Series comparison

-[Qemu-devel] [PULL 0/5] Block layer patches
+[PULL 00/22] Block layer patches
-The following changes since commit a395717cbd26e7593d3c3fe81faca121ec6d13e8:
+The following changes since commit 825b96dbcee23d134b691fc75618b59c5f53da32:
-  Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging (2018-07-03 11:49:51 +0100)
+  Merge tag 'migration-20250310-pull-request' of https://gitlab.com/farosas/qemu into staging (2025-03-11 09:32:07 +0800)
-are available in the git repository at:
+are available in the Git repository at:
-  git://repo.or.cz/qemu/kevin.git tags/for-upstream
+  https://repo.or.cz/qemu/kevin.git tags/for-upstream
-for you to fetch changes up to 59738025a1674bb7e07713c3c93ff4fb9c5079f5:
+for you to fetch changes up to a93c04f3cbe690877b3297a9df4767aa811fcd97:
-  block: Add blklogwrites (2018-07-03 16:09:48 +0200)
+  virtio-scsi: only expose cmd vqs via iothread-vq-mapping (2025-03-11 15:49:22 +0100)
 ----------------------------------------------------------------
-Block layer patches:
+Block layer patches
-- qcow2: Use worker threads for compression to improve performance of
+- virtio-scsi: add iothread-vq-mapping parameter
-  'qemu-img convert -W' and compressed backup jobs
+- Improve writethrough performance
-- blklogwrites: New filter driver to log write requests to an image in
+- Fix missing zero init in bdrv_snapshot_goto()
-  the dm-log-writes format
+- Code cleanup and iotests fixes
 ----------------------------------------------------------------
-Aapo Vienamo (1):
+Kevin Wolf (8):
-      block: Add blklogwrites
+      block: Remove unused blk_op_is_blocked()
       block: Zero block driver state before reopening
       file-posix: Support FUA writes
       block/io: Ignore FUA with cache.no-flush=on
       aio: Create AioPolledEvent
       aio-posix: Factor out adjust_polling_time()
       aio-posix: Separate AioPolledEvent per AioHandler
       aio-posix: Adjust polling time also for new handlers
-Ari Sundholm (1):
+Stefan Hajnoczi (13):
-      block: Move two block permission constants to the relevant enum
+      scsi-disk: drop unused SCSIDiskState->bh field
       dma: use current AioContext for dma_blk_io()
       scsi: track per-SCSIRequest AioContext
       scsi: introduce requests_lock
       virtio-scsi: introduce event and ctrl virtqueue locks
       virtio-scsi: protect events_dropped field
       virtio-scsi: perform TMFs in appropriate AioContexts
       virtio-blk: extract cleanup_iothread_vq_mapping() function
       virtio-blk: tidy up iothread_vq_mapping functions
       virtio: extract iothread-vq-mapping.h API
       virtio-scsi: add iothread-vq-mapping parameter
       virtio-scsi: handle ctrl virtqueue in main loop
       virtio-scsi: only expose cmd vqs via iothread-vq-mapping
-Vladimir Sementsov-Ogievskiy (3):
+Thomas Huth (1):
-      qemu-img: allow compressed not-in-order writes
+      iotests: Limit qsd-migrate to working formats
       qcow2: refactor data compression
       qcow2: add compress threads
- qapi/block-core.json  |  33 ++++-
+ include/block/aio.h                         |   5 +-
- block/qcow2.h         |   3 +
+ include/block/raw-aio.h                     |   8 +-
- include/block/block.h |   7 +
+ include/hw/scsi/scsi.h                      |   8 +-
- block.c               |   6 -
+ include/hw/virtio/iothread-vq-mapping.h     |  45 +++
- block/blklogwrites.c  | 392 ++++++++++++++++++++++++++++++++++++++++++++++++++
+ include/hw/virtio/virtio-scsi.h             |  15 +-
- block/qcow2.c         | 136 ++++++++++++++----
+ include/system/block-backend-global-state.h |   1 -
- qemu-img.c            |   5 -
+ include/system/dma.h                        |   3 +-
- MAINTAINERS           |   6 +
+ util/aio-posix.h                            |   1 +
- block/Makefile.objs   |   1 +
+ block/block-backend.c                       |  12 -
-files changed, 545 insertions(+), 44 deletions(-)
+ block/file-posix.c                          |  26 +-
- create mode 100644 block/blklogwrites.c
+ block/io.c                                  |   4 +
+ block/io_uring.c                            |  13 +-
  block/linux-aio.c                           |  24 +-
  block/snapshot.c                            |   1 +
  hw/block/virtio-blk.c                       | 132 +-------
  hw/ide/core.c                               |   3 +-
  hw/ide/macio.c                              |   3 +-
  hw/scsi/scsi-bus.c                          | 121 +++++--
  hw/scsi/scsi-disk.c                         |  24 +-
  hw/scsi/virtio-scsi-dataplane.c             | 103 ++++--
  hw/scsi/virtio-scsi.c                       | 502 ++++++++++++++++------------
  hw/virtio/iothread-vq-mapping.c             | 131 ++++++++
  system/dma-helpers.c                        |   8 +-
  util/aio-posix.c                            | 114 ++++---
  util/async.c                                |   1 -
  hw/virtio/meson.build                       |   1 +
  meson.build                                 |   4 +
  tests/qemu-iotests/tests/qsd-migrate        |   2 +-
 files changed, 803 insertions(+), 512 deletions(-)
  create mode 100644 include/hw/virtio/iothread-vq-mapping.h
  create mode 100644 hw/virtio/iothread-vq-mapping.c

-[Qemu-devel] [PULL 2/5] qcow2: refactor data compression
+[PULL 01/22] block: Remove unused blk_op_is_blocked()
-From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+Commit fc4e394b28 removed the last caller of blk_op_is_blocked(). Remove
 the now unused function.
-Make a separate function for compression to be parallelized later.
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
- - use .avail_out field instead of .next_out to calculate size of
+Message-ID: <20250206165331.379033-1-kwolf@redhat.com>
-   compressed data. It looks more natural and it allows to keep dest to
+Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
-   be void pointer
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
  - set avail_out to be at least one byte less than input, to be sure
    avoid inefficient compression earlier
 Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
- block/qcow2.c | 76 ++++++++++++++++++++++++++++++++++++++---------------------
+ include/system/block-backend-global-state.h |  1 -
-file changed, 49 insertions(+), 27 deletions(-)
+ block/block-backend.c                       | 12 ------------
 files changed, 13 deletions(-)
-diff --git a/block/qcow2.c b/block/qcow2.c
+diff --git a/include/system/block-backend-global-state.h b/include/system/block-backend-global-state.h
 index XXXXXXX..XXXXXXX 100644
---- a/block/qcow2.c
+--- a/include/system/block-backend-global-state.h
-+++ b/block/qcow2.c
++++ b/include/system/block-backend-global-state.h
-@@ -XXX,XX +XXX,XX @@
+@@ -XXX,XX +XXX,XX @@ bool blk_supports_write_perm(BlockBackend *blk);
-  */
+ bool blk_is_sg(BlockBackend *blk);
+ void blk_set_enable_write_cache(BlockBackend *blk, bool wce);
- #include "qemu/osdep.h"
+ int blk_get_flags(BlockBackend *blk);
-+
+-bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp);
-+#define ZLIB_CONST
+ int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
-+#include <zlib.h>
+                         Error **errp);
-+
+ void blk_add_aio_context_notifier(BlockBackend *blk,
- #include "block/block_int.h"
+diff --git a/block/block-backend.c b/block/block-backend.c
- #include "block/qdict.h"
+index XXXXXXX..XXXXXXX 100644
- #include "sysemu/block-backend.h"
+--- a/block/block-backend.c
- #include "qemu/module.h"
++++ b/block/block-backend.c
--#include <zlib.h>
+@@ -XXX,XX +XXX,XX @@ void *blk_blockalign(BlockBackend *blk, size_t size)
- #include "qcow2.h"
+     return qemu_blockalign(blk ? blk_bs(blk) : NULL, size);
  #include "qemu/error-report.h"
  #include "qapi/error.h"
@@ -XXX,XX +XXX,XX @@ fail:
      return ret;
  }
-+/*
+-bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp)
-+ * qcow2_compress()
+-{
-+ *
+-    BlockDriverState *bs = blk_bs(blk);
-+ * @dest - destination buffer, at least of @size-1 bytes
+-    GLOBAL_STATE_CODE();
-+ * @src - source buffer, @size bytes
+-    GRAPH_RDLOCK_GUARD_MAINLOOP();
-+ *
+-
-+ * Returns: compressed size on success
+-    if (!bs) {
-+ *          -1 if compression is inefficient
+-        return false;
 + *          -2 on any other error
 + */
 +static ssize_t qcow2_compress(void *dest, const void *src, size_t size)
 +{
 +    ssize_t ret;
 +    z_stream strm;
 +
 +    /* best compression, small window, no zlib header */
 +    memset(&strm, 0, sizeof(strm));
 +    ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
 +                       -12, 9, Z_DEFAULT_STRATEGY);
 +    if (ret != 0) {
 +        return -2;
 +    }
 +
 +    strm.avail_in = size;
 +    strm.next_in = src;
 +    strm.avail_out = size - 1;
 +    strm.next_out = dest;
 +
 +    ret = deflate(&strm, Z_FINISH);
 +    if (ret == Z_STREAM_END) {
 +        ret = size - 1 - strm.avail_out;
 +    } else {
 +        ret = (ret == Z_OK ? -1 : -2);
 +    }
 +
 +    deflateEnd(&strm);
 +
 +    return ret;
 +}
 +
  /* XXX: put compressed sectors first, then all the cluster aligned
     tables to avoid losing bytes in alignment */
  static coroutine_fn int
@@ -XXX,XX +XXX,XX @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
      BDRVQcow2State *s = bs->opaque;
      QEMUIOVector hd_qiov;
      struct iovec iov;
 -    z_stream strm;
 -    int ret, out_len;
 +    int ret;
 +    size_t out_len;
      uint8_t *buf, *out_buf;
      int64_t cluster_offset;
@@ -XXX,XX +XXX,XX @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
      out_buf = g_malloc(s->cluster_size);
 -    /* best compression, small window, no zlib header */
 -    memset(&strm, 0, sizeof(strm));
 -    ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
 -                       Z_DEFLATED, -12,
 -                       9, Z_DEFAULT_STRATEGY);
 -    if (ret != 0) {
 +    out_len = qcow2_compress(out_buf, buf, s->cluster_size);
 +    if (out_len == -2) {
          ret = -EINVAL;
          goto fail;
 -    }
 -
--    strm.avail_in = s->cluster_size;
+-    return bdrv_op_is_blocked(bs, op, errp);
--    strm.next_in = (uint8_t *)buf;
+-}
--    strm.avail_out = s->cluster_size;
--    strm.next_out = out_buf;
+ /**
--
+  * Return BB's current AioContext.  Note that this context may change
 -    ret = deflate(&strm, Z_FINISH);
 -    if (ret != Z_STREAM_END && ret != Z_OK) {
 -        deflateEnd(&strm);
 -        ret = -EINVAL;
 -        goto fail;
 -    }
 -    out_len = strm.next_out - out_buf;
 -
 -    deflateEnd(&strm);
 -
 -    if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
 +    } else if (out_len == -1) {
          /* could not compress: write normal cluster */
          ret = qcow2_co_pwritev(bs, offset, bytes, qiov, 0);
          if (ret < 0) {
 --
-.13.6
+.48.1

-New patch
+[PULL 02/22] block: Zero block driver state before reopening
+Block drivers assume in their .bdrv_open() implementation that their
+state in bs->opaque has been zeroed; it is initially allocated with
+g_malloc0() in bdrv_open_driver().
+bdrv_snapshot_goto() needs to make sure that it is zeroed again before
+calling drv->bdrv_open() to avoid that block drivers use stale values.
+One symptom of this bug is VMDK running into a double free when the user
+tries to apply an internal snapshot like 'qemu-img snapshot -a test
+test.vmdk'. This should be a graceful error because VMDK doesn't support
+internal snapshots.
+==25507== Invalid free() / delete / delete[] / realloc()
+==25507==    at 0x484B347: realloc (vg_replace_malloc.c:1801)
+==25507==    by 0x54B592A: g_realloc (gmem.c:171)
+==25507==    by 0x1B221D: vmdk_add_extent (../block/vmdk.c:570)
+==25507==    by 0x1B1084: vmdk_open_sparse (../block/vmdk.c:1059)
+==25507==    by 0x1AF3D8: vmdk_open (../block/vmdk.c:1371)
+==25507==    by 0x1A2AE0: bdrv_snapshot_goto (../block/snapshot.c:299)
+==25507==    by 0x205C77: img_snapshot (../qemu-img.c:3500)
+==25507==    by 0x58FA087: (below main) (libc_start_call_main.h:58)
+==25507==  Address 0x832f3e0 is 0 bytes inside a block of size 272 free'd
+==25507==    at 0x4846B83: free (vg_replace_malloc.c:989)
+==25507==    by 0x54AEAC4: g_free (gmem.c:208)
+==25507==    by 0x1AF629: vmdk_close (../block/vmdk.c:2889)
+==25507==    by 0x1A2A9C: bdrv_snapshot_goto (../block/snapshot.c:290)
+==25507==    by 0x205C77: img_snapshot (../qemu-img.c:3500)
+==25507==    by 0x58FA087: (below main) (libc_start_call_main.h:58)
+This error was discovered by fuzzing qemu-img.
+Cc: qemu-stable@nongnu.org
+Closes: https://gitlab.com/qemu-project/qemu/-/issues/2853
+Closes: https://gitlab.com/qemu-project/qemu/-/issues/2851
+Reported-by: Denis Rastyogin <gerben@altlinux.org>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250310104858.28221-1-kwolf@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ block/snapshot.c | 1 +
+file changed, 1 insertion(+)
+diff --git a/block/snapshot.c b/block/snapshot.c
+index XXXXXXX..XXXXXXX 100644
+--- a/block/snapshot.c
++++ b/block/snapshot.c
+@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
+         bdrv_graph_wrunlock();
+         ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
++        memset(bs->opaque, 0, drv->instance_size);
+         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
+         qobject_unref(options);
+         if (open_ret < 0) {
+--
+.48.1

-New patch
+[PULL 03/22] file-posix: Support FUA writes
+Until now, FUA was always emulated with a separate flush after the write
 for file-posix. The overhead of processing a second request can reduce
 performance significantly for a guest disk that has disabled the write
 cache, especially if the host disk is already write through, too, and
 the flush isn't actually doing anything.
 Advertise support for REQ_FUA in write requests and implement it for
 Linux AIO and io_uring using the RWF_DSYNC flag for write requests. The
 thread pool still performs a separate fdatasync() call. This can be
 improved later by using the pwritev2() syscall if available.
 As an example, this is how fio numbers can be improved in some scenarios
 with this patch (all using virtio-blk with cache=directsync on an nvme
 block device for the VM, fio with ioengine=libaio,direct=1,sync=1):
                               | old           | with FUA support
 ------------------------------+---------------+-------------------
 bs=4k, iodepth=1, numjobs=1   |  45.6k iops   |  56.1k iops
 bs=4k, iodepth=1, numjobs=16  | 183.3k iops   | 236.0k iops
 bs=4k, iodepth=16, numjobs=1  | 258.4k iops   | 311.1k iops
 However, not all scenarios are clear wins. On another slower disk I saw
 little to no improvment. In fact, in two corner case scenarios, I even
 observed a regression, which I however consider acceptable:
 . On slow host disks in a write through cache mode, when the guest is
    using virtio-blk in a separate iothread so that polling can be
    enabled, and each completion is quickly followed up with a new
    request (so that polling gets it), it can happen that enabling FUA
    makes things slower - the additional very fast no-op flush we used to
    have gave the adaptive polling algorithm a success so that it kept
    polling. Without it, we only have the slow write request, which
    disables polling. This is a problem in the polling algorithm that
    will be fixed later in this series.
 . With a high queue depth, it can be beneficial to have flush requests
    for another reason: The optimisation in bdrv_co_flush() that flushes
    only once per write generation acts as a synchronisation mechanism
    that lets all requests complete at the same time. This can result in
    better batching and if the disk is very fast (I only saw this with a
    null_blk backend), this can make up for the overhead of the flush and
    improve throughput. In theory, we could optionally introduce a
    similar artificial latency in the normal completion path to achieve
    the same kind of completion batching. This is not implemented in this
    series.
 Compatibility is not a concern for io_uring, it has supported RWF_DSYNC
 from the start. Linux AIO started supporting it in Linux 4.13 and libaio
 .3.111. The kernel is not a problem for any supported build platform,
 so it's not necessary to add runtime checks. However, openSUSE is still
 stuck with an older libaio version that would break the build. We must
 detect this at build time to avoid build failures.
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 Message-ID: <20250307221634.71951-2-kwolf@redhat.com>
 Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
  include/block/raw-aio.h |  8 ++++++--
  block/file-posix.c      | 26 ++++++++++++++++++--------
  block/io_uring.c        | 13 ++++++++-----
  block/linux-aio.c       | 24 +++++++++++++++++++++---
  meson.build             |  4 ++++
 files changed, 57 insertions(+), 18 deletions(-)
 diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h
 index XXXXXXX..XXXXXXX 100644
 --- a/include/block/raw-aio.h
 +++ b/include/block/raw-aio.h
@@ -XXX,XX +XXX,XX @@
  #define QEMU_RAW_AIO_H
  #include "block/aio.h"
 +#include "block/block-common.h"
  #include "qemu/iov.h"
  /* AIO request types */
@@ -XXX,XX +XXX,XX @@ void laio_cleanup(LinuxAioState *s);
  /* laio_co_submit: submit I/O requests in the thread's current AioContext. */
  int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
 -                                int type, uint64_t dev_max_batch);
 +                                int type, BdrvRequestFlags flags,
 +                                uint64_t dev_max_batch);
  bool laio_has_fdsync(int);
 +bool laio_has_fua(void);
  void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context);
  void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context);
  #endif
@@ -XXX,XX +XXX,XX @@ void luring_cleanup(LuringState *s);
  /* luring_co_submit: submit I/O requests in the thread's current AioContext. */
  int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
 -                                  QEMUIOVector *qiov, int type);
 +                                  QEMUIOVector *qiov, int type,
 +                                  BdrvRequestFlags flags);
  void luring_detach_aio_context(LuringState *s, AioContext *old_context);
  void luring_attach_aio_context(LuringState *s, AioContext *new_context);
  #endif
 diff --git a/block/file-posix.c b/block/file-posix.c
 index XXXXXXX..XXXXXXX 100644
 --- a/block/file-posix.c
 +++ b/block/file-posix.c
@@ -XXX,XX +XXX,XX @@ static int fd_open(BlockDriverState *bs)
  }
  static int64_t raw_getlength(BlockDriverState *bs);
 +static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs);
  typedef struct RawPosixAIOData {
      BlockDriverState *bs;
@@ -XXX,XX +XXX,XX @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
  #endif
      s->needs_alignment = raw_needs_alignment(bs);
 +    if (!s->use_linux_aio || laio_has_fua()) {
 +        bs->supported_write_flags = BDRV_REQ_FUA;
 +    }
 +
      bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK;
      if (S_ISREG(st.st_mode)) {
          /* When extending regular files, we get zeros from the OS */
@@ -XXX,XX +XXX,XX @@ static inline bool raw_check_linux_aio(BDRVRawState *s)
  #endif
  static int coroutine_fn raw_co_prw(BlockDriverState *bs, int64_t *offset_ptr,
 -                                   uint64_t bytes, QEMUIOVector *qiov, int type)
 +                                   uint64_t bytes, QEMUIOVector *qiov, int type,
 +                                   int flags)
  {
      BDRVRawState *s = bs->opaque;
      RawPosixAIOData acb;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, int64_t *offset_ptr,
  #ifdef CONFIG_LINUX_IO_URING
      } else if (raw_check_linux_io_uring(s)) {
          assert(qiov->size == bytes);
 -        ret = luring_co_submit(bs, s->fd, offset, qiov, type);
 +        ret = luring_co_submit(bs, s->fd, offset, qiov, type, flags);
          goto out;
  #endif
  #ifdef CONFIG_LINUX_AIO
      } else if (raw_check_linux_aio(s)) {
          assert(qiov->size == bytes);
 -        ret = laio_co_submit(s->fd, offset, qiov, type,
 +        ret = laio_co_submit(s->fd, offset, qiov, type, flags,
                                s->aio_max_batch);
          goto out;
  #endif
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, int64_t *offset_ptr,
      assert(qiov->size == bytes);
      ret = raw_thread_pool_submit(handle_aiocb_rw, &acb);
 +    if (ret == 0 && (flags & BDRV_REQ_FUA)) {
 +        /* TODO Use pwritev2() instead if it's available */
 +        ret = raw_co_flush_to_disk(bs);
 +    }
      goto out; /* Avoid the compiler err of unused label */
  out:
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_preadv(BlockDriverState *bs, int64_t offset,
                                        int64_t bytes, QEMUIOVector *qiov,
                                        BdrvRequestFlags flags)
  {
 -    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_READ);
 +    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_READ, flags);
  }
  static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, int64_t offset,
                                         int64_t bytes, QEMUIOVector *qiov,
                                         BdrvRequestFlags flags)
  {
 -    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_WRITE);
 +    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_WRITE, flags);
  }
  static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
  #ifdef CONFIG_LINUX_IO_URING
      if (raw_check_linux_io_uring(s)) {
 -        return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH);
 +        return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH, 0);
      }
  #endif
  #ifdef CONFIG_LINUX_AIO
      if (s->has_laio_fdsync && raw_check_linux_aio(s)) {
 -        return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0);
 +        return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0, 0);
      }
  #endif
      return raw_thread_pool_submit(handle_aiocb_flush, &acb);
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_zone_append(BlockDriverState *bs,
      }
      trace_zbd_zone_append(bs, *offset >> BDRV_SECTOR_BITS);
 -    return raw_co_prw(bs, offset, len, qiov, QEMU_AIO_ZONE_APPEND);
 +    return raw_co_prw(bs, offset, len, qiov, QEMU_AIO_ZONE_APPEND, 0);
  }
  #endif
 diff --git a/block/io_uring.c b/block/io_uring.c
 index XXXXXXX..XXXXXXX 100644
 --- a/block/io_uring.c
 +++ b/block/io_uring.c
@@ -XXX,XX +XXX,XX @@ static void luring_deferred_fn(void *opaque)
   *
   */
  static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
 -                            uint64_t offset, int type)
 +                            uint64_t offset, int type, BdrvRequestFlags flags)
  {
      int ret;
      struct io_uring_sqe *sqes = &luringcb->sqeq;
 +    int luring_flags;
      switch (type) {
      case QEMU_AIO_WRITE:
 -        io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
 -                             luringcb->qiov->niov, offset);
 +        luring_flags = (flags & BDRV_REQ_FUA) ? RWF_DSYNC : 0;
 +        io_uring_prep_writev2(sqes, fd, luringcb->qiov->iov,
 +                              luringcb->qiov->niov, offset, luring_flags);
          break;
      case QEMU_AIO_ZONE_APPEND:
          io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
@@ -XXX,XX +XXX,XX @@ static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
  }
  int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
 -                                  QEMUIOVector *qiov, int type)
 +                                  QEMUIOVector *qiov, int type,
 +                                  BdrvRequestFlags flags)
  {
      int ret;
      AioContext *ctx = qemu_get_current_aio_context();
@@ -XXX,XX +XXX,XX @@ int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
      };
      trace_luring_co_submit(bs, s, &luringcb, fd, offset, qiov ? qiov->size : 0,
                             type);
 -    ret = luring_do_submit(fd, &luringcb, s, offset, type);
 +    ret = luring_do_submit(fd, &luringcb, s, offset, type, flags);
      if (ret < 0) {
          return ret;
 diff --git a/block/linux-aio.c b/block/linux-aio.c
 index XXXXXXX..XXXXXXX 100644
 --- a/block/linux-aio.c
 +++ b/block/linux-aio.c
@@ -XXX,XX +XXX,XX @@ static void laio_deferred_fn(void *opaque)
  }
  static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
 -                          int type, uint64_t dev_max_batch)
 +                          int type, BdrvRequestFlags flags,
 +                          uint64_t dev_max_batch)
  {
      LinuxAioState *s = laiocb->ctx;
      struct iocb *iocbs = &laiocb->iocb;
      QEMUIOVector *qiov = laiocb->qiov;
 +    int laio_flags;
      switch (type) {
      case QEMU_AIO_WRITE:
 +#ifdef HAVE_IO_PREP_PWRITEV2
 +        laio_flags = (flags & BDRV_REQ_FUA) ? RWF_DSYNC : 0;
 +        io_prep_pwritev2(iocbs, fd, qiov->iov, qiov->niov, offset, laio_flags);
 +#else
 +        assert(flags == 0);
          io_prep_pwritev(iocbs, fd, qiov->iov, qiov->niov, offset);
 +#endif
          break;
      case QEMU_AIO_ZONE_APPEND:
          io_prep_pwritev(iocbs, fd, qiov->iov, qiov->niov, offset);
@@ -XXX,XX +XXX,XX @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
  }
  int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
 -                                int type, uint64_t dev_max_batch)
 +                                int type, BdrvRequestFlags flags,
 +                                uint64_t dev_max_batch)
  {
      int ret;
      AioContext *ctx = qemu_get_current_aio_context();
@@ -XXX,XX +XXX,XX @@ int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
          .qiov       = qiov,
      };
 -    ret = laio_do_submit(fd, &laiocb, offset, type, dev_max_batch);
 +    ret = laio_do_submit(fd, &laiocb, offset, type, flags, dev_max_batch);
      if (ret < 0) {
          return ret;
      }
@@ -XXX,XX +XXX,XX @@ bool laio_has_fdsync(int fd)
      io_destroy(ctx);
      return (ret == -EINVAL) ? false : true;
  }
 +
 +bool laio_has_fua(void)
 +{
 +#ifdef HAVE_IO_PREP_PWRITEV2
 +    return true;
 +#else
 +    return false;
 +#endif
 +}
 diff --git a/meson.build b/meson.build
 index XXXXXXX..XXXXXXX 100644
 --- a/meson.build
 +++ b/meson.build
@@ -XXX,XX +XXX,XX @@ config_host_data.set('HAVE_OPTRESET',
                       cc.has_header_symbol('getopt.h', 'optreset'))
  config_host_data.set('HAVE_IPPROTO_MPTCP',
                       cc.has_header_symbol('netinet/in.h', 'IPPROTO_MPTCP'))
 +if libaio.found()
 +  config_host_data.set('HAVE_IO_PREP_PWRITEV2',
 +                       cc.has_header_symbol('libaio.h', 'io_prep_pwritev2'))
 +endif
  # has_member
  config_host_data.set('HAVE_SIGEV_NOTIFY_THREAD_ID',
 --
 .48.1

-New patch
+[PULL 04/22] block/io: Ignore FUA with cache.no-flush=on
+For block drivers that don't advertise FUA support, we already call
+bdrv_co_flush(), which considers BDRV_O_NO_FLUSH. However, drivers that
+do support FUA still see the FUA flag with BDRV_O_NO_FLUSH and get the
+associated performance penalty that cache.no-flush=on was supposed to
+avoid.
+Clear FUA for write requests if BDRV_O_NO_FLUSH is set.
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250307221634.71951-3-kwolf@redhat.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ block/io.c | 4 ++++
+file changed, 4 insertions(+)
+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_driver_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
+         return -ENOMEDIUM;
+     }
++    if (bs->open_flags & BDRV_O_NO_FLUSH) {
++        flags &= ~BDRV_REQ_FUA;
++    }
++
+     if ((flags & BDRV_REQ_FUA) &&
+         (~bs->supported_write_flags & BDRV_REQ_FUA)) {
+         flags &= ~BDRV_REQ_FUA;
+--
+.48.1

-New patch
+[PULL 05/22] aio: Create AioPolledEvent
+As a preparation for having multiple adaptive polling states per
+AioContext, move the 'ns' field into a separate struct.
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250307221634.71951-4-kwolf@redhat.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/block/aio.h |  6 +++++-
+ util/aio-posix.c    | 31 ++++++++++++++++---------------
+ util/async.c        |  3 ++-
+files changed, 23 insertions(+), 17 deletions(-)
+diff --git a/include/block/aio.h b/include/block/aio.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/block/aio.h
++++ b/include/block/aio.h
+@@ -XXX,XX +XXX,XX @@ struct BHListSlice {
+ typedef QSLIST_HEAD(, AioHandler) AioHandlerSList;
++typedef struct AioPolledEvent {
++    int64_t ns;        /* current polling time in nanoseconds */
++} AioPolledEvent;
++
+ struct AioContext {
+     GSource source;
+@@ -XXX,XX +XXX,XX @@ struct AioContext {
+     int poll_disable_cnt;
+     /* Polling mode parameters */
+-    int64_t poll_ns;        /* current polling time in nanoseconds */
++    AioPolledEvent poll;
+     int64_t poll_max_ns;    /* maximum polling time in nanoseconds */
+     int64_t poll_grow;      /* polling time growth factor */
+     int64_t poll_shrink;    /* polling time shrink factor */
+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,
+         return false;
+     }
+-    max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
++    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
+@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
+     if (ctx->poll_max_ns) {
+         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
+-        if (block_ns <= ctx->poll_ns) {
++        if (block_ns <= ctx->poll.ns) {
+             /* This is the sweet spot, no adjustment needed */
+         } else if (block_ns > ctx->poll_max_ns) {
+             /* We'd have to poll for too long, poll less */
+-            int64_t old = ctx->poll_ns;
++            int64_t old = ctx->poll.ns;
+             if (ctx->poll_shrink) {
+-                ctx->poll_ns /= ctx->poll_shrink;
++                ctx->poll.ns /= ctx->poll_shrink;
+             } else {
+-                ctx->poll_ns = 0;
++                ctx->poll.ns = 0;
+             }
+-            trace_poll_shrink(ctx, old, ctx->poll_ns);
+-        } else if (ctx->poll_ns < ctx->poll_max_ns &&
++            trace_poll_shrink(ctx, old, ctx->poll.ns);
++        } else if (ctx->poll.ns < ctx->poll_max_ns &&
+                    block_ns < ctx->poll_max_ns) {
+             /* There is room to grow, poll longer */
+-            int64_t old = ctx->poll_ns;
++            int64_t old = ctx->poll.ns;
+             int64_t grow = ctx->poll_grow;
+             if (grow == 0) {
+                 grow = 2;
+             }
+-            if (ctx->poll_ns) {
+-                ctx->poll_ns *= grow;
++            if (ctx->poll.ns) {
++                ctx->poll.ns *= grow;
+             } else {
+-                ctx->poll_ns = 4000; /* start polling at 4 microseconds */
++                ctx->poll.ns = 4000; /* start polling at 4 microseconds */
+             }
+-            if (ctx->poll_ns > ctx->poll_max_ns) {
+-                ctx->poll_ns = ctx->poll_max_ns;
++            if (ctx->poll.ns > ctx->poll_max_ns) {
++                ctx->poll.ns = ctx->poll_max_ns;
+             }
+-            trace_poll_grow(ctx, old, ctx->poll_ns);
++            trace_poll_grow(ctx, old, ctx->poll.ns);
+         }
+     }
+@@ -XXX,XX +XXX,XX @@ void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
+     /* No thread synchronization here, it doesn't matter if an incorrect value
+      * is used once.
+      */
++    ctx->poll.ns = 0;
++
+     ctx->poll_max_ns = max_ns;
+-    ctx->poll_ns = 0;
+     ctx->poll_grow = grow;
+     ctx->poll_shrink = shrink;
+diff --git a/util/async.c b/util/async.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/async.c
++++ b/util/async.c
+@@ -XXX,XX +XXX,XX @@ AioContext *aio_context_new(Error **errp)
+     qemu_rec_mutex_init(&ctx->lock);
+     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
+-    ctx->poll_ns = 0;
++    ctx->poll.ns = 0;
++
+     ctx->poll_max_ns = 0;
+     ctx->poll_grow = 0;
+     ctx->poll_shrink = 0;
+--
+.48.1

-New patch
+[PULL 06/22] aio-posix: Factor out adjust_polling_time()
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250307221634.71951-5-kwolf@redhat.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ util/aio-posix.c | 77 ++++++++++++++++++++++++++----------------------
+file changed, 41 insertions(+), 36 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,
+     return false;
+ }
++static void adjust_polling_time(AioContext *ctx, AioPolledEvent *poll,
++                                int64_t block_ns)
++{
++    if (block_ns <= poll->ns) {
++        /* This is the sweet spot, no adjustment needed */
++    } else if (block_ns > ctx->poll_max_ns) {
++        /* We'd have to poll for too long, poll less */
++        int64_t old = poll->ns;
++
++        if (ctx->poll_shrink) {
++            poll->ns /= ctx->poll_shrink;
++        } else {
++            poll->ns = 0;
++        }
++
++        trace_poll_shrink(ctx, old, poll->ns);
++    } else if (poll->ns < ctx->poll_max_ns &&
++               block_ns < ctx->poll_max_ns) {
++        /* There is room to grow, poll longer */
++        int64_t old = poll->ns;
++        int64_t grow = ctx->poll_grow;
++
++        if (grow == 0) {
++            grow = 2;
++        }
++
++        if (poll->ns) {
++            poll->ns *= grow;
++        } else {
++            poll->ns = 4000; /* start polling at 4 microseconds */
++        }
++
++        if (poll->ns > ctx->poll_max_ns) {
++            poll->ns = ctx->poll_max_ns;
++        }
++
++        trace_poll_grow(ctx, old, poll->ns);
++    }
++}
++
+ bool aio_poll(AioContext *ctx, bool blocking)
+ {
+     AioHandlerList ready_list = QLIST_HEAD_INITIALIZER(ready_list);
+@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
+     /* Adjust polling time */
+     if (ctx->poll_max_ns) {
+         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
+-
+-        if (block_ns <= ctx->poll.ns) {
+-            /* This is the sweet spot, no adjustment needed */
+-        } else if (block_ns > ctx->poll_max_ns) {
+-            /* We'd have to poll for too long, poll less */
+-            int64_t old = ctx->poll.ns;
+-
+-            if (ctx->poll_shrink) {
+-                ctx->poll.ns /= ctx->poll_shrink;
+-            } else {
+-                ctx->poll.ns = 0;
+-            }
+-
+-            trace_poll_shrink(ctx, old, ctx->poll.ns);
+-        } else if (ctx->poll.ns < ctx->poll_max_ns &&
+-                   block_ns < ctx->poll_max_ns) {
+-            /* There is room to grow, poll longer */
+-            int64_t old = ctx->poll.ns;
+-            int64_t grow = ctx->poll_grow;
+-
+-            if (grow == 0) {
+-                grow = 2;
+-            }
+-
+-            if (ctx->poll.ns) {
+-                ctx->poll.ns *= grow;
+-            } else {
+-                ctx->poll.ns = 4000; /* start polling at 4 microseconds */
+-            }
+-
+-            if (ctx->poll.ns > ctx->poll_max_ns) {
+-                ctx->poll.ns = ctx->poll_max_ns;
+-            }
+-
+-            trace_poll_grow(ctx, old, ctx->poll.ns);
+-        }
++        adjust_polling_time(ctx, &ctx->poll, block_ns);
+     }
+     progress |= aio_bh_poll(ctx);
+--
+.48.1

