Series comparison

-[Qemu-devel] [PULL for-2.10 0/3] Block patches
+[PULL 0/3] Block patches
-The following changes since commit b38df311c174c98ef8cce7dec9f46603b083018e:
+The following changes since commit 00b1faea41d283e931256aa78aa975a369ec3ae6:
-  Merge remote-tracking branch 'remotes/dgibson/tags/ppc-for-2.10-20170809' into staging (2017-08-10 11:12:36 +0100)
+  Merge tag 'pull-target-arm-20230123' of https://git.linaro.org/people/pmaydell/qemu-arm into staging (2023-01-23 13:40:28 +0000)
-are available in the git repository at:
+are available in the Git repository at:
-  git://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 17d0bc01bfcce0ad4fb5105d4502595224569ff0:
+for you to fetch changes up to 4f01a9bb0461e8c11ee0c94d90a504cb7d580a85:
-  virtio-blk: handle blk_getlength() errors (2017-08-10 14:33:43 +0100)
+  block/blkio: Fix inclusion of required headers (2023-01-23 15:02:07 -0500)
 ----------------------------------------------------------------
 Pull request
 ----------------------------------------------------------------
-----------------------------------------------------------------
+Chao Gao (1):
   util/aio: Defer disabling poll mode as long as possible
-Kevin Wolf (1):
+Peter Krempa (1):
-  IDE: test flush on empty CDROM
+  block/blkio: Fix inclusion of required headers
-Stefan Hajnoczi (2):
+Stefan Hajnoczi (1):
-  IDE: Do not flush empty CDROM drives
+  virtio-blk: simplify virtio_blk_dma_restart_cb()
   virtio-blk: handle blk_getlength() errors
- hw/block/virtio-blk.c |  4 +++-
+ include/hw/virtio/virtio-blk.h  |  2 --
- hw/ide/core.c         | 10 +++++++++-
+ block/blkio.c                   |  2 ++
- tests/ide-test.c      | 19 +++++++++++++++++++
+ hw/block/dataplane/virtio-blk.c | 17 +++++-------
-files changed, 31 insertions(+), 2 deletions(-)
+ hw/block/virtio-blk.c           | 46 ++++++++++++++-------------------
  util/aio-posix.c                | 21 ++++++++++-----
 files changed, 43 insertions(+), 45 deletions(-)
 --
-.13.4
+.39.0

