL_FEATURES;
 
-    if (!vdev_blk->writable) {
+    if (!vexp->writable) {
         features |= 1ull << VIRTIO_BLK_F_RO;
     }
 
     return features;
 }
 
-static uint64_t vu_block_get_protocol_features(VuDev *dev)
+static uint64_t vu_blk_get_protocol_features(VuDev *dev)
 {
     return 1ull << VHOST_USER_PROTOCOL_F_CONFIG |
            1ull << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD;
 }
 
 static int
-vu_block_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
+vu_blk_get_config(VuDev *vu_dev, uint8_t *config, uint32_t len)
 {
+    /* TODO blkcfg must be little-endian for VIRTIO 1.0 */
     VuServer *server = container_of(vu_dev, VuServer, vu_dev);
-    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
-    memcpy(config, &vdev_blk->blkcfg, len);
-
+    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
+    memcpy(config, &vexp->blkcfg, len);
     return 0;
 }
 
 static int
-vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
+vu_blk_set_config(VuDev *vu_dev, const uint8_t *data,
                     uint32_t offset, uint32_t size, uint32_t flags)
 {
     VuServer *server = container_of(vu_dev, VuServer, vu_dev);
-    VuBlockDev *vdev_blk = get_vu_block_device_by_server(server);
+    VuBlkExport *vexp = container_of(server, VuBlkExport, vu_server);
     uint8_t wce;
 
     /* don't support live migration */
@@ -XXX,XX +XXX,XX @@ vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
     }
 
     wce = *data;
-    vdev_blk->blkcfg.wce = wce;
-    blk_set_enable_write_cache(vdev_blk->backend, wce);
+    vexp->blkcfg.wce = wce;
+    blk_set_enable_write_cache(vexp->export.blk, wce);
     return 0;
 }
 
@@ -XXX,XX +XXX,XX @@ vu_block_set_config(VuDev *vu_dev, const uint8_t *data,
  * of vu_process_message.
  *
  */
-static int vu_block_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
+static int vu_blk_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
 {
     if (vmsg->request == VHOST_USER_NONE) {
         dev->panic(dev, "disconnect");
@@ -XXX,XX +XXX,XX @@ static int vu_block_process_msg(VuDev *dev, VhostUserMsg *vmsg, int *do_reply)
     return false;
 }
 
-static const VuDevIface vu_block_iface = {
-    .get_features          = vu_block_get_features,
-    .queue_set_started     = vu_block_queue_set_started,
-    .get_protocol_features = vu_block_get_protocol_features,
-    .get_config            = vu_block_get_config,
-    .set_config            = vu_block_set_config,
-    .process_msg           = vu_block_process_msg,
+static const VuDevIface vu_blk_iface = {
+    .get_features          = vu_blk_get_features,
+    .queue_set_started     = vu_blk_queue_set_started,
+    .get_protocol_features = vu_blk_get_protocol_features,
+    .get_config            = vu_blk_get_config,
+    .set_config            = vu_blk_set_config,
+    .process_msg           = vu_blk_process_msg,
 };
 
 static void blk_aio_attached(AioContext *ctx, void *opaque)
 {
-    VuBlockDev *vub_dev = opaque;
-    vhost_user_server_attach_aio_context(&vub_dev->vu_server, ctx);
+    VuBlkExport *vexp = opaque;
+    vhost_user_server_attach_aio_context(&vexp->vu_server, ctx);
 }
 
 static void blk_aio_detach(void *opaque)
 {
-    VuBlockDev *vub_dev = opaque;
-    vhost_user_server_detach_aio_context(&vub_dev->vu_server);
+    VuBlkExport *vexp = opaque;
+    vhost_user_server_detach_aio_context(&vexp->vu_server);
 }
 
 static void
-vu_block_initialize_config(BlockDriverState *bs,
+vu_blk_initialize_config(BlockDriverState *bs,
                            struct virtio_blk_config *config, uint32_t blk_size)
 {
     config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
@@ -XXX,XX +XXX,XX @@ vu_block_initialize_config(BlockDriverState *bs,
     config->max_write_zeroes_seg = 1;
 }
 
-static VuBlockDev *vu_block_init(VuBlockDev *vu_block_device, Error **errp)
+static void vu_blk_exp_request_shutdown(BlockExport *exp)
 {
+    VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
 
-    BlockBackend *blk;
-    Error *local_error = NULL;
-    const char *node_name = vu_block_device->node_name;
-    bool writable = vu_block_device->writable;
-    uint64_t perm = BLK_PERM_CONSISTENT_READ;
-    int ret;
-
-    AioContext *ctx;
-
-    BlockDriverState *bs = bdrv_lookup_bs(node_name, node_name, &local_error);
-
-    if (!bs) {
-        error_propagate(errp, local_error);
-        return NULL;
-    }
-
-    if (bdrv_is_read_only(bs)) {
-        writable = false;
-    }
-
-    if (writable) {
-        perm |= BLK_PERM_WRITE;
-    }
-
-    ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
-    bdrv_invalidate_cache(bs, NULL);
-    aio_context_release(ctx);
-
-    /*
-     * Don't allow resize while the vhost user server is running,
-     * otherwise we don't care what happens with the node.
-     */
-    blk = blk_new(bdrv_get_aio_context(bs), perm,
-                  BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
-                  BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
-    ret = blk_insert_bs(blk, bs, errp);
-
-    if (ret < 0) {
-        goto fail;
-    }
-
-    blk_set_enable_write_cache(blk, false);
-
-    blk_set_allow_aio_context_change(blk, true);
-
-    vu_block_device->blkcfg.wce = 0;
-    vu_block_device->backend = blk;
-    if (!vu_block_device->blk_size) {
-        vu_block_device->blk_size = BDRV_SECTOR_SIZE;
-    }
-    vu_block_device->blkcfg.blk_size = vu_block_device->blk_size;
-    blk_set_guest_block_size(blk, vu_block_device->blk_size);
-    vu_block_initialize_config(bs, &vu_block_device->blkcfg,
-                                   vu_block_device->blk_size);
-    return vu_block_device;
-
-fail:
-    blk_unref(blk);
-    return NULL;
-}
-
-static void vu_block_deinit(VuBlockDev *vu_block_device)
-{
-    if (vu_block_device->backend) {
-        blk_remove_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
-                                        blk_aio_detach, vu_block_device);
-    }
-
-    blk_unref(vu_block_device->backend);
-}
-
-static void vhost_user_blk_server_stop(VuBlockDev *vu_block_device)
-{
-    vhost_user_server_stop(&vu_block_device->vu_server);
-    vu_block_deinit(vu_block_device);
-}
-
-static void vhost_user_blk_server_start(VuBlockDev *vu_block_device,
-                                        Error **errp)
-{
-    AioContext *ctx;
-    SocketAddress *addr = vu_block_device->addr;
-
-    if (!vu_block_init(vu_block_device, errp)) {
-        return;
-    }
-
-    ctx = bdrv_get_aio_context(blk_bs(vu_block_device->backend));
-
-    if (!vhost_user_server_start(&vu_block_device->vu_server, addr, ctx,
-                                 VHOST_USER_BLK_MAX_QUEUES, &vu_block_iface,
-                                 errp)) {
-        goto error;
-    }
-
-    blk_add_aio_context_notifier(vu_block_device->backend, blk_aio_attached,
-                                 blk_aio_detach, vu_block_device);
-    vu_block_device->running = true;
-    return;
-
- error:
-    vu_block_deinit(vu_block_device);
-}
-
-static bool vu_prop_modifiable(VuBlockDev *vus, Error **errp)
-{
-    if (vus->running) {
-            error_setg(errp, "The property can't be modified "
-                       "while the server is running");
-            return false;
-    }
-    return true;
-}
-
-static void vu_set_node_name(Object *obj, const char *value, Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-
-    if (!vu_prop_modifiable(vus, errp)) {
-        return;
-    }
-
-    if (vus->node_name) {
-        g_free(vus->node_name);
-    }
-
-    vus->node_name = g_strdup(value);
-}
-
-static char *vu_get_node_name(Object *obj, Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-    return g_strdup(vus->node_name);
-}
-
-static void free_socket_addr(SocketAddress *addr)
-{
-        g_free(addr->u.q_unix.path);
-        g_free(addr);
-}
-
-static void vu_set_unix_socket(Object *obj, const char *value,
-                               Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-
-    if (!vu_prop_modifiable(vus, errp)) {
-        return;
-    }
-
-    if (vus->addr) {
-        free_socket_addr(vus->addr);
-    }
-
-    SocketAddress *addr = g_new0(SocketAddress, 1);
-    addr->type = SOCKET_ADDRESS_TYPE_UNIX;
-    addr->u.q_unix.path = g_strdup(value);
-    vus->addr = addr;
+    vhost_user_server_stop(&vexp->vu_server);
 }
 