-New patch
+[PULL 07/22] aio-posix: Separate AioPolledEvent per AioHandler
+Adaptive polling has a big problem: It doesn't consider that an event
+loop can wait for many different events that may have very different
+typical latencies.
+For example, think of a guest that tends to send a new I/O request soon
+after the previous I/O request completes, but the storage on the host is
+rather slow. In this case, getting the new request from guest quickly
+means that polling is enabled, but the next thing is performing the I/O
+request on the backend, which is slow and disables polling again for the
+next guest request. This means that in such a scenario, polling could
+help for every other event, but is only ever enabled when it can't
+succeed.
+In order to fix this, keep a separate AioPolledEvent for each
+AioHandler. We will then know that the backend file descriptor always
+has a high latency and isn't worth polling for, but we also know that
+the guest is always fast and we should poll for it. This solves at least
+half of the problem, we can now keep polling for those cases where it
+makes sense and get the improved performance from it.
+Since the event loop doesn't know which event will be next, we still do
+some unnecessary polling while we're waiting for the slow disk. I made
+some attempts to be more clever than just randomly growing and shrinking
+the polling time, and even to let callers be explicit about when they
+expect a new event, but so far this hasn't resulted in improved
+performance or even caused performance regressions. For now, let's just
+fix the part that is easy enough to fix, we can revisit the rest later.
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250307221634.71951-6-kwolf@redhat.com>
+Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/block/aio.h |  1 -
+ util/aio-posix.h    |  1 +
+ util/aio-posix.c    | 26 ++++++++++++++++++++++----
+ util/async.c        |  2 --
+files changed, 23 insertions(+), 7 deletions(-)
+diff --git a/include/block/aio.h b/include/block/aio.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/block/aio.h
++++ b/include/block/aio.h
+@@ -XXX,XX +XXX,XX @@ struct AioContext {
+     int poll_disable_cnt;
+     /* Polling mode parameters */
+-    AioPolledEvent poll;
+     int64_t poll_max_ns;    /* maximum polling time in nanoseconds */
+     int64_t poll_grow;      /* polling time growth factor */
+     int64_t poll_shrink;    /* polling time shrink factor */
+diff --git a/util/aio-posix.h b/util/aio-posix.h
+index XXXXXXX..XXXXXXX 100644
+--- a/util/aio-posix.h
++++ b/util/aio-posix.h
+@@ -XXX,XX +XXX,XX @@ struct AioHandler {
+ #endif
+     int64_t poll_idle_timeout; /* when to stop userspace polling */
+     bool poll_ready; /* has polling detected an event? */
++    AioPolledEvent poll;
+ };
+ /* Add a handler to a ready list */
+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(AioContext *ctx, AioHandlerList *ready_list,
+ static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list,
+                           int64_t *timeout)
+ {
++    AioHandler *node;
+     int64_t max_ns;
+     if (QLIST_EMPTY_RCU(&ctx->poll_aio_handlers)) {
+         return false;
+     }
+-    max_ns = qemu_soonest_timeout(*timeout, ctx->poll.ns);
++    max_ns = 0;
++    QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
++        max_ns = MAX(max_ns, node->poll.ns);
++    }
++    max_ns = qemu_soonest_timeout(*timeout, max_ns);
++
+     if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
+         /*
+          * Enable poll mode. It pairs with the poll_set_started() in
+@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
+     /* Adjust polling time */
+     if (ctx->poll_max_ns) {
++        AioHandler *node;
+         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
+-        adjust_polling_time(ctx, &ctx->poll, block_ns);
++
++        QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
++            if (QLIST_IS_INSERTED(node, node_ready)) {
++                adjust_polling_time(ctx, &node->poll, block_ns);
++            }
++        }
+     }
+     progress |= aio_bh_poll(ctx);
+@@ -XXX,XX +XXX,XX @@ void aio_context_use_g_source(AioContext *ctx)
+ void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
+                                  int64_t grow, int64_t shrink, Error **errp)
+ {
++    AioHandler *node;
++
++    qemu_lockcnt_inc(&ctx->list_lock);
++    QLIST_FOREACH(node, &ctx->aio_handlers, node) {
++        node->poll.ns = 0;
++    }
++    qemu_lockcnt_dec(&ctx->list_lock);
++
+     /* No thread synchronization here, it doesn't matter if an incorrect value
+      * is used once.
+      */
+-    ctx->poll.ns = 0;
+-
+     ctx->poll_max_ns = max_ns;
+     ctx->poll_grow = grow;
+     ctx->poll_shrink = shrink;
+diff --git a/util/async.c b/util/async.c
+index XXXXXXX..XXXXXXX 100644
+--- a/util/async.c
++++ b/util/async.c
+@@ -XXX,XX +XXX,XX @@ AioContext *aio_context_new(Error **errp)
+     qemu_rec_mutex_init(&ctx->lock);
+     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
+-    ctx->poll.ns = 0;
+-
+     ctx->poll_max_ns = 0;
+     ctx->poll_grow = 0;
+     ctx->poll_shrink = 0;
+--
+.48.1

-New patch
+[PULL 08/22] aio-posix: Adjust polling time also for new handlers
+aio_dispatch_handler() adds handlers to ctx->poll_aio_handlers if
+polling should be enabled. If we call adjust_polling_time() for all
+polling handlers before this, new polling handlers are still left at
+poll->ns = 0 and polling is only actually enabled after the next event.
+Move the adjust_polling_time() call after aio_dispatch_handler().
+This fixes test-nested-aio-poll, which expects that polling becomes
+effective the first time around.
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250311141912.135657-1-kwolf@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ util/aio-posix.c | 28 +++++++++++++++++-----------
+file changed, 17 insertions(+), 11 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 @@
+ /* Stop userspace polling on a handler if it isn't active for some time */
+ #define POLL_IDLE_INTERVAL_NS (7 * NANOSECONDS_PER_SECOND)
++static void adjust_polling_time(AioContext *ctx, AioPolledEvent *poll,
++                                int64_t block_ns);
++
+ bool aio_poll_disabled(AioContext *ctx)
+ {
+     return qatomic_read(&ctx->poll_disable_cnt);
+@@ -XXX,XX +XXX,XX @@ static bool aio_dispatch_handler(AioContext *ctx, AioHandler *node)
+  * scanning all handlers with aio_dispatch_handlers().
+  */
+ static bool aio_dispatch_ready_handlers(AioContext *ctx,
+-                                        AioHandlerList *ready_list)
++                                        AioHandlerList *ready_list,
++                                        int64_t block_ns)
+ {
+     bool progress = false;
+     AioHandler *node;
+@@ -XXX,XX +XXX,XX @@ static bool aio_dispatch_ready_handlers(AioContext *ctx,
+     while ((node = QLIST_FIRST(ready_list))) {
+         QLIST_REMOVE(node, node_ready);
+         progress = aio_dispatch_handler(ctx, node) || progress;
++
++        /*
++         * Adjust polling time only after aio_dispatch_handler(), which can
++         * add the handler to ctx->poll_aio_handlers.
++         */
++        if (ctx->poll_max_ns && QLIST_IS_INSERTED(node, node_poll)) {
++            adjust_polling_time(ctx, &node->poll, block_ns);
++        }
+     }
+     return progress;
+@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
+     bool use_notify_me;
+     int64_t timeout;
+     int64_t start = 0;
++    int64_t block_ns = 0;
+     /*
+      * There cannot be two concurrent aio_poll calls for the same AioContext (or
+@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
+     aio_notify_accept(ctx);
+-    /* Adjust polling time */
++    /* Calculate blocked time for adaptive polling */
+     if (ctx->poll_max_ns) {
+-        AioHandler *node;
+-        int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
+-
+-        QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
+-            if (QLIST_IS_INSERTED(node, node_ready)) {
+-                adjust_polling_time(ctx, &node->poll, block_ns);
+-            }
+-        }
++        block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
+     }
+     progress |= aio_bh_poll(ctx);
+-    progress |= aio_dispatch_ready_handlers(ctx, &ready_list);
++    progress |= aio_dispatch_ready_handlers(ctx, &ready_list, block_ns);
+     aio_free_deleted_handlers(ctx);
+--
+.48.1

-New patch
+[PULL 09/22] iotests: Limit qsd-migrate to working formats
+From: Thomas Huth <thuth@redhat.com>
+qsd-migrate is currently only working for raw, qcow2 and qed.
+Other formats are failing, e.g. because they don't support migration.
+Thus let's limit this test to the three usable formats now.
+Suggested-by: Kevin Wolf <kwolf@redhat.com>
+Signed-off-by: Thomas Huth <thuth@redhat.com>
+Message-ID: <20250224214058.205889-1-thuth@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ tests/qemu-iotests/tests/qsd-migrate | 2 +-
+file changed, 1 insertion(+), 1 deletion(-)
+diff --git a/tests/qemu-iotests/tests/qsd-migrate b/tests/qemu-iotests/tests/qsd-migrate
+index XXXXXXX..XXXXXXX 100755
+--- a/tests/qemu-iotests/tests/qsd-migrate
++++ b/tests/qemu-iotests/tests/qsd-migrate
+@@ -XXX,XX +XXX,XX @@ import iotests
+ from iotests import filter_qemu_io, filter_qtest
+-iotests.script_initialize(supported_fmts=['generic'],
++iotests.script_initialize(supported_fmts=['qcow2', 'qed', 'raw'],
+                           supported_protocols=['file'],
+                           supported_platforms=['linux'])
+--
+.48.1

-[Qemu-devel] [PULL 1/5] qemu-img: allow compressed not-in-order writes
+[PULL 10/22] scsi-disk: drop unused SCSIDiskState->bh field
-From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+From: Stefan Hajnoczi <stefanha@redhat.com>
-No reason to forbid them, and they are needed to improve performance
+Commit 71544d30a6f8 ("scsi: push request restart to SCSIDevice") removed
-with compress-threads in further patches.
+the only user of SCSIDiskState->bh.
-Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
 Reviewed-by: Kevin Wolf <kwolf@redhat.com>
 Message-ID: <20250311132616.1049687-2-stefanha@redhat.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
- qemu-img.c | 5 -----
+ hw/scsi/scsi-disk.c | 1 -
-file changed, 5 deletions(-)
+file changed, 1 deletion(-)
-diff --git a/qemu-img.c b/qemu-img.c
+diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
 index XXXXXXX..XXXXXXX 100644
---- a/qemu-img.c
+--- a/hw/scsi/scsi-disk.c
-+++ b/qemu-img.c
++++ b/hw/scsi/scsi-disk.c
-@@ -XXX,XX +XXX,XX @@ static int img_convert(int argc, char **argv)
+@@ -XXX,XX +XXX,XX @@ struct SCSIDiskState {
-         goto fail_getopt;
+     uint64_t max_unmap_size;
-     }
+     uint64_t max_io_size;
+     uint32_t quirks;
--    if (!s.wr_in_order && s.compressed) {
+-    QEMUBH *bh;
--        error_report("Out of order write and compress are mutually exclusive");
+     char *version;
--        goto fail_getopt;
+     char *serial;
--    }
+     char *vendor;
 -
      if (tgt_image_opts && !skip_create) {
          error_report("--target-image-opts requires use of -n flag");
          goto fail_getopt;
 --
-.13.6
+.48.1

-New patch
+[PULL 11/22] dma: use current AioContext for dma_blk_io()
+From: Stefan Hajnoczi <stefanha@redhat.com>
+In the past a single AioContext was used for block I/O and it was
+fetched using blk_get_aio_context(). Nowadays the block layer supports
+running I/O from any AioContext and multiple AioContexts at the same
+time. Remove the dma_blk_io() AioContext argument and use the current
+AioContext instead.
+This makes calling the function easier and enables multiple IOThreads to
+use dma_blk_io() concurrently for the same block device.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250311132616.1049687-3-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/system/dma.h | 3 +--
+ hw/ide/core.c        | 3 +--
+ hw/ide/macio.c       | 3 +--
+ hw/scsi/scsi-disk.c  | 6 ++----
+ system/dma-helpers.c | 8 ++++----
+files changed, 9 insertions(+), 14 deletions(-)
+diff --git a/include/system/dma.h b/include/system/dma.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/system/dma.h
++++ b/include/system/dma.h
+@@ -XXX,XX +XXX,XX @@ typedef BlockAIOCB *DMAIOFunc(int64_t offset, QEMUIOVector *iov,
+                               BlockCompletionFunc *cb, void *cb_opaque,
+                               void *opaque);
+-BlockAIOCB *dma_blk_io(AioContext *ctx,
+-                       QEMUSGList *sg, uint64_t offset, uint32_t align,
++BlockAIOCB *dma_blk_io(QEMUSGList *sg, uint64_t offset, uint32_t align,
+                        DMAIOFunc *io_func, void *io_func_opaque,
+                        BlockCompletionFunc *cb, void *opaque, DMADirection dir);
+ BlockAIOCB *dma_blk_read(BlockBackend *blk,
+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_dma_cb(void *opaque, int ret)
+                                            BDRV_SECTOR_SIZE, ide_dma_cb, s);
+         break;
+     case IDE_DMA_TRIM:
+-        s->bus->dma->aiocb = dma_blk_io(blk_get_aio_context(s->blk),
+-                                        &s->sg, offset, BDRV_SECTOR_SIZE,
++        s->bus->dma->aiocb = dma_blk_io(&s->sg, offset, BDRV_SECTOR_SIZE,
+                                         ide_issue_trim, s, ide_dma_cb, s,
+                                         DMA_DIRECTION_TO_DEVICE);
+         break;
+diff --git a/hw/ide/macio.c b/hw/ide/macio.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/ide/macio.c
++++ b/hw/ide/macio.c
+@@ -XXX,XX +XXX,XX @@ static void pmac_ide_transfer_cb(void *opaque, int ret)
+                                            pmac_ide_transfer_cb, io);
+         break;
+     case IDE_DMA_TRIM:
+-        s->bus->dma->aiocb = dma_blk_io(blk_get_aio_context(s->blk), &s->sg,
+-                                        offset, 0x1, ide_issue_trim, s,
++        s->bus->dma->aiocb = dma_blk_io(&s->sg, offset, 0x1, ide_issue_trim, s,
+                                         pmac_ide_transfer_cb, io,
+                                         DMA_DIRECTION_TO_DEVICE);
+         break;
+diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/scsi-disk.c
++++ b/hw/scsi/scsi-disk.c
+@@ -XXX,XX +XXX,XX @@ static void scsi_do_read(SCSIDiskReq *r, int ret)
+     if (r->req.sg) {
+         dma_acct_start(s->qdev.conf.blk, &r->acct, r->req.sg, BLOCK_ACCT_READ);
+         r->req.residual -= r->req.sg->size;
+-        r->req.aiocb = dma_blk_io(blk_get_aio_context(s->qdev.conf.blk),
+-                                  r->req.sg, r->sector << BDRV_SECTOR_BITS,
++        r->req.aiocb = dma_blk_io(r->req.sg, r->sector << BDRV_SECTOR_BITS,
+                                   BDRV_SECTOR_SIZE,
+                                   sdc->dma_readv, r, scsi_dma_complete, r,
+                                   DMA_DIRECTION_FROM_DEVICE);
+@@ -XXX,XX +XXX,XX @@ static void scsi_write_data(SCSIRequest *req)
+     if (r->req.sg) {
+         dma_acct_start(s->qdev.conf.blk, &r->acct, r->req.sg, BLOCK_ACCT_WRITE);
+         r->req.residual -= r->req.sg->size;
+-        r->req.aiocb = dma_blk_io(blk_get_aio_context(s->qdev.conf.blk),
+-                                  r->req.sg, r->sector << BDRV_SECTOR_BITS,
++        r->req.aiocb = dma_blk_io(r->req.sg, r->sector << BDRV_SECTOR_BITS,
+                                   BDRV_SECTOR_SIZE,
+                                   sdc->dma_writev, r, scsi_dma_complete, r,
+                                   DMA_DIRECTION_TO_DEVICE);
+diff --git a/system/dma-helpers.c b/system/dma-helpers.c
+index XXXXXXX..XXXXXXX 100644
+--- a/system/dma-helpers.c
++++ b/system/dma-helpers.c
+@@ -XXX,XX +XXX,XX @@ static const AIOCBInfo dma_aiocb_info = {
+     .cancel_async       = dma_aio_cancel,
+ };
+-BlockAIOCB *dma_blk_io(AioContext *ctx,
++BlockAIOCB *dma_blk_io(
+     QEMUSGList *sg, uint64_t offset, uint32_t align,
+     DMAIOFunc *io_func, void *io_func_opaque,
+     BlockCompletionFunc *cb,
+@@ -XXX,XX +XXX,XX @@ BlockAIOCB *dma_blk_io(AioContext *ctx,
+     dbs->acb = NULL;
+     dbs->sg = sg;
+-    dbs->ctx = ctx;
++    dbs->ctx = qemu_get_current_aio_context();
+     dbs->offset = offset;
+     dbs->align = align;
+     dbs->sg_cur_index = 0;
+@@ -XXX,XX +XXX,XX @@ BlockAIOCB *dma_blk_read(BlockBackend *blk,
+                          QEMUSGList *sg, uint64_t offset, uint32_t align,
+                          void (*cb)(void *opaque, int ret), void *opaque)
+ {
+-    return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
++    return dma_blk_io(sg, offset, align,
+                       dma_blk_read_io_func, blk, cb, opaque,
+                       DMA_DIRECTION_FROM_DEVICE);
+ }
+@@ -XXX,XX +XXX,XX @@ BlockAIOCB *dma_blk_write(BlockBackend *blk,
+                           QEMUSGList *sg, uint64_t offset, uint32_t align,
+                           void (*cb)(void *opaque, int ret), void *opaque)
+ {
+-    return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
++    return dma_blk_io(sg, offset, align,
+                       dma_blk_write_io_func, blk, cb, opaque,
+                       DMA_DIRECTION_TO_DEVICE);
+ }
+--
+.48.1

-New patch
+[PULL 12/22] scsi: track per-SCSIRequest AioContext
+From: Stefan Hajnoczi <stefanha@redhat.com>
+Until now, a SCSIDevice's I/O requests have run in a single AioContext.
+In order to support multiple IOThreads it will be necessary to move to
+the concept of a per-SCSIRequest AioContext.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250311132616.1049687-4-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/hw/scsi/scsi.h |  1 +
+ hw/scsi/scsi-bus.c     |  1 +
+ hw/scsi/scsi-disk.c    | 17 ++++++-----------
+files changed, 8 insertions(+), 11 deletions(-)
+diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/hw/scsi/scsi.h
++++ b/include/hw/scsi/scsi.h
+@@ -XXX,XX +XXX,XX @@ struct SCSIRequest {
+     SCSIBus           *bus;
+     SCSIDevice        *dev;
+     const SCSIReqOps  *ops;
++    AioContext        *ctx;
+     uint32_t          refcount;
+     uint32_t          tag;
+     uint32_t          lun;
+diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/scsi-bus.c
++++ b/hw/scsi/scsi-bus.c
+@@ -XXX,XX +XXX,XX @@ invalid_opcode:
+         }
+     }
++    req->ctx = qemu_get_current_aio_context();
+     req->cmd = cmd;
+     req->residual = req->cmd.xfer;
+diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/scsi-disk.c
++++ b/hw/scsi/scsi-disk.c
+@@ -XXX,XX +XXX,XX @@ static void scsi_aio_complete(void *opaque, int ret)
+     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
+     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
+-    /* The request must only run in the BlockBackend's AioContext */
+-    assert(blk_get_aio_context(s->qdev.conf.blk) ==
+-           qemu_get_current_aio_context());
++    /* The request must run in its AioContext */
++    assert(r->req.ctx == qemu_get_current_aio_context());
+     assert(r->req.aiocb != NULL);
+     r->req.aiocb = NULL;
+@@ -XXX,XX +XXX,XX @@ static void scsi_dma_complete(void *opaque, int ret)
+ static void scsi_read_complete_noio(SCSIDiskReq *r, int ret)
+ {
+-    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
+     uint32_t n;
+-    /* The request must only run in the BlockBackend's AioContext */
+-    assert(blk_get_aio_context(s->qdev.conf.blk) ==
+-           qemu_get_current_aio_context());
++    /* The request must run in its AioContext */
++    assert(r->req.ctx == qemu_get_current_aio_context());
+     assert(r->req.aiocb == NULL);
+     if (scsi_disk_req_check_error(r, ret, ret > 0)) {
+@@ -XXX,XX +XXX,XX @@ static void scsi_read_data(SCSIRequest *req)
+ static void scsi_write_complete_noio(SCSIDiskReq *r, int ret)
+ {
+-    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
+     uint32_t n;
+-    /* The request must only run in the BlockBackend's AioContext */
+-    assert(blk_get_aio_context(s->qdev.conf.blk) ==
+-           qemu_get_current_aio_context());
++    /* The request must run in its AioContext */
++    assert(r->req.ctx == qemu_get_current_aio_context());
+     assert (r->req.aiocb == NULL);
+     if (scsi_disk_req_check_error(r, ret, ret > 0)) {
+--
+.48.1

-New patch
+[PULL 13/22] scsi: introduce requests_lock
+From: Stefan Hajnoczi <stefanha@redhat.com>
+SCSIDevice keeps track of in-flight requests for device reset and Task
+Management Functions (TMFs). The request list requires protection so
+that multi-threaded SCSI emulation can be implemented in commits that
+follow.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250311132616.1049687-5-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/hw/scsi/scsi.h |   7 ++-
+ hw/scsi/scsi-bus.c     | 120 +++++++++++++++++++++++++++++------------
+files changed, 88 insertions(+), 39 deletions(-)
+diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/hw/scsi/scsi.h
++++ b/include/hw/scsi/scsi.h
+@@ -XXX,XX +XXX,XX @@ struct SCSIRequest {
+     bool              dma_started;
+     BlockAIOCB        *aiocb;
+     QEMUSGList        *sg;
++
++    /* Protected by SCSIDevice->requests_lock */
+     QTAILQ_ENTRY(SCSIRequest) next;
+ };
+@@ -XXX,XX +XXX,XX @@ struct SCSIDevice
+     uint8_t sense[SCSI_SENSE_BUF_SIZE];
+     uint32_t sense_len;
+-    /*
+-     * The requests list is only accessed from the AioContext that executes
+-     * requests or from the main loop when IOThread processing is stopped.
+-     */
++    QemuMutex requests_lock; /* protects the requests list */
+     QTAILQ_HEAD(, SCSIRequest) requests;
+     uint32_t channel;
+diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/scsi-bus.c
++++ b/hw/scsi/scsi-bus.c
+@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_sync(SCSIDevice *s,
+     assert(!runstate_is_running());
+     assert(qemu_in_main_thread());
+-    QTAILQ_FOREACH_SAFE(req, &s->requests, next, next_req) {
+-        fn(req, opaque);
++    /*
++     * Locking is not necessary because the guest is stopped and no other
++     * threads can be accessing the requests list, but take the lock for
++     * consistency.
++     */
++    WITH_QEMU_LOCK_GUARD(&s->requests_lock) {
++        QTAILQ_FOREACH_SAFE(req, &s->requests, next, next_req) {
++            fn(req, opaque);
++        }
+     }
+ }
+@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_async_bh(void *opaque)
+ {
+     g_autofree SCSIDeviceForEachReqAsyncData *data = opaque;
+     SCSIDevice *s = data->s;
+-    AioContext *ctx;
+-    SCSIRequest *req;
+-    SCSIRequest *next;
++    g_autoptr(GList) reqs = NULL;
+     /*
+-     * The BB cannot have changed contexts between this BH being scheduled and
+-     * now: BBs' AioContexts, when they have a node attached, can only be
+-     * changed via bdrv_try_change_aio_context(), in a drained section.  While
+-     * we have the in-flight counter incremented, that drain must block.
++     * Build a list of requests in this AioContext so fn() can be invoked later
++     * outside requests_lock.
+      */
+-    ctx = blk_get_aio_context(s->conf.blk);
+-    assert(ctx == qemu_get_current_aio_context());
++    WITH_QEMU_LOCK_GUARD(&s->requests_lock) {
++        AioContext *ctx = qemu_get_current_aio_context();
++        SCSIRequest *req;
++        SCSIRequest *next;
++
++        QTAILQ_FOREACH_SAFE(req, &s->requests, next, next) {
++            if (req->ctx == ctx) {
++                scsi_req_ref(req); /* dropped after calling fn() */
++                reqs = g_list_prepend(reqs, req);
++            }
++        }
++    }
+-    QTAILQ_FOREACH_SAFE(req, &s->requests, next, next) {
+-        data->fn(req, data->fn_opaque);
++    /* Call fn() on each request */
++    for (GList *elem = g_list_first(reqs); elem; elem = g_list_next(elem)) {
++        data->fn(elem->data, data->fn_opaque);
++        scsi_req_unref(elem->data);
+     }
+     /* Drop the reference taken by scsi_device_for_each_req_async() */
+@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_async_bh(void *opaque)
+     blk_dec_in_flight(s->conf.blk);
+ }
++static void scsi_device_for_each_req_async_do_ctx(gpointer key, gpointer value,
++                                                  gpointer user_data)
++{
++    AioContext *ctx = key;
++    SCSIDeviceForEachReqAsyncData *params = user_data;
++    SCSIDeviceForEachReqAsyncData *data;
++
++    data = g_new(SCSIDeviceForEachReqAsyncData, 1);
++    data->s = params->s;
++    data->fn = params->fn;
++    data->fn_opaque = params->fn_opaque;
++
++    /*
++     * Hold a reference to the SCSIDevice until
++     * scsi_device_for_each_req_async_bh() finishes.
++     */
++    object_ref(OBJECT(data->s));
++
++    /* Paired with scsi_device_for_each_req_async_bh() */
++    blk_inc_in_flight(data->s->conf.blk);
++
++    aio_bh_schedule_oneshot(ctx, scsi_device_for_each_req_async_bh, data);
++}
++
+ /*
+  * Schedule @fn() to be invoked for each enqueued request in device @s. @fn()
+- * runs in the AioContext that is executing the request.
++ * must be thread-safe because it runs concurrently in each AioContext that is
++ * executing a request.
++ *
+  * Keeps the BlockBackend's in-flight counter incremented until everything is
+  * done, so draining it will settle all scheduled @fn() calls.
+  */
+@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_async(SCSIDevice *s,
+ {
+     assert(qemu_in_main_thread());
+-    SCSIDeviceForEachReqAsyncData *data =
+-        g_new(SCSIDeviceForEachReqAsyncData, 1);
+-
+-    data->s = s;
+-    data->fn = fn;
+-    data->fn_opaque = opaque;
+-
+-    /*
+-     * Hold a reference to the SCSIDevice until
+-     * scsi_device_for_each_req_async_bh() finishes.
+-     */
+-    object_ref(OBJECT(s));
++    /* The set of AioContexts where the requests are being processed */
++    g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
++    WITH_QEMU_LOCK_GUARD(&s->requests_lock) {
++        SCSIRequest *req;
++        QTAILQ_FOREACH(req, &s->requests, next) {
++            g_hash_table_add(aio_contexts, req->ctx);
++        }
++    }
+-    /* Paired with blk_dec_in_flight() in scsi_device_for_each_req_async_bh() */
+-    blk_inc_in_flight(s->conf.blk);
+-    aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.blk),
+-                            scsi_device_for_each_req_async_bh,
+-                            data);
++    /* Schedule a BH for each AioContext */
++    SCSIDeviceForEachReqAsyncData params = {
++        .s = s,
++        .fn = fn,
++        .fn_opaque = opaque,
++    };
++    g_hash_table_foreach(
++            aio_contexts,
++            scsi_device_for_each_req_async_do_ctx,
++            &params
++    );
+ }
+ static void scsi_device_realize(SCSIDevice *s, Error **errp)
+@@ -XXX,XX +XXX,XX @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
+         dev->lun = lun;
+     }
++    qemu_mutex_init(&dev->requests_lock);
+     QTAILQ_INIT(&dev->requests);
+     scsi_device_realize(dev, &local_err);
+     if (local_err) {
+@@ -XXX,XX +XXX,XX @@ static void scsi_qdev_unrealize(DeviceState *qdev)
+     scsi_device_purge_requests(dev, SENSE_CODE(NO_SENSE));
++    qemu_mutex_destroy(&dev->requests_lock);
++
+     scsi_device_unrealize(dev);
+     blockdev_mark_auto_del(dev->conf.blk);
+@@ -XXX,XX +XXX,XX @@ static void scsi_req_enqueue_internal(SCSIRequest *req)
+         req->sg = NULL;
+     }
+     req->enqueued = true;
+-    QTAILQ_INSERT_TAIL(&req->dev->requests, req, next);
++
++    WITH_QEMU_LOCK_GUARD(&req->dev->requests_lock) {
++        QTAILQ_INSERT_TAIL(&req->dev->requests, req, next);
++    }
+ }
+ int32_t scsi_req_enqueue(SCSIRequest *req)
+@@ -XXX,XX +XXX,XX @@ static void scsi_req_dequeue(SCSIRequest *req)
+     trace_scsi_req_dequeue(req->dev->id, req->lun, req->tag);
+     req->retry = false;
+     if (req->enqueued) {
+-        QTAILQ_REMOVE(&req->dev->requests, req, next);
++        WITH_QEMU_LOCK_GUARD(&req->dev->requests_lock) {
++            QTAILQ_REMOVE(&req->dev->requests, req, next);
++        }
+         req->enqueued = false;
+         scsi_req_unref(req);
+     }
+@@ -XXX,XX +XXX,XX @@ static void scsi_device_class_init(ObjectClass *klass, void *data)
+ static void scsi_dev_instance_init(Object *obj)
+ {
+-    DeviceState *dev = DEVICE(obj);
+-    SCSIDevice *s = SCSI_DEVICE(dev);
++    SCSIDevice *s = SCSI_DEVICE(obj);
+     device_add_bootindex_property(obj, &s->conf.bootindex,
+                                   "bootindex", NULL,
+--
+.48.1