-[Qemu-devel] [PULL for-2.10 2/3] IDE: test flush on empty CDROM
+[PULL 1/3] util/aio: Defer disabling poll mode as long as possible
-From: Kevin Wolf <kwolf@redhat.com>
+From: Chao Gao <chao.gao@intel.com>
-Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+When we measure FIO read performance (cache=writethrough, bs=4k,
-Signed-off-by: John Snow <jsnow@redhat.com>
+iodepth=64) in VMs, ~80K/s notifications (e.g., EPT_MISCONFIG) are observed
-Reviewed-by: Eric Blake <eblake@redhat.com>
+from guest to qemu.
-Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Message-id: 20170809160212.29976-3-stefanha@redhat.com
+It turns out those frequent notificatons are caused by interference from
 worker threads. Worker threads queue bottom halves after completing IO
 requests.  Pending bottom halves may lead to either aio_compute_timeout()
 zeros timeout and pass it to try_poll_mode() or run_poll_handlers() returns
 no progress after noticing pending aio_notify() events. Both cause
 run_poll_handlers() to call poll_set_started(false) to disable poll mode.
 However, for both cases, as timeout is already zeroed, the event loop
 (i.e., aio_poll()) just processes bottom halves and then starts the next
 event loop iteration. So, disabling poll mode has no value but leads to
 unnecessary notifications from guest.
 To minimize unnecessary notifications from guest, defer disabling poll
 mode to when the event loop is about to be blocked.
 With this patch applied, FIO seq-read performance (bs=4k, iodepth=64,
 cache=writethrough) in VMs increases from 330K/s to 413K/s IOPS.
 Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
 Signed-off-by: Chao Gao <chao.gao@intel.com>
 Message-id: 20220710120849.63086-1-chao.gao@intel.com
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- tests/ide-test.c | 19 +++++++++++++++++++
+ util/aio-posix.c | 21 +++++++++++++++------
-file changed, 19 insertions(+)
+file changed, 15 insertions(+), 6 deletions(-)
-diff --git a/tests/ide-test.c b/tests/ide-test.c
+diff --git a/util/aio-posix.c b/util/aio-posix.c
 index XXXXXXX..XXXXXXX 100644
---- a/tests/ide-test.c
+--- a/util/aio-posix.c
-+++ b/tests/ide-test.c
++++ b/util/aio-posix.c
-@@ -XXX,XX +XXX,XX @@ static void test_flush_nodev(void)
+@@ -XXX,XX +XXX,XX @@ static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list,
-     ide_test_quit();
      max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
      if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
 +        /*
 +         * Enable poll mode. It pairs with the poll_set_started() in
 +         * aio_poll() which disables poll mode.
 +         */
          poll_set_started(ctx, ready_list, true);
          if (run_poll_handlers(ctx, ready_list, max_ns, timeout)) {
              return true;
          }
      }
 -
 -    if (poll_set_started(ctx, ready_list, false)) {
 -        *timeout = 0;
 -        return true;
 -    }
 -
      return false;
  }
-+static void test_flush_empty_drive(void)
+@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
-+{
+      * system call---a single round of run_poll_handlers_once suffices.
-+    QPCIDevice *dev;
+      */
-+    QPCIBar bmdma_bar, ide_bar;
+     if (timeout || ctx->fdmon_ops->need_wait(ctx)) {
 +        /*
 +         * Disable poll mode. poll mode should be disabled before the call
 +         * of ctx->fdmon_ops->wait() so that guest's notification can wake
 +         * up IO threads when some work becomes pending. It is essential to
 +         * avoid hangs or unnecessary latency.
 +         */
 +        if (poll_set_started(ctx, &ready_list, false)) {
 +            timeout = 0;
 +            progress = true;
 +        }
 +
-+    ide_test_start("-device ide-cd,bus=ide.0");
+         ctx->fdmon_ops->wait(ctx, &ready_list, timeout);
-+    dev = get_pci_device(&bmdma_bar, &ide_bar);
+     }
 +
 +    /* FLUSH CACHE command on device 0 */
 +    qpci_io_writeb(dev, ide_bar, reg_device, 0);
 +    qpci_io_writeb(dev, ide_bar, reg_command, CMD_FLUSH_CACHE);
 +
 +    /* Just testing that qemu doesn't crash... */
 +
 +    free_pci_device(dev);
 +    ide_test_quit();
 +}
 +
  static void test_pci_retry_flush(void)
  {
      test_retry_flush("pc");
@@ -XXX,XX +XXX,XX @@ int main(int argc, char **argv)
      qtest_add_func("/ide/flush", test_flush);
      qtest_add_func("/ide/flush/nodev", test_flush_nodev);
 +    qtest_add_func("/ide/flush/empty_drive", test_flush_empty_drive);
      qtest_add_func("/ide/flush/retry_pci", test_pci_retry_flush);
      qtest_add_func("/ide/flush/retry_isa", test_isa_retry_flush);
 --
-.13.4
+.39.0