-static char *vu_get_unix_socket(Object *obj, Error **errp)
+static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
+                             Error **errp)
 {
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-    return g_strdup(vus->addr->u.q_unix.path);
-}
-
-static bool vu_get_block_writable(Object *obj, Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-    return vus->writable;
-}
-
-static void vu_set_block_writable(Object *obj, bool value, Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-
-    if (!vu_prop_modifiable(vus, errp)) {
-            return;
-    }
-
-    vus->writable = value;
-}
-
-static void vu_get_blk_size(Object *obj, Visitor *v, const char *name,
-                            void *opaque, Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-    uint32_t value = vus->blk_size;
-
-    visit_type_uint32(v, name, &value, errp);
-}
-
-static void vu_set_blk_size(Object *obj, Visitor *v, const char *name,
-                            void *opaque, Error **errp)
-{
-    VuBlockDev *vus = VHOST_USER_BLK_SERVER(obj);
-
+    VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
+    BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk;
     Error *local_err = NULL;
-    uint32_t value;
+    uint64_t logical_block_size;
 
-    if (!vu_prop_modifiable(vus, errp)) {
-            return;
-    }
+    vexp->writable = opts->writable;
+    vexp->blkcfg.wce = 0;
 
-    visit_type_uint32(v, name, &value, &local_err);
-    if (local_err) {
-        goto out;
+    if (vu_opts->has_logical_block_size) {
+        logical_block_size = vu_opts->logical_block_size;
+    } else {
+        logical_block_size = BDRV_SECTOR_SIZE;
     }
-
-    check_block_size(object_get_typename(obj), name, value, &local_err);
+    check_block_size(exp->id, "logical-block-size", logical_block_size,
+                     &local_err);
     if (local_err) {
-        goto out;
+        error_propagate(errp, local_err);
+        return -EINVAL;
+    }
+    vexp->blk_size = logical_block_size;
+    blk_set_guest_block_size(exp->blk, logical_block_size);
+    vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
+                               logical_block_size);
+
+    blk_set_allow_aio_context_change(exp->blk, true);
+    blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
+                                 vexp);
+
+    if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx,
+                                 VHOST_USER_BLK_MAX_QUEUES, &vu_blk_iface,
+                                 errp)) {
+        blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
+                                        blk_aio_detach, vexp);
+        return -EADDRNOTAVAIL;
     }
 
-    vus->blk_size = value;
-
-out:
-    error_propagate(errp, local_err);
-}
-
-static void vhost_user_blk_server_instance_finalize(Object *obj)
-{
-    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
-
-    vhost_user_blk_server_stop(vub);
-
-    /*
-     * Unlike object_property_add_str, object_class_property_add_str
-     * doesn't have a release method. Thus manual memory freeing is
-     * needed.
-     */
-    free_socket_addr(vub->addr);
-    g_free(vub->node_name);
-}
-
-static void vhost_user_blk_server_complete(UserCreatable *obj, Error **errp)
-{
-    VuBlockDev *vub = VHOST_USER_BLK_SERVER(obj);
-
-    vhost_user_blk_server_start(vub, errp);
+    return 0;
 }
 
-static void vhost_user_blk_server_class_init(ObjectClass *klass,
-                                             void *class_data)
+static void vu_blk_exp_delete(BlockExport *exp)
 {
-    UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
-    ucc->complete = vhost_user_blk_server_complete;
-
-    object_class_property_add_bool(klass, "writable",
-                                   vu_get_block_writable,
-                                   vu_set_block_writable);
-
-    object_class_property_add_str(klass, "node-name",
-                                  vu_get_node_name,
-                                  vu_set_node_name);
-
-    object_class_property_add_str(klass, "unix-socket",
-                                  vu_get_unix_socket,
-                                  vu_set_unix_socket);
+    VuBlkExport *vexp = container_of(exp, VuBlkExport, export);
 
-    object_class_property_add(klass, "logical-block-size", "uint32",
-                              vu_get_blk_size, vu_set_blk_size,
-                              NULL, NULL);
+    blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
+                                    vexp);
 }
 