-New patch
+[PULL 14/22] virtio-scsi: introduce event and ctrl virtqueue locks
+From: Stefan Hajnoczi <stefanha@redhat.com>
 Virtqueues are not thread-safe. Until now this was not a major issue
 since all virtqueue processing happened in the same thread. The ctrl
 queue's Task Management Function (TMF) requests sometimes need the main
 loop, so a BH was used to schedule the virtqueue completion back in the
 thread that has virtqueue access.
 When IOThread Virtqueue Mapping is introduced in later commits, event
 and ctrl virtqueue accesses from other threads will become necessary.
 Introduce an optional per-virtqueue lock so the event and ctrl
 virtqueues can be protected in the commits that follow.
 The addition of the ctrl virtqueue lock makes
 virtio_scsi_complete_req_from_main_loop() and its BH unnecessary.
 Instead, take the ctrl virtqueue lock from the main loop thread.
 The cmd virtqueue does not have a lock because the entirety of SCSI
 command processing happens in one thread. Only one thread accesses the
 cmd virtqueue and a lock is unnecessary.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 Reviewed-by: Kevin Wolf <kwolf@redhat.com>
 Message-ID: <20250311132616.1049687-6-stefanha@redhat.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
  include/hw/virtio/virtio-scsi.h |  3 ++
  hw/scsi/virtio-scsi.c           | 84 ++++++++++++++++++---------------
 files changed, 49 insertions(+), 38 deletions(-)
 diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
 index XXXXXXX..XXXXXXX 100644
 --- a/include/hw/virtio/virtio-scsi.h
 +++ b/include/hw/virtio/virtio-scsi.h
@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
      int resetting; /* written from main loop thread, read from any thread */
      bool events_dropped;
 +    QemuMutex ctrl_lock; /* protects ctrl_vq */
 +    QemuMutex event_lock; /* protects event_vq */
 +
      /*
       * TMFs deferred to main loop BH. These fields are protected by
       * tmf_bh_lock.
 diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
 index XXXXXXX..XXXXXXX 100644
 --- a/hw/scsi/virtio-scsi.c
 +++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_free_req(VirtIOSCSIReq *req)
      g_free(req);
  }
 -static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
 +static void virtio_scsi_complete_req(VirtIOSCSIReq *req, QemuMutex *vq_lock)
  {
      VirtIOSCSI *s = req->dev;
      VirtQueue *vq = req->vq;
      VirtIODevice *vdev = VIRTIO_DEVICE(s);
      qemu_iovec_from_buf(&req->resp_iov, 0, &req->resp, req->resp_size);
 +
 +    if (vq_lock) {
 +        qemu_mutex_lock(vq_lock);
 +    }
 +
      virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
      if (s->dataplane_started && !s->dataplane_fenced) {
          virtio_notify_irqfd(vdev, vq);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
          virtio_notify(vdev, vq);
      }
 +    if (vq_lock) {
 +        qemu_mutex_unlock(vq_lock);
 +    }
 +
      if (req->sreq) {
          req->sreq->hba_private = NULL;
          scsi_req_unref(req->sreq);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
      virtio_scsi_free_req(req);
  }
 -static void virtio_scsi_complete_req_bh(void *opaque)
 +static void virtio_scsi_bad_req(VirtIOSCSIReq *req, QemuMutex *vq_lock)
  {
 -    VirtIOSCSIReq *req = opaque;
 +    virtio_error(VIRTIO_DEVICE(req->dev), "wrong size for virtio-scsi headers");
 -    virtio_scsi_complete_req(req);
 -}
 +    if (vq_lock) {
 +        qemu_mutex_lock(vq_lock);
 +    }
 -/*
 - * Called from virtio_scsi_do_one_tmf_bh() in main loop thread. The main loop
 - * thread cannot touch the virtqueue since that could race with an IOThread.
 - */
 -static void virtio_scsi_complete_req_from_main_loop(VirtIOSCSIReq *req)
 -{
 -    VirtIOSCSI *s = req->dev;
 +    virtqueue_detach_element(req->vq, &req->elem, 0);
 -    if (!s->ctx || s->ctx == qemu_get_aio_context()) {
 -        /* No need to schedule a BH when there is no IOThread */
 -        virtio_scsi_complete_req(req);
 -    } else {
 -        /* Run request completion in the IOThread */
 -        aio_wait_bh_oneshot(s->ctx, virtio_scsi_complete_req_bh, req);
 +    if (vq_lock) {
 +        qemu_mutex_unlock(vq_lock);
      }
 -}
 -static void virtio_scsi_bad_req(VirtIOSCSIReq *req)
 -{
 -    virtio_error(VIRTIO_DEVICE(req->dev), "wrong size for virtio-scsi headers");
 -    virtqueue_detach_element(req->vq, &req->elem, 0);
      virtio_scsi_free_req(req);
  }
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_parse_req(VirtIOSCSIReq *req,
      return 0;
  }
 -static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq)
 +static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq, QemuMutex *vq_lock)
  {
      VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
      VirtIOSCSIReq *req;
 +    if (vq_lock) {
 +        qemu_mutex_lock(vq_lock);
 +    }
 +
      req = virtqueue_pop(vq, sizeof(VirtIOSCSIReq) + vs->cdb_size);
 +
 +    if (vq_lock) {
 +        qemu_mutex_unlock(vq_lock);
 +    }
 +
      if (!req) {
          return NULL;
      }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
          trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(req->req.tmf.lun),
                                     req->req.tmf.tag, req->resp.tmf.response);
 -        virtio_scsi_complete_req(req);
 +        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
      }
      g_free(n);
  }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
  out:
      object_unref(OBJECT(d));
 -    virtio_scsi_complete_req_from_main_loop(req);
 +    virtio_scsi_complete_req(req, &s->ctrl_lock);
  }
  /* Some TMFs must be processed from the main loop thread */
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s)
          /* SAM-6 6.3.2 Hard reset */
          req->resp.tmf.response = VIRTIO_SCSI_S_TARGET_FAILURE;
 -        virtio_scsi_complete_req(req);
 +        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
      }
  }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
      if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0,
                  &type, sizeof(type)) < sizeof(type)) {
 -        virtio_scsi_bad_req(req);
 +        virtio_scsi_bad_req(req, &s->ctrl_lock);
          return;
      }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
      if (type == VIRTIO_SCSI_T_TMF) {
          if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlTMFReq),
                      sizeof(VirtIOSCSICtrlTMFResp)) < 0) {
 -            virtio_scsi_bad_req(req);
 +            virtio_scsi_bad_req(req, &s->ctrl_lock);
              return;
          } else {
              r = virtio_scsi_do_tmf(s, req);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
                 type == VIRTIO_SCSI_T_AN_SUBSCRIBE) {
          if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlANReq),
                      sizeof(VirtIOSCSICtrlANResp)) < 0) {
 -            virtio_scsi_bad_req(req);
 +            virtio_scsi_bad_req(req, &s->ctrl_lock);
              return;
          } else {
              req->req.an.event_requested =
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
                   type == VIRTIO_SCSI_T_AN_SUBSCRIBE)
              trace_virtio_scsi_an_resp(virtio_scsi_get_lun(req->req.an.lun),
                                        req->resp.an.response);
 -        virtio_scsi_complete_req(req);
 +        virtio_scsi_complete_req(req, &s->ctrl_lock);
      } else {
          assert(r == -EINPROGRESS);
      }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq)
  {
      VirtIOSCSIReq *req;
 -    while ((req = virtio_scsi_pop_req(s, vq))) {
 +    while ((req = virtio_scsi_pop_req(s, vq, &s->ctrl_lock))) {
          virtio_scsi_handle_ctrl_req(s, req);
      }
  }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_complete_cmd_req(VirtIOSCSIReq *req)
       * in virtio_scsi_command_complete.
       */
      req->resp_size = sizeof(VirtIOSCSICmdResp);
 -    virtio_scsi_complete_req(req);
 +    virtio_scsi_complete_req(req, NULL);
  }
  static void virtio_scsi_command_failed(SCSIRequest *r)
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
              virtio_scsi_fail_cmd_req(req);
              return -ENOTSUP;
          } else {
 -            virtio_scsi_bad_req(req);
 +            virtio_scsi_bad_req(req, NULL);
              return -EINVAL;
          }
      }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq)
              virtio_queue_set_notification(vq, 0);
          }
 -        while ((req = virtio_scsi_pop_req(s, vq))) {
 +        while ((req = virtio_scsi_pop_req(s, vq, NULL))) {
              ret = virtio_scsi_handle_cmd_req_prepare(s, req);
              if (!ret) {
                  QTAILQ_INSERT_TAIL(&reqs, req, next);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
          return;
      }
 -    req = virtio_scsi_pop_req(s, vs->event_vq);
 +    req = virtio_scsi_pop_req(s, vs->event_vq, &s->event_lock);
      if (!req) {
          s->events_dropped = true;
          return;
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
      }
      if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
 -        virtio_scsi_bad_req(req);
 +        virtio_scsi_bad_req(req, &s->event_lock);
          return;
      }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
      }
      trace_virtio_scsi_event(virtio_scsi_get_lun(evt->lun), event, reason);
 -    virtio_scsi_complete_req(req);
 +    virtio_scsi_complete_req(req, &s->event_lock);
  }
  static void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq)
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
      Error *err = NULL;
      QTAILQ_INIT(&s->tmf_bh_list);
 +    qemu_mutex_init(&s->ctrl_lock);
 +    qemu_mutex_init(&s->event_lock);
      qemu_mutex_init(&s->tmf_bh_lock);
      virtio_scsi_common_realize(dev,
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_unrealize(DeviceState *dev)
      qbus_set_hotplug_handler(BUS(&s->bus), NULL);
      virtio_scsi_common_unrealize(dev);
      qemu_mutex_destroy(&s->tmf_bh_lock);
 +    qemu_mutex_destroy(&s->event_lock);
 +    qemu_mutex_destroy(&s->ctrl_lock);
  }
  static const Property virtio_scsi_properties[] = {
 --
 .48.1

-New patch
+[PULL 15/22] virtio-scsi: protect events_dropped field
+From: Stefan Hajnoczi <stefanha@redhat.com>
+The block layer can invoke the resize callback from any AioContext that
+is processing requests. The virtqueue is already protected but the
+events_dropped field also needs to be protected against races. Cover it
+using the event virtqueue lock because it is closely associated with
+accesses to the virtqueue.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250311132616.1049687-7-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/hw/virtio/virtio-scsi.h |  3 ++-
+ hw/scsi/virtio-scsi.c           | 29 ++++++++++++++++++++---------
+files changed, 22 insertions(+), 10 deletions(-)
+diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/hw/virtio/virtio-scsi.h
++++ b/include/hw/virtio/virtio-scsi.h
+@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
+     SCSIBus bus;
+     int resetting; /* written from main loop thread, read from any thread */
++
++    QemuMutex event_lock; /* protects event_vq and events_dropped */
+     bool events_dropped;
+     QemuMutex ctrl_lock; /* protects ctrl_vq */
+-    QemuMutex event_lock; /* protects event_vq */
+     /*
+      * TMFs deferred to main loop BH. These fields are protected by
+diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/virtio-scsi.c
++++ b/hw/scsi/virtio-scsi.c
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset(VirtIODevice *vdev)
+     vs->sense_size = VIRTIO_SCSI_SENSE_DEFAULT_SIZE;
+     vs->cdb_size = VIRTIO_SCSI_CDB_DEFAULT_SIZE;
+-    s->events_dropped = false;
++
++    WITH_QEMU_LOCK_GUARD(&s->event_lock) {
++        s->events_dropped = false;
++    }
+ }
+ typedef struct {
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
+     }
+     req = virtio_scsi_pop_req(s, vs->event_vq, &s->event_lock);
+-    if (!req) {
+-        s->events_dropped = true;
+-        return;
+-    }
++    WITH_QEMU_LOCK_GUARD(&s->event_lock) {
++        if (!req) {
++            s->events_dropped = true;
++            return;
++        }
+-    if (s->events_dropped) {
+-        event |= VIRTIO_SCSI_T_EVENTS_MISSED;
+-        s->events_dropped = false;
++        if (s->events_dropped) {
++            event |= VIRTIO_SCSI_T_EVENTS_MISSED;
++            s->events_dropped = false;
++        }
+     }
+     if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
+ static void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq)
+ {
+-    if (s->events_dropped) {
++    bool events_dropped;
++
++    WITH_QEMU_LOCK_GUARD(&s->event_lock) {
++        events_dropped = s->events_dropped;
++    }
++
++    if (events_dropped) {
+         VirtIOSCSIEventInfo info = {
+             .event = VIRTIO_SCSI_T_NO_EVENT,
+         };
+--
+.48.1

-New patch
+[PULL 16/22] virtio-scsi: perform TMFs in appropriate AioContexts
+From: Stefan Hajnoczi <stefanha@redhat.com>
 With IOThread Virtqueue Mapping there will be multiple AioContexts
 processing SCSI requests. scsi_req_cancel() and other SCSI request
 operations must be performed from the AioContext where the request is
 running.
 Introduce a virtio_scsi_defer_tmf_to_aio_context() function and the
 necessary VirtIOSCSIReq->remaining refcount infrastructure to move the
 TMF code into the AioContext where the request is running.
 For the time being there is still just one AioContext: the main loop or
 the IOThread. When the iothread-vq-mapping parameter is added in a later
 patch this will be changed to per-virtqueue AioContexts.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 Reviewed-by: Kevin Wolf <kwolf@redhat.com>
 Message-ID: <20250311132616.1049687-8-stefanha@redhat.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
  hw/scsi/virtio-scsi.c | 270 ++++++++++++++++++++++++++++++++----------
 file changed, 206 insertions(+), 64 deletions(-)
 diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
 index XXXXXXX..XXXXXXX 100644
 --- a/hw/scsi/virtio-scsi.c
 +++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@ typedef struct VirtIOSCSIReq {
      /* Used for two-stage request submission and TMFs deferred to BH */
      QTAILQ_ENTRY(VirtIOSCSIReq) next;
 -    /* Used for cancellation of request during TMFs */
 +    /* Used for cancellation of request during TMFs. Atomic. */
      int remaining;
      SCSIRequest *sreq;
@@ -XXX,XX +XXX,XX @@ typedef struct {
      VirtIOSCSIReq  *tmf_req;
  } VirtIOSCSICancelNotifier;
 +static void virtio_scsi_tmf_dec_remaining(VirtIOSCSIReq *tmf)
 +{
 +    if (qatomic_fetch_dec(&tmf->remaining) == 1) {
 +        trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(tmf->req.tmf.lun),
 +                                   tmf->req.tmf.tag, tmf->resp.tmf.response);
 +
 +        virtio_scsi_complete_req(tmf, &tmf->dev->ctrl_lock);
 +    }
 +}
 +
  static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
  {
      VirtIOSCSICancelNotifier *n = container_of(notifier,
                                                 VirtIOSCSICancelNotifier,
                                                 notifier);
 -    if (--n->tmf_req->remaining == 0) {
 -        VirtIOSCSIReq *req = n->tmf_req;
 -
 -        trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(req->req.tmf.lun),
 -                                   req->req.tmf.tag, req->resp.tmf.response);
 -        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
 -    }
 +    virtio_scsi_tmf_dec_remaining(n->tmf_req);
      g_free(n);
  }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s)
      }
  }
 -static void virtio_scsi_defer_tmf_to_bh(VirtIOSCSIReq *req)
 +static void virtio_scsi_defer_tmf_to_main_loop(VirtIOSCSIReq *req)
  {
      VirtIOSCSI *s = req->dev;
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_defer_tmf_to_bh(VirtIOSCSIReq *req)
      }
  }
 +static void virtio_scsi_tmf_cancel_req(VirtIOSCSIReq *tmf, SCSIRequest *r)
 +{
 +    VirtIOSCSICancelNotifier *notifier;
 +
 +    assert(r->ctx == qemu_get_current_aio_context());
 +
 +    /* Decremented in virtio_scsi_cancel_notify() */
 +    qatomic_inc(&tmf->remaining);
 +
 +    notifier = g_new(VirtIOSCSICancelNotifier, 1);
 +    notifier->notifier.notify = virtio_scsi_cancel_notify;
 +    notifier->tmf_req = tmf;
 +    scsi_req_cancel_async(r, &notifier->notifier);
 +}
 +
 +/* Execute a TMF on the requests in the current AioContext */
 +static void virtio_scsi_do_tmf_aio_context(void *opaque)
 +{
 +    AioContext *ctx = qemu_get_current_aio_context();
 +    VirtIOSCSIReq *tmf = opaque;
 +    VirtIOSCSI *s = tmf->dev;
 +    SCSIDevice *d = virtio_scsi_device_get(s, tmf->req.tmf.lun);
 +    SCSIRequest *r;
 +    bool match_tag;
 +
 +    if (!d) {
 +        tmf->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
 +        virtio_scsi_tmf_dec_remaining(tmf);
 +        return;
 +    }
 +
 +    /*
 +     * This function could handle other subtypes that need to be processed in
 +     * the request's AioContext in the future, but for now only request
 +     * cancelation subtypes are performed here.
 +     */
 +    switch (tmf->req.tmf.subtype) {
 +    case VIRTIO_SCSI_T_TMF_ABORT_TASK:
 +        match_tag = true;
 +        break;
 +    case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
 +    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET:
 +        match_tag = false;
 +        break;
 +    default:
 +        g_assert_not_reached();
 +    }
 +
 +    WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
 +        QTAILQ_FOREACH(r, &d->requests, next) {
 +            VirtIOSCSIReq *cmd_req = r->hba_private;
 +            assert(cmd_req); /* request has hba_private while enqueued */
 +
 +            if (r->ctx != ctx) {
 +                continue;
 +            }
 +            if (match_tag && cmd_req->req.cmd.tag != tmf->req.tmf.tag) {
 +                continue;
 +            }
 +            virtio_scsi_tmf_cancel_req(tmf, r);
 +        }
 +    }
 +
 +    /* Incremented by virtio_scsi_do_tmf() */
 +    virtio_scsi_tmf_dec_remaining(tmf);
 +
 +    object_unref(d);
 +}
 +
 +static void dummy_bh(void *opaque)
 +{
 +    /* Do nothing */
 +}
 +
 +/*
 + * Wait for pending virtio_scsi_defer_tmf_to_aio_context() BHs.
 + */
 +static void virtio_scsi_flush_defer_tmf_to_aio_context(VirtIOSCSI *s)
 +{
 +    GLOBAL_STATE_CODE();
 +
 +    assert(!s->dataplane_started);
 +
 +    if (s->ctx) {
 +        /* Our BH only runs after previously scheduled BHs */
 +        aio_wait_bh_oneshot(s->ctx, dummy_bh, NULL);
 +    }
 +}
 +
 +/*
 + * Run the TMF in a specific AioContext, handling only requests in that
 + * AioContext. This is necessary because requests can run in different
 + * AioContext and it is only possible to cancel them from the AioContext where
 + * they are running.
 + */
 +static void virtio_scsi_defer_tmf_to_aio_context(VirtIOSCSIReq *tmf,
 +                                                 AioContext *ctx)
 +{
 +    /* Decremented in virtio_scsi_do_tmf_aio_context() */
 +    qatomic_inc(&tmf->remaining);
 +
 +    /* See virtio_scsi_flush_defer_tmf_to_aio_context() cleanup during reset */
 +    aio_bh_schedule_oneshot(ctx, virtio_scsi_do_tmf_aio_context, tmf);
 +}
 +
 +/*
 + * Returns the AioContext for a given TMF's tag field or NULL. Note that the
 + * request identified by the tag may have completed by the time you can execute
 + * a BH in the AioContext, so don't assume the request still exists in your BH.
 + */
 +static AioContext *find_aio_context_for_tmf_tag(SCSIDevice *d,
 +                                                VirtIOSCSIReq *tmf)
 +{
 +    WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
 +        SCSIRequest *r;
 +        SCSIRequest *next;
 +
 +        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
 +            VirtIOSCSIReq *cmd_req = r->hba_private;
 +
 +            /* hba_private is non-NULL while the request is enqueued */
 +            assert(cmd_req);
 +
 +            if (cmd_req->req.cmd.tag == tmf->req.tmf.tag) {
 +                return r->ctx;
 +            }
 +        }
 +    }
 +    return NULL;
 +}
 +
  /* Return 0 if the request is ready to be completed and return to guest;
   * -EINPROGRESS if the request is submitted and will be completed later, in the
   *  case of async cancellation. */
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
  {
      SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
      SCSIRequest *r, *next;
 +    AioContext *ctx;
      int ret = 0;
      virtio_scsi_ctx_check(s, d);
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
                                req->req.tmf.tag, req->req.tmf.subtype);
      switch (req->req.tmf.subtype) {
 -    case VIRTIO_SCSI_T_TMF_ABORT_TASK:
 -    case VIRTIO_SCSI_T_TMF_QUERY_TASK:
 +    case VIRTIO_SCSI_T_TMF_ABORT_TASK: {
          if (!d) {
              goto fail;
          }
          if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
              goto incorrect_lun;
          }
 -        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
 -            VirtIOSCSIReq *cmd_req = r->hba_private;
 -            if (cmd_req && cmd_req->req.cmd.tag == req->req.tmf.tag) {
 -                break;
 -            }
 +
 +        ctx = find_aio_context_for_tmf_tag(d, req);
 +        if (ctx) {
 +            virtio_scsi_defer_tmf_to_aio_context(req, ctx);
 +            ret = -EINPROGRESS;
          }
 -        if (r) {
 -            /*
 -             * Assert that the request has not been completed yet, we
 -             * check for it in the loop above.
 -             */
 -            assert(r->hba_private);
 -            if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK) {
 -                /* "If the specified command is present in the task set, then
 -                 * return a service response set to FUNCTION SUCCEEDED".
 -                 */
 -                req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
 -            } else {
 -                VirtIOSCSICancelNotifier *notifier;
 -
 -                req->remaining = 1;
 -                notifier = g_new(VirtIOSCSICancelNotifier, 1);
 -                notifier->tmf_req = req;
 -                notifier->notifier.notify = virtio_scsi_cancel_notify;
 -                scsi_req_cancel_async(r, &notifier->notifier);
 -                ret = -EINPROGRESS;
 +        break;
 +    }
 +
 +    case VIRTIO_SCSI_T_TMF_QUERY_TASK:
 +        if (!d) {
 +            goto fail;
 +        }
 +        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
 +            goto incorrect_lun;
 +        }
 +
 +        WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
 +            QTAILQ_FOREACH(r, &d->requests, next) {
 +                VirtIOSCSIReq *cmd_req = r->hba_private;
 +                assert(cmd_req); /* request has hba_private while enqueued */
 +
 +                if (cmd_req->req.cmd.tag == req->req.tmf.tag) {
 +                    /*
 +                     * "If the specified command is present in the task set,
 +                     * then return a service response set to FUNCTION
 +                     * SUCCEEDED".
 +                     */
 +                    req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
 +                }
              }
          }
          break;
      case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
      case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
 -        virtio_scsi_defer_tmf_to_bh(req);
 +        virtio_scsi_defer_tmf_to_main_loop(req);
          ret = -EINPROGRESS;
          break;
      case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
 -    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET:
 +    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
 +        if (!d) {
 +            goto fail;
 +        }
 +        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
 +            goto incorrect_lun;
 +        }
 +
 +        qatomic_inc(&req->remaining);
 +
 +        ctx = s->ctx ?: qemu_get_aio_context();
 +        virtio_scsi_defer_tmf_to_aio_context(req, ctx);
 +
 +        virtio_scsi_tmf_dec_remaining(req);
 +        ret = -EINPROGRESS;
 +        break;
 +    }
 +
      case VIRTIO_SCSI_T_TMF_QUERY_TASK_SET:
          if (!d) {
              goto fail;
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
              goto incorrect_lun;
          }
 -        /* Add 1 to "remaining" until virtio_scsi_do_tmf returns.
 -         * This way, if the bus starts calling back to the notifiers
 -         * even before we finish the loop, virtio_scsi_cancel_notify
 -         * will not complete the TMF too early.
 -         */
 -        req->remaining = 1;
 -        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
 -            if (r->hba_private) {
 -                if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK_SET) {
 -                    /* "If there is any command present in the task set, then
 -                     * return a service response set to FUNCTION SUCCEEDED".
 -                     */
 -                    req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
 -                    break;
 -                } else {
 -                    VirtIOSCSICancelNotifier *notifier;
 -
 -                    req->remaining++;
 -                    notifier = g_new(VirtIOSCSICancelNotifier, 1);
 -                    notifier->notifier.notify = virtio_scsi_cancel_notify;
 -                    notifier->tmf_req = req;
 -                    scsi_req_cancel_async(r, &notifier->notifier);
 -                }
 +        WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
 +            QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
 +                /* Request has hba_private while enqueued */
 +                assert(r->hba_private);
 +
 +                /*
 +                 * "If there is any command present in the task set, then
 +                 * return a service response set to FUNCTION SUCCEEDED".
 +                 */
 +                req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
 +                break;
              }
          }
 -        if (--req->remaining > 0) {
 -            ret = -EINPROGRESS;
 -        }
          break;
      case VIRTIO_SCSI_T_TMF_CLEAR_ACA:
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset(VirtIODevice *vdev)
      assert(!s->dataplane_started);
      virtio_scsi_reset_tmf_bh(s);
 +    virtio_scsi_flush_defer_tmf_to_aio_context(s);
      qatomic_inc(&s->resetting);
      bus_cold_reset(BUS(&s->bus));
 --
 .48.1

-New patch
+[PULL 17/22] virtio-blk: extract cleanup_iothread_vq_mapping() function
+From: Stefan Hajnoczi <stefanha@redhat.com>
+This is the cleanup function that must be called after
+apply_iothread_vq_mapping() succeeds. virtio-scsi will need this
+function too, so extract it.
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
+Message-ID: <20250311132616.1049687-9-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ hw/block/virtio-blk.c | 27 +++++++++++++++++++++------
+file changed, 21 insertions(+), 6 deletions(-)
+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 @@ validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
+  * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
+  * the iothread-vq-mapping parameter in @iothread_vq_mapping_list.
+  *
++ * cleanup_iothread_vq_mapping() must be called to free IOThread object
++ * references after this function returns success.
++ *
+  * Returns: %true on success, %false on failure.
+  **/
+ static bool apply_iothread_vq_mapping(
+@@ -XXX,XX +XXX,XX @@ static bool apply_iothread_vq_mapping(
+     return true;
+ }
++/**
++ * cleanup_iothread_vq_mapping:
++ * @list: The mapping of virtqueues to IOThreads.
++ *
++ * Release IOThread object references that were acquired by
++ * apply_iothread_vq_mapping().
++ */
++static void cleanup_iothread_vq_mapping(IOThreadVirtQueueMappingList *list)
++{
++    IOThreadVirtQueueMappingList *node;
++
++    for (node = list; node; node = node->next) {
++        IOThread *iothread = iothread_by_id(node->value->iothread);
++        object_unref(OBJECT(iothread));
++    }
++}
++
+ /* Context: BQL held */
+ static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
+ {
+@@ -XXX,XX +XXX,XX @@ static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
+     assert(!s->ioeventfd_started);
+     if (conf->iothread_vq_mapping_list) {
+-        IOThreadVirtQueueMappingList *node;
+-
+-        for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
+-            IOThread *iothread = iothread_by_id(node->value->iothread);
+-            object_unref(OBJECT(iothread));
+-        }
++        cleanup_iothread_vq_mapping(conf->iothread_vq_mapping_list);
+     }
+     if (conf->iothread) {
+--
+.48.1

-[Qemu-devel] [PULL 4/5] block: Move two block permission constants to the relevant enum
+[PULL 18/22] virtio-blk: tidy up iothread_vq_mapping functions
-From: Ari Sundholm <ari@tuxera.com>
+From: Stefan Hajnoczi <stefanha@redhat.com>
-This allows using the two constants outside of block.c, which will
+Use noun_verb() function naming instead of verb_noun() because the
-happen in a subsequent patch.
+former is the most common naming style for APIs. The next commit will
 move these functions into a header file so that virtio-scsi can call
 them.
-Signed-off-by: Ari Sundholm <ari@tuxera.com>
+Shorten iothread_vq_mapping_apply()'s iothread_vq_mapping_list argument
 to just "list" like in the other functions.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 Reviewed-by: Kevin Wolf <kwolf@redhat.com>
 Message-ID: <20250311132616.1049687-10-stefanha@redhat.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
- include/block/block.h | 7 +++++++
+ hw/block/virtio-blk.c | 33 ++++++++++++++++-----------------
- block.c               | 6 ------
+file changed, 16 insertions(+), 17 deletions(-)
 files changed, 7 insertions(+), 6 deletions(-)
-diff --git a/include/block/block.h b/include/block/block.h
+diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
 index XXXXXXX..XXXXXXX 100644
---- a/include/block/block.h
+--- a/hw/block/virtio-blk.c
-+++ b/include/block/block.h
++++ b/hw/block/virtio-blk.c
-@@ -XXX,XX +XXX,XX @@ enum {
+@@ -XXX,XX +XXX,XX @@ static const BlockDevOps virtio_block_ops = {
      BLK_PERM_GRAPH_MOD          = 0x10,
      BLK_PERM_ALL                = 0x1f,
 +
 +    DEFAULT_PERM_PASSTHROUGH    = BLK_PERM_CONSISTENT_READ
 +                                 | BLK_PERM_WRITE
 +                                 | BLK_PERM_WRITE_UNCHANGED
 +                                 | BLK_PERM_RESIZE,
 +
 +    DEFAULT_PERM_UNCHANGED      = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
  };
- char *bdrv_perm_names(uint64_t perm);
+ static bool
-diff --git a/block.c b/block.c
+-validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
-index XXXXXXX..XXXXXXX 100644
+-        uint16_t num_queues, Error **errp)
---- a/block.c
++iothread_vq_mapping_validate(IOThreadVirtQueueMappingList *list, uint16_t
-+++ b/block.c
++        num_queues, Error **errp)
-@@ -XXX,XX +XXX,XX @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
+ {
-     return 0;
+     g_autofree unsigned long *vqs = bitmap_new(num_queues);
      g_autoptr(GHashTable) iothreads =
@@ -XXX,XX +XXX,XX @@ validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
  }
--#define DEFAULT_PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
+ /**
--                                 | BLK_PERM_WRITE \
+- * apply_iothread_vq_mapping:
--                                 | BLK_PERM_WRITE_UNCHANGED \
+- * @iothread_vq_mapping_list: The mapping of virtqueues to IOThreads.
--                                 | BLK_PERM_RESIZE)
++ * iothread_vq_mapping_apply:
--#define DEFAULT_PERM_UNCHANGED (BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH)
++ * @list: The mapping of virtqueues to IOThreads.
--
+  * @vq_aio_context: The array of AioContext pointers to fill in.
- void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
+  * @num_queues: The length of @vq_aio_context.
-                                const BdrvChildRole *role,
+  * @errp: If an error occurs, a pointer to the area to store the error.
-                                BlockReopenQueue *reopen_queue,
+  *
   * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
 - * the iothread-vq-mapping parameter in @iothread_vq_mapping_list.
 + * the iothread-vq-mapping parameter in @list.
   *
 - * cleanup_iothread_vq_mapping() must be called to free IOThread object
 + * iothread_vq_mapping_cleanup() must be called to free IOThread object
   * references after this function returns success.
   *
   * Returns: %true on success, %false on failure.
   **/
 -static bool apply_iothread_vq_mapping(
 -        IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
 +static bool iothread_vq_mapping_apply(
 +        IOThreadVirtQueueMappingList *list,
          AioContext **vq_aio_context,
          uint16_t num_queues,
          Error **errp)
@@ -XXX,XX +XXX,XX @@ static bool apply_iothread_vq_mapping(
      size_t num_iothreads = 0;
      size_t cur_iothread = 0;
 -    if (!validate_iothread_vq_mapping_list(iothread_vq_mapping_list,
 -                                           num_queues, errp)) {
 +    if (!iothread_vq_mapping_validate(list, num_queues, errp)) {
          return false;
      }
 -    for (node = iothread_vq_mapping_list; node; node = node->next) {
 +    for (node = list; node; node = node->next) {
          num_iothreads++;
      }
 -    for (node = iothread_vq_mapping_list; node; node = node->next) {
 +    for (node = list; node; node = node->next) {
          IOThread *iothread = iothread_by_id(node->value->iothread);
          AioContext *ctx = iothread_get_aio_context(iothread);
@@ -XXX,XX +XXX,XX @@ static bool apply_iothread_vq_mapping(
  }
  /**
 - * cleanup_iothread_vq_mapping:
 + * iothread_vq_mapping_cleanup:
   * @list: The mapping of virtqueues to IOThreads.
   *
   * Release IOThread object references that were acquired by
 - * apply_iothread_vq_mapping().
 + * iothread_vq_mapping_apply().
   */
 -static void cleanup_iothread_vq_mapping(IOThreadVirtQueueMappingList *list)
 +static void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list)
  {
      IOThreadVirtQueueMappingList *node;
@@ -XXX,XX +XXX,XX @@ static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
      s->vq_aio_context = g_new(AioContext *, conf->num_queues);
      if (conf->iothread_vq_mapping_list) {
 -        if (!apply_iothread_vq_mapping(conf->iothread_vq_mapping_list,
 +        if (!iothread_vq_mapping_apply(conf->iothread_vq_mapping_list,
                                         s->vq_aio_context,
                                         conf->num_queues,
                                         errp)) {
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
      assert(!s->ioeventfd_started);
      if (conf->iothread_vq_mapping_list) {
 -        cleanup_iothread_vq_mapping(conf->iothread_vq_mapping_list);
 +        iothread_vq_mapping_cleanup(conf->iothread_vq_mapping_list);
      }
      if (conf->iothread) {
 --
-.13.6
+.48.1