-[Qemu-devel] [PULL for-2.10 3/3] virtio-blk: handle blk_getlength() errors
+[PULL 2/3] virtio-blk: simplify virtio_blk_dma_restart_cb()
-If blk_getlength() fails in virtio_blk_update_config() consider the disk
+virtio_blk_dma_restart_cb() is tricky because the BH must deal with
-image length to be 0 bytes.
+virtio_blk_data_plane_start()/virtio_blk_data_plane_stop() being called.
+There are two issues with the code:
+. virtio_blk_realize() should use qdev_add_vm_change_state_handler()
+   instead of qemu_add_vm_change_state_handler(). This ensures the
+   ordering with virtio_init()'s vm change state handler that calls
+   virtio_blk_data_plane_start()/virtio_blk_data_plane_stop() is
+   well-defined. Then blk's AioContext is guaranteed to be up-to-date in
+   virtio_blk_dma_restart_cb() and it's no longer necessary to have a
+   special case for virtio_blk_data_plane_start().
+. Only blk_drain() waits for virtio_blk_dma_restart_cb()'s
+   blk_inc_in_flight() to be decremented. The bdrv_drain() family of
+   functions do not wait for BlockBackend's in_flight counter to reach
+   zero. virtio_blk_data_plane_stop() relies on blk_set_aio_context()'s
+   implicit drain, but that's a bdrv_drain() and not a blk_drain().
+   Note that virtio_blk_reset() already correctly relies on blk_drain().
+   If virtio_blk_data_plane_stop() switches to blk_drain() then we can
+   properly wait for pending virtio_blk_dma_restart_bh() calls.
+Once these issues are taken care of the code becomes simpler. This
+change is in preparation for multiple IOThreads in virtio-blk where we
+need to clean up the multi-threading behavior.
+I ran the reproducer from commit 49b44549ace7 ("virtio-blk: On restart,
+process queued requests in the proper context") to check that there is
+no regression.
+Cc: Sergio Lopez <slp@redhat.com>
+Cc: Kevin Wolf <kwolf@redhat.com>
+Cc: Emanuele Giuseppe Esposito <eesposit@redhat.com>
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-Reviewed-by: Fam Zheng <famz@redhat.com>
+Acked-by: Michael S. Tsirkin <mst@redhat.com>
-Message-id: 20170808122251.29815-1-stefanha@redhat.com
+Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
 Message-id: 20221102182337.252202-1-stefanha@redhat.com
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- hw/block/virtio-blk.c | 4 +++-
+ include/hw/virtio/virtio-blk.h  |  2 --
-file changed, 3 insertions(+), 1 deletion(-)
+ hw/block/dataplane/virtio-blk.c | 17 +++++-------
  hw/block/virtio-blk.c           | 46 ++++++++++++++-------------------
 files changed, 26 insertions(+), 39 deletions(-)
+diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/hw/virtio/virtio-blk.h
++++ b/include/hw/virtio/virtio-blk.h
+@@ -XXX,XX +XXX,XX @@ struct VirtIOBlock {
+     VirtIODevice parent_obj;
+     BlockBackend *blk;
+     void *rq;
+-    QEMUBH *bh;
+     VirtIOBlkConf conf;
+     unsigned short sector_mask;
+     bool original_wce;
+@@ -XXX,XX +XXX,XX @@ typedef struct MultiReqBuffer {
+ } MultiReqBuffer;
+ void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
+-void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh);
+ #endif
+diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/block/dataplane/virtio-blk.c
++++ b/hw/block/dataplane/virtio-blk.c
+@@ -XXX,XX +XXX,XX @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
+         goto fail_aio_context;
+     }
+-    /* Process queued requests before the ones in vring */
+-    virtio_blk_process_queued_requests(vblk, false);
+-
+     /* Kick right away to begin processing requests already in vring */
+     for (i = 0; i < nvqs; i++) {
+         VirtQueue *vq = virtio_get_queue(s->vdev, i);
+@@ -XXX,XX +XXX,XX @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
+   fail_host_notifiers:
+     k->set_guest_notifiers(qbus->parent, nvqs, false);
+   fail_guest_notifiers:
+-    /*
+-     * If we failed to set up the guest notifiers queued requests will be
+-     * processed on the main context.
+-     */
+-    virtio_blk_process_queued_requests(vblk, false);
+     vblk->dataplane_disabled = true;
+     s->starting = false;
+     vblk->dataplane_started = true;
+@@ -XXX,XX +XXX,XX @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
+     aio_context_acquire(s->ctx);
+     aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s);
+-    /* Drain and try to switch bs back to the QEMU main loop. If other users
+-     * keep the BlockBackend in the iothread, that's ok */
++    /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
++    blk_drain(s->conf->conf.blk);
++
++    /*
++     * Try to switch bs back to the QEMU main loop. If other users keep the
++     * BlockBackend in the iothread, that's ok
++     */
+     blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
+     aio_context_release(s->ctx);
 diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
 index XXXXXXX..XXXXXXX 100644
 --- a/hw/block/virtio-blk.c
 +++ b/hw/block/virtio-blk.c
-@@ -XXX,XX +XXX,XX @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
+@@ -XXX,XX +XXX,XX @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
-     BlockConf *conf = &s->conf.conf;
+     virtio_blk_handle_vq(s, vq);
-     struct virtio_blk_config blkcfg;
+ }
-     uint64_t capacity;
-+    int64_t length;
+-void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
-     int blk_size = conf->logical_block_size;
++static void virtio_blk_dma_restart_bh(void *opaque)
+ {
-     blk_get_geometry(s->blk, &capacity);
++    VirtIOBlock *s = opaque;
-@@ -XXX,XX +XXX,XX @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
++
-      * divided by 512 - instead it is the amount of blk_size blocks
+     VirtIOBlockReq *req = s->rq;
-      * per track (cylinder).
+     MultiReqBuffer mrb = {};
-      */
--    if (blk_getlength(s->blk) /  conf->heads / conf->secs % blk_size) {
+@@ -XXX,XX +XXX,XX @@ void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
-+    length = blk_getlength(s->blk);
+     if (mrb.num_reqs) {
-+    if (length > 0 && length / conf->heads / conf->secs % blk_size) {
+         virtio_blk_submit_multireq(s, &mrb);
-         blkcfg.geometry.sectors = conf->secs & ~s->sector_mask;
+     }
-     } else {
+-    if (is_bh) {
-         blkcfg.geometry.sectors = conf->secs;
+-        blk_dec_in_flight(s->conf.conf.blk);
 -    }
 +
 +    /* Paired with inc in virtio_blk_dma_restart_cb() */
 +    blk_dec_in_flight(s->conf.conf.blk);
 +
      aio_context_release(blk_get_aio_context(s->conf.conf.blk));
  }
 -static void virtio_blk_dma_restart_bh(void *opaque)
 -{
 -    VirtIOBlock *s = opaque;
 -
 -    qemu_bh_delete(s->bh);
 -    s->bh = NULL;
 -
 -    virtio_blk_process_queued_requests(s, true);
 -}
 -
  static void virtio_blk_dma_restart_cb(void *opaque, bool running,
                                        RunState state)
  {
      VirtIOBlock *s = opaque;
 -    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
 -    VirtioBusState *bus = VIRTIO_BUS(qbus);
      if (!running) {
          return;
      }
 -    /*
 -     * If ioeventfd is enabled, don't schedule the BH here as queued
 -     * requests will be processed while starting the data plane.
 -     */
 -    if (!s->bh && !virtio_bus_ioeventfd_enabled(bus)) {
 -        s->bh = aio_bh_new(blk_get_aio_context(s->conf.conf.blk),
 -                           virtio_blk_dma_restart_bh, s);
 -        blk_inc_in_flight(s->conf.conf.blk);
 -        qemu_bh_schedule(s->bh);
 -    }
 +    /* Paired with dec in virtio_blk_dma_restart_bh() */
 +    blk_inc_in_flight(s->conf.conf.blk);
 +
 +    aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.conf.blk),
 +            virtio_blk_dma_restart_bh, s);
  }
  static void virtio_blk_reset(VirtIODevice *vdev)
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
          return;
      }
 -    s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
 +    /*
 +     * This must be after virtio_init() so virtio_blk_dma_restart_cb() gets
 +     * called after ->start_ioeventfd() has already set blk's AioContext.
 +     */
 +    s->change =
 +        qdev_add_vm_change_state_handler(dev, virtio_blk_dma_restart_cb, s);
 +
      blk_ram_registrar_init(&s->blk_ram_registrar, s->blk);
      blk_set_dev_ops(s->blk, &virtio_block_ops, s);
 --
-.13.4
+.39.0