-static const TypeInfo vhost_user_blk_server_info = {
-    .name = TYPE_VHOST_USER_BLK_SERVER,
-    .parent = TYPE_OBJECT,
-    .instance_size = sizeof(VuBlockDev),
-    .instance_finalize = vhost_user_blk_server_instance_finalize,
-    .class_init = vhost_user_blk_server_class_init,
-    .interfaces = (InterfaceInfo[]) {
-        {TYPE_USER_CREATABLE},
-        {}
-    },
+const BlockExportDriver blk_exp_vhost_user_blk = {
+    .type               = BLOCK_EXPORT_TYPE_VHOST_USER_BLK,
+    .instance_size      = sizeof(VuBlkExport),
+    .create             = vu_blk_exp_create,
+    .delete             = vu_blk_exp_delete,
+    .request_shutdown   = vu_blk_exp_request_shutdown,
 };
-
-static void vhost_user_blk_server_register_types(void)
-{
-    type_register_static(&vhost_user_blk_server_info);
-}
-
-type_init(vhost_user_blk_server_register_types)
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@ bool vhost_user_server_start(VuServer *server,
                              Error **errp)
 {
     QEMUBH *bh;
-    QIONetListener *listener = qio_net_listener_new();
+    QIONetListener *listener;
+
+    if (socket_addr->type != SOCKET_ADDRESS_TYPE_UNIX &&
+        socket_addr->type != SOCKET_ADDRESS_TYPE_FD) {
+        error_setg(errp, "Only socket address types 'unix' and 'fd' are supported");
+        return false;
+    }
+
+    listener = qio_net_listener_new();
     if (qio_net_listener_open_sync(listener, socket_addr, 1,
                                    errp) < 0) {
         object_unref(OBJECT(listener));
diff --git a/block/export/meson.build b/block/export/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/block/export/meson.build
+++ b/block/export/meson.build
@@ -1 +1,2 @@
 block_ss.add(files('export.c'))
+block_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-blk-server.c', '../../contrib/libvhost-user/libvhost-user.c'))
diff --git a/block/meson.build b/block/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/block/meson.build
+++ b/block/meson.build
@@ -XXX,XX +XXX,XX @@ block_ss.add(when: 'CONFIG_WIN32', if_true: files('file-win32.c', 'win32-aio.c')
 block_ss.add(when: 'CONFIG_POSIX', if_true: [files('file-posix.c'), coref, iokit])
 block_ss.add(when: 'CONFIG_LIBISCSI', if_true: files('iscsi-opts.c'))
 block_ss.add(when: 'CONFIG_LINUX', if_true: files('nvme.c'))
-block_ss.add(when: 'CONFIG_LINUX', if_true: files('export/vhost-user-blk-server.c', '../contrib/libvhost-user/libvhost-user.c'))
 block_ss.add(when: 'CONFIG_REPLICATION', if_true: files('replication.c'))
 block_ss.add(when: 'CONFIG_SHEEPDOG', if_true: files('sheepdog.c'))
 block_ss.add(when: ['CONFIG_LINUX_AIO', libaio], if_true: files('linux-aio.c'))
-- 
2.26.2

Headers used by other subsystems are located in include/. Also add the
vhost-user-server and vhost-user-blk-server headers to MAINTAINERS.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-13-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 MAINTAINERS                                | 4 +++-
 {util => include/qemu}/vhost-user-server.h | 0
 block/export/vhost-user-blk-server.c       | 2 +-
 util/vhost-user-server.c                   | 2 +-
 4 files changed, 5 insertions(+), 3 deletions(-)
 rename {util => include/qemu}/vhost-user-server.h (100%)

diff --git a/MAINTAINERS b/MAINTAINERS
index XXXXXXX..XXXXXXX 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -XXX,XX +XXX,XX @@ Vhost-user block device backend server
 M: Coiby Xu <Coiby.Xu@gmail.com>
 S: Maintained
 F: block/export/vhost-user-blk-server.c
-F: util/vhost-user-server.c
+F: block/export/vhost-user-blk-server.h
+F: include/qemu/vhost-user-server.h
 F: tests/qtest/libqos/vhost-user-blk.c
+F: util/vhost-user-server.c
 
 Replication
 M: Wen Congyang <wencongyang2@huawei.com>
diff --git a/util/vhost-user-server.h b/include/qemu/vhost-user-server.h
similarity index 100%
rename from util/vhost-user-server.h
rename to include/qemu/vhost-user-server.h
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@
 #include "block/block.h"
 #include "contrib/libvhost-user/libvhost-user.h"
 #include "standard-headers/linux/virtio_blk.h"
-#include "util/vhost-user-server.h"
+#include "qemu/vhost-user-server.h"
 #include "vhost-user-blk-server.h"
 #include "qapi/error.h"
 #include "qom/object_interfaces.h"
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index XXXXXXX..XXXXXXX 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -XXX,XX +XXX,XX @@
  */
 #include "qemu/osdep.h"
 #include "qemu/main-loop.h"
+#include "qemu/vhost-user-server.h"
 #include "block/aio-wait.h"
-#include "vhost-user-server.h"
 
 /*
  * Theory of operation:
-- 
2.26.2

Don't compile contrib/libvhost-user/libvhost-user.c again. Instead build
the static library once and then reuse it throughout QEMU.

Also switch from CONFIG_LINUX to CONFIG_VHOST_USER, which is what the
vhost-user tools (vhost-user-gpu, etc) do.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200924151549.913737-14-stefanha@redhat.com
[Added CONFIG_LINUX again because libvhost-user doesn't build on macOS.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/export/export.c             | 8 ++++----
 block/export/meson.build          | 2 +-
 contrib/libvhost-user/meson.build | 1 +
 meson.build                       | 6 +++++-
 util/meson.build                  | 4 +++-
 5 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/block/export/export.c b/block/export/export.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -XXX,XX +XXX,XX @@
 #include "sysemu/block-backend.h"
 #include "block/export.h"
 #include "block/nbd.h"
-#if CONFIG_LINUX
-#include "block/export/vhost-user-blk-server.h"
-#endif
 #include "qapi/error.h"
 #include "qapi/qapi-commands-block-export.h"
 #include "qapi/qapi-events-block-export.h"
 #include "qemu/id.h"
+#ifdef CONFIG_VHOST_USER
+#include "vhost-user-blk-server.h"
+#endif
 
 static const BlockExportDriver *blk_exp_drivers[] = {
     &blk_exp_nbd,
-#if CONFIG_LINUX
+#ifdef CONFIG_VHOST_USER
     &blk_exp_vhost_user_blk,
 #endif
 };
diff --git a/block/export/meson.build b/block/export/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/block/export/meson.build
+++ b/block/export/meson.build
@@ -XXX,XX +XXX,XX @@
 block_ss.add(files('export.c'))
-block_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-blk-server.c', '../../contrib/libvhost-user/libvhost-user.c'))
+block_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: files('vhost-user-blk-server.c'))
diff --git a/contrib/libvhost-user/meson.build b/contrib/libvhost-user/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/contrib/libvhost-user/meson.build
+++ b/contrib/libvhost-user/meson.build
@@ -XXX,XX +XXX,XX @@
 libvhost_user = static_library('vhost-user',
                                files('libvhost-user.c', 'libvhost-user-glib.c'),
                                build_by_default: false)
+vhost_user = declare_dependency(link_with: libvhost_user)
diff --git a/meson.build b/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/meson.build
+++ b/meson.build
@@ -XXX,XX +XXX,XX @@ trace_events_subdirs += [
   'util',
 ]
 