-[Qemu-devel] [PULL 5/5] block: Add blklogwrites
+[PULL 19/22] virtio: extract iothread-vq-mapping.h API
-From: Aapo Vienamo <aapo@tuxera.com>
+From: Stefan Hajnoczi <stefanha@redhat.com>
-Implements a block device write logging system, similar to Linux kernel
+The code that builds an array of AioContext pointers indexed by the
-device mapper dm-log-writes. The write operations that are performed
+virtqueue is not specific to virtio-blk. virtio-scsi will need to do the
-on a block device are logged to a file or another block device. The
+same thing, so extract the functions.
 write log format is identical to the dm-log-writes format. Currently,
 log markers are not supported.
-This functionality can be used for crash consistency and fs consistency
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-testing. By implementing it in qemu, tests utilizing write logs can be
+Reviewed-by: Kevin Wolf <kwolf@redhat.com>
-be used to test non-Linux drivers and older kernels.
+Message-ID: <20250311132616.1049687-11-stefanha@redhat.com>
 The driver accepts an optional parameter to set the sector size used
 for logging. This makes the driver require all requests to be aligned
 to this sector size and also makes offsets and sizes of writes in the
 log metadata to be expressed in terms of this value (the log format has
 a granularity of one sector for offsets and sizes). This allows
 accurate logging of writes to guest block devices that have unusual
 sector sizes.
 The implementation is based on the blkverify and blkdebug block
 drivers.
 Signed-off-by: Aapo Vienamo <aapo@tuxera.com>
 Signed-off-by: Ari Sundholm <ari@tuxera.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
- qapi/block-core.json |  33 ++++-
+ include/hw/virtio/iothread-vq-mapping.h |  45 ++++++++
- block/blklogwrites.c | 392 +++++++++++++++++++++++++++++++++++++++++++++++++++
+ hw/block/virtio-blk.c                   | 142 +-----------------------
- MAINTAINERS          |   6 +
+ hw/virtio/iothread-vq-mapping.c         | 131 ++++++++++++++++++++++
- block/Makefile.objs  |   1 +
+ hw/virtio/meson.build                   |   1 +
-files changed, 426 insertions(+), 6 deletions(-)
+files changed, 178 insertions(+), 141 deletions(-)
- create mode 100644 block/blklogwrites.c
+ create mode 100644 include/hw/virtio/iothread-vq-mapping.h
  create mode 100644 hw/virtio/iothread-vq-mapping.c
-diff --git a/qapi/block-core.json b/qapi/block-core.json
+diff --git a/include/hw/virtio/iothread-vq-mapping.h b/include/hw/virtio/iothread-vq-mapping.h
 index XXXXXXX..XXXXXXX 100644
 --- a/qapi/block-core.json
 +++ b/qapi/block-core.json
@@ -XXX,XX +XXX,XX @@
  # @throttle: Since 2.11
  # @nvme: Since 2.12
  # @copy-on-read: Since 3.0
 +# @blklogwrites: Since 3.0
  #
  # Since: 2.9
  ##
  { 'enum': 'BlockdevDriver',
 -  'data': [ 'blkdebug', 'blkverify', 'bochs', 'cloop', 'copy-on-read',
 -            'dmg', 'file', 'ftp', 'ftps', 'gluster', 'host_cdrom',
 -            'host_device', 'http', 'https', 'iscsi', 'luks', 'nbd', 'nfs',
 -            'null-aio', 'null-co', 'nvme', 'parallels', 'qcow', 'qcow2', 'qed',
 -            'quorum', 'raw', 'rbd', 'replication', 'sheepdog', 'ssh',
 -            'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
 +  'data': [ 'blkdebug', 'blklogwrites', 'blkverify', 'bochs', 'cloop',
 +            'copy-on-read', 'dmg', 'file', 'ftp', 'ftps', 'gluster',
 +            'host_cdrom', 'host_device', 'http', 'https', 'iscsi', 'luks',
 +            'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels', 'qcow',
 +            'qcow2', 'qed', 'quorum', 'raw', 'rbd', 'replication', 'sheepdog',
 +            'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
  ##
  # @BlockdevOptionsFile:
@@ -XXX,XX +XXX,XX @@
              '*set-state': ['BlkdebugSetStateOptions'] } }
  ##
 +# @BlockdevOptionsBlklogwrites:
 +#
 +# Driver specific block device options for blklogwrites.
 +#
 +# @file:            block device
 +#
 +# @log:             block device used to log writes to @file
 +#
 +# @log-sector-size: sector size used in logging writes to @file, determines
 +#                   granularity of offsets and sizes of writes (default: 512)
 +#
 +# Since: 3.0
 +##
 +{ 'struct': 'BlockdevOptionsBlklogwrites',
 +  'data': { 'file': 'BlockdevRef',
 +            'log': 'BlockdevRef',
 +            '*log-sector-size': 'uint32' } }
 +
 +##
  # @BlockdevOptionsBlkverify:
  #
  # Driver specific block device options for blkverify.
@@ -XXX,XX +XXX,XX @@
    'discriminator': 'driver',
    'data': {
        'blkdebug':   'BlockdevOptionsBlkdebug',
 +      'blklogwrites':'BlockdevOptionsBlklogwrites',
        'blkverify':  'BlockdevOptionsBlkverify',
        'bochs':      'BlockdevOptionsGenericFormat',
        'cloop':      'BlockdevOptionsGenericFormat',
 diff --git a/block/blklogwrites.c b/block/blklogwrites.c
 new file mode 100644
 index XXXXXXX..XXXXXXX
 --- /dev/null
-+++ b/block/blklogwrites.c
++++ b/include/hw/virtio/iothread-vq-mapping.h
 @@ -XXX,XX +XXX,XX @@
 +/*
-+ * Write logging blk driver based on blkverify and blkdebug.
++ * IOThread Virtqueue Mapping
 + *
-+ * Copyright (c) 2017 Tuomas Tynkkynen <tuomas@tuxera.com>
++ * Copyright Red Hat, Inc
-+ * Copyright (c) 2018 Aapo Vienamo <aapo@tuxera.com>
++ *
-+ * Copyright (c) 2018 Ari Sundholm <ari@tuxera.com>
++ * SPDX-License-Identifier: GPL-2.0-only
 + *
 + * 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 HW_VIRTIO_IOTHREAD_VQ_MAPPING_H
++#define HW_VIRTIO_IOTHREAD_VQ_MAPPING_H
++
++#include "qapi/error.h"
++#include "qapi/qapi-types-virtio.h"
++
++/**
++ * iothread_vq_mapping_apply:
++ * @list: The mapping of virtqueues to IOThreads.
++ * @vq_aio_context: The array of AioContext pointers to fill in.
++ * @num_queues: The length of @vq_aio_context.
++ * @errp: If an error occurs, a pointer to the area to store the error.
++ *
++ * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
++ * the iothread-vq-mapping parameter in @list.
++ *
++ * iothread_vq_mapping_cleanup() must be called to free IOThread object
++ * references after this function returns success.
++ *
++ * Returns: %true on success, %false on failure.
++ **/
++bool iothread_vq_mapping_apply(
++        IOThreadVirtQueueMappingList *list,
++        AioContext **vq_aio_context,
++        uint16_t num_queues,
++        Error **errp);
++
++/**
++ * iothread_vq_mapping_cleanup:
++ * @list: The mapping of virtqueues to IOThreads.
++ *
++ * Release IOThread object references that were acquired by
++ * iothread_vq_mapping_apply().
++ */
++void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list);
++
++#endif /* HW_VIRTIO_IOTHREAD_VQ_MAPPING_H */
+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 @@
+ #endif
+ #include "hw/virtio/virtio-bus.h"
+ #include "migration/qemu-file-types.h"
++#include "hw/virtio/iothread-vq-mapping.h"
+ #include "hw/virtio/virtio-access.h"
+ #include "hw/virtio/virtio-blk-common.h"
+ #include "qemu/coroutine.h"
+@@ -XXX,XX +XXX,XX @@ static const BlockDevOps virtio_block_ops = {
+     .drained_end   = virtio_blk_drained_end,
+ };
+-static bool
+-iothread_vq_mapping_validate(IOThreadVirtQueueMappingList *list, uint16_t
+-        num_queues, Error **errp)
+-{
+-    g_autofree unsigned long *vqs = bitmap_new(num_queues);
+-    g_autoptr(GHashTable) iothreads =
+-        g_hash_table_new(g_str_hash, g_str_equal);
+-
+-    for (IOThreadVirtQueueMappingList *node = list; node; node = node->next) {
+-        const char *name = node->value->iothread;
+-        uint16List *vq;
+-
+-        if (!iothread_by_id(name)) {
+-            error_setg(errp, "IOThread \"%s\" object does not exist", name);
+-            return false;
+-        }
+-
+-        if (!g_hash_table_add(iothreads, (gpointer)name)) {
+-            error_setg(errp,
+-                    "duplicate IOThread name \"%s\" in iothread-vq-mapping",
+-                    name);
+-            return false;
+-        }
+-
+-        if (node != list) {
+-            if (!!node->value->vqs != !!list->value->vqs) {
+-                error_setg(errp, "either all items in iothread-vq-mapping "
+-                                 "must have vqs or none of them must have it");
+-                return false;
+-            }
+-        }
+-
+-        for (vq = node->value->vqs; vq; vq = vq->next) {
+-            if (vq->value >= num_queues) {
+-                error_setg(errp, "vq index %u for IOThread \"%s\" must be "
+-                        "less than num_queues %u in iothread-vq-mapping",
+-                        vq->value, name, num_queues);
+-                return false;
+-            }
+-
+-            if (test_and_set_bit(vq->value, vqs)) {
+-                error_setg(errp, "cannot assign vq %u to IOThread \"%s\" "
+-                        "because it is already assigned", vq->value, name);
+-                return false;
+-            }
+-        }
+-    }
+-
+-    if (list->value->vqs) {
+-        for (uint16_t i = 0; i < num_queues; i++) {
+-            if (!test_bit(i, vqs)) {
+-                error_setg(errp,
+-                        "missing vq %u IOThread assignment in iothread-vq-mapping",
+-                        i);
+-                return false;
+-            }
+-        }
+-    }
+-
+-    return true;
+-}
+-
+-/**
+- * iothread_vq_mapping_apply:
+- * @list: The mapping of virtqueues to IOThreads.
+- * @vq_aio_context: The array of AioContext pointers to fill in.
+- * @num_queues: The length of @vq_aio_context.
+- * @errp: If an error occurs, a pointer to the area to store the error.
+- *
+- * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
+- * the iothread-vq-mapping parameter in @list.
+- *
+- * iothread_vq_mapping_cleanup() must be called to free IOThread object
+- * references after this function returns success.
+- *
+- * Returns: %true on success, %false on failure.
+- **/
+-static bool iothread_vq_mapping_apply(
+-        IOThreadVirtQueueMappingList *list,
+-        AioContext **vq_aio_context,
+-        uint16_t num_queues,
+-        Error **errp)
+-{
+-    IOThreadVirtQueueMappingList *node;
+-    size_t num_iothreads = 0;
+-    size_t cur_iothread = 0;
+-
+-    if (!iothread_vq_mapping_validate(list, num_queues, errp)) {
+-        return false;
+-    }
+-
+-    for (node = list; node; node = node->next) {
+-        num_iothreads++;
+-    }
+-
+-    for (node = list; node; node = node->next) {
+-        IOThread *iothread = iothread_by_id(node->value->iothread);
+-        AioContext *ctx = iothread_get_aio_context(iothread);
+-
+-        /* Released in virtio_blk_vq_aio_context_cleanup() */
+-        object_ref(OBJECT(iothread));
+-
+-        if (node->value->vqs) {
+-            uint16List *vq;
+-
+-            /* Explicit vq:IOThread assignment */
+-            for (vq = node->value->vqs; vq; vq = vq->next) {
+-                assert(vq->value < num_queues);
+-                vq_aio_context[vq->value] = ctx;
+-            }
+-        } else {
+-            /* Round-robin vq:IOThread assignment */
+-            for (unsigned i = cur_iothread; i < num_queues;
+-                 i += num_iothreads) {
+-                vq_aio_context[i] = ctx;
+-            }
+-        }
+-
+-        cur_iothread++;
+-    }
+-
+-    return true;
+-}
+-
+-/**
+- * iothread_vq_mapping_cleanup:
+- * @list: The mapping of virtqueues to IOThreads.
+- *
+- * Release IOThread object references that were acquired by
+- * iothread_vq_mapping_apply().
+- */
+-static void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list)
+-{
+-    IOThreadVirtQueueMappingList *node;
+-
+-    for (node = list; node; node = node->next) {
+-        IOThread *iothread = iothread_by_id(node->value->iothread);
+-        object_unref(OBJECT(iothread));
+-    }
+-}
+-
+ /* Context: BQL held */
+ static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
+ {
+diff --git a/hw/virtio/iothread-vq-mapping.c b/hw/virtio/iothread-vq-mapping.c
+new file mode 100644
+index XXXXXXX..XXXXXXX
+--- /dev/null
++++ b/hw/virtio/iothread-vq-mapping.c
+@@ -XXX,XX +XXX,XX @@
++/*
++ * IOThread Virtqueue Mapping
++ *
++ * Copyright Red Hat, Inc
++ *
++ * SPDX-License-Identifier: GPL-2.0-only
++ */
++
 +#include "qemu/osdep.h"
-+#include "qapi/error.h"
++#include "system/iothread.h"
-+#include "qemu/sockets.h" /* for EINPROGRESS on Windows */
++#include "hw/virtio/iothread-vq-mapping.h"
-+#include "block/block_int.h"
++
-+#include "qapi/qmp/qdict.h"
++static bool
-+#include "qapi/qmp/qstring.h"
++iothread_vq_mapping_validate(IOThreadVirtQueueMappingList *list, uint16_t
-+#include "qemu/cutils.h"
++        num_queues, Error **errp)
 +#include "qemu/option.h"
 +
 +/* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */
 +
 +#define LOG_FLUSH_FLAG   (1 << 0)
 +#define LOG_FUA_FLAG     (1 << 1)
 +#define LOG_DISCARD_FLAG (1 << 2)
 +#define LOG_MARK_FLAG    (1 << 3)
 +
 +#define WRITE_LOG_VERSION 1ULL
 +#define WRITE_LOG_MAGIC 0x6a736677736872ULL
 +
 +/* All fields are little-endian. */
 +struct log_write_super {
 +    uint64_t magic;
 +    uint64_t version;
 +    uint64_t nr_entries;
 +    uint32_t sectorsize;
 +} QEMU_PACKED;
 +
 +struct log_write_entry {
 +    uint64_t sector;
 +    uint64_t nr_sectors;
 +    uint64_t flags;
 +    uint64_t data_len;
 +} QEMU_PACKED;
 +
 +/* End of disk format structures. */
 +
 +typedef struct {
 +    BdrvChild *log_file;
 +    uint32_t sectorsize;
 +    uint32_t sectorbits;
 +    uint64_t cur_log_sector;
 +    uint64_t nr_entries;
 +} BDRVBlkLogWritesState;
 +
 +static inline uint32_t blk_log_writes_log2(uint32_t value)
 +{
-+    assert(value > 0);
++    g_autofree unsigned long *vqs = bitmap_new(num_queues);
-+    return 31 - clz32(value);
++    g_autoptr(GHashTable) iothreads =
 +        g_hash_table_new(g_str_hash, g_str_equal);
 +
 +    for (IOThreadVirtQueueMappingList *node = list; node; node = node->next) {
 +        const char *name = node->value->iothread;
 +        uint16List *vq;
 +
 +        if (!iothread_by_id(name)) {
 +            error_setg(errp, "IOThread \"%s\" object does not exist", name);
 +            return false;
 +        }
 +
 +        if (!g_hash_table_add(iothreads, (gpointer)name)) {
 +            error_setg(errp,
 +                    "duplicate IOThread name \"%s\" in iothread-vq-mapping",
 +                    name);
 +            return false;
 +        }
 +
 +        if (node != list) {
 +            if (!!node->value->vqs != !!list->value->vqs) {
 +                error_setg(errp, "either all items in iothread-vq-mapping "
 +                                 "must have vqs or none of them must have it");
 +                return false;
 +            }
 +        }
 +
 +        for (vq = node->value->vqs; vq; vq = vq->next) {
 +            if (vq->value >= num_queues) {
 +                error_setg(errp, "vq index %u for IOThread \"%s\" must be "
 +                        "less than num_queues %u in iothread-vq-mapping",
 +                        vq->value, name, num_queues);
 +                return false;
 +            }
 +
 +            if (test_and_set_bit(vq->value, vqs)) {
 +                error_setg(errp, "cannot assign vq %u to IOThread \"%s\" "
 +                        "because it is already assigned", vq->value, name);
 +                return false;
 +            }
 +        }
 +    }
 +
 +    if (list->value->vqs) {
 +        for (uint16_t i = 0; i < num_queues; i++) {
 +            if (!test_bit(i, vqs)) {
 +                error_setg(errp,
 +                        "missing vq %u IOThread assignment in iothread-vq-mapping",
 +                        i);
 +                return false;
 +            }
 +        }
 +    }
 +
 +    return true;
 +}
 +
-+static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
++bool iothread_vq_mapping_apply(
-+                               Error **errp)
++        IOThreadVirtQueueMappingList *list,
 +        AioContext **vq_aio_context,
 +        uint16_t num_queues,
 +        Error **errp)
 +{
-+    BDRVBlkLogWritesState *s = bs->opaque;
++    IOThreadVirtQueueMappingList *node;
-+    Error *local_err = NULL;
++    size_t num_iothreads = 0;
-+    int ret;
++    size_t cur_iothread = 0;
-+    int64_t log_sector_size = BDRV_SECTOR_SIZE;
++
-+
++    if (!iothread_vq_mapping_validate(list, num_queues, errp)) {
-+    /* Open the file */
++        return false;
-+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
++    }
-+                               &local_err);
++
-+    if (local_err) {
++    for (node = list; node; node = node->next) {
-+        ret = -EINVAL;
++        num_iothreads++;
-+        error_propagate(errp, local_err);
++    }
-+        goto fail;
++
-+    }
++    for (node = list; node; node = node->next) {
-+
++        IOThread *iothread = iothread_by_id(node->value->iothread);
-+    if (qdict_haskey(options, "log-sector-size")) {
++        AioContext *ctx = iothread_get_aio_context(iothread);
-+        log_sector_size = qdict_get_int(options, "log-sector-size");
++
-+        qdict_del(options, "log-sector-size");
++        /* Released in virtio_blk_vq_aio_context_cleanup() */
-+    }
++        object_ref(OBJECT(iothread));
 +
-+    if (log_sector_size < 0 || log_sector_size >= (1ull << 32) ||
++        if (node->value->vqs) {
-+        !is_power_of_2(log_sector_size))
++            uint16List *vq;
-+    {
++
-+        ret = -EINVAL;
++            /* Explicit vq:IOThread assignment */
-+        error_setg(errp, "Invalid log sector size %"PRId64, log_sector_size);
++            for (vq = node->value->vqs; vq; vq = vq->next) {
-+        goto fail;
++                assert(vq->value < num_queues);
-+    }
++                vq_aio_context[vq->value] = ctx;
-+
++            }
-+    s->sectorsize = log_sector_size;
++        } else {
-+    s->sectorbits = blk_log_writes_log2(log_sector_size);
++            /* Round-robin vq:IOThread assignment */
-+    s->cur_log_sector = 1;
++            for (unsigned i = cur_iothread; i < num_queues;
-+    s->nr_entries = 0;
++                 i += num_iothreads) {
-+
++                vq_aio_context[i] = ctx;
-+    /* Open the log file */
++            }
-+    s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_file, false,
++        }
-+                                  &local_err);
++
-+    if (local_err) {
++        cur_iothread++;
-+        ret = -EINVAL;
++    }
-+        error_propagate(errp, local_err);
++
-+        goto fail;
++    return true;
 +    }
 +
 +    ret = 0;
 +fail:
 +    if (ret < 0) {
 +        bdrv_unref_child(bs, bs->file);
 +        bs->file = NULL;
 +    }
 +    return ret;
 +}
 +
-+static void blk_log_writes_close(BlockDriverState *bs)
++void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list)
 +{
-+    BDRVBlkLogWritesState *s = bs->opaque;
++    IOThreadVirtQueueMappingList *node;
 +
-+    bdrv_unref_child(bs, s->log_file);
++    for (node = list; node; node = node->next) {
-+    s->log_file = NULL;
++        IOThread *iothread = iothread_by_id(node->value->iothread);
 +        object_unref(OBJECT(iothread));
 +    }
 +}
 +
-+static int64_t blk_log_writes_getlength(BlockDriverState *bs)
+diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
 +{
 +    return bdrv_getlength(bs->file->bs);
 +}
 +
 +static void blk_log_writes_refresh_filename(BlockDriverState *bs,
 +                                            QDict *options)
 +{
 +    BDRVBlkLogWritesState *s = bs->opaque;
 +
 +    /* bs->file->bs has already been refreshed */
 +    bdrv_refresh_filename(s->log_file->bs);
 +
 +    if (bs->file->bs->full_open_options
 +        && s->log_file->bs->full_open_options)
 +    {
 +        QDict *opts = qdict_new();
 +        qdict_put_str(opts, "driver", "blklogwrites");
 +
 +        qobject_ref(bs->file->bs->full_open_options);
 +        qdict_put_obj(opts, "file", QOBJECT(bs->file->bs->full_open_options));
 +        qobject_ref(s->log_file->bs->full_open_options);
 +        qdict_put_obj(opts, "log",
 +                      QOBJECT(s->log_file->bs->full_open_options));
 +
 +        bs->full_open_options = opts;
 +    }
 +}
 +
 +static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
 +                                      const BdrvChildRole *role,
 +                                      BlockReopenQueue *ro_q,
 +                                      uint64_t perm, uint64_t shrd,
 +                                      uint64_t *nperm, uint64_t *nshrd)
 +{
 +    if (!c) {
 +        *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
 +        *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
 +        return;
 +    }
 +
 +    if (!strcmp(c->name, "log")) {
 +        bdrv_format_default_perms(bs, c, role, ro_q, perm, shrd, nperm, nshrd);
 +    } else {
 +        bdrv_filter_default_perms(bs, c, role, ro_q, perm, shrd, nperm, nshrd);
 +    }
 +}
 +
 +static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
 +{
 +    BDRVBlkLogWritesState *s = bs->opaque;
 +    bs->bl.request_alignment = s->sectorsize;
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 +                         QEMUIOVector *qiov, int flags)
 +{
 +    return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
 +}
 +
 +typedef struct BlkLogWritesFileReq {
 +    BlockDriverState *bs;
 +    uint64_t offset;
 +    uint64_t bytes;
 +    int file_flags;
 +    QEMUIOVector *qiov;
 +    int (*func)(struct BlkLogWritesFileReq *r);
 +    int file_ret;
 +} BlkLogWritesFileReq;
 +
 +typedef struct {
 +    BlockDriverState *bs;
 +    QEMUIOVector *qiov;
 +    struct log_write_entry entry;
 +    uint64_t zero_size;
 +    int log_ret;
 +} BlkLogWritesLogReq;
 +
 +static void coroutine_fn blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
 +{
 +    BDRVBlkLogWritesState *s = lr->bs->opaque;
 +    uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
 +
 +    s->nr_entries++;
 +    s->cur_log_sector +=
 +            ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
 +
 +    lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
 +                                  lr->qiov, 0);
 +
 +    /* Logging for the "write zeroes" operation */
 +    if (lr->log_ret == 0 && lr->zero_size) {
 +        cur_log_offset = s->cur_log_sector << s->sectorbits;
 +        s->cur_log_sector +=
 +                ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
 +
 +        lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
 +                                            lr->zero_size, 0);
 +    }
 +
 +    /* Update super block on flush */
 +    if (lr->log_ret == 0 && lr->entry.flags & LOG_FLUSH_FLAG) {
 +        struct log_write_super super = {
 +            .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
 +            .version    = cpu_to_le64(WRITE_LOG_VERSION),
 +            .nr_entries = cpu_to_le64(s->nr_entries),
 +            .sectorsize = cpu_to_le32(s->sectorsize),
 +        };
 +        void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
 +        QEMUIOVector qiov;
 +
 +        qemu_iovec_init(&qiov, 2);
 +        qemu_iovec_add(&qiov, &super, sizeof(super));
 +        qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
 +
 +        lr->log_ret =
 +            bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
 +        if (lr->log_ret == 0) {
 +            lr->log_ret = bdrv_co_flush(s->log_file->bs);
 +        }
 +        qemu_iovec_destroy(&qiov);
 +        g_free(zeroes);
 +    }
 +}
 +
 +static void coroutine_fn blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
 +{
 +    fr->file_ret = fr->func(fr);
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 +                      QEMUIOVector *qiov, int flags,
 +                      int (*file_func)(BlkLogWritesFileReq *r),
 +                      uint64_t entry_flags, bool is_zero_write)
 +{
 +    QEMUIOVector log_qiov;
 +    size_t niov = qiov ? qiov->niov : 0;
 +    BDRVBlkLogWritesState *s = bs->opaque;
 +    BlkLogWritesFileReq fr = {
 +        .bs         = bs,
 +        .offset     = offset,
 +        .bytes      = bytes,
 +        .file_flags = flags,
 +        .qiov       = qiov,
 +        .func       = file_func,
 +    };
 +    BlkLogWritesLogReq lr = {
 +        .bs             = bs,
 +        .qiov           = &log_qiov,
 +        .entry = {
 +            .sector     = cpu_to_le64(offset >> s->sectorbits),
 +            .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
 +            .flags      = cpu_to_le64(entry_flags),
 +            .data_len   = 0,
 +        },
 +        .zero_size = is_zero_write ? bytes : 0,
 +    };
 +    void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
 +
 +    assert((1 << s->sectorbits) == s->sectorsize);
 +    assert(bs->bl.request_alignment == s->sectorsize);
 +    assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
 +    assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
 +
 +    qemu_iovec_init(&log_qiov, niov + 2);
 +    qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
 +    qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
 +    if (qiov) {
 +        qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
 +    }
 +
 +    blk_log_writes_co_do_file(&fr);
 +    blk_log_writes_co_do_log(&lr);
 +
 +    qemu_iovec_destroy(&log_qiov);
 +    g_free(zeroes);
 +
 +    if (lr.log_ret < 0) {
 +        return lr.log_ret;
 +    }
 +
 +    return fr.file_ret;
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
 +{
 +    return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
 +                           fr->qiov, fr->file_flags);
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
 +{
 +    return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
 +                                 fr->file_flags);
 +}
 +
 +static int coroutine_fn blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
 +{
 +    return bdrv_co_flush(fr->bs->file->bs);
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
 +{
 +    return bdrv_co_pdiscard(fr->bs->file->bs, fr->offset, fr->bytes);
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
 +                          QEMUIOVector *qiov, int flags)
 +{
 +    return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
 +                                 blk_log_writes_co_do_file_pwritev, 0, false);
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
 +                                BdrvRequestFlags flags)
 +{
 +    return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
 +                                 blk_log_writes_co_do_file_pwrite_zeroes, 0,
 +                                 true);
 +}
 +
 +static int coroutine_fn blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
 +{
 +    return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
 +                                 blk_log_writes_co_do_file_flush,
 +                                 LOG_FLUSH_FLAG, false);
 +}
 +
 +static int coroutine_fn
 +blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
 +{
 +    return blk_log_writes_co_log(bs, offset, count, NULL, 0,
 +                                 blk_log_writes_co_do_file_pdiscard,
 +                                 LOG_DISCARD_FLAG, false);
 +}
 +
 +static BlockDriver bdrv_blk_log_writes = {
 +    .format_name            = "blklogwrites",
 +    .instance_size          = sizeof(BDRVBlkLogWritesState),
 +
 +    .bdrv_open              = blk_log_writes_open,
 +    .bdrv_close             = blk_log_writes_close,
 +    .bdrv_getlength         = blk_log_writes_getlength,
 +    .bdrv_refresh_filename  = blk_log_writes_refresh_filename,
 +    .bdrv_child_perm        = blk_log_writes_child_perm,
 +    .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
 +
 +    .bdrv_co_preadv         = blk_log_writes_co_preadv,
 +    .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
 +    .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
 +    .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
 +    .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
 +    .bdrv_co_block_status   = bdrv_co_block_status_from_file,
 +
 +    .is_filter              = true,
 +};
 +
 +static void bdrv_blk_log_writes_init(void)
 +{
 +    bdrv_register(&bdrv_blk_log_writes);
 +}
 +
 +block_init(bdrv_blk_log_writes_init);
 diff --git a/MAINTAINERS b/MAINTAINERS
 index XXXXXXX..XXXXXXX 100644
---- a/MAINTAINERS
+--- a/hw/virtio/meson.build
-+++ b/MAINTAINERS
++++ b/hw/virtio/meson.build
-@@ -XXX,XX +XXX,XX @@ S: Supported
+@@ -XXX,XX +XXX,XX @@
- F: block/quorum.c
+ system_virtio_ss = ss.source_set()
- L: qemu-block@nongnu.org
+ system_virtio_ss.add(files('virtio-bus.c'))
++system_virtio_ss.add(files('iothread-vq-mapping.c'))
-+blklogwrites
+ system_virtio_ss.add(when: 'CONFIG_VIRTIO_PCI', if_true: files('virtio-pci.c'))
-+M: Ari Sundholm <ari@tuxera.com>
+ system_virtio_ss.add(when: 'CONFIG_VIRTIO_MMIO', if_true: files('virtio-mmio.c'))
-+L: qemu-block@nongnu.org
+ system_virtio_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('virtio-crypto.c'))
 +S: Supported
 +F: block/blklogwrites.c
 +
  blkverify
  M: Stefan Hajnoczi <stefanha@redhat.com>
  L: qemu-block@nongnu.org
 diff --git a/block/Makefile.objs b/block/Makefile.objs
 index XXXXXXX..XXXXXXX 100644
 --- a/block/Makefile.objs
 +++ b/block/Makefile.objs
@@ -XXX,XX +XXX,XX @@ block-obj-y += qed-check.o
  block-obj-y += vhdx.o vhdx-endian.o vhdx-log.o
  block-obj-y += quorum.o
  block-obj-y += parallels.o blkdebug.o blkverify.o blkreplay.o
 +block-obj-y += blklogwrites.o
  block-obj-y += block-backend.o snapshot.o qapi.o
  block-obj-$(CONFIG_WIN32) += file-win32.o win32-aio.o
  block-obj-$(CONFIG_POSIX) += file-posix.o
 --
-.13.6
+.48.1