-[Qemu-devel] [PULL for-2.10 1/3] IDE: Do not flush empty CDROM drives
+[PULL 3/3] block/blkio: Fix inclusion of required headers
-The block backend changed in a way that flushing empty CDROM drives now
+From: Peter Krempa <pkrempa@redhat.com>
 crashes.  Amend IDE to avoid doing so until the root problem can be
 addressed for 2.11.
-Original patch by John Snow <jsnow@redhat.com>.
+After recent header file inclusion rework the build fails when the blkio
 module is enabled:
-Reported-by: Kieron Shorrock <kshorrock@paloaltonetworks.com>
+../block/blkio.c: In function ‘blkio_detach_aio_context’:
-Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+../block/blkio.c:321:24: error: implicit declaration of function ‘bdrv_get_aio_context’; did you mean ‘qemu_get_aio_context’? [-Werror=implicit-function-declaration]
-Reviewed-by: Eric Blake <eblake@redhat.com>
+|     aio_set_fd_handler(bdrv_get_aio_context(bs),
-Message-id: 20170809160212.29976-2-stefanha@redhat.com
+      |                        ^~~~~~~~~~~~~~~~~~~~
       |                        qemu_get_aio_context
 ../block/blkio.c:321:24: error: nested extern declaration of ‘bdrv_get_aio_context’ [-Werror=nested-externs]
 ../block/blkio.c:321:24: error: passing argument 1 of ‘aio_set_fd_handler’ makes pointer from integer without a cast [-Werror=int-conversion]
 |     aio_set_fd_handler(bdrv_get_aio_context(bs),
       |                        ^~~~~~~~~~~~~~~~~~~~~~~~
       |                        |
       |                        int
 In file included from /home/pipo/git/qemu.git/include/qemu/job.h:33,
                  from /home/pipo/git/qemu.git/include/block/blockjob.h:30,
                  from /home/pipo/git/qemu.git/include/block/block_int-global-state.h:28,
                  from /home/pipo/git/qemu.git/include/block/block_int.h:27,
                  from ../block/blkio.c:13:
 /home/pipo/git/qemu.git/include/block/aio.h:476:37: note: expected ‘AioContext *’ but argument is of type ‘int’
 | void aio_set_fd_handler(AioContext *ctx,
       |                         ~~~~~~~~~~~~^~~
 ../block/blkio.c: In function ‘blkio_file_open’:
 ../block/blkio.c:821:34: error: passing argument 2 of ‘blkio_attach_aio_context’ makes pointer from integer without a cast [-Werror=int-conversion]
 |     blkio_attach_aio_context(bs, bdrv_get_aio_context(bs));
       |                                  ^~~~~~~~~~~~~~~~~~~~~~~~
       |                                  |
       |                                  int
 Fix it by including 'block/block-io.h' which contains the required
 declarations.
 Fixes: e2c1c34f139f49ef909bb4322607fb8b39002312
 Signed-off-by: Peter Krempa <pkrempa@redhat.com>
 Reviewed-by: Markus Armbruster <armbru@redhat.com>
 Message-id: 2bc956011404a1ab03342aefde0087b5b4762562.1674477350.git.pkrempa@redhat.com
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 ---
- hw/ide/core.c | 10 +++++++++-
+ block/blkio.c | 2 ++
-file changed, 9 insertions(+), 1 deletion(-)
+file changed, 2 insertions(+)
-diff --git a/hw/ide/core.c b/hw/ide/core.c
+diff --git a/block/blkio.c b/block/blkio.c
 index XXXXXXX..XXXXXXX 100644
---- a/hw/ide/core.c
+--- a/block/blkio.c
-+++ b/hw/ide/core.c
++++ b/block/blkio.c
-@@ -XXX,XX +XXX,XX @@ static void ide_flush_cache(IDEState *s)
+@@ -XXX,XX +XXX,XX @@
-     s->status |= BUSY_STAT;
+ #include "qemu/module.h"
-     ide_set_retry(s);
+ #include "exec/memory.h" /* for ram_block_discard_disable() */
-     block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
--    s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
++#include "block/block-io.h"
 +
-+    if (blk_bs(s->blk)) {
+ /*
-+        s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+  * Keep the QEMU BlockDriver names identical to the libblkio driver names.
-+    } else {
+  * Using macros instead of typing out the string literals avoids typos.
 +        /* XXX blk_aio_flush() crashes when blk_bs(blk) is NULL, remove this
 +         * temporary workaround when blk_aio_*() functions handle NULL blk_bs.
 +         */
 +        ide_flush_cb(s, 0);
 +    }
  }
  static void ide_cfata_metadata_inquiry(IDEState *s)
 --
-.13.4
+.39.0