+vhost_user = not_found
+if 'CONFIG_VHOST_USER' in config_host
+  subdir('contrib/libvhost-user')
+endif
+
 subdir('qapi')
 subdir('qobject')
 subdir('stubs')
@@ -XXX,XX +XXX,XX @@ if have_tools
              install: true)
 
   if 'CONFIG_VHOST_USER' in config_host
-    subdir('contrib/libvhost-user')
     subdir('contrib/vhost-user-blk')
     subdir('contrib/vhost-user-gpu')
     subdir('contrib/vhost-user-input')
diff --git a/util/meson.build b/util/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/util/meson.build
+++ b/util/meson.build
@@ -XXX,XX +XXX,XX @@ if have_block
   util_ss.add(files('main-loop.c'))
   util_ss.add(files('nvdimm-utils.c'))
   util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c'))
-  util_ss.add(when: 'CONFIG_LINUX', if_true: files('vhost-user-server.c'))
+  util_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: [
+    files('vhost-user-server.c'), vhost_user
+  ])
   util_ss.add(files('block-helpers.c'))
   util_ss.add(files('qemu-coroutine-sleep.c'))
   util_ss.add(files('qemu-co-shared-resource.c'))
-- 
2.26.2

Introduce libblkdev.fa to avoid recompiling blockdev_ss twice.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200929125516.186715-3-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 meson.build                | 12 ++++++++++--
 storage-daemon/meson.build |  3 +--
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/meson.build b/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/meson.build
+++ b/meson.build
@@ -XXX,XX +XXX,XX @@ blockdev_ss.add(files(
 # os-win32.c does not
 blockdev_ss.add(when: 'CONFIG_POSIX', if_true: files('os-posix.c'))
 softmmu_ss.add(when: 'CONFIG_WIN32', if_true: [files('os-win32.c')])
-softmmu_ss.add_all(blockdev_ss)
 
 common_ss.add(files('cpus-common.c'))
 
@@ -XXX,XX +XXX,XX @@ block = declare_dependency(link_whole: [libblock],
                            link_args: '@block.syms',
                            dependencies: [crypto, io])
 
+blockdev_ss = blockdev_ss.apply(config_host, strict: false)
+libblockdev = static_library('blockdev', blockdev_ss.sources() + genh,
+                             dependencies: blockdev_ss.dependencies(),
+                             name_suffix: 'fa',
+                             build_by_default: false)
+
+blockdev = declare_dependency(link_whole: [libblockdev],
+                              dependencies: [block])
+
 qmp_ss = qmp_ss.apply(config_host, strict: false)
 libqmp = static_library('qmp', qmp_ss.sources() + genh,
                         dependencies: qmp_ss.dependencies(),
@@ -XXX,XX +XXX,XX @@ foreach m : block_mods + softmmu_mods
                 install_dir: config_host['qemu_moddir'])
 endforeach
 
-softmmu_ss.add(authz, block, chardev, crypto, io, qmp)
+softmmu_ss.add(authz, blockdev, chardev, crypto, io, qmp)
 common_ss.add(qom, qemuutil)
 
 common_ss.add_all(when: 'CONFIG_SOFTMMU', if_true: [softmmu_ss])
diff --git a/storage-daemon/meson.build b/storage-daemon/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/storage-daemon/meson.build
+++ b/storage-daemon/meson.build
@@ -XXX,XX +XXX,XX @@
 qsd_ss = ss.source_set()
 qsd_ss.add(files('qemu-storage-daemon.c'))
-qsd_ss.add(block, chardev, qmp, qom, qemuutil)
-qsd_ss.add_all(blockdev_ss)
+qsd_ss.add(blockdev, chardev, qmp, qom, qemuutil)
 
 subdir('qapi')
 
-- 
2.26.2

Block exports are used by softmmu, qemu-storage-daemon, and qemu-nbd.
They are not used by other programs and are not otherwise needed in
libblock.

Undo the recent move of blockdev-nbd.c from blockdev_ss into block_ss.
Since bdrv_close_all() (libblock) calls blk_exp_close_all()
(libblockdev) a stub function is required..

Make qemu-nbd.c use signal handling utility functions instead of
duplicating the code. This helps because os-posix.c is in libblockdev
and it depends on a qemu_system_killed() symbol that qemu-nbd.c lacks.
Once we use the signal handling utility functions we also end up
providing the necessary symbol.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20200929125516.186715-4-stefanha@redhat.com
[Fixed s/ndb/nbd/ typo in commit description as suggested by Eric Blake
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qemu-nbd.c                | 21 ++++++++-------------
 stubs/blk-exp-close-all.c |  7 +++++++
 block/export/meson.build  |  4 ++--
 meson.build               |  4 ++--
 nbd/meson.build           |  2 ++
 stubs/meson.build         |  1 +
 6 files changed, 22 insertions(+), 17 deletions(-)
 create mode 100644 stubs/blk-exp-close-all.c

diff --git a/qemu-nbd.c b/qemu-nbd.c
index XXXXXXX..XXXXXXX 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -XXX,XX +XXX,XX @@
 #include "qapi/error.h"
 #include "qemu/cutils.h"
 #include "sysemu/block-backend.h"
+#include "sysemu/runstate.h" /* for qemu_system_killed() prototype */
 #include "block/block_int.h"
 #include "block/nbd.h"
 #include "qemu/main-loop.h"
@@ -XXX,XX +XXX,XX @@ QEMU_COPYRIGHT "\n"
 }
 
 #ifdef CONFIG_POSIX
-static void termsig_handler(int signum)
+/*
+ * The client thread uses SIGTERM to interrupt the server.  A signal
+ * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
+ */
+void qemu_system_killed(int signum, pid_t pid)
 {
     qatomic_cmpxchg(&state, RUNNING, TERMINATE);
     qemu_notify_event();
@@ -XXX,XX +XXX,XX @@ int main(int argc, char **argv)
     BlockExportOptions *export_opts;
 
 #ifdef CONFIG_POSIX
-    /*
-     * Exit gracefully on various signals, which includes SIGTERM used
-     * by 'qemu-nbd -v -c'.
-     */
-    struct sigaction sa_sigterm;
-    memset(&sa_sigterm, 0, sizeof(sa_sigterm));
-    sa_sigterm.sa_handler = termsig_handler;
-    sigaction(SIGTERM, &sa_sigterm, NULL);
-    sigaction(SIGINT, &sa_sigterm, NULL);
-    sigaction(SIGHUP, &sa_sigterm, NULL);
-
-    signal(SIGPIPE, SIG_IGN);
+    os_setup_early_signal_handling();
+    os_setup_signal_handling();
 #endif
 
     socket_init();
diff --git a/stubs/blk-exp-close-all.c b/stubs/blk-exp-close-all.c
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/stubs/blk-exp-close-all.c
@@ -XXX,XX +XXX,XX @@
+#include "qemu/osdep.h"
+#include "block/export.h"
+
+/* Only used in programs that support block exports (libblockdev.fa) */
+void blk_exp_close_all(void)
+{
+}
diff --git a/block/export/meson.build b/block/export/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/block/export/meson.build
+++ b/block/export/meson.build
@@ -XXX,XX +XXX,XX @@
-block_ss.add(files('export.c'))
-block_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: files('vhost-user-blk-server.c'))
+blockdev_ss.add(files('export.c'))
+blockdev_ss.add(when: ['CONFIG_LINUX', 'CONFIG_VHOST_USER'], if_true: files('vhost-user-blk-server.c'))
diff --git a/meson.build b/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/meson.build
+++ b/meson.build
@@ -XXX,XX +XXX,XX @@ subdir('dump')
 