-New patch
+[PULL 20/22] virtio-scsi: add iothread-vq-mapping parameter
+From: Stefan Hajnoczi <stefanha@redhat.com>
+Allow virtio-scsi virtqueues to be assigned to different IOThreads. This
+makes it possible to take advantage of host multi-queue block layer
+scalability by assigning virtqueues that have affinity with vCPUs to
+different IOThreads that have affinity with host CPUs. The same feature
+was introduced for virtio-blk in the past:
+https://developers.redhat.com/articles/2024/09/05/scaling-virtio-blk-disk-io-iothread-virtqueue-mapping
+Here are fio randread 4k iodepth=64 results from a 4 vCPU guest with an
+Intel P4800X SSD:
+iothreads IOPS
+------------------------------
+189576
+312698
+346744
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-ID: <20250311132616.1049687-12-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ include/hw/virtio/virtio-scsi.h |  5 +-
+ hw/scsi/virtio-scsi-dataplane.c | 90 ++++++++++++++++++++++++---------
+ hw/scsi/virtio-scsi.c           | 63 ++++++++++++++---------
+files changed, 107 insertions(+), 51 deletions(-)
+diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
+index XXXXXXX..XXXXXXX 100644
+--- a/include/hw/virtio/virtio-scsi.h
++++ b/include/hw/virtio/virtio-scsi.h
+@@ -XXX,XX +XXX,XX @@
+ #include "hw/virtio/virtio.h"
+ #include "hw/scsi/scsi.h"
+ #include "chardev/char-fe.h"
++#include "qapi/qapi-types-virtio.h"
+ #include "system/iothread.h"
+ #define TYPE_VIRTIO_SCSI_COMMON "virtio-scsi-common"
+@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSIConf {
+     CharBackend chardev;
+     uint32_t boot_tpgt;
+     IOThread *iothread;
++    IOThreadVirtQueueMappingList *iothread_vq_mapping_list;
+ };
+ struct VirtIOSCSI;
+@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
+     QTAILQ_HEAD(, VirtIOSCSIReq) tmf_bh_list;
+     /* Fields for dataplane below */
+-    AioContext *ctx; /* one iothread per virtio-scsi-pci for now */
++    AioContext **vq_aio_context; /* per-virtqueue AioContext pointer */
+     bool dataplane_started;
+     bool dataplane_starting;
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_common_realize(DeviceState *dev,
+ void virtio_scsi_common_unrealize(DeviceState *dev);
+ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp);
++void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s);
+ int virtio_scsi_dataplane_start(VirtIODevice *s);
+ void virtio_scsi_dataplane_stop(VirtIODevice *s);
+diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/virtio-scsi-dataplane.c
++++ b/hw/scsi/virtio-scsi-dataplane.c
+@@ -XXX,XX +XXX,XX @@
+ #include "system/block-backend.h"
+ #include "hw/scsi/scsi.h"
+ #include "scsi/constants.h"
++#include "hw/virtio/iothread-vq-mapping.h"
+ #include "hw/virtio/virtio-bus.h"
+ /* Context: BQL held */
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
+     VirtIODevice *vdev = VIRTIO_DEVICE(s);
+     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
++    uint16_t num_vqs = vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED;
+-    if (vs->conf.iothread) {
++    if (vs->conf.iothread && vs->conf.iothread_vq_mapping_list) {
++        error_setg(errp,
++                   "iothread and iothread-vq-mapping properties cannot be set "
++                   "at the same time");
++        return;
++    }
++
++    if (vs->conf.iothread || vs->conf.iothread_vq_mapping_list) {
+         if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
+             error_setg(errp,
+                        "device is incompatible with iothread "
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
+             error_setg(errp, "ioeventfd is required for iothread");
+             return;
+         }
+-        s->ctx = iothread_get_aio_context(vs->conf.iothread);
+-    } else {
+-        if (!virtio_device_ioeventfd_enabled(vdev)) {
++    }
++
++    s->vq_aio_context = g_new(AioContext *, num_vqs);
++
++    if (vs->conf.iothread_vq_mapping_list) {
++        if (!iothread_vq_mapping_apply(vs->conf.iothread_vq_mapping_list,
++                                       s->vq_aio_context, num_vqs, errp)) {
++            g_free(s->vq_aio_context);
++            s->vq_aio_context = NULL;
+             return;
+         }
+-        s->ctx = qemu_get_aio_context();
++    } else if (vs->conf.iothread) {
++        AioContext *ctx = iothread_get_aio_context(vs->conf.iothread);
++        for (uint16_t i = 0; i < num_vqs; i++) {
++            s->vq_aio_context[i] = ctx;
++        }
++
++        /* Released in virtio_scsi_dataplane_cleanup() */
++        object_ref(OBJECT(vs->conf.iothread));
++    } else {
++        AioContext *ctx = qemu_get_aio_context();
++        for (unsigned i = 0; i < num_vqs; i++) {
++            s->vq_aio_context[i] = ctx;
++        }
++    }
++}
++
++/* Context: BQL held */
++void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s)
++{
++    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
++
++    if (vs->conf.iothread_vq_mapping_list) {
++        iothread_vq_mapping_cleanup(vs->conf.iothread_vq_mapping_list);
+     }
++
++    if (vs->conf.iothread) {
++        object_unref(OBJECT(vs->conf.iothread));
++    }
++
++    g_free(s->vq_aio_context);
++    s->vq_aio_context = NULL;
+ }
+ static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
+@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
+ }
+ /* Context: BH in IOThread */
+-static void virtio_scsi_dataplane_stop_bh(void *opaque)
++static void virtio_scsi_dataplane_stop_vq_bh(void *opaque)
+ {
+-    VirtIOSCSI *s = opaque;
+-    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
++    AioContext *ctx = qemu_get_current_aio_context();
++    VirtQueue *vq = opaque;
+     EventNotifier *host_notifier;
+-    int i;
+-    virtio_queue_aio_detach_host_notifier(vs->ctrl_vq, s->ctx);
+-    host_notifier = virtio_queue_get_host_notifier(vs->ctrl_vq);
++    virtio_queue_aio_detach_host_notifier(vq, ctx);
++    host_notifier = virtio_queue_get_host_notifier(vq);
+     /*
+      * Test and clear notifier after disabling event, in case poll callback
+      * didn't have time to run.
+      */
+     virtio_queue_host_notifier_read(host_notifier);
+-
+-    virtio_queue_aio_detach_host_notifier(vs->event_vq, s->ctx);
+-    host_notifier = virtio_queue_get_host_notifier(vs->event_vq);
+-    virtio_queue_host_notifier_read(host_notifier);
+-
+-    for (i = 0; i < vs->conf.num_queues; i++) {
+-        virtio_queue_aio_detach_host_notifier(vs->cmd_vqs[i], s->ctx);
+-        host_notifier = virtio_queue_get_host_notifier(vs->cmd_vqs[i]);
+-        virtio_queue_host_notifier_read(host_notifier);
+-    }
+ }
+ /* Context: BQL held */
+@@ -XXX,XX +XXX,XX @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
+     smp_wmb(); /* paired with aio_notify_accept() */
+     if (s->bus.drain_count == 0) {
+-        virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx);
+-        virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx);
++        virtio_queue_aio_attach_host_notifier(vs->ctrl_vq,
++                                              s->vq_aio_context[0]);
++        virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq,
++                                                      s->vq_aio_context[1]);
+         for (i = 0; i < vs->conf.num_queues; i++) {
+-            virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx);
++            AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
++            virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], ctx);
+         }
+     }
+     return 0;
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
+     s->dataplane_stopping = true;
+     if (s->bus.drain_count == 0) {
+-        aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
++        for (i = 0; i < vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED; i++) {
++            VirtQueue *vq = virtio_get_queue(&vs->parent_obj, i);
++            AioContext *ctx = s->vq_aio_context[i];
++            aio_wait_bh_oneshot(ctx, virtio_scsi_dataplane_stop_vq_bh, vq);
++        }
+     }
+     blk_drain_all(); /* ensure there are no in-flight requests */
+diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/virtio-scsi.c
++++ b/hw/scsi/virtio-scsi.c
+@@ -XXX,XX +XXX,XX @@
+ #include "hw/qdev-properties.h"
+ #include "hw/scsi/scsi.h"
+ #include "scsi/constants.h"
++#include "hw/virtio/iothread-vq-mapping.h"
+ #include "hw/virtio/virtio-bus.h"
+ #include "hw/virtio/virtio-access.h"
+ #include "trace.h"
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
+     g_free(n);
+ }
+-static inline void virtio_scsi_ctx_check(VirtIOSCSI *s, SCSIDevice *d)
+-{
+-    if (s->dataplane_started && d && blk_is_available(d->conf.blk)) {
+-        assert(blk_get_aio_context(d->conf.blk) == s->ctx);
+-    }
+-}
+-
+ static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
+ {
+     VirtIOSCSI *s = req->dev;
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_flush_defer_tmf_to_aio_context(VirtIOSCSI *s)
+     assert(!s->dataplane_started);
+-    if (s->ctx) {
++    for (uint32_t i = 0; i < s->parent_obj.conf.num_queues; i++) {
++        AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
++
+         /* Our BH only runs after previously scheduled BHs */
+-        aio_wait_bh_oneshot(s->ctx, dummy_bh, NULL);
++        aio_wait_bh_oneshot(ctx, dummy_bh, NULL);
+     }
+ }
+@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
+     AioContext *ctx;
+     int ret = 0;
+-    virtio_scsi_ctx_check(s, d);
+     /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
+     req->resp.tmf.response = VIRTIO_SCSI_S_OK;
+@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
+     case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
+     case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
++        g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
++
+         if (!d) {
+             goto fail;
+         }
+@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
+         qatomic_inc(&req->remaining);
+-        ctx = s->ctx ?: qemu_get_aio_context();
+-        virtio_scsi_defer_tmf_to_aio_context(req, ctx);
++        for (uint32_t i = 0; i < s->parent_obj.conf.num_queues; i++) {
++            ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
++
++            if (!g_hash_table_add(aio_contexts, ctx)) {
++                continue; /* skip previously added AioContext */
++            }
++
++            virtio_scsi_defer_tmf_to_aio_context(req, ctx);
++        }
+         virtio_scsi_tmf_dec_remaining(req);
+         ret = -EINPROGRESS;
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq)
+  */
+ static bool virtio_scsi_defer_to_dataplane(VirtIOSCSI *s)
+ {
+-    if (!s->ctx || s->dataplane_started) {
++    if (s->dataplane_started) {
+         return false;
+     }
++    if (s->vq_aio_context[0] == qemu_get_aio_context()) {
++        return false; /* not using IOThreads */
++    }
+     virtio_device_start_ioeventfd(&s->parent_obj.parent_obj);
+     return !s->dataplane_fenced;
+@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
+         virtio_scsi_complete_cmd_req(req);
+         return -ENOENT;
+     }
+-    virtio_scsi_ctx_check(s, d);
+     req->sreq = scsi_req_new(d, req->req.cmd.tag,
+                              virtio_scsi_get_lun(req->req.cmd.lun),
+                              req->req.cmd.cdb, vs->cdb_size, req);
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
+ {
+     VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
+     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
++    AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED];
+     SCSIDevice *sd = SCSI_DEVICE(dev);
+-    int ret;
+-    if (s->ctx && !s->dataplane_fenced) {
+-        ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
+-        if (ret < 0) {
+-            return;
+-        }
++    if (ctx != qemu_get_aio_context() && !s->dataplane_fenced) {
++        /*
++         * Try to make the BlockBackend's AioContext match ours. Ignore failure
++         * because I/O will still work although block jobs and other users
++         * might be slower when multiple AioContexts use a BlockBackend.
++         */
++        blk_set_aio_context(sd->conf.blk, ctx, errp);
+     }
+     if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
+     qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
+-    if (s->ctx) {
++    if (s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED] != qemu_get_aio_context()) {
+         /* If other users keep the BlockBackend in the iothread, that's ok */
+         blk_set_aio_context(sd->conf.blk, qemu_get_aio_context(), NULL);
+     }
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_drained_begin(SCSIBus *bus)
+     for (uint32_t i = 0; i < total_queues; i++) {
+         VirtQueue *vq = virtio_get_queue(vdev, i);
+-        virtio_queue_aio_detach_host_notifier(vq, s->ctx);
++        virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
+     }
+ }
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_drained_end(SCSIBus *bus)
+     for (uint32_t i = 0; i < total_queues; i++) {
+         VirtQueue *vq = virtio_get_queue(vdev, i);
++        AioContext *ctx = s->vq_aio_context[i];
++
+         if (vq == vs->event_vq) {
+-            virtio_queue_aio_attach_host_notifier_no_poll(vq, s->ctx);
++            virtio_queue_aio_attach_host_notifier_no_poll(vq, ctx);
+         } else {
+-            virtio_queue_aio_attach_host_notifier(vq, s->ctx);
++            virtio_queue_aio_attach_host_notifier(vq, ctx);
+         }
+     }
+ }
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_common_unrealize(DeviceState *dev)
+     virtio_cleanup(vdev);
+ }
++/* main loop */
+ static void virtio_scsi_device_unrealize(DeviceState *dev)
+ {
+     VirtIOSCSI *s = VIRTIO_SCSI(dev);
+     virtio_scsi_reset_tmf_bh(s);
+-
++    virtio_scsi_dataplane_cleanup(s);
+     qbus_set_hotplug_handler(BUS(&s->bus), NULL);
+     virtio_scsi_common_unrealize(dev);
+     qemu_mutex_destroy(&s->tmf_bh_lock);
+@@ -XXX,XX +XXX,XX @@ static const Property virtio_scsi_properties[] = {
+                                                 VIRTIO_SCSI_F_CHANGE, true),
+     DEFINE_PROP_LINK("iothread", VirtIOSCSI, parent_obj.conf.iothread,
+                      TYPE_IOTHREAD, IOThread *),
++    DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST("iothread-vq-mapping", VirtIOSCSI,
++            parent_obj.conf.iothread_vq_mapping_list),
+ };
+ static const VMStateDescription vmstate_virtio_scsi = {
+--
+.48.1

-[Qemu-devel] [PULL 3/5] qcow2: add compress threads
+[PULL 21/22] virtio-scsi: handle ctrl virtqueue in main loop
-From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
+From: Stefan Hajnoczi <stefanha@redhat.com>
-Do data compression in separate threads. This significantly improve
+Previously the ctrl virtqueue was handled in the AioContext where SCSI
-performance for qemu-img convert with -W (allow async writes) and -c
+requests are processed. When IOThread Virtqueue Mapping was added things
-(compressed) options.
+become more complicated because SCSI requests could run in other
+AioContexts.
-Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
 Simplify by handling the ctrl virtqueue in the main loop where reset
 operations can be performed. Note that BHs are still used canceling SCSI
 requests in their AioContexts but at least the mean loop activity
 doesn't need BHs anymore.
 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 Message-ID: <20250311132616.1049687-13-stefanha@redhat.com>
 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
 ---
- block/qcow2.h |  3 +++
+ include/hw/virtio/virtio-scsi.h |   8 --
- block/qcow2.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
+ hw/scsi/virtio-scsi-dataplane.c |   6 ++
-files changed, 64 insertions(+), 1 deletion(-)
+ hw/scsi/virtio-scsi.c           | 144 ++++++--------------------------
+files changed, 33 insertions(+), 125 deletions(-)
-diff --git a/block/qcow2.h b/block/qcow2.h
 diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
 index XXXXXXX..XXXXXXX 100644
---- a/block/qcow2.h
+--- a/include/hw/virtio/virtio-scsi.h
-+++ b/block/qcow2.h
++++ b/include/hw/virtio/virtio-scsi.h
-@@ -XXX,XX +XXX,XX @@ typedef struct BDRVQcow2State {
+@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
-      * override) */
-     char *image_backing_file;
+     QemuMutex ctrl_lock; /* protects ctrl_vq */
-     char *image_backing_format;
-+
+-    /*
-+    CoQueue compress_wait_queue;
+-     * TMFs deferred to main loop BH. These fields are protected by
-+    int nb_compress_threads;
+-     * tmf_bh_lock.
- } BDRVQcow2State;
+-     */
+-    QemuMutex tmf_bh_lock;
- typedef struct Qcow2COWRegion {
+-    QEMUBH *tmf_bh;
-diff --git a/block/qcow2.c b/block/qcow2.c
+-    QTAILQ_HEAD(, VirtIOSCSIReq) tmf_bh_list;
 -
      /* Fields for dataplane below */
      AioContext **vq_aio_context; /* per-virtqueue AioContext pointer */
 diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
 index XXXXXXX..XXXXXXX 100644
---- a/block/qcow2.c
+--- a/hw/scsi/virtio-scsi-dataplane.c
-+++ b/block/qcow2.c
++++ b/hw/scsi/virtio-scsi-dataplane.c
-@@ -XXX,XX +XXX,XX @@
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
- #include "qapi/qobject-input-visitor.h"
+             s->vq_aio_context[i] = ctx;
- #include "qapi/qapi-visit-block-core.h"
+         }
  #include "crypto.h"
 +#include "block/thread-pool.h"
  /*
    Differences with QCOW:
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
          qcow2_check_refcounts(bs, &result, 0);
      }
- #endif
++
-+
++    /*
-+    qemu_co_queue_init(&s->compress_wait_queue);
++     * Always handle the ctrl virtqueue in the main loop thread where device
-+
++     * resets can be performed.
-     return ret;
++     */
++    s->vq_aio_context[0] = qemu_get_aio_context();
   fail:
@@ -XXX,XX +XXX,XX @@ static ssize_t qcow2_compress(void *dest, const void *src, size_t size)
      return ret;
  }
-+#define MAX_COMPRESS_THREADS 4
+ /* Context: BQL held */
-+
+diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
-+typedef struct Qcow2CompressData {
+index XXXXXXX..XXXXXXX 100644
-+    void *dest;
+--- a/hw/scsi/virtio-scsi.c
-+    const void *src;
++++ b/hw/scsi/virtio-scsi.c
-+    size_t size;
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
-+    ssize_t ret;
+     g_free(n);
-+} Qcow2CompressData;
+ }
-+
-+static int qcow2_compress_pool_func(void *opaque)
+-static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
-+{
+-{
-+    Qcow2CompressData *data = opaque;
+-    VirtIOSCSI *s = req->dev;
-+
+-    SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
-+    data->ret = qcow2_compress(data->dest, data->src, data->size);
+-    BusChild *kid;
-+
+-    int target;
-+    return 0;
+-
-+}
+-    switch (req->req.tmf.subtype) {
-+
+-    case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
-+static void qcow2_compress_complete(void *opaque, int ret)
+-        if (!d) {
-+{
+-            req->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
-+    qemu_coroutine_enter(opaque);
+-            goto out;
-+}
+-        }
-+
+-        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
-+/* See qcow2_compress definition for parameters description */
+-            req->resp.tmf.response = VIRTIO_SCSI_S_INCORRECT_LUN;
-+static ssize_t qcow2_co_compress(BlockDriverState *bs,
+-            goto out;
-+                                 void *dest, const void *src, size_t size)
+-        }
-+{
+-        qatomic_inc(&s->resetting);
-+    BDRVQcow2State *s = bs->opaque;
+-        device_cold_reset(&d->qdev);
-+    BlockAIOCB *acb;
+-        qatomic_dec(&s->resetting);
-+    ThreadPool *pool = aio_get_thread_pool(bdrv_get_aio_context(bs));
+-        break;
-+    Qcow2CompressData arg = {
+-
-+        .dest = dest,
+-    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
-+        .src = src,
+-        target = req->req.tmf.lun[1];
-+        .size = size,
+-        qatomic_inc(&s->resetting);
-+    };
+-
-+
+-        rcu_read_lock();
-+    while (s->nb_compress_threads >= MAX_COMPRESS_THREADS) {
+-        QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
-+        qemu_co_queue_wait(&s->compress_wait_queue, NULL);
+-            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
 -            if (d1->channel == 0 && d1->id == target) {
 -                device_cold_reset(&d1->qdev);
 -            }
 -        }
 -        rcu_read_unlock();
 -
 -        qatomic_dec(&s->resetting);
 -        break;
 -
 -    default:
 -        g_assert_not_reached();
 -    }
 -
 -out:
 -    object_unref(OBJECT(d));
 -    virtio_scsi_complete_req(req, &s->ctrl_lock);
 -}
 -
 -/* Some TMFs must be processed from the main loop thread */
 -static void virtio_scsi_do_tmf_bh(void *opaque)
 -{
 -    VirtIOSCSI *s = opaque;
 -    QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
 -    VirtIOSCSIReq *req;
 -    VirtIOSCSIReq *tmp;
 -
 -    GLOBAL_STATE_CODE();
 -
 -    WITH_QEMU_LOCK_GUARD(&s->tmf_bh_lock) {
 -        QTAILQ_FOREACH_SAFE(req, &s->tmf_bh_list, next, tmp) {
 -            QTAILQ_REMOVE(&s->tmf_bh_list, req, next);
 -            QTAILQ_INSERT_TAIL(&reqs, req, next);
 -        }
 -
 -        qemu_bh_delete(s->tmf_bh);
 -        s->tmf_bh = NULL;
 -    }
 -
 -    QTAILQ_FOREACH_SAFE(req, &reqs, next, tmp) {
 -        QTAILQ_REMOVE(&reqs, req, next);
 -        virtio_scsi_do_one_tmf_bh(req);
 -    }
 -}
 -
 -static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s)
 -{
 -    VirtIOSCSIReq *req;
 -    VirtIOSCSIReq *tmp;
 -
 -    GLOBAL_STATE_CODE();
 -
 -    /* Called after ioeventfd has been stopped, so tmf_bh_lock is not needed */
 -    if (s->tmf_bh) {
 -        qemu_bh_delete(s->tmf_bh);
 -        s->tmf_bh = NULL;
 -    }
 -
 -    QTAILQ_FOREACH_SAFE(req, &s->tmf_bh_list, next, tmp) {
 -        QTAILQ_REMOVE(&s->tmf_bh_list, req, next);
 -
 -        /* SAM-6 6.3.2 Hard reset */
 -        req->resp.tmf.response = VIRTIO_SCSI_S_TARGET_FAILURE;
 -        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
 -    }
 -}
 -
 -static void virtio_scsi_defer_tmf_to_main_loop(VirtIOSCSIReq *req)
 -{
 -    VirtIOSCSI *s = req->dev;
 -
 -    WITH_QEMU_LOCK_GUARD(&s->tmf_bh_lock) {
 -        QTAILQ_INSERT_TAIL(&s->tmf_bh_list, req, next);
 -
 -        if (!s->tmf_bh) {
 -            s->tmf_bh = qemu_bh_new(virtio_scsi_do_tmf_bh, s);
 -            qemu_bh_schedule(s->tmf_bh);
 -        }
 -    }
 -}
 -
  static void virtio_scsi_tmf_cancel_req(VirtIOSCSIReq *tmf, SCSIRequest *r)
  {
      VirtIOSCSICancelNotifier *notifier;
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
          break;
      case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
 -    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
 -        virtio_scsi_defer_tmf_to_main_loop(req);
 -        ret = -EINPROGRESS;
 +        if (!d) {
 +            goto fail;
 +        }
 +        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
 +            goto incorrect_lun;
 +        }
 +        qatomic_inc(&s->resetting);
 +        device_cold_reset(&d->qdev);
 +        qatomic_dec(&s->resetting);
          break;
 +    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET: {
 +        BusChild *kid;
 +        int target = req->req.tmf.lun[1];
 +        qatomic_inc(&s->resetting);
 +
 +        rcu_read_lock();
 +        QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
 +            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
 +            if (d1->channel == 0 && d1->id == target) {
 +                device_cold_reset(&d1->qdev);
 +            }
 +        }
 +        rcu_read_unlock();
 +
 +        qatomic_dec(&s->resetting);
 +        break;
 +    }
 +
-+    s->nb_compress_threads++;
+     case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
-+    acb = thread_pool_submit_aio(pool, qcow2_compress_pool_func, &arg,
+     case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
-+                                 qcow2_compress_complete,
+         g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
-+                                 qemu_coroutine_self());
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset(VirtIODevice *vdev)
-+
-+    if (!acb) {
+     assert(!s->dataplane_started);
-+        s->nb_compress_threads--;
-+        return -EINVAL;
+-    virtio_scsi_reset_tmf_bh(s);
-+    }
+     virtio_scsi_flush_defer_tmf_to_aio_context(s);
-+    qemu_coroutine_yield();
-+    s->nb_compress_threads--;
+     qatomic_inc(&s->resetting);
-+    qemu_co_queue_next(&s->compress_wait_queue);
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
-+
+     VirtIOSCSI *s = VIRTIO_SCSI(dev);
-+    return arg.ret;
+     Error *err = NULL;
-+}
-+
+-    QTAILQ_INIT(&s->tmf_bh_list);
- /* XXX: put compressed sectors first, then all the cluster aligned
+     qemu_mutex_init(&s->ctrl_lock);
-    tables to avoid losing bytes in alignment */
+     qemu_mutex_init(&s->event_lock);
- static coroutine_fn int
+-    qemu_mutex_init(&s->tmf_bh_lock);
-@@ -XXX,XX +XXX,XX @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
+     virtio_scsi_common_realize(dev,
-     out_buf = g_malloc(s->cluster_size);
+                                virtio_scsi_handle_ctrl,
+@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_unrealize(DeviceState *dev)
--    out_len = qcow2_compress(out_buf, buf, s->cluster_size);
+ {
-+    out_len = qcow2_co_compress(bs, out_buf, buf, s->cluster_size);
+     VirtIOSCSI *s = VIRTIO_SCSI(dev);
-     if (out_len == -2) {
-         ret = -EINVAL;
+-    virtio_scsi_reset_tmf_bh(s);
-         goto fail;
+     virtio_scsi_dataplane_cleanup(s);
      qbus_set_hotplug_handler(BUS(&s->bus), NULL);
      virtio_scsi_common_unrealize(dev);
 -    qemu_mutex_destroy(&s->tmf_bh_lock);
      qemu_mutex_destroy(&s->event_lock);
      qemu_mutex_destroy(&s->ctrl_lock);
  }
 --
-.13.6
+.48.1

-New patch
+[PULL 22/22] virtio-scsi: only expose cmd vqs via iothread-vq-mapping
+From: Stefan Hajnoczi <stefanha@redhat.com>
+Peter Krempa and Kevin Wolf observed that iothread-vq-mapping is
+confusing to use because the control and event virtqueues have a fixed
+location before the command virtqueues but need to be treated
+differently.
+Only expose the command virtqueues via iothread-vq-mapping so that the
+command-line parameter is intuitive: it controls where SCSI requests are
+processed.
+The control virtqueue needs to be hardcoded to the main loop thread for
+technical reasons anyway. Kevin also pointed out that it's better to
+place the event virtqueue in the main loop thread since its no poll
+behavior would prevent polling if assigned to an IOThread.
+This change is its own commit to avoid squashing the previous commit.
+Suggested-by: Kevin Wolf <kwolf@redhat.com>
+Suggested-by: Peter Krempa <pkrempa@redhat.com>
+Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
+Message-ID: <20250311132616.1049687-14-stefanha@redhat.com>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+---
+ hw/scsi/virtio-scsi-dataplane.c | 33 ++++++++++++++++++++-------------
+file changed, 20 insertions(+), 13 deletions(-)
+diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
+index XXXXXXX..XXXXXXX 100644
+--- a/hw/scsi/virtio-scsi-dataplane.c
++++ b/hw/scsi/virtio-scsi-dataplane.c
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
+     VirtIODevice *vdev = VIRTIO_DEVICE(s);
+     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
+     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+-    uint16_t num_vqs = vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED;
+     if (vs->conf.iothread && vs->conf.iothread_vq_mapping_list) {
+         error_setg(errp,
+@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
+         }
+     }
+-    s->vq_aio_context = g_new(AioContext *, num_vqs);
++    s->vq_aio_context = g_new(AioContext *, vs->conf.num_queues +
++                                            VIRTIO_SCSI_VQ_NUM_FIXED);
++
++    /*
++     * Handle the ctrl virtqueue in the main loop thread where device resets
++     * can be performed.
++     */
++    s->vq_aio_context[0] = qemu_get_aio_context();
++
++    /*
++     * Handle the event virtqueue in the main loop thread where its no_poll
++     * behavior won't stop IOThread polling.
++     */
++    s->vq_aio_context[1] = qemu_get_aio_context();
+     if (vs->conf.iothread_vq_mapping_list) {
+         if (!iothread_vq_mapping_apply(vs->conf.iothread_vq_mapping_list,
+-                                       s->vq_aio_context, num_vqs, errp)) {
++                    &s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED],
++                    vs->conf.num_queues, errp)) {
+             g_free(s->vq_aio_context);
+             s->vq_aio_context = NULL;
+             return;
+         }
+     } else if (vs->conf.iothread) {
+         AioContext *ctx = iothread_get_aio_context(vs->conf.iothread);
+-        for (uint16_t i = 0; i < num_vqs; i++) {
+-            s->vq_aio_context[i] = ctx;
++        for (uint16_t i = 0; i < vs->conf.num_queues; i++) {
++            s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i] = ctx;
+         }
+         /* Released in virtio_scsi_dataplane_cleanup() */
+         object_ref(OBJECT(vs->conf.iothread));
+     } else {
+         AioContext *ctx = qemu_get_aio_context();
+-        for (unsigned i = 0; i < num_vqs; i++) {
+-            s->vq_aio_context[i] = ctx;
++        for (unsigned i = 0; i < vs->conf.num_queues; i++) {
++            s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i] = ctx;
+         }
+     }
+-
+-    /*
+-     * Always handle the ctrl virtqueue in the main loop thread where device
+-     * resets can be performed.
+-     */
+-    s->vq_aio_context[0] = qemu_get_aio_context();
+ }
+ /* Context: BQL held */
+--
+.48.1

The following changes since commit a395717cbd26e7593d3c3fe81faca121ec6d13e8:

Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging (2018-07-03 11:49:51 +0100)

are available in the git repository at:

git://repo.or.cz/qemu/kevin.git tags/for-upstream

for you to fetch changes up to 59738025a1674bb7e07713c3c93ff4fb9c5079f5:

block: Add blklogwrites (2018-07-03 16:09:48 +0200)

----------------------------------------------------------------
Block layer patches:

- qcow2: Use worker threads for compression to improve performance of
  'qemu-img convert -W' and compressed backup jobs
- blklogwrites: New filter driver to log write requests to an image in
  the dm-log-writes format

----------------------------------------------------------------
Aapo Vienamo (1):
      block: Add blklogwrites

Ari Sundholm (1):
      block: Move two block permission constants to the relevant enum

Vladimir Sementsov-Ogievskiy (3):
      qemu-img: allow compressed not-in-order writes
      qcow2: refactor data compression
      qcow2: add compress threads

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

Make a separate function for compression to be parallelized later.
 - use .avail_out field instead of .next_out to calculate size of
   compressed data. It looks more natural and it allows to keep dest to
   be void pointer
 - set avail_out to be at least one byte less than input, to be sure
   avoid inefficient compression earlier

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.c | 76 ++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 49 insertions(+), 27 deletions(-)

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 @@
  */
 
 #include "qemu/osdep.h"
+
+#define ZLIB_CONST
+#include <zlib.h>
+
 #include "block/block_int.h"
 #include "block/qdict.h"
 #include "sysemu/block-backend.h"
 #include "qemu/module.h"
-#include <zlib.h>
 #include "qcow2.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
@@ -XXX,XX +XXX,XX @@ fail:
     return ret;
 }
 
+/*
+ * qcow2_compress()
+ *
+ * @dest - destination buffer, at least of @size-1 bytes
+ * @src - source buffer, @size bytes
+ *
+ * Returns: compressed size on success
+ *          -1 if compression is inefficient
+ *          -2 on any other error
+ */
+static ssize_t qcow2_compress(void *dest, const void *src, size_t size)
+{
+    ssize_t ret;
+    z_stream strm;
+
+    /* best compression, small window, no zlib header */
+    memset(&strm, 0, sizeof(strm));
+    ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+                       -12, 9, Z_DEFAULT_STRATEGY);
+    if (ret != 0) {
+        return -2;
+    }
+
+    strm.avail_in = size;
+    strm.next_in = src;
+    strm.avail_out = size - 1;
+    strm.next_out = dest;
+
+    ret = deflate(&strm, Z_FINISH);
+    if (ret == Z_STREAM_END) {
+        ret = size - 1 - strm.avail_out;
+    } else {
+        ret = (ret == Z_OK ? -1 : -2);
+    }
+
+    deflateEnd(&strm);
+
+    return ret;
+}
+
 /* XXX: put compressed sectors first, then all the cluster aligned
    tables to avoid losing bytes in alignment */
 static coroutine_fn int
@@ -XXX,XX +XXX,XX @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
     BDRVQcow2State *s = bs->opaque;
     QEMUIOVector hd_qiov;
     struct iovec iov;
-    z_stream strm;
-    int ret, out_len;
+    int ret;
+    size_t out_len;
     uint8_t *buf, *out_buf;
     int64_t cluster_offset;
 
@@ -XXX,XX +XXX,XX @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 
     out_buf = g_malloc(s->cluster_size);
 
-    /* best compression, small window, no zlib header */
-    memset(&strm, 0, sizeof(strm));
-    ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
-                       Z_DEFLATED, -12,
-                       9, Z_DEFAULT_STRATEGY);
-    if (ret != 0) {
+    out_len = qcow2_compress(out_buf, buf, s->cluster_size);
+    if (out_len == -2) {
         ret = -EINVAL;
         goto fail;
-    }
-
-    strm.avail_in = s->cluster_size;
-    strm.next_in = (uint8_t *)buf;
-    strm.avail_out = s->cluster_size;
-    strm.next_out = out_buf;
-
-    ret = deflate(&strm, Z_FINISH);
-    if (ret != Z_STREAM_END && ret != Z_OK) {
-        deflateEnd(&strm);
-        ret = -EINVAL;
-        goto fail;
-    }
-    out_len = strm.next_out - out_buf;
-
-    deflateEnd(&strm);
-
-    if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
+    } else if (out_len == -1) {
         /* could not compress: write normal cluster */
         ret = qcow2_co_pwritev(bs, offset, bytes, qiov, 0);
         if (ret < 0) {
-- 
2.13.6

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

Do data compression in separate threads. This significantly improve
performance for qemu-img convert with -W (allow async writes) and -c
(compressed) options.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.h |  3 +++
 block/qcow2.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index XXXXXXX..XXXXXXX 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -XXX,XX +XXX,XX @@ typedef struct BDRVQcow2State {
      * override) */
     char *image_backing_file;
     char *image_backing_format;
+
+    CoQueue compress_wait_queue;
+    int nb_compress_threads;
 } BDRVQcow2State;
 
 typedef struct Qcow2COWRegion {
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 @@
 #include "qapi/qobject-input-visitor.h"
 #include "qapi/qapi-visit-block-core.h"
 #include "crypto.h"
+#include "block/thread-pool.h"
 
 /*
   Differences with QCOW:
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
         qcow2_check_refcounts(bs, &result, 0);
     }
 #endif
+
+    qemu_co_queue_init(&s->compress_wait_queue);
+
     return ret;
 
  fail:
@@ -XXX,XX +XXX,XX @@ static ssize_t qcow2_compress(void *dest, const void *src, size_t size)
     return ret;
 }
 
+#define MAX_COMPRESS_THREADS 4
+
+typedef struct Qcow2CompressData {
+    void *dest;
+    const void *src;
+    size_t size;
+    ssize_t ret;
+} Qcow2CompressData;
+
+static int qcow2_compress_pool_func(void *opaque)
+{
+    Qcow2CompressData *data = opaque;
+
+    data->ret = qcow2_compress(data->dest, data->src, data->size);
+
+    return 0;
+}
+
+static void qcow2_compress_complete(void *opaque, int ret)
+{
+    qemu_coroutine_enter(opaque);
+}
+
+/* See qcow2_compress definition for parameters description */
+static ssize_t qcow2_co_compress(BlockDriverState *bs,
+                                 void *dest, const void *src, size_t size)
+{
+    BDRVQcow2State *s = bs->opaque;
+    BlockAIOCB *acb;
+    ThreadPool *pool = aio_get_thread_pool(bdrv_get_aio_context(bs));
+    Qcow2CompressData arg = {
+        .dest = dest,
+        .src = src,
+        .size = size,
+    };
+
+    while (s->nb_compress_threads >= MAX_COMPRESS_THREADS) {
+        qemu_co_queue_wait(&s->compress_wait_queue, NULL);
+    }
+
+    s->nb_compress_threads++;
+    acb = thread_pool_submit_aio(pool, qcow2_compress_pool_func, &arg,
+                                 qcow2_compress_complete,
+                                 qemu_coroutine_self());
+
+    if (!acb) {
+        s->nb_compress_threads--;
+        return -EINVAL;
+    }
+    qemu_coroutine_yield();
+    s->nb_compress_threads--;
+    qemu_co_queue_next(&s->compress_wait_queue);
+
+    return arg.ret;
+}
+
 /* XXX: put compressed sectors first, then all the cluster aligned
    tables to avoid losing bytes in alignment */
 static coroutine_fn int
@@ -XXX,XX +XXX,XX @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 
     out_buf = g_malloc(s->cluster_size);
 
-    out_len = qcow2_compress(out_buf, buf, s->cluster_size);
+    out_len = qcow2_co_compress(bs, out_buf, buf, s->cluster_size);
     if (out_len == -2) {
         ret = -EINVAL;
         goto fail;
-- 
2.13.6

From: Ari Sundholm <ari@tuxera.com>

This allows using the two constants outside of block.c, which will
happen in a subsequent patch.

Signed-off-by: Ari Sundholm <ari@tuxera.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/block.h | 7 +++++++
 block.c               | 6 ------
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -XXX,XX +XXX,XX @@ enum {
     BLK_PERM_GRAPH_MOD          = 0x10,
 
     BLK_PERM_ALL                = 0x1f,
+
+    DEFAULT_PERM_PASSTHROUGH    = BLK_PERM_CONSISTENT_READ
+                                 | BLK_PERM_WRITE
+                                 | BLK_PERM_WRITE_UNCHANGED
+                                 | BLK_PERM_RESIZE,
+
+    DEFAULT_PERM_UNCHANGED      = BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH,
 };
 
 char *bdrv_perm_names(uint64_t perm);
diff --git a/block.c b/block.c
index XXXXXXX..XXXXXXX 100644
--- a/block.c
+++ b/block.c
@@ -XXX,XX +XXX,XX @@ int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
     return 0;
 }
 
-#define DEFAULT_PERM_PASSTHROUGH (BLK_PERM_CONSISTENT_READ \
-                                 | BLK_PERM_WRITE \
-                                 | BLK_PERM_WRITE_UNCHANGED \
-                                 | BLK_PERM_RESIZE)
-#define DEFAULT_PERM_UNCHANGED (BLK_PERM_ALL & ~DEFAULT_PERM_PASSTHROUGH)
-
 void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
                                const BdrvChildRole *role,
                                BlockReopenQueue *reopen_queue,
-- 
2.13.6

From: Aapo Vienamo <aapo@tuxera.com>

Implements a block device write logging system, similar to Linux kernel
device mapper dm-log-writes. The write operations that are performed
on a block device are logged to a file or another block device. The
write log format is identical to the dm-log-writes format. Currently,
log markers are not supported.

This functionality can be used for crash consistency and fs consistency
testing. By implementing it in qemu, tests utilizing write logs can be
be used to test non-Linux drivers and older kernels.