The block backend changed in a way that flushing empty CDROM drives now
crashes.  Amend IDE to avoid doing so until the root problem can be
addressed for 2.11.

Original patch by John Snow <jsnow@redhat.com>.

Reported-by: Kieron Shorrock <kshorrock@paloaltonetworks.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20170809160212.29976-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/ide/core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -XXX,XX +XXX,XX @@ static void ide_flush_cache(IDEState *s)
     s->status |= BUSY_STAT;
     ide_set_retry(s);
     block_acct_start(blk_get_stats(s->blk), &s->acct, 0, BLOCK_ACCT_FLUSH);
-    s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+
+    if (blk_bs(s->blk)) {
+        s->pio_aiocb = blk_aio_flush(s->blk, ide_flush_cb, s);
+    } else {
+        /* XXX blk_aio_flush() crashes when blk_bs(blk) is NULL, remove this
+         * temporary workaround when blk_aio_*() functions handle NULL blk_bs.
+         */
+        ide_flush_cb(s, 0);
+    }
 }
 
 static void ide_cfata_metadata_inquiry(IDEState *s)
-- 
2.13.4

From: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170809160212.29976-3-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/ide-test.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/tests/ide-test.c b/tests/ide-test.c
index XXXXXXX..XXXXXXX 100644
--- a/tests/ide-test.c
+++ b/tests/ide-test.c
@@ -XXX,XX +XXX,XX @@ static void test_flush_nodev(void)
     ide_test_quit();
 }
 
+static void test_flush_empty_drive(void)
+{
+    QPCIDevice *dev;
+    QPCIBar bmdma_bar, ide_bar;
+
+    ide_test_start("-device ide-cd,bus=ide.0");
+    dev = get_pci_device(&bmdma_bar, &ide_bar);
+
+    /* FLUSH CACHE command on device 0 */
+    qpci_io_writeb(dev, ide_bar, reg_device, 0);
+    qpci_io_writeb(dev, ide_bar, reg_command, CMD_FLUSH_CACHE);
+
+    /* Just testing that qemu doesn't crash... */
+
+    free_pci_device(dev);
+    ide_test_quit();
+}
+
 static void test_pci_retry_flush(void)
 {
     test_retry_flush("pc");
@@ -XXX,XX +XXX,XX @@ int main(int argc, char **argv)
 
     qtest_add_func("/ide/flush", test_flush);
     qtest_add_func("/ide/flush/nodev", test_flush_nodev);
+    qtest_add_func("/ide/flush/empty_drive", test_flush_empty_drive);
     qtest_add_func("/ide/flush/retry_pci", test_pci_retry_flush);
     qtest_add_func("/ide/flush/retry_isa", test_isa_retry_flush);
 