 block_ss.add(files(
   'block.c',
-  'blockdev-nbd.c',
   'blockjob.c',
   'job.c',
   'qemu-io-cmds.c',
@@ -XXX,XX +XXX,XX @@ subdir('block')
 
 blockdev_ss.add(files(
   'blockdev.c',
+  'blockdev-nbd.c',
   'iothread.c',
   'job-qmp.c',
 ))
@@ -XXX,XX +XXX,XX @@ if have_tools
   qemu_io = executable('qemu-io', files('qemu-io.c'),
              dependencies: [block, qemuutil], install: true)
   qemu_nbd = executable('qemu-nbd', files('qemu-nbd.c'),
-               dependencies: [block, qemuutil], install: true)
+               dependencies: [blockdev, qemuutil], install: true)
 
   subdir('storage-daemon')
   subdir('contrib/rdmacm-mux')
diff --git a/nbd/meson.build b/nbd/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/nbd/meson.build
+++ b/nbd/meson.build
@@ -XXX,XX +XXX,XX @@
 block_ss.add(files(
   'client.c',
   'common.c',
+))
+blockdev_ss.add(files(
   'server.c',
 ))
diff --git a/stubs/meson.build b/stubs/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/stubs/meson.build
+++ b/stubs/meson.build
@@ -XXX,XX +XXX,XX @@
 stub_ss.add(files('arch_type.c'))
 stub_ss.add(files('bdrv-next-monitor-owned.c'))
 stub_ss.add(files('blk-commit-all.c'))
+stub_ss.add(files('blk-exp-close-all.c'))
 stub_ss.add(files('blockdev-close-all-bdrv-states.c'))
 stub_ss.add(files('change-state-handler.c'))
 stub_ss.add(files('cmos.c'))
-- 
2.26.2

Make it possible to specify the iothread where the export will run. By
default the block node can be moved to other AioContexts later and the
export will follow. The fixed-iothread option forces strict behavior
that prevents changing AioContext while the export is active. See the
QAPI docs for details.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200929125516.186715-5-stefanha@redhat.com
[Fix stray '#' character in block-export.json and add missing "(since:
5.2)" as suggested by Eric Blake.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qapi/block-export.json               | 11 ++++++++++
 block/export/export.c                | 31 +++++++++++++++++++++++++++-
 block/export/vhost-user-blk-server.c |  5 ++++-
 nbd/server.c                         |  2 --
 4 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/qapi/block-export.json b/qapi/block-export.json
index XXXXXXX..XXXXXXX 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -XXX,XX +XXX,XX @@
 #                export before completion is signalled. (since: 5.2;
 #                default: false)
 #
+# @iothread: The name of the iothread object where the export will run. The
+#            default is to use the thread currently associated with the
+#            block node. (since: 5.2)
+#
+# @fixed-iothread: True prevents the block node from being moved to another
+#                  thread while the export is active. If true and @iothread is
+#                  given, export creation fails if the block node cannot be
+#                  moved to the iothread. The default is false. (since: 5.2)
+#
 # Since: 4.2
 ##
 { 'union': 'BlockExportOptions',
   'base': { 'type': 'BlockExportType',
             'id': 'str',
+	    '*fixed-iothread': 'bool',
+	    '*iothread': 'str',
             'node-name': 'str',
             '*writable': 'bool',
             '*writethrough': 'bool' },
diff --git a/block/export/export.c b/block/export/export.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -XXX,XX +XXX,XX @@
 
 #include "block/block.h"
 #include "sysemu/block-backend.h"
+#include "sysemu/iothread.h"
 #include "block/export.h"
 #include "block/nbd.h"
 #include "qapi/error.h"
@@ -XXX,XX +XXX,XX @@ static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
 
 BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
 {
+    bool fixed_iothread = export->has_fixed_iothread && export->fixed_iothread;
     const BlockExportDriver *drv;
     BlockExport *exp = NULL;
     BlockDriverState *bs;
-    BlockBackend *blk;
+    BlockBackend *blk = NULL;
     AioContext *ctx;
     uint64_t perm;
     int ret;
@@ -XXX,XX +XXX,XX @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     ctx = bdrv_get_aio_context(bs);
     aio_context_acquire(ctx);
 
+    if (export->has_iothread) {
+        IOThread *iothread;
+        AioContext *new_ctx;
+
+        iothread = iothread_by_id(export->iothread);
+        if (!iothread) {
+            error_setg(errp, "iothread \"%s\" not found", export->iothread);
+            goto fail;
+        }
+
+        new_ctx = iothread_get_aio_context(iothread);
+
+        ret = bdrv_try_set_aio_context(bs, new_ctx, errp);
+        if (ret == 0) {
+            aio_context_release(ctx);
+            aio_context_acquire(new_ctx);
+            ctx = new_ctx;
+        } else if (fixed_iothread) {
+            goto fail;
+        }
+    }
+
     /*
      * Block exports are used for non-shared storage migration. Make sure
      * that BDRV_O_INACTIVE is cleared and the image is ready for write
@@ -XXX,XX +XXX,XX @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
     }
 
     blk = blk_new(ctx, perm, BLK_PERM_ALL);
+
+    if (!fixed_iothread) {
+        blk_set_allow_aio_context_change(blk, true);
+    }
+
     ret = blk_insert_bs(blk, bs, errp);
     if (ret < 0) {
         goto fail;
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@ static const VuDevIface vu_blk_iface = {
 static void blk_aio_attached(AioContext *ctx, void *opaque)
 {
     VuBlkExport *vexp = opaque;
+
+    vexp->export.ctx = ctx;
     vhost_user_server_attach_aio_context(&vexp->vu_server, ctx);
 }
 
 static void blk_aio_detach(void *opaque)
 {
     VuBlkExport *vexp = opaque;
+
     vhost_user_server_detach_aio_context(&vexp->vu_server);
+    vexp->export.ctx = NULL;
 }
 
 static void
@@ -XXX,XX +XXX,XX @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
     vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
                                logical_block_size);
 
-    blk_set_allow_aio_context_change(exp->blk, true);
     blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
                                  vexp);
 
diff --git a/nbd/server.c b/nbd/server.c
index XXXXXXX..XXXXXXX 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -XXX,XX +XXX,XX @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
         return ret;
     }
 
-    blk_set_allow_aio_context_change(blk, true);
-
     QTAILQ_INIT(&exp->clients);
     exp->name = g_strdup(arg->name);
     exp->description = g_strdup(arg->description);
-- 
2.26.2

Allow the number of queues to be configured using --export
vhost-user-blk,num-queues=N. This setting should match the QEMU --device
vhost-user-blk-pci,num-queues=N setting but QEMU vhost-user-blk.c lowers
its own value if the vhost-user-blk backend offers fewer queues than
QEMU.