The driver accepts an optional parameter to set the sector size used
for logging. This makes the driver require all requests to be aligned
to this sector size and also makes offsets and sizes of writes in the
log metadata to be expressed in terms of this value (the log format has
a granularity of one sector for offsets and sizes). This allows
accurate logging of writes to guest block devices that have unusual
sector sizes.

The implementation is based on the blkverify and blkdebug block
drivers.

Signed-off-by: Aapo Vienamo <aapo@tuxera.com>
Signed-off-by: Ari Sundholm <ari@tuxera.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qapi/block-core.json |  33 ++++-
 block/blklogwrites.c | 392 +++++++++++++++++++++++++++++++++++++++++++++++++++
 MAINTAINERS          |   6 +
 block/Makefile.objs  |   1 +
 4 files changed, 426 insertions(+), 6 deletions(-)
 create mode 100644 block/blklogwrites.c

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 @@
 # @throttle: Since 2.11
 # @nvme: Since 2.12
 # @copy-on-read: Since 3.0
+# @blklogwrites: Since 3.0
 #
 # Since: 2.9
 ##
 { 'enum': 'BlockdevDriver',
-  'data': [ 'blkdebug', 'blkverify', 'bochs', 'cloop', 'copy-on-read',
-            'dmg', 'file', 'ftp', 'ftps', 'gluster', 'host_cdrom',
-            'host_device', 'http', 'https', 'iscsi', 'luks', 'nbd', 'nfs',
-            'null-aio', 'null-co', 'nvme', 'parallels', 'qcow', 'qcow2', 'qed',
-            'quorum', 'raw', 'rbd', 'replication', 'sheepdog', 'ssh',
-            'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
+  'data': [ 'blkdebug', 'blklogwrites', 'blkverify', 'bochs', 'cloop',
+            'copy-on-read', 'dmg', 'file', 'ftp', 'ftps', 'gluster',
+            'host_cdrom', 'host_device', 'http', 'https', 'iscsi', 'luks',
+            'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels', 'qcow',
+            'qcow2', 'qed', 'quorum', 'raw', 'rbd', 'replication', 'sheepdog',
+            'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
 
 ##
 # @BlockdevOptionsFile:
@@ -XXX,XX +XXX,XX @@
             '*set-state': ['BlkdebugSetStateOptions'] } }
 
 ##
+# @BlockdevOptionsBlklogwrites:
+#
+# Driver specific block device options for blklogwrites.
+#
+# @file:            block device
+#
+# @log:             block device used to log writes to @file
+#
+# @log-sector-size: sector size used in logging writes to @file, determines
+#                   granularity of offsets and sizes of writes (default: 512)
+#
+# Since: 3.0
+##
+{ 'struct': 'BlockdevOptionsBlklogwrites',
+  'data': { 'file': 'BlockdevRef',
+            'log': 'BlockdevRef',
+            '*log-sector-size': 'uint32' } }
+
+##
 # @BlockdevOptionsBlkverify:
 #
 # Driver specific block device options for blkverify.
@@ -XXX,XX +XXX,XX @@
   'discriminator': 'driver',
   'data': {
       'blkdebug':   'BlockdevOptionsBlkdebug',
+      'blklogwrites':'BlockdevOptionsBlklogwrites',
       'blkverify':  'BlockdevOptionsBlkverify',
       'bochs':      'BlockdevOptionsGenericFormat',
       'cloop':      'BlockdevOptionsGenericFormat',
diff --git a/block/blklogwrites.c b/block/blklogwrites.c
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/block/blklogwrites.c
@@ -XXX,XX +XXX,XX @@
+/*
+ * Write logging blk driver based on blkverify and blkdebug.
+ *
+ * Copyright (c) 2017 Tuomas Tynkkynen <tuomas@tuxera.com>
+ * Copyright (c) 2018 Aapo Vienamo <aapo@tuxera.com>
+ * Copyright (c) 2018 Ari Sundholm <ari@tuxera.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 "qemu/sockets.h" /* for EINPROGRESS on Windows */
+#include "block/block_int.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
+#include "qemu/cutils.h"
+#include "qemu/option.h"
+
+/* Disk format stuff - taken from Linux drivers/md/dm-log-writes.c */
+
+#define LOG_FLUSH_FLAG   (1 << 0)
+#define LOG_FUA_FLAG     (1 << 1)
+#define LOG_DISCARD_FLAG (1 << 2)
+#define LOG_MARK_FLAG    (1 << 3)
+
+#define WRITE_LOG_VERSION 1ULL
+#define WRITE_LOG_MAGIC 0x6a736677736872ULL
+
+/* All fields are little-endian. */
+struct log_write_super {
+    uint64_t magic;
+    uint64_t version;
+    uint64_t nr_entries;
+    uint32_t sectorsize;
+} QEMU_PACKED;
+
+struct log_write_entry {
+    uint64_t sector;
+    uint64_t nr_sectors;
+    uint64_t flags;
+    uint64_t data_len;
+} QEMU_PACKED;
+
+/* End of disk format structures. */
+
+typedef struct {
+    BdrvChild *log_file;
+    uint32_t sectorsize;
+    uint32_t sectorbits;
+    uint64_t cur_log_sector;
+    uint64_t nr_entries;
+} BDRVBlkLogWritesState;
+
+static inline uint32_t blk_log_writes_log2(uint32_t value)
+{
+    assert(value > 0);
+    return 31 - clz32(value);
+}
+
+static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
+                               Error **errp)
+{
+    BDRVBlkLogWritesState *s = bs->opaque;
+    Error *local_err = NULL;
+    int ret;
+    int64_t log_sector_size = BDRV_SECTOR_SIZE;
+
+    /* Open the file */
+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, false,
+                               &local_err);
+    if (local_err) {
+        ret = -EINVAL;
+        error_propagate(errp, local_err);
+        goto fail;
+    }
+
+    if (qdict_haskey(options, "log-sector-size")) {
+        log_sector_size = qdict_get_int(options, "log-sector-size");
+        qdict_del(options, "log-sector-size");
+    }
+
+    if (log_sector_size < 0 || log_sector_size >= (1ull << 32) ||
+        !is_power_of_2(log_sector_size))
+    {
+        ret = -EINVAL;
+        error_setg(errp, "Invalid log sector size %"PRId64, log_sector_size);
+        goto fail;
+    }
+
+    s->sectorsize = log_sector_size;
+    s->sectorbits = blk_log_writes_log2(log_sector_size);
+    s->cur_log_sector = 1;
+    s->nr_entries = 0;
+
+    /* Open the log file */
+    s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_file, false,
+                                  &local_err);
+    if (local_err) {
+        ret = -EINVAL;
+        error_propagate(errp, local_err);
+        goto fail;
+    }
+
+    ret = 0;
+fail:
+    if (ret < 0) {
+        bdrv_unref_child(bs, bs->file);
+        bs->file = NULL;
+    }
+    return ret;
+}
+
+static void blk_log_writes_close(BlockDriverState *bs)
+{
+    BDRVBlkLogWritesState *s = bs->opaque;
+
+    bdrv_unref_child(bs, s->log_file);
+    s->log_file = NULL;
+}
+
+static int64_t blk_log_writes_getlength(BlockDriverState *bs)
+{
+    return bdrv_getlength(bs->file->bs);
+}
+
+static void blk_log_writes_refresh_filename(BlockDriverState *bs,
+                                            QDict *options)
+{
+    BDRVBlkLogWritesState *s = bs->opaque;
+
+    /* bs->file->bs has already been refreshed */
+    bdrv_refresh_filename(s->log_file->bs);
+
+    if (bs->file->bs->full_open_options
+        && s->log_file->bs->full_open_options)
+    {
+        QDict *opts = qdict_new();
+        qdict_put_str(opts, "driver", "blklogwrites");
+
+        qobject_ref(bs->file->bs->full_open_options);
+        qdict_put_obj(opts, "file", QOBJECT(bs->file->bs->full_open_options));
+        qobject_ref(s->log_file->bs->full_open_options);
+        qdict_put_obj(opts, "log",
+                      QOBJECT(s->log_file->bs->full_open_options));
+
+        bs->full_open_options = opts;
+    }
+}
+
+static void blk_log_writes_child_perm(BlockDriverState *bs, BdrvChild *c,
+                                      const BdrvChildRole *role,
+                                      BlockReopenQueue *ro_q,
+                                      uint64_t perm, uint64_t shrd,
+                                      uint64_t *nperm, uint64_t *nshrd)
+{
+    if (!c) {
+        *nperm = perm & DEFAULT_PERM_PASSTHROUGH;
+        *nshrd = (shrd & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
+        return;
+    }
+
+    if (!strcmp(c->name, "log")) {
+        bdrv_format_default_perms(bs, c, role, ro_q, perm, shrd, nperm, nshrd);
+    } else {
+        bdrv_filter_default_perms(bs, c, role, ro_q, perm, shrd, nperm, nshrd);
+    }
+}
+
+static void blk_log_writes_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+    BDRVBlkLogWritesState *s = bs->opaque;
+    bs->bl.request_alignment = s->sectorsize;
+}
+
+static int coroutine_fn
+blk_log_writes_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                         QEMUIOVector *qiov, int flags)
+{
+    return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
+}
+
+typedef struct BlkLogWritesFileReq {
+    BlockDriverState *bs;
+    uint64_t offset;
+    uint64_t bytes;
+    int file_flags;
+    QEMUIOVector *qiov;
+    int (*func)(struct BlkLogWritesFileReq *r);
+    int file_ret;
+} BlkLogWritesFileReq;
+
+typedef struct {
+    BlockDriverState *bs;
+    QEMUIOVector *qiov;
+    struct log_write_entry entry;
+    uint64_t zero_size;
+    int log_ret;
+} BlkLogWritesLogReq;
+
+static void coroutine_fn blk_log_writes_co_do_log(BlkLogWritesLogReq *lr)
+{
+    BDRVBlkLogWritesState *s = lr->bs->opaque;
+    uint64_t cur_log_offset = s->cur_log_sector << s->sectorbits;
+
+    s->nr_entries++;
+    s->cur_log_sector +=
+            ROUND_UP(lr->qiov->size, s->sectorsize) >> s->sectorbits;
+
+    lr->log_ret = bdrv_co_pwritev(s->log_file, cur_log_offset, lr->qiov->size,
+                                  lr->qiov, 0);
+
+    /* Logging for the "write zeroes" operation */
+    if (lr->log_ret == 0 && lr->zero_size) {
+        cur_log_offset = s->cur_log_sector << s->sectorbits;
+        s->cur_log_sector +=
+                ROUND_UP(lr->zero_size, s->sectorsize) >> s->sectorbits;
+
+        lr->log_ret = bdrv_co_pwrite_zeroes(s->log_file, cur_log_offset,
+                                            lr->zero_size, 0);
+    }
+
+    /* Update super block on flush */
+    if (lr->log_ret == 0 && lr->entry.flags & LOG_FLUSH_FLAG) {
+        struct log_write_super super = {
+            .magic      = cpu_to_le64(WRITE_LOG_MAGIC),
+            .version    = cpu_to_le64(WRITE_LOG_VERSION),
+            .nr_entries = cpu_to_le64(s->nr_entries),
+            .sectorsize = cpu_to_le32(s->sectorsize),
+        };
+        void *zeroes = g_malloc0(s->sectorsize - sizeof(super));
+        QEMUIOVector qiov;
+
+        qemu_iovec_init(&qiov, 2);
+        qemu_iovec_add(&qiov, &super, sizeof(super));
+        qemu_iovec_add(&qiov, zeroes, s->sectorsize - sizeof(super));
+
+        lr->log_ret =
+            bdrv_co_pwritev(s->log_file, 0, s->sectorsize, &qiov, 0);
+        if (lr->log_ret == 0) {
+            lr->log_ret = bdrv_co_flush(s->log_file->bs);
+        }
+        qemu_iovec_destroy(&qiov);
+        g_free(zeroes);
+    }
+}
+
+static void coroutine_fn blk_log_writes_co_do_file(BlkLogWritesFileReq *fr)
+{
+    fr->file_ret = fr->func(fr);
+}
+
+static int coroutine_fn
+blk_log_writes_co_log(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                      QEMUIOVector *qiov, int flags,
+                      int (*file_func)(BlkLogWritesFileReq *r),
+                      uint64_t entry_flags, bool is_zero_write)
+{
+    QEMUIOVector log_qiov;
+    size_t niov = qiov ? qiov->niov : 0;
+    BDRVBlkLogWritesState *s = bs->opaque;
+    BlkLogWritesFileReq fr = {
+        .bs         = bs,
+        .offset     = offset,
+        .bytes      = bytes,
+        .file_flags = flags,
+        .qiov       = qiov,
+        .func       = file_func,
+    };
+    BlkLogWritesLogReq lr = {
+        .bs             = bs,
+        .qiov           = &log_qiov,
+        .entry = {
+            .sector     = cpu_to_le64(offset >> s->sectorbits),
+            .nr_sectors = cpu_to_le64(bytes >> s->sectorbits),
+            .flags      = cpu_to_le64(entry_flags),
+            .data_len   = 0,
+        },
+        .zero_size = is_zero_write ? bytes : 0,
+    };
+    void *zeroes = g_malloc0(s->sectorsize - sizeof(lr.entry));
+
+    assert((1 << s->sectorbits) == s->sectorsize);
+    assert(bs->bl.request_alignment == s->sectorsize);
+    assert(QEMU_IS_ALIGNED(offset, bs->bl.request_alignment));
+    assert(QEMU_IS_ALIGNED(bytes, bs->bl.request_alignment));
+
+    qemu_iovec_init(&log_qiov, niov + 2);
+    qemu_iovec_add(&log_qiov, &lr.entry, sizeof(lr.entry));
+    qemu_iovec_add(&log_qiov, zeroes, s->sectorsize - sizeof(lr.entry));
+    if (qiov) {
+        qemu_iovec_concat(&log_qiov, qiov, 0, qiov->size);
+    }
+
+    blk_log_writes_co_do_file(&fr);
+    blk_log_writes_co_do_log(&lr);
+
+    qemu_iovec_destroy(&log_qiov);
+    g_free(zeroes);
+
+    if (lr.log_ret < 0) {
+        return lr.log_ret;
+    }
+
+    return fr.file_ret;
+}
+
+static int coroutine_fn
+blk_log_writes_co_do_file_pwritev(BlkLogWritesFileReq *fr)
+{
+    return bdrv_co_pwritev(fr->bs->file, fr->offset, fr->bytes,
+                           fr->qiov, fr->file_flags);
+}
+
+static int coroutine_fn
+blk_log_writes_co_do_file_pwrite_zeroes(BlkLogWritesFileReq *fr)
+{
+    return bdrv_co_pwrite_zeroes(fr->bs->file, fr->offset, fr->bytes,
+                                 fr->file_flags);
+}
+
+static int coroutine_fn blk_log_writes_co_do_file_flush(BlkLogWritesFileReq *fr)
+{
+    return bdrv_co_flush(fr->bs->file->bs);
+}
+
+static int coroutine_fn
+blk_log_writes_co_do_file_pdiscard(BlkLogWritesFileReq *fr)
+{
+    return bdrv_co_pdiscard(fr->bs->file->bs, fr->offset, fr->bytes);
+}
+
+static int coroutine_fn
+blk_log_writes_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
+                          QEMUIOVector *qiov, int flags)
+{
+    return blk_log_writes_co_log(bs, offset, bytes, qiov, flags,
+                                 blk_log_writes_co_do_file_pwritev, 0, false);
+}
+
+static int coroutine_fn
+blk_log_writes_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int bytes,
+                                BdrvRequestFlags flags)
+{
+    return blk_log_writes_co_log(bs, offset, bytes, NULL, flags,
+                                 blk_log_writes_co_do_file_pwrite_zeroes, 0,
+                                 true);
+}
+
+static int coroutine_fn blk_log_writes_co_flush_to_disk(BlockDriverState *bs)
+{
+    return blk_log_writes_co_log(bs, 0, 0, NULL, 0,
+                                 blk_log_writes_co_do_file_flush,
+                                 LOG_FLUSH_FLAG, false);
+}
+
+static int coroutine_fn
+blk_log_writes_co_pdiscard(BlockDriverState *bs, int64_t offset, int count)
+{
+    return blk_log_writes_co_log(bs, offset, count, NULL, 0,
+                                 blk_log_writes_co_do_file_pdiscard,
+                                 LOG_DISCARD_FLAG, false);
+}
+
+static BlockDriver bdrv_blk_log_writes = {
+    .format_name            = "blklogwrites",
+    .instance_size          = sizeof(BDRVBlkLogWritesState),
+
+    .bdrv_open              = blk_log_writes_open,
+    .bdrv_close             = blk_log_writes_close,
+    .bdrv_getlength         = blk_log_writes_getlength,
+    .bdrv_refresh_filename  = blk_log_writes_refresh_filename,
+    .bdrv_child_perm        = blk_log_writes_child_perm,
+    .bdrv_refresh_limits    = blk_log_writes_refresh_limits,
+
+    .bdrv_co_preadv         = blk_log_writes_co_preadv,
+    .bdrv_co_pwritev        = blk_log_writes_co_pwritev,
+    .bdrv_co_pwrite_zeroes  = blk_log_writes_co_pwrite_zeroes,
+    .bdrv_co_flush_to_disk  = blk_log_writes_co_flush_to_disk,
+    .bdrv_co_pdiscard       = blk_log_writes_co_pdiscard,
+    .bdrv_co_block_status   = bdrv_co_block_status_from_file,
+
+    .is_filter              = true,
+};
+
+static void bdrv_blk_log_writes_init(void)
+{
+    bdrv_register(&bdrv_blk_log_writes);
+}
+
+block_init(bdrv_blk_log_writes_init);
diff --git a/MAINTAINERS b/MAINTAINERS
index XXXXXXX..XXXXXXX 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -XXX,XX +XXX,XX @@ S: Supported
 F: block/quorum.c
 L: qemu-block@nongnu.org
 
+blklogwrites
+M: Ari Sundholm <ari@tuxera.com>
+L: qemu-block@nongnu.org
+S: Supported
+F: block/blklogwrites.c
+
 blkverify
 M: Stefan Hajnoczi <stefanha@redhat.com>
 L: qemu-block@nongnu.org
diff --git a/block/Makefile.objs b/block/Makefile.objs
index XXXXXXX..XXXXXXX 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -XXX,XX +XXX,XX @@ block-obj-y += qed-check.o
 block-obj-y += vhdx.o vhdx-endian.o vhdx-log.o
 block-obj-y += quorum.o
 block-obj-y += parallels.o blkdebug.o blkverify.o blkreplay.o
+block-obj-y += blklogwrites.o
 block-obj-y += block-backend.o snapshot.o qapi.o
 block-obj-$(CONFIG_WIN32) += file-win32.o win32-aio.o
 block-obj-$(CONFIG_POSIX) += file-posix.o
-- 
2.13.6

The following changes since commit 825b96dbcee23d134b691fc75618b59c5f53da32:

Merge tag 'migration-20250310-pull-request' of https://gitlab.com/farosas/qemu into staging (2025-03-11 09:32:07 +0800)

are available in the Git repository at:

https://repo.or.cz/qemu/kevin.git tags/for-upstream

for you to fetch changes up to a93c04f3cbe690877b3297a9df4767aa811fcd97:

virtio-scsi: only expose cmd vqs via iothread-vq-mapping (2025-03-11 15:49:22 +0100)

----------------------------------------------------------------
Block layer patches

- virtio-scsi: add iothread-vq-mapping parameter
- Improve writethrough performance
- Fix missing zero init in bdrv_snapshot_goto()
- Code cleanup and iotests fixes

----------------------------------------------------------------
Kevin Wolf (8):
      block: Remove unused blk_op_is_blocked()
      block: Zero block driver state before reopening
      file-posix: Support FUA writes
      block/io: Ignore FUA with cache.no-flush=on
      aio: Create AioPolledEvent
      aio-posix: Factor out adjust_polling_time()
      aio-posix: Separate AioPolledEvent per AioHandler
      aio-posix: Adjust polling time also for new handlers

Stefan Hajnoczi (13):
      scsi-disk: drop unused SCSIDiskState->bh field
      dma: use current AioContext for dma_blk_io()
      scsi: track per-SCSIRequest AioContext
      scsi: introduce requests_lock
      virtio-scsi: introduce event and ctrl virtqueue locks
      virtio-scsi: protect events_dropped field
      virtio-scsi: perform TMFs in appropriate AioContexts
      virtio-blk: extract cleanup_iothread_vq_mapping() function
      virtio-blk: tidy up iothread_vq_mapping functions
      virtio: extract iothread-vq-mapping.h API
      virtio-scsi: add iothread-vq-mapping parameter
      virtio-scsi: handle ctrl virtqueue in main loop
      virtio-scsi: only expose cmd vqs via iothread-vq-mapping

Thomas Huth (1):
      iotests: Limit qsd-migrate to working formats

Commit fc4e394b28 removed the last caller of blk_op_is_blocked(). Remove
the now unused function.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250206165331.379033-1-kwolf@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/system/block-backend-global-state.h |  1 -
 block/block-backend.c                       | 12 ------------
 2 files changed, 13 deletions(-)

diff --git a/include/system/block-backend-global-state.h b/include/system/block-backend-global-state.h
index XXXXXXX..XXXXXXX 100644
--- a/include/system/block-backend-global-state.h
+++ b/include/system/block-backend-global-state.h
@@ -XXX,XX +XXX,XX @@ bool blk_supports_write_perm(BlockBackend *blk);
 bool blk_is_sg(BlockBackend *blk);
 void blk_set_enable_write_cache(BlockBackend *blk, bool wce);
 int blk_get_flags(BlockBackend *blk);
-bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp);
 int blk_set_aio_context(BlockBackend *blk, AioContext *new_context,
                         Error **errp);
 void blk_add_aio_context_notifier(BlockBackend *blk,
diff --git a/block/block-backend.c b/block/block-backend.c
index XXXXXXX..XXXXXXX 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -XXX,XX +XXX,XX @@ void *blk_blockalign(BlockBackend *blk, size_t size)
     return qemu_blockalign(blk ? blk_bs(blk) : NULL, size);
 }
 
-bool blk_op_is_blocked(BlockBackend *blk, BlockOpType op, Error **errp)
-{
-    BlockDriverState *bs = blk_bs(blk);
-    GLOBAL_STATE_CODE();
-    GRAPH_RDLOCK_GUARD_MAINLOOP();
-
-    if (!bs) {
-        return false;
-    }
-
-    return bdrv_op_is_blocked(bs, op, errp);
-}
 
 /**
  * Return BB's current AioContext.  Note that this context may change
-- 
2.48.1

Block drivers assume in their .bdrv_open() implementation that their
state in bs->opaque has been zeroed; it is initially allocated with
g_malloc0() in bdrv_open_driver().

bdrv_snapshot_goto() needs to make sure that it is zeroed again before
calling drv->bdrv_open() to avoid that block drivers use stale values.

One symptom of this bug is VMDK running into a double free when the user
tries to apply an internal snapshot like 'qemu-img snapshot -a test
test.vmdk'. This should be a graceful error because VMDK doesn't support
internal snapshots.

==25507== Invalid free() / delete / delete[] / realloc()
==25507==    at 0x484B347: realloc (vg_replace_malloc.c:1801)
==25507==    by 0x54B592A: g_realloc (gmem.c:171)
==25507==    by 0x1B221D: vmdk_add_extent (../block/vmdk.c:570)
==25507==    by 0x1B1084: vmdk_open_sparse (../block/vmdk.c:1059)
==25507==    by 0x1AF3D8: vmdk_open (../block/vmdk.c:1371)
==25507==    by 0x1A2AE0: bdrv_snapshot_goto (../block/snapshot.c:299)
==25507==    by 0x205C77: img_snapshot (../qemu-img.c:3500)
==25507==    by 0x58FA087: (below main) (libc_start_call_main.h:58)
==25507==  Address 0x832f3e0 is 0 bytes inside a block of size 272 free'd
==25507==    at 0x4846B83: free (vg_replace_malloc.c:989)
==25507==    by 0x54AEAC4: g_free (gmem.c:208)
==25507==    by 0x1AF629: vmdk_close (../block/vmdk.c:2889)
==25507==    by 0x1A2A9C: bdrv_snapshot_goto (../block/snapshot.c:290)
==25507==    by 0x205C77: img_snapshot (../qemu-img.c:3500)
==25507==    by 0x58FA087: (below main) (libc_start_call_main.h:58)

This error was discovered by fuzzing qemu-img.

Cc: qemu-stable@nongnu.org
Closes: https://gitlab.com/qemu-project/qemu/-/issues/2853
Closes: https://gitlab.com/qemu-project/qemu/-/issues/2851
Reported-by: Denis Rastyogin <gerben@altlinux.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250310104858.28221-1-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/snapshot.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/snapshot.c b/block/snapshot.c
index XXXXXXX..XXXXXXX 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -XXX,XX +XXX,XX @@ int bdrv_snapshot_goto(BlockDriverState *bs,
         bdrv_graph_wrunlock();
 
         ret = bdrv_snapshot_goto(fallback_bs, snapshot_id, errp);
+        memset(bs->opaque, 0, drv->instance_size);
         open_ret = drv->bdrv_open(bs, options, bs->open_flags, &local_err);
         qobject_unref(options);
         if (open_ret < 0) {
-- 
2.48.1

Until now, FUA was always emulated with a separate flush after the write
for file-posix. The overhead of processing a second request can reduce
performance significantly for a guest disk that has disabled the write
cache, especially if the host disk is already write through, too, and
the flush isn't actually doing anything.

Advertise support for REQ_FUA in write requests and implement it for
Linux AIO and io_uring using the RWF_DSYNC flag for write requests. The
thread pool still performs a separate fdatasync() call. This can be
improved later by using the pwritev2() syscall if available.

As an example, this is how fio numbers can be improved in some scenarios
with this patch (all using virtio-blk with cache=directsync on an nvme
block device for the VM, fio with ioengine=libaio,direct=1,sync=1):

However, not all scenarios are clear wins. On another slower disk I saw
little to no improvment. In fact, in two corner case scenarios, I even
observed a regression, which I however consider acceptable:

1. On slow host disks in a write through cache mode, when the guest is
   using virtio-blk in a separate iothread so that polling can be
   enabled, and each completion is quickly followed up with a new
   request (so that polling gets it), it can happen that enabling FUA
   makes things slower - the additional very fast no-op flush we used to
   have gave the adaptive polling algorithm a success so that it kept
   polling. Without it, we only have the slow write request, which
   disables polling. This is a problem in the polling algorithm that
   will be fixed later in this series.

2. With a high queue depth, it can be beneficial to have flush requests
   for another reason: The optimisation in bdrv_co_flush() that flushes
   only once per write generation acts as a synchronisation mechanism
   that lets all requests complete at the same time. This can result in
   better batching and if the disk is very fast (I only saw this with a
   null_blk backend), this can make up for the overhead of the flush and
   improve throughput. In theory, we could optionally introduce a
   similar artificial latency in the normal completion path to achieve
   the same kind of completion batching. This is not implemented in this
   series.

Compatibility is not a concern for io_uring, it has supported RWF_DSYNC
from the start. Linux AIO started supporting it in Linux 4.13 and libaio
0.3.111. The kernel is not a problem for any supported build platform,
so it's not necessary to add runtime checks. However, openSUSE is still
stuck with an older libaio version that would break the build. We must
detect this at build time to avoid build failures.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-2-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/raw-aio.h |  8 ++++++--
 block/file-posix.c      | 26 ++++++++++++++++++--------
 block/io_uring.c        | 13 ++++++++-----
 block/linux-aio.c       | 24 +++++++++++++++++++++---
 meson.build             |  4 ++++
 5 files changed, 57 insertions(+), 18 deletions(-)

diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/raw-aio.h
+++ b/include/block/raw-aio.h
@@ -XXX,XX +XXX,XX @@
 #define QEMU_RAW_AIO_H
 
 #include "block/aio.h"
+#include "block/block-common.h"
 #include "qemu/iov.h"
 
 /* AIO request types */
@@ -XXX,XX +XXX,XX @@ void laio_cleanup(LinuxAioState *s);
 
 /* laio_co_submit: submit I/O requests in the thread's current AioContext. */
 int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
-                                int type, uint64_t dev_max_batch);
+                                int type, BdrvRequestFlags flags,
+                                uint64_t dev_max_batch);
 
 bool laio_has_fdsync(int);
+bool laio_has_fua(void);
 void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context);
 void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context);
 #endif
@@ -XXX,XX +XXX,XX @@ void luring_cleanup(LuringState *s);
 
 /* luring_co_submit: submit I/O requests in the thread's current AioContext. */
 int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
-                                  QEMUIOVector *qiov, int type);
+                                  QEMUIOVector *qiov, int type,
+                                  BdrvRequestFlags flags);
 void luring_detach_aio_context(LuringState *s, AioContext *old_context);
 void luring_attach_aio_context(LuringState *s, AioContext *new_context);
 #endif
diff --git a/block/file-posix.c b/block/file-posix.c
index XXXXXXX..XXXXXXX 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -XXX,XX +XXX,XX @@ static int fd_open(BlockDriverState *bs)
 }
 
 static int64_t raw_getlength(BlockDriverState *bs);
+static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs);
 
 typedef struct RawPosixAIOData {
     BlockDriverState *bs;
@@ -XXX,XX +XXX,XX @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
 #endif
     s->needs_alignment = raw_needs_alignment(bs);
 
+    if (!s->use_linux_aio || laio_has_fua()) {
+        bs->supported_write_flags = BDRV_REQ_FUA;
+    }
+
     bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK;
     if (S_ISREG(st.st_mode)) {
         /* When extending regular files, we get zeros from the OS */
@@ -XXX,XX +XXX,XX @@ static inline bool raw_check_linux_aio(BDRVRawState *s)
 #endif
 
 static int coroutine_fn raw_co_prw(BlockDriverState *bs, int64_t *offset_ptr,
-                                   uint64_t bytes, QEMUIOVector *qiov, int type)
+                                   uint64_t bytes, QEMUIOVector *qiov, int type,
+                                   int flags)
 {
     BDRVRawState *s = bs->opaque;
     RawPosixAIOData acb;
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, int64_t *offset_ptr,
 #ifdef CONFIG_LINUX_IO_URING
     } else if (raw_check_linux_io_uring(s)) {
         assert(qiov->size == bytes);
-        ret = luring_co_submit(bs, s->fd, offset, qiov, type);
+        ret = luring_co_submit(bs, s->fd, offset, qiov, type, flags);
         goto out;
 #endif
 #ifdef CONFIG_LINUX_AIO
     } else if (raw_check_linux_aio(s)) {
         assert(qiov->size == bytes);
-        ret = laio_co_submit(s->fd, offset, qiov, type,
+        ret = laio_co_submit(s->fd, offset, qiov, type, flags,
                               s->aio_max_batch);
         goto out;
 #endif
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, int64_t *offset_ptr,
 
     assert(qiov->size == bytes);
     ret = raw_thread_pool_submit(handle_aiocb_rw, &acb);
+    if (ret == 0 && (flags & BDRV_REQ_FUA)) {
+        /* TODO Use pwritev2() instead if it's available */
+        ret = raw_co_flush_to_disk(bs);
+    }
     goto out; /* Avoid the compiler err of unused label */
 
 out:
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_preadv(BlockDriverState *bs, int64_t offset,
                                       int64_t bytes, QEMUIOVector *qiov,
                                       BdrvRequestFlags flags)
 {
-    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_READ);
+    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_READ, flags);
 }
 
 static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, int64_t offset,
                                        int64_t bytes, QEMUIOVector *qiov,
                                        BdrvRequestFlags flags)
 {
-    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_WRITE);
+    return raw_co_prw(bs, &offset, bytes, qiov, QEMU_AIO_WRITE, flags);
 }
 
 static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_flush_to_disk(BlockDriverState *bs)
 
 #ifdef CONFIG_LINUX_IO_URING
     if (raw_check_linux_io_uring(s)) {
-        return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH);
+        return luring_co_submit(bs, s->fd, 0, NULL, QEMU_AIO_FLUSH, 0);
     }
 #endif
 #ifdef CONFIG_LINUX_AIO
     if (s->has_laio_fdsync && raw_check_linux_aio(s)) {
-        return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0);
+        return laio_co_submit(s->fd, 0, NULL, QEMU_AIO_FLUSH, 0, 0);
     }
 #endif
     return raw_thread_pool_submit(handle_aiocb_flush, &acb);
@@ -XXX,XX +XXX,XX @@ static int coroutine_fn raw_co_zone_append(BlockDriverState *bs,
     }
 
     trace_zbd_zone_append(bs, *offset >> BDRV_SECTOR_BITS);
-    return raw_co_prw(bs, offset, len, qiov, QEMU_AIO_ZONE_APPEND);
+    return raw_co_prw(bs, offset, len, qiov, QEMU_AIO_ZONE_APPEND, 0);
 }
 #endif
 
diff --git a/block/io_uring.c b/block/io_uring.c
index XXXXXXX..XXXXXXX 100644
--- a/block/io_uring.c
+++ b/block/io_uring.c
@@ -XXX,XX +XXX,XX @@ static void luring_deferred_fn(void *opaque)
  *
  */
 static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
-                            uint64_t offset, int type)
+                            uint64_t offset, int type, BdrvRequestFlags flags)
 {
     int ret;
     struct io_uring_sqe *sqes = &luringcb->sqeq;
+    int luring_flags;
 
     switch (type) {
     case QEMU_AIO_WRITE:
-        io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
-                             luringcb->qiov->niov, offset);
+        luring_flags = (flags & BDRV_REQ_FUA) ? RWF_DSYNC : 0;
+        io_uring_prep_writev2(sqes, fd, luringcb->qiov->iov,
+                              luringcb->qiov->niov, offset, luring_flags);
         break;
     case QEMU_AIO_ZONE_APPEND:
         io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
@@ -XXX,XX +XXX,XX @@ static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
 }
 
 int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
-                                  QEMUIOVector *qiov, int type)
+                                  QEMUIOVector *qiov, int type,
+                                  BdrvRequestFlags flags)
 {
     int ret;
     AioContext *ctx = qemu_get_current_aio_context();
@@ -XXX,XX +XXX,XX @@ int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
     };
     trace_luring_co_submit(bs, s, &luringcb, fd, offset, qiov ? qiov->size : 0,
                            type);
-    ret = luring_do_submit(fd, &luringcb, s, offset, type);
+    ret = luring_do_submit(fd, &luringcb, s, offset, type, flags);
 
     if (ret < 0) {
         return ret;
diff --git a/block/linux-aio.c b/block/linux-aio.c
index XXXXXXX..XXXXXXX 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -XXX,XX +XXX,XX @@ static void laio_deferred_fn(void *opaque)
 }
 
 static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
-                          int type, uint64_t dev_max_batch)
+                          int type, BdrvRequestFlags flags,
+                          uint64_t dev_max_batch)
 {
     LinuxAioState *s = laiocb->ctx;
     struct iocb *iocbs = &laiocb->iocb;
     QEMUIOVector *qiov = laiocb->qiov;
+    int laio_flags;
 
     switch (type) {
     case QEMU_AIO_WRITE:
+#ifdef HAVE_IO_PREP_PWRITEV2
+        laio_flags = (flags & BDRV_REQ_FUA) ? RWF_DSYNC : 0;
+        io_prep_pwritev2(iocbs, fd, qiov->iov, qiov->niov, offset, laio_flags);
+#else
+        assert(flags == 0);
         io_prep_pwritev(iocbs, fd, qiov->iov, qiov->niov, offset);
+#endif
         break;
     case QEMU_AIO_ZONE_APPEND:
         io_prep_pwritev(iocbs, fd, qiov->iov, qiov->niov, offset);
@@ -XXX,XX +XXX,XX @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
 }
 
 int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
-                                int type, uint64_t dev_max_batch)
+                                int type, BdrvRequestFlags flags,
+                                uint64_t dev_max_batch)
 {
     int ret;
     AioContext *ctx = qemu_get_current_aio_context();
@@ -XXX,XX +XXX,XX @@ int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov,
         .qiov       = qiov,
     };
 
-    ret = laio_do_submit(fd, &laiocb, offset, type, dev_max_batch);
+    ret = laio_do_submit(fd, &laiocb, offset, type, flags, dev_max_batch);
     if (ret < 0) {
         return ret;
     }
@@ -XXX,XX +XXX,XX @@ bool laio_has_fdsync(int fd)
     io_destroy(ctx);
     return (ret == -EINVAL) ? false : true;
 }
+
+bool laio_has_fua(void)
+{
+#ifdef HAVE_IO_PREP_PWRITEV2
+    return true;
+#else
+    return false;
+#endif
+}
diff --git a/meson.build b/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/meson.build
+++ b/meson.build
@@ -XXX,XX +XXX,XX @@ config_host_data.set('HAVE_OPTRESET',
                      cc.has_header_symbol('getopt.h', 'optreset'))
 config_host_data.set('HAVE_IPPROTO_MPTCP',
                      cc.has_header_symbol('netinet/in.h', 'IPPROTO_MPTCP'))
+if libaio.found()
+  config_host_data.set('HAVE_IO_PREP_PWRITEV2',
+                       cc.has_header_symbol('libaio.h', 'io_prep_pwritev2'))
+endif
 
 # has_member
 config_host_data.set('HAVE_SIGEV_NOTIFY_THREAD_ID',
-- 
2.48.1

For block drivers that don't advertise FUA support, we already call
bdrv_co_flush(), which considers BDRV_O_NO_FLUSH. However, drivers that
do support FUA still see the FUA flag with BDRV_O_NO_FLUSH and get the
associated performance penalty that cache.no-flush=on was supposed to
avoid.