-- 
2.13.4

If blk_getlength() fails in virtio_blk_update_config() consider the disk
image length to be 0 bytes.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170808122251.29815-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 hw/block/virtio-blk.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
     BlockConf *conf = &s->conf.conf;
     struct virtio_blk_config blkcfg;
     uint64_t capacity;
+    int64_t length;
     int blk_size = conf->logical_block_size;
 
     blk_get_geometry(s->blk, &capacity);
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config)
      * divided by 512 - instead it is the amount of blk_size blocks
      * per track (cylinder).
      */
-    if (blk_getlength(s->blk) /  conf->heads / conf->secs % blk_size) {
+    length = blk_getlength(s->blk);
+    if (length > 0 && length / conf->heads / conf->secs % blk_size) {
         blkcfg.geometry.sectors = conf->secs & ~s->sector_mask;
     } else {
         blkcfg.geometry.sectors = conf->secs;
-- 
2.13.4

The following changes since commit 00b1faea41d283e931256aa78aa975a369ec3ae6:

Merge tag 'pull-target-arm-20230123' of https://git.linaro.org/people/pmaydell/qemu-arm into staging (2023-01-23 13:40:28 +0000)

are available in the Git repository at:

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

for you to fetch changes up to 4f01a9bb0461e8c11ee0c94d90a504cb7d580a85:

block/blkio: Fix inclusion of required headers (2023-01-23 15:02:07 -0500)

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

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

Chao Gao (1):
  util/aio: Defer disabling poll mode as long as possible

Peter Krempa (1):
  block/blkio: Fix inclusion of required headers

Stefan Hajnoczi (1):
  virtio-blk: simplify virtio_blk_dma_restart_cb()

include/hw/virtio/virtio-blk.h  |  2 --
 block/blkio.c                   |  2 ++
 hw/block/dataplane/virtio-blk.c | 17 +++++-------
 hw/block/virtio-blk.c           | 46 ++++++++++++++-------------------
 util/aio-posix.c                | 21 ++++++++++-----
 5 files changed, 43 insertions(+), 45 deletions(-)

-- 
2.39.0

From: Chao Gao <chao.gao@intel.com>

When we measure FIO read performance (cache=writethrough, bs=4k,
iodepth=64) in VMs, ~80K/s notifications (e.g., EPT_MISCONFIG) are observed
from guest to qemu.

It turns out those frequent notificatons are caused by interference from
worker threads. Worker threads queue bottom halves after completing IO
requests.  Pending bottom halves may lead to either aio_compute_timeout()
zeros timeout and pass it to try_poll_mode() or run_poll_handlers() returns
no progress after noticing pending aio_notify() events. Both cause
run_poll_handlers() to call poll_set_started(false) to disable poll mode.
However, for both cases, as timeout is already zeroed, the event loop
(i.e., aio_poll()) just processes bottom halves and then starts the next
event loop iteration. So, disabling poll mode has no value but leads to
unnecessary notifications from guest.

To minimize unnecessary notifications from guest, defer disabling poll
mode to when the event loop is about to be blocked.

With this patch applied, FIO seq-read performance (bs=4k, iodepth=64,
cache=writethrough) in VMs increases from 330K/s to 413K/s IOPS.

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Message-id: 20220710120849.63086-1-chao.gao@intel.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 util/aio-posix.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 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 try_poll_mode(AioContext *ctx, AioHandlerList *ready_list,
 
     max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
     if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
+        /*
+         * Enable poll mode. It pairs with the poll_set_started() in
+         * aio_poll() which disables poll mode.
+         */
         poll_set_started(ctx, ready_list, true);
 
         if (run_poll_handlers(ctx, ready_list, max_ns, timeout)) {
             return true;
         }
     }
-
-    if (poll_set_started(ctx, ready_list, false)) {
-        *timeout = 0;
-        return true;
-    }
-
     return false;
 }
 
@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
      * system call---a single round of run_poll_handlers_once suffices.
      */
     if (timeout || ctx->fdmon_ops->need_wait(ctx)) {
+        /*
+         * Disable poll mode. poll mode should be disabled before the call
+         * of ctx->fdmon_ops->wait() so that guest's notification can wake
+         * up IO threads when some work becomes pending. It is essential to
+         * avoid hangs or unnecessary latency.
+         */
+        if (poll_set_started(ctx, &ready_list, false)) {
+            timeout = 0;
+            progress = true;
+        }
+
         ctx->fdmon_ops->wait(ctx, &ready_list, timeout);
     }
 
-- 
2.39.0

virtio_blk_dma_restart_cb() is tricky because the BH must deal with
virtio_blk_data_plane_start()/virtio_blk_data_plane_stop() being called.