The vhost-user-blk-server.c code is already capable of multi-queue. All
virtqueue processing runs in the same AioContext. No new locking is
needed.

Add the num-queues=N option and set the VIRTIO_BLK_F_MQ feature bit.
Note that the feature bit only announces the presence of the num_queues
configuration space field. It does not promise that there is more than 1
virtqueue, so we can set it unconditionally.

I tested multi-queue by running a random read fio test with numjobs=4 on
an -smp 4 guest. After the benchmark finished the guest /proc/interrupts
file showed activity on all 4 virtio-blk MSI-X. The /sys/block/vda/mq/
directory shows that Linux blk-mq has 4 queues configured.

An automated test is included in the next commit.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20201001144604.559733-2-stefanha@redhat.com
[Fixed accidental tab characters as suggested by Markus Armbruster
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qapi/block-export.json               | 10 +++++++---
 block/export/vhost-user-blk-server.c | 24 ++++++++++++++++++------
 2 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/qapi/block-export.json b/qapi/block-export.json
index XXXXXXX..XXXXXXX 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -XXX,XX +XXX,XX @@
 #        SocketAddress types are supported. Passed fds must be UNIX domain
 #        sockets.
 # @logical-block-size: Logical block size in bytes. Defaults to 512 bytes.
+# @num-queues: Number of request virtqueues. Must be greater than 0. Defaults
+#              to 1.
 #
 # Since: 5.2
 ##
 { 'struct': 'BlockExportOptionsVhostUserBlk',
-  'data': { 'addr': 'SocketAddress', '*logical-block-size': 'size' } }
+  'data': { 'addr': 'SocketAddress',
+	    '*logical-block-size': 'size',
+            '*num-queues': 'uint16'} }
 
 ##
 # @NbdServerAddOptions:
@@ -XXX,XX +XXX,XX @@
 { 'union': 'BlockExportOptions',
   'base': { 'type': 'BlockExportType',
             'id': 'str',
-	    '*fixed-iothread': 'bool',
-	    '*iothread': 'str',
+            '*fixed-iothread': 'bool',
+            '*iothread': 'str',
             'node-name': 'str',
             '*writable': 'bool',
             '*writethrough': 'bool' },
diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c
index XXXXXXX..XXXXXXX 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -XXX,XX +XXX,XX @@
 #include "util/block-helpers.h"
 
 enum {
-    VHOST_USER_BLK_MAX_QUEUES = 1,
+    VHOST_USER_BLK_NUM_QUEUES_DEFAULT = 1,
 };
 struct virtio_blk_inhdr {
     unsigned char status;
@@ -XXX,XX +XXX,XX @@ static uint64_t vu_blk_get_features(VuDev *dev)
                1ull << VIRTIO_BLK_F_DISCARD |
                1ull << VIRTIO_BLK_F_WRITE_ZEROES |
                1ull << VIRTIO_BLK_F_CONFIG_WCE |
+               1ull << VIRTIO_BLK_F_MQ |
                1ull << VIRTIO_F_VERSION_1 |
                1ull << VIRTIO_RING_F_INDIRECT_DESC |
                1ull << VIRTIO_RING_F_EVENT_IDX |
@@ -XXX,XX +XXX,XX @@ static void blk_aio_detach(void *opaque)
 
 static void
 vu_blk_initialize_config(BlockDriverState *bs,
-                           struct virtio_blk_config *config, uint32_t blk_size)
+                         struct virtio_blk_config *config,
+                         uint32_t blk_size,
+                         uint16_t num_queues)
 {
     config->capacity = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
     config->blk_size = blk_size;
@@ -XXX,XX +XXX,XX @@ vu_blk_initialize_config(BlockDriverState *bs,
     config->seg_max = 128 - 2;
     config->min_io_size = 1;
     config->opt_io_size = 1;
-    config->num_queues = VHOST_USER_BLK_MAX_QUEUES;
+    config->num_queues = num_queues;
     config->max_discard_sectors = 32768;
     config->max_discard_seg = 1;
     config->discard_sector_alignment = config->blk_size >> 9;
@@ -XXX,XX +XXX,XX @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
     BlockExportOptionsVhostUserBlk *vu_opts = &opts->u.vhost_user_blk;
     Error *local_err = NULL;
     uint64_t logical_block_size;
+    uint16_t num_queues = VHOST_USER_BLK_NUM_QUEUES_DEFAULT;
 
     vexp->writable = opts->writable;
     vexp->blkcfg.wce = 0;
@@ -XXX,XX +XXX,XX @@ static int vu_blk_exp_create(BlockExport *exp, BlockExportOptions *opts,
     }
     vexp->blk_size = logical_block_size;
     blk_set_guest_block_size(exp->blk, logical_block_size);
+
+    if (vu_opts->has_num_queues) {
+        num_queues = vu_opts->num_queues;
+    }
+    if (num_queues == 0) {
+        error_setg(errp, "num-queues must be greater than 0");
+        return -EINVAL;
+    }
+
     vu_blk_initialize_config(blk_bs(exp->blk), &vexp->blkcfg,
-                               logical_block_size);
+                             logical_block_size, num_queues);
 
     blk_add_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach,
                                  vexp);
 
     if (!vhost_user_server_start(&vexp->vu_server, vu_opts->addr, exp->ctx,
-                                 VHOST_USER_BLK_MAX_QUEUES, &vu_blk_iface,
-                                 errp)) {
+                                 num_queues, &vu_blk_iface, errp)) {
         blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
                                         blk_aio_detach, vexp);
         return -EADDRNOTAVAIL;
-- 
2.26.2

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

bdrv_co_block_status_above has several design problems with handling
short backing files:

1. With want_zeros=true, it may return ret with BDRV_BLOCK_ZERO but
without BDRV_BLOCK_ALLOCATED flag, when actually short backing file
which produces these after-EOF zeros is inside requested backing
sequence.

2. With want_zero=false, it may return pnum=0 prior to actual EOF,
because of EOF of short backing file.

Fix these things, making logic about short backing files clearer.

With fixed bdrv_block_status_above we also have to improve is_zero in
qcow2 code, otherwise iotest 154 will fail, because with this patch we
stop to merge zeros of different types (produced by fully unallocated
in the whole backing chain regions vs produced by short backing files).