Clear FUA for write requests if BDRV_O_NO_FLUSH is set.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-3-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/io.c | 4 ++++
 1 file changed, 4 insertions(+)

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_driver_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
         return -ENOMEDIUM;
     }
 
+    if (bs->open_flags & BDRV_O_NO_FLUSH) {
+        flags &= ~BDRV_REQ_FUA;
+    }
+
     if ((flags & BDRV_REQ_FUA) &&
         (~bs->supported_write_flags & BDRV_REQ_FUA)) {
         flags &= ~BDRV_REQ_FUA;
-- 
2.48.1

As a preparation for having multiple adaptive polling states per
AioContext, move the 'ns' field into a separate struct.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-4-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/aio.h |  6 +++++-
 util/aio-posix.c    | 31 ++++++++++++++++---------------
 util/async.c        |  3 ++-
 3 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/include/block/aio.h b/include/block/aio.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -XXX,XX +XXX,XX @@ struct BHListSlice {
 
 typedef QSLIST_HEAD(, AioHandler) AioHandlerSList;
 
+typedef struct AioPolledEvent {
+    int64_t ns;        /* current polling time in nanoseconds */
+} AioPolledEvent;
+
 struct AioContext {
     GSource source;
 
@@ -XXX,XX +XXX,XX @@ struct AioContext {
     int poll_disable_cnt;
 
     /* Polling mode parameters */
-    int64_t poll_ns;        /* current polling time in nanoseconds */
+    AioPolledEvent poll;
     int64_t poll_max_ns;    /* maximum polling time in nanoseconds */
     int64_t poll_grow;      /* polling time growth factor */
     int64_t poll_shrink;    /* polling time shrink factor */
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,
         return false;
     }
 
-    max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns);
+    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
@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
     if (ctx->poll_max_ns) {
         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
 
-        if (block_ns <= ctx->poll_ns) {
+        if (block_ns <= ctx->poll.ns) {
             /* This is the sweet spot, no adjustment needed */
         } else if (block_ns > ctx->poll_max_ns) {
             /* We'd have to poll for too long, poll less */
-            int64_t old = ctx->poll_ns;
+            int64_t old = ctx->poll.ns;
 
             if (ctx->poll_shrink) {
-                ctx->poll_ns /= ctx->poll_shrink;
+                ctx->poll.ns /= ctx->poll_shrink;
             } else {
-                ctx->poll_ns = 0;
+                ctx->poll.ns = 0;
             }
 
-            trace_poll_shrink(ctx, old, ctx->poll_ns);
-        } else if (ctx->poll_ns < ctx->poll_max_ns &&
+            trace_poll_shrink(ctx, old, ctx->poll.ns);
+        } else if (ctx->poll.ns < ctx->poll_max_ns &&
                    block_ns < ctx->poll_max_ns) {
             /* There is room to grow, poll longer */
-            int64_t old = ctx->poll_ns;
+            int64_t old = ctx->poll.ns;
             int64_t grow = ctx->poll_grow;
 
             if (grow == 0) {
                 grow = 2;
             }
 
-            if (ctx->poll_ns) {
-                ctx->poll_ns *= grow;
+            if (ctx->poll.ns) {
+                ctx->poll.ns *= grow;
             } else {
-                ctx->poll_ns = 4000; /* start polling at 4 microseconds */
+                ctx->poll.ns = 4000; /* start polling at 4 microseconds */
             }
 
-            if (ctx->poll_ns > ctx->poll_max_ns) {
-                ctx->poll_ns = ctx->poll_max_ns;
+            if (ctx->poll.ns > ctx->poll_max_ns) {
+                ctx->poll.ns = ctx->poll_max_ns;
             }
 
-            trace_poll_grow(ctx, old, ctx->poll_ns);
+            trace_poll_grow(ctx, old, ctx->poll.ns);
         }
     }
 
@@ -XXX,XX +XXX,XX @@ void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
     /* No thread synchronization here, it doesn't matter if an incorrect value
      * is used once.
      */
+    ctx->poll.ns = 0;
+
     ctx->poll_max_ns = max_ns;
-    ctx->poll_ns = 0;
     ctx->poll_grow = grow;
     ctx->poll_shrink = shrink;
 
diff --git a/util/async.c b/util/async.c
index XXXXXXX..XXXXXXX 100644
--- a/util/async.c
+++ b/util/async.c
@@ -XXX,XX +XXX,XX @@ AioContext *aio_context_new(Error **errp)
     qemu_rec_mutex_init(&ctx->lock);
     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
 
-    ctx->poll_ns = 0;
+    ctx->poll.ns = 0;
+
     ctx->poll_max_ns = 0;
     ctx->poll_grow = 0;
     ctx->poll_shrink = 0;
-- 
2.48.1

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-5-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 util/aio-posix.c | 77 ++++++++++++++++++++++++++----------------------
 1 file changed, 41 insertions(+), 36 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,
     return false;
 }
 
+static void adjust_polling_time(AioContext *ctx, AioPolledEvent *poll,
+                                int64_t block_ns)
+{
+    if (block_ns <= poll->ns) {
+        /* This is the sweet spot, no adjustment needed */
+    } else if (block_ns > ctx->poll_max_ns) {
+        /* We'd have to poll for too long, poll less */
+        int64_t old = poll->ns;
+
+        if (ctx->poll_shrink) {
+            poll->ns /= ctx->poll_shrink;
+        } else {
+            poll->ns = 0;
+        }
+
+        trace_poll_shrink(ctx, old, poll->ns);
+    } else if (poll->ns < ctx->poll_max_ns &&
+               block_ns < ctx->poll_max_ns) {
+        /* There is room to grow, poll longer */
+        int64_t old = poll->ns;
+        int64_t grow = ctx->poll_grow;
+
+        if (grow == 0) {
+            grow = 2;
+        }
+
+        if (poll->ns) {
+            poll->ns *= grow;
+        } else {
+            poll->ns = 4000; /* start polling at 4 microseconds */
+        }
+
+        if (poll->ns > ctx->poll_max_ns) {
+            poll->ns = ctx->poll_max_ns;
+        }
+
+        trace_poll_grow(ctx, old, poll->ns);
+    }
+}
+
 bool aio_poll(AioContext *ctx, bool blocking)
 {
     AioHandlerList ready_list = QLIST_HEAD_INITIALIZER(ready_list);
@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
     /* Adjust polling time */
     if (ctx->poll_max_ns) {
         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
-
-        if (block_ns <= ctx->poll.ns) {
-            /* This is the sweet spot, no adjustment needed */
-        } else if (block_ns > ctx->poll_max_ns) {
-            /* We'd have to poll for too long, poll less */
-            int64_t old = ctx->poll.ns;
-
-            if (ctx->poll_shrink) {
-                ctx->poll.ns /= ctx->poll_shrink;
-            } else {
-                ctx->poll.ns = 0;
-            }
-
-            trace_poll_shrink(ctx, old, ctx->poll.ns);
-        } else if (ctx->poll.ns < ctx->poll_max_ns &&
-                   block_ns < ctx->poll_max_ns) {
-            /* There is room to grow, poll longer */
-            int64_t old = ctx->poll.ns;
-            int64_t grow = ctx->poll_grow;
-
-            if (grow == 0) {
-                grow = 2;
-            }
-
-            if (ctx->poll.ns) {
-                ctx->poll.ns *= grow;
-            } else {
-                ctx->poll.ns = 4000; /* start polling at 4 microseconds */
-            }
-
-            if (ctx->poll.ns > ctx->poll_max_ns) {
-                ctx->poll.ns = ctx->poll_max_ns;
-            }
-
-            trace_poll_grow(ctx, old, ctx->poll.ns);
-        }
+        adjust_polling_time(ctx, &ctx->poll, block_ns);
     }
 
     progress |= aio_bh_poll(ctx);
-- 
2.48.1

Adaptive polling has a big problem: It doesn't consider that an event
loop can wait for many different events that may have very different
typical latencies.

For example, think of a guest that tends to send a new I/O request soon
after the previous I/O request completes, but the storage on the host is
rather slow. In this case, getting the new request from guest quickly
means that polling is enabled, but the next thing is performing the I/O
request on the backend, which is slow and disables polling again for the
next guest request. This means that in such a scenario, polling could
help for every other event, but is only ever enabled when it can't
succeed.

In order to fix this, keep a separate AioPolledEvent for each
AioHandler. We will then know that the backend file descriptor always
has a high latency and isn't worth polling for, but we also know that
the guest is always fast and we should poll for it. This solves at least
half of the problem, we can now keep polling for those cases where it
makes sense and get the improved performance from it.

Since the event loop doesn't know which event will be next, we still do
some unnecessary polling while we're waiting for the slow disk. I made
some attempts to be more clever than just randomly growing and shrinking
the polling time, and even to let callers be explicit about when they
expect a new event, but so far this hasn't resulted in improved
performance or even caused performance regressions. For now, let's just
fix the part that is easy enough to fix, we can revisit the rest later.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-6-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/aio.h |  1 -
 util/aio-posix.h    |  1 +
 util/aio-posix.c    | 26 ++++++++++++++++++++++----
 util/async.c        |  2 --
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/include/block/aio.h b/include/block/aio.h
index XXXXXXX..XXXXXXX 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -XXX,XX +XXX,XX @@ struct AioContext {
     int poll_disable_cnt;
 
     /* Polling mode parameters */
-    AioPolledEvent poll;
     int64_t poll_max_ns;    /* maximum polling time in nanoseconds */
     int64_t poll_grow;      /* polling time growth factor */
     int64_t poll_shrink;    /* polling time shrink factor */
diff --git a/util/aio-posix.h b/util/aio-posix.h
index XXXXXXX..XXXXXXX 100644
--- a/util/aio-posix.h
+++ b/util/aio-posix.h
@@ -XXX,XX +XXX,XX @@ struct AioHandler {
 #endif
     int64_t poll_idle_timeout; /* when to stop userspace polling */
     bool poll_ready; /* has polling detected an event? */
+    AioPolledEvent poll;
 };
 
 /* Add a handler to a ready list */
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(AioContext *ctx, AioHandlerList *ready_list,
 static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list,
                           int64_t *timeout)
 {
+    AioHandler *node;
     int64_t max_ns;
 
     if (QLIST_EMPTY_RCU(&ctx->poll_aio_handlers)) {
         return false;
     }
 
-    max_ns = qemu_soonest_timeout(*timeout, ctx->poll.ns);
+    max_ns = 0;
+    QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
+        max_ns = MAX(max_ns, node->poll.ns);
+    }
+    max_ns = qemu_soonest_timeout(*timeout, max_ns);
+
     if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) {
         /*
          * Enable poll mode. It pairs with the poll_set_started() in
@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
 
     /* Adjust polling time */
     if (ctx->poll_max_ns) {
+        AioHandler *node;
         int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
-        adjust_polling_time(ctx, &ctx->poll, block_ns);
+
+        QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
+            if (QLIST_IS_INSERTED(node, node_ready)) {
+                adjust_polling_time(ctx, &node->poll, block_ns);
+            }
+        }
     }
 
     progress |= aio_bh_poll(ctx);
@@ -XXX,XX +XXX,XX @@ void aio_context_use_g_source(AioContext *ctx)
 void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
                                  int64_t grow, int64_t shrink, Error **errp)
 {
+    AioHandler *node;
+
+    qemu_lockcnt_inc(&ctx->list_lock);
+    QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+        node->poll.ns = 0;
+    }
+    qemu_lockcnt_dec(&ctx->list_lock);
+
     /* No thread synchronization here, it doesn't matter if an incorrect value
      * is used once.
      */
-    ctx->poll.ns = 0;
-
     ctx->poll_max_ns = max_ns;
     ctx->poll_grow = grow;
     ctx->poll_shrink = shrink;
diff --git a/util/async.c b/util/async.c
index XXXXXXX..XXXXXXX 100644
--- a/util/async.c
+++ b/util/async.c
@@ -XXX,XX +XXX,XX @@ AioContext *aio_context_new(Error **errp)
     qemu_rec_mutex_init(&ctx->lock);
     timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
 
-    ctx->poll.ns = 0;
-
     ctx->poll_max_ns = 0;
     ctx->poll_grow = 0;
     ctx->poll_shrink = 0;
-- 
2.48.1

aio_dispatch_handler() adds handlers to ctx->poll_aio_handlers if
polling should be enabled. If we call adjust_polling_time() for all
polling handlers before this, new polling handlers are still left at
poll->ns = 0 and polling is only actually enabled after the next event.
Move the adjust_polling_time() call after aio_dispatch_handler().

This fixes test-nested-aio-poll, which expects that polling becomes
effective the first time around.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311141912.135657-1-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 util/aio-posix.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 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 @@
 /* Stop userspace polling on a handler if it isn't active for some time */
 #define POLL_IDLE_INTERVAL_NS (7 * NANOSECONDS_PER_SECOND)
 
+static void adjust_polling_time(AioContext *ctx, AioPolledEvent *poll,
+                                int64_t block_ns);
+
 bool aio_poll_disabled(AioContext *ctx)
 {
     return qatomic_read(&ctx->poll_disable_cnt);
@@ -XXX,XX +XXX,XX @@ static bool aio_dispatch_handler(AioContext *ctx, AioHandler *node)
  * scanning all handlers with aio_dispatch_handlers().
  */
 static bool aio_dispatch_ready_handlers(AioContext *ctx,
-                                        AioHandlerList *ready_list)
+                                        AioHandlerList *ready_list,
+                                        int64_t block_ns)
 {
     bool progress = false;
     AioHandler *node;
@@ -XXX,XX +XXX,XX @@ static bool aio_dispatch_ready_handlers(AioContext *ctx,
     while ((node = QLIST_FIRST(ready_list))) {
         QLIST_REMOVE(node, node_ready);
         progress = aio_dispatch_handler(ctx, node) || progress;
+
+        /*
+         * Adjust polling time only after aio_dispatch_handler(), which can
+         * add the handler to ctx->poll_aio_handlers.
+         */
+        if (ctx->poll_max_ns && QLIST_IS_INSERTED(node, node_poll)) {
+            adjust_polling_time(ctx, &node->poll, block_ns);
+        }
     }
 
     return progress;
@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
     bool use_notify_me;
     int64_t timeout;
     int64_t start = 0;
+    int64_t block_ns = 0;
 
     /*
      * There cannot be two concurrent aio_poll calls for the same AioContext (or
@@ -XXX,XX +XXX,XX @@ bool aio_poll(AioContext *ctx, bool blocking)
 
     aio_notify_accept(ctx);
 
-    /* Adjust polling time */
+    /* Calculate blocked time for adaptive polling */
     if (ctx->poll_max_ns) {
-        AioHandler *node;
-        int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
-
-        QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) {
-            if (QLIST_IS_INSERTED(node, node_ready)) {
-                adjust_polling_time(ctx, &node->poll, block_ns);
-            }
-        }
+        block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start;
     }
 
     progress |= aio_bh_poll(ctx);
-    progress |= aio_dispatch_ready_handlers(ctx, &ready_list);
+    progress |= aio_dispatch_ready_handlers(ctx, &ready_list, block_ns);
 
     aio_free_deleted_handlers(ctx);
 
-- 
2.48.1

From: Thomas Huth <thuth@redhat.com>

qsd-migrate is currently only working for raw, qcow2 and qed.
Other formats are failing, e.g. because they don't support migration.
Thus let's limit this test to the three usable formats now.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20250224214058.205889-1-thuth@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 tests/qemu-iotests/tests/qsd-migrate | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/tests/qsd-migrate b/tests/qemu-iotests/tests/qsd-migrate
index XXXXXXX..XXXXXXX 100755
--- a/tests/qemu-iotests/tests/qsd-migrate
+++ b/tests/qemu-iotests/tests/qsd-migrate
@@ -XXX,XX +XXX,XX @@ import iotests
 
 from iotests import filter_qemu_io, filter_qtest
 
-iotests.script_initialize(supported_fmts=['generic'],
+iotests.script_initialize(supported_fmts=['qcow2', 'qed', 'raw'],
                           supported_protocols=['file'],
                           supported_platforms=['linux'])
 
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

In the past a single AioContext was used for block I/O and it was
fetched using blk_get_aio_context(). Nowadays the block layer supports
running I/O from any AioContext and multiple AioContexts at the same
time. Remove the dma_blk_io() AioContext argument and use the current
AioContext instead.

This makes calling the function easier and enables multiple IOThreads to
use dma_blk_io() concurrently for the same block device.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/system/dma.h | 3 +--
 hw/ide/core.c        | 3 +--
 hw/ide/macio.c       | 3 +--
 hw/scsi/scsi-disk.c  | 6 ++----
 system/dma-helpers.c | 8 ++++----
 5 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/include/system/dma.h b/include/system/dma.h
index XXXXXXX..XXXXXXX 100644
--- a/include/system/dma.h
+++ b/include/system/dma.h
@@ -XXX,XX +XXX,XX @@ typedef BlockAIOCB *DMAIOFunc(int64_t offset, QEMUIOVector *iov,
                               BlockCompletionFunc *cb, void *cb_opaque,
                               void *opaque);
 
-BlockAIOCB *dma_blk_io(AioContext *ctx,
-                       QEMUSGList *sg, uint64_t offset, uint32_t align,
+BlockAIOCB *dma_blk_io(QEMUSGList *sg, uint64_t offset, uint32_t align,
                        DMAIOFunc *io_func, void *io_func_opaque,
                        BlockCompletionFunc *cb, void *opaque, DMADirection dir);
 BlockAIOCB *dma_blk_read(BlockBackend *blk,
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_dma_cb(void *opaque, int ret)
                                            BDRV_SECTOR_SIZE, ide_dma_cb, s);
         break;
     case IDE_DMA_TRIM:
-        s->bus->dma->aiocb = dma_blk_io(blk_get_aio_context(s->blk),
-                                        &s->sg, offset, BDRV_SECTOR_SIZE,
+        s->bus->dma->aiocb = dma_blk_io(&s->sg, offset, BDRV_SECTOR_SIZE,
                                         ide_issue_trim, s, ide_dma_cb, s,
                                         DMA_DIRECTION_TO_DEVICE);
         break;
diff --git a/hw/ide/macio.c b/hw/ide/macio.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/ide/macio.c
+++ b/hw/ide/macio.c
@@ -XXX,XX +XXX,XX @@ static void pmac_ide_transfer_cb(void *opaque, int ret)
                                            pmac_ide_transfer_cb, io);
         break;
     case IDE_DMA_TRIM:
-        s->bus->dma->aiocb = dma_blk_io(blk_get_aio_context(s->blk), &s->sg,
-                                        offset, 0x1, ide_issue_trim, s,
+        s->bus->dma->aiocb = dma_blk_io(&s->sg, offset, 0x1, ide_issue_trim, s,
                                         pmac_ide_transfer_cb, io,
                                         DMA_DIRECTION_TO_DEVICE);
         break;
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -XXX,XX +XXX,XX @@ static void scsi_do_read(SCSIDiskReq *r, int ret)
     if (r->req.sg) {
         dma_acct_start(s->qdev.conf.blk, &r->acct, r->req.sg, BLOCK_ACCT_READ);
         r->req.residual -= r->req.sg->size;
-        r->req.aiocb = dma_blk_io(blk_get_aio_context(s->qdev.conf.blk),
-                                  r->req.sg, r->sector << BDRV_SECTOR_BITS,
+        r->req.aiocb = dma_blk_io(r->req.sg, r->sector << BDRV_SECTOR_BITS,
                                   BDRV_SECTOR_SIZE,
                                   sdc->dma_readv, r, scsi_dma_complete, r,
                                   DMA_DIRECTION_FROM_DEVICE);
@@ -XXX,XX +XXX,XX @@ static void scsi_write_data(SCSIRequest *req)
     if (r->req.sg) {
         dma_acct_start(s->qdev.conf.blk, &r->acct, r->req.sg, BLOCK_ACCT_WRITE);
         r->req.residual -= r->req.sg->size;
-        r->req.aiocb = dma_blk_io(blk_get_aio_context(s->qdev.conf.blk),
-                                  r->req.sg, r->sector << BDRV_SECTOR_BITS,
+        r->req.aiocb = dma_blk_io(r->req.sg, r->sector << BDRV_SECTOR_BITS,
                                   BDRV_SECTOR_SIZE,
                                   sdc->dma_writev, r, scsi_dma_complete, r,
                                   DMA_DIRECTION_TO_DEVICE);
diff --git a/system/dma-helpers.c b/system/dma-helpers.c
index XXXXXXX..XXXXXXX 100644
--- a/system/dma-helpers.c
+++ b/system/dma-helpers.c
@@ -XXX,XX +XXX,XX @@ static const AIOCBInfo dma_aiocb_info = {
     .cancel_async       = dma_aio_cancel,
 };
 
-BlockAIOCB *dma_blk_io(AioContext *ctx,
+BlockAIOCB *dma_blk_io(
     QEMUSGList *sg, uint64_t offset, uint32_t align,
     DMAIOFunc *io_func, void *io_func_opaque,
     BlockCompletionFunc *cb,
@@ -XXX,XX +XXX,XX @@ BlockAIOCB *dma_blk_io(AioContext *ctx,
 
     dbs->acb = NULL;
     dbs->sg = sg;
-    dbs->ctx = ctx;
+    dbs->ctx = qemu_get_current_aio_context();
     dbs->offset = offset;
     dbs->align = align;
     dbs->sg_cur_index = 0;
@@ -XXX,XX +XXX,XX @@ BlockAIOCB *dma_blk_read(BlockBackend *blk,
                          QEMUSGList *sg, uint64_t offset, uint32_t align,
                          void (*cb)(void *opaque, int ret), void *opaque)
 {
-    return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
+    return dma_blk_io(sg, offset, align,
                       dma_blk_read_io_func, blk, cb, opaque,
                       DMA_DIRECTION_FROM_DEVICE);
 }
@@ -XXX,XX +XXX,XX @@ BlockAIOCB *dma_blk_write(BlockBackend *blk,
                           QEMUSGList *sg, uint64_t offset, uint32_t align,
                           void (*cb)(void *opaque, int ret), void *opaque)
 {
-    return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
+    return dma_blk_io(sg, offset, align,
                       dma_blk_write_io_func, blk, cb, opaque,
                       DMA_DIRECTION_TO_DEVICE);
 }
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

Until now, a SCSIDevice's I/O requests have run in a single AioContext.
In order to support multiple IOThreads it will be necessary to move to
the concept of a per-SCSIRequest AioContext.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-4-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/scsi/scsi.h |  1 +
 hw/scsi/scsi-bus.c     |  1 +
 hw/scsi/scsi-disk.c    | 17 ++++++-----------
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -XXX,XX +XXX,XX @@ struct SCSIRequest {
     SCSIBus           *bus;
     SCSIDevice        *dev;
     const SCSIReqOps  *ops;
+    AioContext        *ctx;
     uint32_t          refcount;
     uint32_t          tag;
     uint32_t          lun;
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -XXX,XX +XXX,XX @@ invalid_opcode:
         }
     }
 
+    req->ctx = qemu_get_current_aio_context();
     req->cmd = cmd;
     req->residual = req->cmd.xfer;
 
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -XXX,XX +XXX,XX @@ static void scsi_aio_complete(void *opaque, int ret)
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
-    /* The request must only run in the BlockBackend's AioContext */
-    assert(blk_get_aio_context(s->qdev.conf.blk) ==
-           qemu_get_current_aio_context());
+    /* The request must run in its AioContext */
+    assert(r->req.ctx == qemu_get_current_aio_context());
 
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
@@ -XXX,XX +XXX,XX @@ static void scsi_dma_complete(void *opaque, int ret)
 
 static void scsi_read_complete_noio(SCSIDiskReq *r, int ret)
 {
-    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
     uint32_t n;
 
-    /* The request must only run in the BlockBackend's AioContext */
-    assert(blk_get_aio_context(s->qdev.conf.blk) ==
-           qemu_get_current_aio_context());
+    /* The request must run in its AioContext */
+    assert(r->req.ctx == qemu_get_current_aio_context());
 
     assert(r->req.aiocb == NULL);
     if (scsi_disk_req_check_error(r, ret, ret > 0)) {
@@ -XXX,XX +XXX,XX @@ static void scsi_read_data(SCSIRequest *req)
 
 static void scsi_write_complete_noio(SCSIDiskReq *r, int ret)
 {
-    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
     uint32_t n;
 
-    /* The request must only run in the BlockBackend's AioContext */
-    assert(blk_get_aio_context(s->qdev.conf.blk) ==
-           qemu_get_current_aio_context());
+    /* The request must run in its AioContext */
+    assert(r->req.ctx == qemu_get_current_aio_context());
 
     assert (r->req.aiocb == NULL);
     if (scsi_disk_req_check_error(r, ret, ret > 0)) {
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

SCSIDevice keeps track of in-flight requests for device reset and Task
Management Functions (TMFs). The request list requires protection so
that multi-threaded SCSI emulation can be implemented in commits that
follow.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-5-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/scsi/scsi.h |   7 ++-
 hw/scsi/scsi-bus.c     | 120 +++++++++++++++++++++++++++++------------
 2 files changed, 88 insertions(+), 39 deletions(-)

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -XXX,XX +XXX,XX @@ struct SCSIRequest {
     bool              dma_started;
     BlockAIOCB        *aiocb;
     QEMUSGList        *sg;
+
+    /* Protected by SCSIDevice->requests_lock */
     QTAILQ_ENTRY(SCSIRequest) next;
 };
 
@@ -XXX,XX +XXX,XX @@ struct SCSIDevice
     uint8_t sense[SCSI_SENSE_BUF_SIZE];
     uint32_t sense_len;
 
-    /*
-     * The requests list is only accessed from the AioContext that executes
-     * requests or from the main loop when IOThread processing is stopped.
-     */
+    QemuMutex requests_lock; /* protects the requests list */
     QTAILQ_HEAD(, SCSIRequest) requests;
 
     uint32_t channel;
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_sync(SCSIDevice *s,
     assert(!runstate_is_running());
     assert(qemu_in_main_thread());
 
-    QTAILQ_FOREACH_SAFE(req, &s->requests, next, next_req) {
-        fn(req, opaque);
+    /*
+     * Locking is not necessary because the guest is stopped and no other
+     * threads can be accessing the requests list, but take the lock for
+     * consistency.
+     */
+    WITH_QEMU_LOCK_GUARD(&s->requests_lock) {
+        QTAILQ_FOREACH_SAFE(req, &s->requests, next, next_req) {
+            fn(req, opaque);
+        }
     }
 }
 
@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_async_bh(void *opaque)
 {
     g_autofree SCSIDeviceForEachReqAsyncData *data = opaque;
     SCSIDevice *s = data->s;
-    AioContext *ctx;
-    SCSIRequest *req;
-    SCSIRequest *next;
+    g_autoptr(GList) reqs = NULL;
 
     /*
-     * The BB cannot have changed contexts between this BH being scheduled and
-     * now: BBs' AioContexts, when they have a node attached, can only be
-     * changed via bdrv_try_change_aio_context(), in a drained section.  While
-     * we have the in-flight counter incremented, that drain must block.
+     * Build a list of requests in this AioContext so fn() can be invoked later
+     * outside requests_lock.
      */
-    ctx = blk_get_aio_context(s->conf.blk);
-    assert(ctx == qemu_get_current_aio_context());
+    WITH_QEMU_LOCK_GUARD(&s->requests_lock) {
+        AioContext *ctx = qemu_get_current_aio_context();
+        SCSIRequest *req;
+        SCSIRequest *next;
+
+        QTAILQ_FOREACH_SAFE(req, &s->requests, next, next) {
+            if (req->ctx == ctx) {
+                scsi_req_ref(req); /* dropped after calling fn() */
+                reqs = g_list_prepend(reqs, req);
+            }
+        }
+    }
 
-    QTAILQ_FOREACH_SAFE(req, &s->requests, next, next) {
-        data->fn(req, data->fn_opaque);
+    /* Call fn() on each request */
+    for (GList *elem = g_list_first(reqs); elem; elem = g_list_next(elem)) {
+        data->fn(elem->data, data->fn_opaque);
+        scsi_req_unref(elem->data);
     }
 
     /* Drop the reference taken by scsi_device_for_each_req_async() */
@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_async_bh(void *opaque)
     blk_dec_in_flight(s->conf.blk);
 }
 
+static void scsi_device_for_each_req_async_do_ctx(gpointer key, gpointer value,
+                                                  gpointer user_data)
+{
+    AioContext *ctx = key;
+    SCSIDeviceForEachReqAsyncData *params = user_data;
+    SCSIDeviceForEachReqAsyncData *data;
+
+    data = g_new(SCSIDeviceForEachReqAsyncData, 1);
+    data->s = params->s;
+    data->fn = params->fn;
+    data->fn_opaque = params->fn_opaque;
+
+    /*
+     * Hold a reference to the SCSIDevice until
+     * scsi_device_for_each_req_async_bh() finishes.
+     */
+    object_ref(OBJECT(data->s));
+
+    /* Paired with scsi_device_for_each_req_async_bh() */
+    blk_inc_in_flight(data->s->conf.blk);
+
+    aio_bh_schedule_oneshot(ctx, scsi_device_for_each_req_async_bh, data);
+}
+
 /*
  * Schedule @fn() to be invoked for each enqueued request in device @s. @fn()
- * runs in the AioContext that is executing the request.
+ * must be thread-safe because it runs concurrently in each AioContext that is
+ * executing a request.
+ *
  * Keeps the BlockBackend's in-flight counter incremented until everything is
  * done, so draining it will settle all scheduled @fn() calls.
  */
@@ -XXX,XX +XXX,XX @@ static void scsi_device_for_each_req_async(SCSIDevice *s,
 {
     assert(qemu_in_main_thread());
 
-    SCSIDeviceForEachReqAsyncData *data =
-        g_new(SCSIDeviceForEachReqAsyncData, 1);
-
-    data->s = s;
-    data->fn = fn;
-    data->fn_opaque = opaque;
-
-    /*
-     * Hold a reference to the SCSIDevice until
-     * scsi_device_for_each_req_async_bh() finishes.
-     */
-    object_ref(OBJECT(s));
+    /* The set of AioContexts where the requests are being processed */
+    g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
+    WITH_QEMU_LOCK_GUARD(&s->requests_lock) {
+        SCSIRequest *req;
+        QTAILQ_FOREACH(req, &s->requests, next) {
+            g_hash_table_add(aio_contexts, req->ctx);
+        }
+    }
 
-    /* Paired with blk_dec_in_flight() in scsi_device_for_each_req_async_bh() */
-    blk_inc_in_flight(s->conf.blk);
-    aio_bh_schedule_oneshot(blk_get_aio_context(s->conf.blk),
-                            scsi_device_for_each_req_async_bh,
-                            data);
+    /* Schedule a BH for each AioContext */
+    SCSIDeviceForEachReqAsyncData params = {
+        .s = s,
+        .fn = fn,
+        .fn_opaque = opaque,
+    };
+    g_hash_table_foreach(
+            aio_contexts,
+            scsi_device_for_each_req_async_do_ctx,
+            &params
+    );
 }
 
 static void scsi_device_realize(SCSIDevice *s, Error **errp)
@@ -XXX,XX +XXX,XX @@ static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
         dev->lun = lun;
     }
 
+    qemu_mutex_init(&dev->requests_lock);
     QTAILQ_INIT(&dev->requests);
     scsi_device_realize(dev, &local_err);
     if (local_err) {
@@ -XXX,XX +XXX,XX @@ static void scsi_qdev_unrealize(DeviceState *qdev)
 
     scsi_device_purge_requests(dev, SENSE_CODE(NO_SENSE));
 
+    qemu_mutex_destroy(&dev->requests_lock);
+
     scsi_device_unrealize(dev);
 
     blockdev_mark_auto_del(dev->conf.blk);
@@ -XXX,XX +XXX,XX @@ static void scsi_req_enqueue_internal(SCSIRequest *req)
         req->sg = NULL;
     }
     req->enqueued = true;
-    QTAILQ_INSERT_TAIL(&req->dev->requests, req, next);
+
+    WITH_QEMU_LOCK_GUARD(&req->dev->requests_lock) {
+        QTAILQ_INSERT_TAIL(&req->dev->requests, req, next);
+    }
 }
 
 int32_t scsi_req_enqueue(SCSIRequest *req)
@@ -XXX,XX +XXX,XX @@ static void scsi_req_dequeue(SCSIRequest *req)
     trace_scsi_req_dequeue(req->dev->id, req->lun, req->tag);
     req->retry = false;
     if (req->enqueued) {
-        QTAILQ_REMOVE(&req->dev->requests, req, next);
+        WITH_QEMU_LOCK_GUARD(&req->dev->requests_lock) {
+            QTAILQ_REMOVE(&req->dev->requests, req, next);
+        }
         req->enqueued = false;
         scsi_req_unref(req);
     }
@@ -XXX,XX +XXX,XX @@ static void scsi_device_class_init(ObjectClass *klass, void *data)
 
 static void scsi_dev_instance_init(Object *obj)
 {
-    DeviceState *dev = DEVICE(obj);
-    SCSIDevice *s = SCSI_DEVICE(dev);
+    SCSIDevice *s = SCSI_DEVICE(obj);
 
     device_add_bootindex_property(obj, &s->conf.bootindex,
                                   "bootindex", NULL,
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

Virtqueues are not thread-safe. Until now this was not a major issue
since all virtqueue processing happened in the same thread. The ctrl
queue's Task Management Function (TMF) requests sometimes need the main
loop, so a BH was used to schedule the virtqueue completion back in the
thread that has virtqueue access.