There are two issues with the code:

1. virtio_blk_realize() should use qdev_add_vm_change_state_handler()
   instead of qemu_add_vm_change_state_handler(). This ensures the
   ordering with virtio_init()'s vm change state handler that calls
   virtio_blk_data_plane_start()/virtio_blk_data_plane_stop() is
   well-defined. Then blk's AioContext is guaranteed to be up-to-date in
   virtio_blk_dma_restart_cb() and it's no longer necessary to have a
   special case for virtio_blk_data_plane_start().

2. Only blk_drain() waits for virtio_blk_dma_restart_cb()'s
   blk_inc_in_flight() to be decremented. The bdrv_drain() family of
   functions do not wait for BlockBackend's in_flight counter to reach
   zero. virtio_blk_data_plane_stop() relies on blk_set_aio_context()'s
   implicit drain, but that's a bdrv_drain() and not a blk_drain().
   Note that virtio_blk_reset() already correctly relies on blk_drain().
   If virtio_blk_data_plane_stop() switches to blk_drain() then we can
   properly wait for pending virtio_blk_dma_restart_bh() calls.

Once these issues are taken care of the code becomes simpler. This
change is in preparation for multiple IOThreads in virtio-blk where we
need to clean up the multi-threading behavior.

I ran the reproducer from commit 49b44549ace7 ("virtio-blk: On restart,
process queued requests in the proper context") to check that there is
no regression.

Cc: Sergio Lopez <slp@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-id: 20221102182337.252202-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/hw/virtio/virtio-blk.h  |  2 --
 hw/block/dataplane/virtio-blk.c | 17 +++++-------
 hw/block/virtio-blk.c           | 46 ++++++++++++++-------------------
 3 files changed, 26 insertions(+), 39 deletions(-)

diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -XXX,XX +XXX,XX @@ struct VirtIOBlock {
     VirtIODevice parent_obj;
     BlockBackend *blk;
     void *rq;
-    QEMUBH *bh;
     VirtIOBlkConf conf;
     unsigned short sector_mask;
     bool original_wce;
@@ -XXX,XX +XXX,XX @@ typedef struct MultiReqBuffer {
 } MultiReqBuffer;
 
 void virtio_blk_handle_vq(VirtIOBlock *s, VirtQueue *vq);
-void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh);
 
 #endif
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -XXX,XX +XXX,XX @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
         goto fail_aio_context;
     }
 
-    /* Process queued requests before the ones in vring */
-    virtio_blk_process_queued_requests(vblk, false);
-
     /* Kick right away to begin processing requests already in vring */
     for (i = 0; i < nvqs; i++) {
         VirtQueue *vq = virtio_get_queue(s->vdev, i);
@@ -XXX,XX +XXX,XX @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
   fail_host_notifiers:
     k->set_guest_notifiers(qbus->parent, nvqs, false);
   fail_guest_notifiers:
-    /*
-     * If we failed to set up the guest notifiers queued requests will be
-     * processed on the main context.
-     */
-    virtio_blk_process_queued_requests(vblk, false);
     vblk->dataplane_disabled = true;
     s->starting = false;
     vblk->dataplane_started = true;
@@ -XXX,XX +XXX,XX @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
     aio_context_acquire(s->ctx);
     aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s);
 
-    /* Drain and try to switch bs back to the QEMU main loop. If other users
-     * keep the BlockBackend in the iothread, that's ok */
+    /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
+    blk_drain(s->conf->conf.blk);
+
+    /*
+     * Try to switch bs back to the QEMU main loop. If other users keep the
+     * BlockBackend in the iothread, that's ok
+     */
     blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
 
     aio_context_release(s->ctx);
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
     virtio_blk_handle_vq(s, vq);
 }
 
-void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
+static void virtio_blk_dma_restart_bh(void *opaque)
 {
+    VirtIOBlock *s = opaque;
+
     VirtIOBlockReq *req = s->rq;
     MultiReqBuffer mrb = {};
 
@@ -XXX,XX +XXX,XX @@ void virtio_blk_process_queued_requests(VirtIOBlock *s, bool is_bh)
     if (mrb.num_reqs) {
         virtio_blk_submit_multireq(s, &mrb);
     }
-    if (is_bh) {
-        blk_dec_in_flight(s->conf.conf.blk);
-    }
+
+    /* Paired with inc in virtio_blk_dma_restart_cb() */
+    blk_dec_in_flight(s->conf.conf.blk);
+
     aio_context_release(blk_get_aio_context(s->conf.conf.blk));
 }
 