Note also, that this patch leaves for another day the general problem
around block-status: misuse of BDRV_BLOCK_ALLOCATED as is-fs-allocated
vs go-to-backing.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20200924194003.22080-2-vsementsov@virtuozzo.com
[Fix s/comes/come/ as suggested by Eric Blake
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/io.c    | 68 ++++++++++++++++++++++++++++++++++++++++-----------
 block/qcow2.c | 16 ++++++++++--
 2 files changed, 68 insertions(+), 16 deletions(-)

diff --git a/block/io.c b/block/io.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io.c
+++ b/block/io.c
@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
                                   int64_t *map,
                                   BlockDriverState **file)
 {
+    int ret;
     BlockDriverState *p;
-    int ret = 0;
-    bool first = true;
+    int64_t eof = 0;
 
     assert(bs != base);
-    for (p = bs; p != base; p = bdrv_filter_or_cow_bs(p)) {
+
+    ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
+    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED) {
+        return ret;
+    }
+
+    if (ret & BDRV_BLOCK_EOF) {
+        eof = offset + *pnum;
+    }
+
+    assert(*pnum <= bytes);
+    bytes = *pnum;
+
+    for (p = bdrv_filter_or_cow_bs(bs); p != base;
+         p = bdrv_filter_or_cow_bs(p))
+    {
         ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
                                    file);
         if (ret < 0) {
-            break;
+            return ret;
         }
-        if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) {
+        if (*pnum == 0) {
             /*
-             * Reading beyond the end of the file continues to read
-             * zeroes, but we can only widen the result to the
-             * unallocated length we learned from an earlier
-             * iteration.
+             * The top layer deferred to this layer, and because this layer is
+             * short, any zeroes that we synthesize beyond EOF behave as if they
+             * were allocated at this layer.
+             *
+             * We don't include BDRV_BLOCK_EOF into ret, as upper layer may be
+             * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see
+             * below.
              */
+            assert(ret & BDRV_BLOCK_EOF);
             *pnum = bytes;
+            if (file) {
+                *file = p;
+            }
+            ret = BDRV_BLOCK_ZERO | BDRV_BLOCK_ALLOCATED;
+            break;
         }
-        if (ret & (BDRV_BLOCK_ZERO | BDRV_BLOCK_DATA)) {
+        if (ret & BDRV_BLOCK_ALLOCATED) {
+            /*
+             * We've found the node and the status, we must break.
+             *
+             * Drop BDRV_BLOCK_EOF, as it's not for upper layer, which may be
+             * larger. We'll add BDRV_BLOCK_EOF if needed at function end, see
+             * below.
+             */
+            ret &= ~BDRV_BLOCK_EOF;
             break;
         }
-        /* [offset, pnum] unallocated on this layer, which could be only
-         * the first part of [offset, bytes].  */
-        bytes = MIN(bytes, *pnum);
-        first = false;
+
+        /*
+         * OK, [offset, offset + *pnum) region is unallocated on this layer,
+         * let's continue the diving.
+         */
+        assert(*pnum <= bytes);
+        bytes = *pnum;
+    }
+
+    if (offset + *pnum == eof) {
+        ret |= BDRV_BLOCK_EOF;
     }
+
     return ret;
 }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -XXX,XX +XXX,XX @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
     if (!bytes) {
         return true;
     }
-    res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
-    return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes;
+
+    /*
+     * bdrv_block_status_above doesn't merge different types of zeros, for
+     * example, zeros which come from the region which is unallocated in
+     * the whole backing chain, and zeros which come because of a short
+     * backing file. So, we need a loop.
+     */
+    do {
+        res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
+        offset += nr;
+        bytes -= nr;
+    } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes);
+
+    return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0;
 }
 
 static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs,
-- 
2.26.2

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

In order to reuse bdrv_common_block_status_above in
bdrv_is_allocated_above, let's support include_base parameter.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20200924194003.22080-3-vsementsov@virtuozzo.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/coroutines.h |  2 ++
 block/io.c         | 21 ++++++++++++++-------
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/block/coroutines.h b/block/coroutines.h
index XXXXXXX..XXXXXXX 100644
--- a/block/coroutines.h
+++ b/block/coroutines.h
@@ -XXX,XX +XXX,XX @@ bdrv_pwritev(BdrvChild *child, int64_t offset, unsigned int bytes,
 int coroutine_fn
 bdrv_co_common_block_status_above(BlockDriverState *bs,
                                   BlockDriverState *base,
+                                  bool include_base,
                                   bool want_zero,
                                   int64_t offset,
                                   int64_t bytes,
@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
 int generated_co_wrapper
 bdrv_common_block_status_above(BlockDriverState *bs,
                                BlockDriverState *base,
+                               bool include_base,
                                bool want_zero,
                                int64_t offset,
                                int64_t bytes,
diff --git a/block/io.c b/block/io.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io.c
+++ b/block/io.c
@@ -XXX,XX +XXX,XX @@ early_out:
 int coroutine_fn
 bdrv_co_common_block_status_above(BlockDriverState *bs,
                                   BlockDriverState *base,
+                                  bool include_base,
                                   bool want_zero,
                                   int64_t offset,
                                   int64_t bytes,
@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
     BlockDriverState *p;
     int64_t eof = 0;
 
-    assert(bs != base);
+    assert(include_base || bs != base);
+    assert(!include_base || base); /* Can't include NULL base */
 
     ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
-    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED) {
+    if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
         return ret;
     }
 
@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
     assert(*pnum <= bytes);
     bytes = *pnum;
 
-    for (p = bdrv_filter_or_cow_bs(bs); p != base;
+    for (p = bdrv_filter_or_cow_bs(bs); include_base || p != base;
          p = bdrv_filter_or_cow_bs(p))
     {
         ret = bdrv_co_block_status(p, want_zero, offset, bytes, pnum, map,
@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
             break;
         }
 
+        if (p == base) {
+            assert(include_base);
+            break;
+        }
+
         /*
          * OK, [offset, offset + *pnum) region is unallocated on this layer,
          * let's continue the diving.
@@ -XXX,XX +XXX,XX @@ int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
                             int64_t offset, int64_t bytes, int64_t *pnum,
                             int64_t *map, BlockDriverState **file)
 {
-    return bdrv_common_block_status_above(bs, base, true, offset, bytes,
+    return bdrv_common_block_status_above(bs, base, false, true, offset, bytes,
                                           pnum, map, file);
 }
 
@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
     int ret;
     int64_t dummy;
 
-    ret = bdrv_common_block_status_above(bs, bdrv_filter_or_cow_bs(bs), false,
-                                         offset, bytes, pnum ? pnum : &dummy,
-                                         NULL, NULL);
+    ret = bdrv_common_block_status_above(bs, bs, true, false, offset,
+                                         bytes, pnum ? pnum : &dummy, NULL,
+                                         NULL);
     if (ret < 0) {
         return ret;
     }
-- 
2.26.2

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

We are going to reuse bdrv_common_block_status_above in
bdrv_is_allocated_above. bdrv_is_allocated_above may be called with
include_base == false and still bs == base (for ex. from img_rebase()).

So, support this corner case.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20200924194003.22080-4-vsementsov@virtuozzo.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/io.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/io.c b/block/io.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io.c
+++ b/block/io.c
@@ -XXX,XX +XXX,XX @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
     BlockDriverState *p;
     int64_t eof = 0;
 
-    assert(include_base || bs != base);
     assert(!include_base || base); /* Can't include NULL base */
 
+    if (!include_base && bs == base) {
+        *pnum = bytes;
+        return 0;
+    }
+
     ret = bdrv_co_block_status(bs, want_zero, offset, bytes, pnum, map, file);
     if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
         return ret;
-- 
2.26.2

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

bdrv_is_allocated_above wrongly handles short backing files: it reports
after-EOF space as UNALLOCATED which is wrong, as on read the data is
generated on the level of short backing file (if all overlays have
unallocated areas at that place).

Reusing bdrv_common_block_status_above fixes the issue and unifies code
path.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20200924194003.22080-5-vsementsov@virtuozzo.com
[Fix s/has/have/ as suggested by Eric Blake. Fix s/area/areas/.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/io.c | 43 +++++--------------------------------------
 1 file changed, 5 insertions(+), 38 deletions(-)

diff --git a/block/io.c b/block/io.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io.c
+++ b/block/io.c
@@ -XXX,XX +XXX,XX @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
  * at 'offset + *pnum' may return the same allocation status (in other
  * words, the result is not necessarily the maximum possible range);
  * but 'pnum' will only be 0 when end of file is reached.
- *
  */
 int bdrv_is_allocated_above(BlockDriverState *top,
                             BlockDriverState *base,
                             bool include_base, int64_t offset,
                             int64_t bytes, int64_t *pnum)
 {
-    BlockDriverState *intermediate;
-    int ret;
-    int64_t n = bytes;
-
-    assert(base || !include_base);
-
-    intermediate = top;
-    while (include_base || intermediate != base) {
-        int64_t pnum_inter;
-        int64_t size_inter;
-
-        assert(intermediate);
-        ret = bdrv_is_allocated(intermediate, offset, bytes, &pnum_inter);
-        if (ret < 0) {
-            return ret;
-        }
-        if (ret) {
-            *pnum = pnum_inter;
-            return 1;
-        }
-
-        size_inter = bdrv_getlength(intermediate);
-        if (size_inter < 0) {
-            return size_inter;
-        }
-        if (n > pnum_inter &&
-            (intermediate == top || offset + pnum_inter < size_inter)) {
-            n = pnum_inter;
-        }
-
-        if (intermediate == base) {
-            break;
-        }
-
-        intermediate = bdrv_filter_or_cow_bs(intermediate);
+    int ret = bdrv_common_block_status_above(top, base, include_base, false,
+                                             offset, bytes, pnum, NULL, NULL);
+    if (ret < 0) {
+        return ret;
     }
 
-    *pnum = n;
-    return 0;
+    return !!(ret & BDRV_BLOCK_ALLOCATED);
 }
 
 int coroutine_fn
-- 
2.26.2

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

These cases are fixed by previous patches around block_status and
is_allocated.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20200924194003.22080-6-vsementsov@virtuozzo.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/qemu-iotests/274     | 20 +++++++++++
 tests/qemu-iotests/274.out | 68 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/tests/qemu-iotests/274 b/tests/qemu-iotests/274
index XXXXXXX..XXXXXXX 100755
--- a/tests/qemu-iotests/274
+++ b/tests/qemu-iotests/274
@@ -XXX,XX +XXX,XX @@ with iotests.FilePath('base') as base, \
     iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, mid)
     iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), mid)
 
+    iotests.log('=== Testing qemu-img commit (top -> base) ===')
+
+    create_chain()
+    iotests.qemu_img_log('commit', '-b', base, top)
+    iotests.img_info_log(base)
+    iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, base)
+    iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), base)
+
+    iotests.log('=== Testing QMP active commit (top -> base) ===')
+
+    create_chain()
+    with create_vm() as vm:
+        vm.launch()
+        vm.qmp_log('block-commit', device='top', base_node='base',
+                   job_id='job0', auto_dismiss=False)
+        vm.run_job('job0', wait=5)
+
+    iotests.img_info_log(mid)
+    iotests.qemu_io_log('-c', 'read -P 1 0 %d' % size_short, base)
+    iotests.qemu_io_log('-c', 'read -P 0 %d %d' % (size_short, size_diff), base)
 
     iotests.log('== Resize tests ==')
 
diff --git a/tests/qemu-iotests/274.out b/tests/qemu-iotests/274.out
index XXXXXXX..XXXXXXX 100644
--- a/tests/qemu-iotests/274.out
+++ b/tests/qemu-iotests/274.out
@@ -XXX,XX +XXX,XX @@ read 1048576/1048576 bytes at offset 0
 read 1048576/1048576 bytes at offset 1048576
 1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
+=== Testing qemu-img commit (top -> base) ===
+Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-mid', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 backing_file=TEST_DIR/PID-base backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-top', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 backing_file=TEST_DIR/PID-mid backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+wrote 2097152/2097152 bytes at offset 0
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+Image committed.
+
+image: TEST_IMG
+file format: IMGFMT
+virtual size: 2 MiB (2097152 bytes)
+cluster_size: 65536
+Format specific information:
+    compat: 1.1
+    compression type: zlib
+    lazy refcounts: false
+    refcount bits: 16
+    corrupt: false
+    extended l2: false
+
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+read 1048576/1048576 bytes at offset 1048576
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+=== Testing QMP active commit (top -> base) ===
+Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-mid', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 backing_file=TEST_DIR/PID-base backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+Formatting 'TEST_DIR/PID-top', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=2097152 backing_file=TEST_DIR/PID-mid backing_fmt=qcow2 lazy_refcounts=off refcount_bits=16
+
+wrote 2097152/2097152 bytes at offset 0
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+{"execute": "block-commit", "arguments": {"auto-dismiss": false, "base-node": "base", "device": "top", "job-id": "job0"}}
+{"return": {}}
+{"execute": "job-complete", "arguments": {"id": "job0"}}
+{"return": {}}
+{"data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_READY", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"device": "job0", "len": 1048576, "offset": 1048576, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"execute": "job-dismiss", "arguments": {"id": "job0"}}
+{"return": {}}
+image: TEST_IMG
+file format: IMGFMT
+virtual size: 1 MiB (1048576 bytes)
+cluster_size: 65536
+backing file: TEST_DIR/PID-base
+backing file format: IMGFMT
+Format specific information:
+    compat: 1.1
+    compression type: zlib
+    lazy refcounts: false
+    refcount bits: 16
+    corrupt: false
+    extended l2: false
+
+read 1048576/1048576 bytes at offset 0
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+read 1048576/1048576 bytes at offset 1048576
+1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
 == Resize tests ==
 === preallocation=off ===
 Formatting 'TEST_DIR/PID-base', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=6442450944 lazy_refcounts=off refcount_bits=16
-- 
2.26.2