-static void virtio_blk_dma_restart_bh(void *opaque)
-{
-    VirtIOBlock *s = opaque;
-
-    qemu_bh_delete(s->bh);
-    s->bh = NULL;
-
-    virtio_blk_process_queued_requests(s, true);
-}
-
 static void virtio_blk_dma_restart_cb(void *opaque, bool running,
                                       RunState state)
 {
     VirtIOBlock *s = opaque;
-    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
-    VirtioBusState *bus = VIRTIO_BUS(qbus);
 
     if (!running) {
         return;
     }
 
-    /*
-     * If ioeventfd is enabled, don't schedule the BH here as queued
-     * requests will be processed while starting the data plane.
-     */
-    if (!s->bh && !virtio_bus_ioeventfd_enabled(bus)) {
-        s->bh = aio_bh_new(blk_get_aio_context(s->conf.conf.blk),
-                           virtio_blk_dma_restart_bh, s);
-        blk_inc_in_flight(s->conf.conf.blk);
-        qemu_bh_schedule(s->bh);
-    }
+    /* Paired with dec in virtio_blk_dma_restart_bh() */
+    blk_inc_in_flight(s->conf.conf.blk);
+
+    aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.conf.blk),
+            virtio_blk_dma_restart_bh, s);
 }
 
 static void virtio_blk_reset(VirtIODevice *vdev)
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    s->change = qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
+    /*
+     * This must be after virtio_init() so virtio_blk_dma_restart_cb() gets
+     * called after ->start_ioeventfd() has already set blk's AioContext.
+     */
+    s->change =
+        qdev_add_vm_change_state_handler(dev, virtio_blk_dma_restart_cb, s);
+
     blk_ram_registrar_init(&s->blk_ram_registrar, s->blk);
     blk_set_dev_ops(s->blk, &virtio_block_ops, s);
 
-- 
2.39.0

From: Peter Krempa <pkrempa@redhat.com>

After recent header file inclusion rework the build fails when the blkio
module is enabled:

../block/blkio.c: In function ‘blkio_detach_aio_context’:
../block/blkio.c:321:24: error: implicit declaration of function ‘bdrv_get_aio_context’; did you mean ‘qemu_get_aio_context’? [-Werror=implicit-function-declaration]
  321 |     aio_set_fd_handler(bdrv_get_aio_context(bs),
      |                        ^~~~~~~~~~~~~~~~~~~~
      |                        qemu_get_aio_context
../block/blkio.c:321:24: error: nested extern declaration of ‘bdrv_get_aio_context’ [-Werror=nested-externs]
../block/blkio.c:321:24: error: passing argument 1 of ‘aio_set_fd_handler’ makes pointer from integer without a cast [-Werror=int-conversion]
  321 |     aio_set_fd_handler(bdrv_get_aio_context(bs),
      |                        ^~~~~~~~~~~~~~~~~~~~~~~~
      |                        |
      |                        int
In file included from /home/pipo/git/qemu.git/include/qemu/job.h:33,
                 from /home/pipo/git/qemu.git/include/block/blockjob.h:30,
                 from /home/pipo/git/qemu.git/include/block/block_int-global-state.h:28,
                 from /home/pipo/git/qemu.git/include/block/block_int.h:27,
                 from ../block/blkio.c:13:
/home/pipo/git/qemu.git/include/block/aio.h:476:37: note: expected ‘AioContext *’ but argument is of type ‘int’
  476 | void aio_set_fd_handler(AioContext *ctx,
      |                         ~~~~~~~~~~~~^~~
../block/blkio.c: In function ‘blkio_file_open’:
../block/blkio.c:821:34: error: passing argument 2 of ‘blkio_attach_aio_context’ makes pointer from integer without a cast [-Werror=int-conversion]
  821 |     blkio_attach_aio_context(bs, bdrv_get_aio_context(bs));
      |                                  ^~~~~~~~~~~~~~~~~~~~~~~~
      |                                  |
      |                                  int

Fix it by including 'block/block-io.h' which contains the required
declarations.

Fixes: e2c1c34f139f49ef909bb4322607fb8b39002312
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 2bc956011404a1ab03342aefde0087b5b4762562.1674477350.git.pkrempa@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/blkio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/blkio.c b/block/blkio.c
index XXXXXXX..XXXXXXX 100644
--- a/block/blkio.c
+++ b/block/blkio.c
@@ -XXX,XX +XXX,XX @@
 #include "qemu/module.h"
 #include "exec/memory.h" /* for ram_block_discard_disable() */
 
+#include "block/block-io.h"
+
 /*
  * Keep the QEMU BlockDriver names identical to the libblkio driver names.
  * Using macros instead of typing out the string literals avoids typos.
-- 
2.39.0