When IOThread Virtqueue Mapping is introduced in later commits, event
and ctrl virtqueue accesses from other threads will become necessary.
Introduce an optional per-virtqueue lock so the event and ctrl
virtqueues can be protected in the commits that follow.

The addition of the ctrl virtqueue lock makes
virtio_scsi_complete_req_from_main_loop() and its BH unnecessary.
Instead, take the ctrl virtqueue lock from the main loop thread.

The cmd virtqueue does not have a lock because the entirety of SCSI
command processing happens in one thread. Only one thread accesses the
cmd virtqueue and a lock is unnecessary.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-6-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/virtio/virtio-scsi.h |  3 ++
 hw/scsi/virtio-scsi.c           | 84 ++++++++++++++++++---------------
 2 files changed, 49 insertions(+), 38 deletions(-)

diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
     int resetting; /* written from main loop thread, read from any thread */
     bool events_dropped;
 
+    QemuMutex ctrl_lock; /* protects ctrl_vq */
+    QemuMutex event_lock; /* protects event_vq */
+
     /*
      * TMFs deferred to main loop BH. These fields are protected by
      * tmf_bh_lock.
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_free_req(VirtIOSCSIReq *req)
     g_free(req);
 }
 
-static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
+static void virtio_scsi_complete_req(VirtIOSCSIReq *req, QemuMutex *vq_lock)
 {
     VirtIOSCSI *s = req->dev;
     VirtQueue *vq = req->vq;
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
 
     qemu_iovec_from_buf(&req->resp_iov, 0, &req->resp, req->resp_size);
+
+    if (vq_lock) {
+        qemu_mutex_lock(vq_lock);
+    }
+
     virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
     if (s->dataplane_started && !s->dataplane_fenced) {
         virtio_notify_irqfd(vdev, vq);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
         virtio_notify(vdev, vq);
     }
 
+    if (vq_lock) {
+        qemu_mutex_unlock(vq_lock);
+    }
+
     if (req->sreq) {
         req->sreq->hba_private = NULL;
         scsi_req_unref(req->sreq);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
     virtio_scsi_free_req(req);
 }
 
-static void virtio_scsi_complete_req_bh(void *opaque)
+static void virtio_scsi_bad_req(VirtIOSCSIReq *req, QemuMutex *vq_lock)
 {
-    VirtIOSCSIReq *req = opaque;
+    virtio_error(VIRTIO_DEVICE(req->dev), "wrong size for virtio-scsi headers");
 
-    virtio_scsi_complete_req(req);
-}
+    if (vq_lock) {
+        qemu_mutex_lock(vq_lock);
+    }
 
-/*
- * Called from virtio_scsi_do_one_tmf_bh() in main loop thread. The main loop
- * thread cannot touch the virtqueue since that could race with an IOThread.
- */
-static void virtio_scsi_complete_req_from_main_loop(VirtIOSCSIReq *req)
-{
-    VirtIOSCSI *s = req->dev;
+    virtqueue_detach_element(req->vq, &req->elem, 0);
 
-    if (!s->ctx || s->ctx == qemu_get_aio_context()) {
-        /* No need to schedule a BH when there is no IOThread */
-        virtio_scsi_complete_req(req);
-    } else {
-        /* Run request completion in the IOThread */
-        aio_wait_bh_oneshot(s->ctx, virtio_scsi_complete_req_bh, req);
+    if (vq_lock) {
+        qemu_mutex_unlock(vq_lock);
     }
-}
 
-static void virtio_scsi_bad_req(VirtIOSCSIReq *req)
-{
-    virtio_error(VIRTIO_DEVICE(req->dev), "wrong size for virtio-scsi headers");
-    virtqueue_detach_element(req->vq, &req->elem, 0);
     virtio_scsi_free_req(req);
 }
 
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_parse_req(VirtIOSCSIReq *req,
     return 0;
 }
 
-static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq)
+static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq, QemuMutex *vq_lock)
 {
     VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
     VirtIOSCSIReq *req;
 
+    if (vq_lock) {
+        qemu_mutex_lock(vq_lock);
+    }
+
     req = virtqueue_pop(vq, sizeof(VirtIOSCSIReq) + vs->cdb_size);
+
+    if (vq_lock) {
+        qemu_mutex_unlock(vq_lock);
+    }
+
     if (!req) {
         return NULL;
     }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
 
         trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(req->req.tmf.lun),
                                    req->req.tmf.tag, req->resp.tmf.response);
-        virtio_scsi_complete_req(req);
+        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
     }
     g_free(n);
 }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
 
 out:
     object_unref(OBJECT(d));
-    virtio_scsi_complete_req_from_main_loop(req);
+    virtio_scsi_complete_req(req, &s->ctrl_lock);
 }
 
 /* Some TMFs must be processed from the main loop thread */
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s)
 
         /* SAM-6 6.3.2 Hard reset */
         req->resp.tmf.response = VIRTIO_SCSI_S_TARGET_FAILURE;
-        virtio_scsi_complete_req(req);
+        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
     }
 }
 
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
 
     if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0,
                 &type, sizeof(type)) < sizeof(type)) {
-        virtio_scsi_bad_req(req);
+        virtio_scsi_bad_req(req, &s->ctrl_lock);
         return;
     }
 
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
     if (type == VIRTIO_SCSI_T_TMF) {
         if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlTMFReq),
                     sizeof(VirtIOSCSICtrlTMFResp)) < 0) {
-            virtio_scsi_bad_req(req);
+            virtio_scsi_bad_req(req, &s->ctrl_lock);
             return;
         } else {
             r = virtio_scsi_do_tmf(s, req);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
                type == VIRTIO_SCSI_T_AN_SUBSCRIBE) {
         if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlANReq),
                     sizeof(VirtIOSCSICtrlANResp)) < 0) {
-            virtio_scsi_bad_req(req);
+            virtio_scsi_bad_req(req, &s->ctrl_lock);
             return;
         } else {
             req->req.an.event_requested =
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
                  type == VIRTIO_SCSI_T_AN_SUBSCRIBE)
             trace_virtio_scsi_an_resp(virtio_scsi_get_lun(req->req.an.lun),
                                       req->resp.an.response);
-        virtio_scsi_complete_req(req);
+        virtio_scsi_complete_req(req, &s->ctrl_lock);
     } else {
         assert(r == -EINPROGRESS);
     }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq)
 {
     VirtIOSCSIReq *req;
 
-    while ((req = virtio_scsi_pop_req(s, vq))) {
+    while ((req = virtio_scsi_pop_req(s, vq, &s->ctrl_lock))) {
         virtio_scsi_handle_ctrl_req(s, req);
     }
 }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_complete_cmd_req(VirtIOSCSIReq *req)
      * in virtio_scsi_command_complete.
      */
     req->resp_size = sizeof(VirtIOSCSICmdResp);
-    virtio_scsi_complete_req(req);
+    virtio_scsi_complete_req(req, NULL);
 }
 
 static void virtio_scsi_command_failed(SCSIRequest *r)
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
             virtio_scsi_fail_cmd_req(req);
             return -ENOTSUP;
         } else {
-            virtio_scsi_bad_req(req);
+            virtio_scsi_bad_req(req, NULL);
             return -EINVAL;
         }
     }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq)
             virtio_queue_set_notification(vq, 0);
         }
 
-        while ((req = virtio_scsi_pop_req(s, vq))) {
+        while ((req = virtio_scsi_pop_req(s, vq, NULL))) {
             ret = virtio_scsi_handle_cmd_req_prepare(s, req);
             if (!ret) {
                 QTAILQ_INSERT_TAIL(&reqs, req, next);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
         return;
     }
 
-    req = virtio_scsi_pop_req(s, vs->event_vq);
+    req = virtio_scsi_pop_req(s, vs->event_vq, &s->event_lock);
     if (!req) {
         s->events_dropped = true;
         return;
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
     }
 
     if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
-        virtio_scsi_bad_req(req);
+        virtio_scsi_bad_req(req, &s->event_lock);
         return;
     }
 
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
     }
     trace_virtio_scsi_event(virtio_scsi_get_lun(evt->lun), event, reason);
 
-    virtio_scsi_complete_req(req);
+    virtio_scsi_complete_req(req, &s->event_lock);
 }
 
 static void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq)
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
     Error *err = NULL;
 
     QTAILQ_INIT(&s->tmf_bh_list);
+    qemu_mutex_init(&s->ctrl_lock);
+    qemu_mutex_init(&s->event_lock);
     qemu_mutex_init(&s->tmf_bh_lock);
 
     virtio_scsi_common_realize(dev,
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_unrealize(DeviceState *dev)
     qbus_set_hotplug_handler(BUS(&s->bus), NULL);
     virtio_scsi_common_unrealize(dev);
     qemu_mutex_destroy(&s->tmf_bh_lock);
+    qemu_mutex_destroy(&s->event_lock);
+    qemu_mutex_destroy(&s->ctrl_lock);
 }
 
 static const Property virtio_scsi_properties[] = {
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

The block layer can invoke the resize callback from any AioContext that
is processing requests. The virtqueue is already protected but the
events_dropped field also needs to be protected against races. Cover it
using the event virtqueue lock because it is closely associated with
accesses to the virtqueue.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/virtio/virtio-scsi.h |  3 ++-
 hw/scsi/virtio-scsi.c           | 29 ++++++++++++++++++++---------
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
 
     SCSIBus bus;
     int resetting; /* written from main loop thread, read from any thread */
+
+    QemuMutex event_lock; /* protects event_vq and events_dropped */
     bool events_dropped;
 
     QemuMutex ctrl_lock; /* protects ctrl_vq */
-    QemuMutex event_lock; /* protects event_vq */
 
     /*
      * TMFs deferred to main loop BH. These fields are protected by
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset(VirtIODevice *vdev)
 
     vs->sense_size = VIRTIO_SCSI_SENSE_DEFAULT_SIZE;
     vs->cdb_size = VIRTIO_SCSI_CDB_DEFAULT_SIZE;
-    s->events_dropped = false;
+
+    WITH_QEMU_LOCK_GUARD(&s->event_lock) {
+        s->events_dropped = false;
+    }
 }
 
 typedef struct {
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
     }
 
     req = virtio_scsi_pop_req(s, vs->event_vq, &s->event_lock);
-    if (!req) {
-        s->events_dropped = true;
-        return;
-    }
+    WITH_QEMU_LOCK_GUARD(&s->event_lock) {
+        if (!req) {
+            s->events_dropped = true;
+            return;
+        }
 
-    if (s->events_dropped) {
-        event |= VIRTIO_SCSI_T_EVENTS_MISSED;
-        s->events_dropped = false;
+        if (s->events_dropped) {
+            event |= VIRTIO_SCSI_T_EVENTS_MISSED;
+            s->events_dropped = false;
+        }
     }
 
     if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
 
 static void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq)
 {
-    if (s->events_dropped) {
+    bool events_dropped;
+
+    WITH_QEMU_LOCK_GUARD(&s->event_lock) {
+        events_dropped = s->events_dropped;
+    }
+
+    if (events_dropped) {
         VirtIOSCSIEventInfo info = {
             .event = VIRTIO_SCSI_T_NO_EVENT,
         };
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

With IOThread Virtqueue Mapping there will be multiple AioContexts
processing SCSI requests. scsi_req_cancel() and other SCSI request
operations must be performed from the AioContext where the request is
running.

Introduce a virtio_scsi_defer_tmf_to_aio_context() function and the
necessary VirtIOSCSIReq->remaining refcount infrastructure to move the
TMF code into the AioContext where the request is running.

For the time being there is still just one AioContext: the main loop or
the IOThread. When the iothread-vq-mapping parameter is added in a later
patch this will be changed to per-virtqueue AioContexts.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-8-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/scsi/virtio-scsi.c | 270 ++++++++++++++++++++++++++++++++----------
 1 file changed, 206 insertions(+), 64 deletions(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@ typedef struct VirtIOSCSIReq {
     /* Used for two-stage request submission and TMFs deferred to BH */
     QTAILQ_ENTRY(VirtIOSCSIReq) next;
 
-    /* Used for cancellation of request during TMFs */
+    /* Used for cancellation of request during TMFs. Atomic. */
     int remaining;
 
     SCSIRequest *sreq;
@@ -XXX,XX +XXX,XX @@ typedef struct {
     VirtIOSCSIReq  *tmf_req;
 } VirtIOSCSICancelNotifier;
 
+static void virtio_scsi_tmf_dec_remaining(VirtIOSCSIReq *tmf)
+{
+    if (qatomic_fetch_dec(&tmf->remaining) == 1) {
+        trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(tmf->req.tmf.lun),
+                                   tmf->req.tmf.tag, tmf->resp.tmf.response);
+
+        virtio_scsi_complete_req(tmf, &tmf->dev->ctrl_lock);
+    }
+}
+
 static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
 {
     VirtIOSCSICancelNotifier *n = container_of(notifier,
                                                VirtIOSCSICancelNotifier,
                                                notifier);
 
-    if (--n->tmf_req->remaining == 0) {
-        VirtIOSCSIReq *req = n->tmf_req;
-
-        trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(req->req.tmf.lun),
-                                   req->req.tmf.tag, req->resp.tmf.response);
-        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
-    }
+    virtio_scsi_tmf_dec_remaining(n->tmf_req);
     g_free(n);
 }
 
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s)
     }
 }
 
-static void virtio_scsi_defer_tmf_to_bh(VirtIOSCSIReq *req)
+static void virtio_scsi_defer_tmf_to_main_loop(VirtIOSCSIReq *req)
 {
     VirtIOSCSI *s = req->dev;
 
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_defer_tmf_to_bh(VirtIOSCSIReq *req)
     }
 }
 
+static void virtio_scsi_tmf_cancel_req(VirtIOSCSIReq *tmf, SCSIRequest *r)
+{
+    VirtIOSCSICancelNotifier *notifier;
+
+    assert(r->ctx == qemu_get_current_aio_context());
+
+    /* Decremented in virtio_scsi_cancel_notify() */
+    qatomic_inc(&tmf->remaining);
+
+    notifier = g_new(VirtIOSCSICancelNotifier, 1);
+    notifier->notifier.notify = virtio_scsi_cancel_notify;
+    notifier->tmf_req = tmf;
+    scsi_req_cancel_async(r, &notifier->notifier);
+}
+
+/* Execute a TMF on the requests in the current AioContext */
+static void virtio_scsi_do_tmf_aio_context(void *opaque)
+{
+    AioContext *ctx = qemu_get_current_aio_context();
+    VirtIOSCSIReq *tmf = opaque;
+    VirtIOSCSI *s = tmf->dev;
+    SCSIDevice *d = virtio_scsi_device_get(s, tmf->req.tmf.lun);
+    SCSIRequest *r;
+    bool match_tag;
+
+    if (!d) {
+        tmf->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
+        virtio_scsi_tmf_dec_remaining(tmf);
+        return;
+    }
+
+    /*
+     * This function could handle other subtypes that need to be processed in
+     * the request's AioContext in the future, but for now only request
+     * cancelation subtypes are performed here.
+     */
+    switch (tmf->req.tmf.subtype) {
+    case VIRTIO_SCSI_T_TMF_ABORT_TASK:
+        match_tag = true;
+        break;
+    case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
+    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET:
+        match_tag = false;
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
+        QTAILQ_FOREACH(r, &d->requests, next) {
+            VirtIOSCSIReq *cmd_req = r->hba_private;
+            assert(cmd_req); /* request has hba_private while enqueued */
+
+            if (r->ctx != ctx) {
+                continue;
+            }
+            if (match_tag && cmd_req->req.cmd.tag != tmf->req.tmf.tag) {
+                continue;
+            }
+            virtio_scsi_tmf_cancel_req(tmf, r);
+        }
+    }
+
+    /* Incremented by virtio_scsi_do_tmf() */
+    virtio_scsi_tmf_dec_remaining(tmf);
+
+    object_unref(d);
+}
+
+static void dummy_bh(void *opaque)
+{
+    /* Do nothing */
+}
+
+/*
+ * Wait for pending virtio_scsi_defer_tmf_to_aio_context() BHs.
+ */
+static void virtio_scsi_flush_defer_tmf_to_aio_context(VirtIOSCSI *s)
+{
+    GLOBAL_STATE_CODE();
+
+    assert(!s->dataplane_started);
+
+    if (s->ctx) {
+        /* Our BH only runs after previously scheduled BHs */
+        aio_wait_bh_oneshot(s->ctx, dummy_bh, NULL);
+    }
+}
+
+/*
+ * Run the TMF in a specific AioContext, handling only requests in that
+ * AioContext. This is necessary because requests can run in different
+ * AioContext and it is only possible to cancel them from the AioContext where
+ * they are running.
+ */
+static void virtio_scsi_defer_tmf_to_aio_context(VirtIOSCSIReq *tmf,
+                                                 AioContext *ctx)
+{
+    /* Decremented in virtio_scsi_do_tmf_aio_context() */
+    qatomic_inc(&tmf->remaining);
+
+    /* See virtio_scsi_flush_defer_tmf_to_aio_context() cleanup during reset */
+    aio_bh_schedule_oneshot(ctx, virtio_scsi_do_tmf_aio_context, tmf);
+}
+
+/*
+ * Returns the AioContext for a given TMF's tag field or NULL. Note that the
+ * request identified by the tag may have completed by the time you can execute
+ * a BH in the AioContext, so don't assume the request still exists in your BH.
+ */
+static AioContext *find_aio_context_for_tmf_tag(SCSIDevice *d,
+                                                VirtIOSCSIReq *tmf)
+{
+    WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
+        SCSIRequest *r;
+        SCSIRequest *next;
+
+        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
+            VirtIOSCSIReq *cmd_req = r->hba_private;
+
+            /* hba_private is non-NULL while the request is enqueued */
+            assert(cmd_req);
+
+            if (cmd_req->req.cmd.tag == tmf->req.tmf.tag) {
+                return r->ctx;
+            }
+        }
+    }
+    return NULL;
+}
+
 /* Return 0 if the request is ready to be completed and return to guest;
  * -EINPROGRESS if the request is submitted and will be completed later, in the
  *  case of async cancellation. */
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 {
     SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
     SCSIRequest *r, *next;
+    AioContext *ctx;
     int ret = 0;
 
     virtio_scsi_ctx_check(s, d);
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
                               req->req.tmf.tag, req->req.tmf.subtype);
 
     switch (req->req.tmf.subtype) {
-    case VIRTIO_SCSI_T_TMF_ABORT_TASK:
-    case VIRTIO_SCSI_T_TMF_QUERY_TASK:
+    case VIRTIO_SCSI_T_TMF_ABORT_TASK: {
         if (!d) {
             goto fail;
         }
         if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
             goto incorrect_lun;
         }
-        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
-            VirtIOSCSIReq *cmd_req = r->hba_private;
-            if (cmd_req && cmd_req->req.cmd.tag == req->req.tmf.tag) {
-                break;
-            }
+
+        ctx = find_aio_context_for_tmf_tag(d, req);
+        if (ctx) {
+            virtio_scsi_defer_tmf_to_aio_context(req, ctx);
+            ret = -EINPROGRESS;
         }
-        if (r) {
-            /*
-             * Assert that the request has not been completed yet, we
-             * check for it in the loop above.
-             */
-            assert(r->hba_private);
-            if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK) {
-                /* "If the specified command is present in the task set, then
-                 * return a service response set to FUNCTION SUCCEEDED".
-                 */
-                req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
-            } else {
-                VirtIOSCSICancelNotifier *notifier;
-
-                req->remaining = 1;
-                notifier = g_new(VirtIOSCSICancelNotifier, 1);
-                notifier->tmf_req = req;
-                notifier->notifier.notify = virtio_scsi_cancel_notify;
-                scsi_req_cancel_async(r, &notifier->notifier);
-                ret = -EINPROGRESS;
+        break;
+    }
+
+    case VIRTIO_SCSI_T_TMF_QUERY_TASK:
+        if (!d) {
+            goto fail;
+        }
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
+            goto incorrect_lun;
+        }
+
+        WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
+            QTAILQ_FOREACH(r, &d->requests, next) {
+                VirtIOSCSIReq *cmd_req = r->hba_private;
+                assert(cmd_req); /* request has hba_private while enqueued */
+
+                if (cmd_req->req.cmd.tag == req->req.tmf.tag) {
+                    /*
+                     * "If the specified command is present in the task set,
+                     * then return a service response set to FUNCTION
+                     * SUCCEEDED".
+                     */
+                    req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+                }
             }
         }
         break;
 
     case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
     case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
-        virtio_scsi_defer_tmf_to_bh(req);
+        virtio_scsi_defer_tmf_to_main_loop(req);
         ret = -EINPROGRESS;
         break;
 
     case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
-    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET:
+    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
+        if (!d) {
+            goto fail;
+        }
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
+            goto incorrect_lun;
+        }
+
+        qatomic_inc(&req->remaining);
+
+        ctx = s->ctx ?: qemu_get_aio_context();
+        virtio_scsi_defer_tmf_to_aio_context(req, ctx);
+
+        virtio_scsi_tmf_dec_remaining(req);
+        ret = -EINPROGRESS;
+        break;
+    }
+
     case VIRTIO_SCSI_T_TMF_QUERY_TASK_SET:
         if (!d) {
             goto fail;
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
             goto incorrect_lun;
         }
 
-        /* Add 1 to "remaining" until virtio_scsi_do_tmf returns.
-         * This way, if the bus starts calling back to the notifiers
-         * even before we finish the loop, virtio_scsi_cancel_notify
-         * will not complete the TMF too early.
-         */
-        req->remaining = 1;
-        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
-            if (r->hba_private) {
-                if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK_SET) {
-                    /* "If there is any command present in the task set, then
-                     * return a service response set to FUNCTION SUCCEEDED".
-                     */
-                    req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
-                    break;
-                } else {
-                    VirtIOSCSICancelNotifier *notifier;
-
-                    req->remaining++;
-                    notifier = g_new(VirtIOSCSICancelNotifier, 1);
-                    notifier->notifier.notify = virtio_scsi_cancel_notify;
-                    notifier->tmf_req = req;
-                    scsi_req_cancel_async(r, &notifier->notifier);
-                }
+        WITH_QEMU_LOCK_GUARD(&d->requests_lock) {
+            QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
+                /* Request has hba_private while enqueued */
+                assert(r->hba_private);
+
+                /*
+                 * "If there is any command present in the task set, then
+                 * return a service response set to FUNCTION SUCCEEDED".
+                 */
+                req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+                break;
             }
         }
-        if (--req->remaining > 0) {
-            ret = -EINPROGRESS;
-        }
         break;
 
     case VIRTIO_SCSI_T_TMF_CLEAR_ACA:
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset(VirtIODevice *vdev)
     assert(!s->dataplane_started);
 
     virtio_scsi_reset_tmf_bh(s);
+    virtio_scsi_flush_defer_tmf_to_aio_context(s);
 
     qatomic_inc(&s->resetting);
     bus_cold_reset(BUS(&s->bus));
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

This is the cleanup function that must be called after
apply_iothread_vq_mapping() succeeds. virtio-scsi will need this
function too, so extract it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-9-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/block/virtio-blk.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

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 @@ validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
  * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
  * the iothread-vq-mapping parameter in @iothread_vq_mapping_list.
  *
+ * cleanup_iothread_vq_mapping() must be called to free IOThread object
+ * references after this function returns success.
+ *
  * Returns: %true on success, %false on failure.
  **/
 static bool apply_iothread_vq_mapping(
@@ -XXX,XX +XXX,XX @@ static bool apply_iothread_vq_mapping(
     return true;
 }
 
+/**
+ * cleanup_iothread_vq_mapping:
+ * @list: The mapping of virtqueues to IOThreads.
+ *
+ * Release IOThread object references that were acquired by
+ * apply_iothread_vq_mapping().
+ */
+static void cleanup_iothread_vq_mapping(IOThreadVirtQueueMappingList *list)
+{
+    IOThreadVirtQueueMappingList *node;
+
+    for (node = list; node; node = node->next) {
+        IOThread *iothread = iothread_by_id(node->value->iothread);
+        object_unref(OBJECT(iothread));
+    }
+}
+
 /* Context: BQL held */
 static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
 {
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
     assert(!s->ioeventfd_started);
 
     if (conf->iothread_vq_mapping_list) {
-        IOThreadVirtQueueMappingList *node;
-
-        for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
-            IOThread *iothread = iothread_by_id(node->value->iothread);
-            object_unref(OBJECT(iothread));
-        }
+        cleanup_iothread_vq_mapping(conf->iothread_vq_mapping_list);
     }
 
     if (conf->iothread) {
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

Use noun_verb() function naming instead of verb_noun() because the
former is the most common naming style for APIs. The next commit will
move these functions into a header file so that virtio-scsi can call
them.

Shorten iothread_vq_mapping_apply()'s iothread_vq_mapping_list argument
to just "list" like in the other functions.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-10-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/block/virtio-blk.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

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 const BlockDevOps virtio_block_ops = {
 };
 
 static bool
-validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
-        uint16_t num_queues, Error **errp)
+iothread_vq_mapping_validate(IOThreadVirtQueueMappingList *list, uint16_t
+        num_queues, Error **errp)
 {
     g_autofree unsigned long *vqs = bitmap_new(num_queues);
     g_autoptr(GHashTable) iothreads =
@@ -XXX,XX +XXX,XX @@ validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
 }
 
 /**
- * apply_iothread_vq_mapping:
- * @iothread_vq_mapping_list: The mapping of virtqueues to IOThreads.
+ * iothread_vq_mapping_apply:
+ * @list: The mapping of virtqueues to IOThreads.
  * @vq_aio_context: The array of AioContext pointers to fill in.
  * @num_queues: The length of @vq_aio_context.
  * @errp: If an error occurs, a pointer to the area to store the error.
  *
  * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
- * the iothread-vq-mapping parameter in @iothread_vq_mapping_list.
+ * the iothread-vq-mapping parameter in @list.
  *
- * cleanup_iothread_vq_mapping() must be called to free IOThread object
+ * iothread_vq_mapping_cleanup() must be called to free IOThread object
  * references after this function returns success.
  *
  * Returns: %true on success, %false on failure.
  **/
-static bool apply_iothread_vq_mapping(
-        IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
+static bool iothread_vq_mapping_apply(
+        IOThreadVirtQueueMappingList *list,
         AioContext **vq_aio_context,
         uint16_t num_queues,
         Error **errp)
@@ -XXX,XX +XXX,XX @@ static bool apply_iothread_vq_mapping(
     size_t num_iothreads = 0;
     size_t cur_iothread = 0;
 
-    if (!validate_iothread_vq_mapping_list(iothread_vq_mapping_list,
-                                           num_queues, errp)) {
+    if (!iothread_vq_mapping_validate(list, num_queues, errp)) {
         return false;
     }
 
-    for (node = iothread_vq_mapping_list; node; node = node->next) {
+    for (node = list; node; node = node->next) {
         num_iothreads++;
     }
 
-    for (node = iothread_vq_mapping_list; node; node = node->next) {
+    for (node = list; node; node = node->next) {
         IOThread *iothread = iothread_by_id(node->value->iothread);
         AioContext *ctx = iothread_get_aio_context(iothread);
 
@@ -XXX,XX +XXX,XX @@ static bool apply_iothread_vq_mapping(
 }
 
 /**
- * cleanup_iothread_vq_mapping:
+ * iothread_vq_mapping_cleanup:
  * @list: The mapping of virtqueues to IOThreads.
  *
  * Release IOThread object references that were acquired by
- * apply_iothread_vq_mapping().
+ * iothread_vq_mapping_apply().
  */
-static void cleanup_iothread_vq_mapping(IOThreadVirtQueueMappingList *list)
+static void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list)
 {
     IOThreadVirtQueueMappingList *node;
 
@@ -XXX,XX +XXX,XX @@ static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
     s->vq_aio_context = g_new(AioContext *, conf->num_queues);
 
     if (conf->iothread_vq_mapping_list) {
-        if (!apply_iothread_vq_mapping(conf->iothread_vq_mapping_list,
+        if (!iothread_vq_mapping_apply(conf->iothread_vq_mapping_list,
                                        s->vq_aio_context,
                                        conf->num_queues,
                                        errp)) {
@@ -XXX,XX +XXX,XX @@ static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
     assert(!s->ioeventfd_started);
 
     if (conf->iothread_vq_mapping_list) {
-        cleanup_iothread_vq_mapping(conf->iothread_vq_mapping_list);
+        iothread_vq_mapping_cleanup(conf->iothread_vq_mapping_list);
     }
 
     if (conf->iothread) {
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

The code that builds an array of AioContext pointers indexed by the
virtqueue is not specific to virtio-blk. virtio-scsi will need to do the
same thing, so extract the functions.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-11-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/virtio/iothread-vq-mapping.h |  45 ++++++++
 hw/block/virtio-blk.c                   | 142 +-----------------------
 hw/virtio/iothread-vq-mapping.c         | 131 ++++++++++++++++++++++
 hw/virtio/meson.build                   |   1 +
 4 files changed, 178 insertions(+), 141 deletions(-)
 create mode 100644 include/hw/virtio/iothread-vq-mapping.h
 create mode 100644 hw/virtio/iothread-vq-mapping.c

diff --git a/include/hw/virtio/iothread-vq-mapping.h b/include/hw/virtio/iothread-vq-mapping.h
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/include/hw/virtio/iothread-vq-mapping.h
@@ -XXX,XX +XXX,XX @@
+/*
+ * IOThread Virtqueue Mapping
+ *
+ * Copyright Red Hat, Inc
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ */
+
+#ifndef HW_VIRTIO_IOTHREAD_VQ_MAPPING_H
+#define HW_VIRTIO_IOTHREAD_VQ_MAPPING_H
+
+#include "qapi/error.h"
+#include "qapi/qapi-types-virtio.h"
+
+/**
+ * iothread_vq_mapping_apply:
+ * @list: The mapping of virtqueues to IOThreads.
+ * @vq_aio_context: The array of AioContext pointers to fill in.
+ * @num_queues: The length of @vq_aio_context.
+ * @errp: If an error occurs, a pointer to the area to store the error.
+ *
+ * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
+ * the iothread-vq-mapping parameter in @list.
+ *
+ * iothread_vq_mapping_cleanup() must be called to free IOThread object
+ * references after this function returns success.
+ *
+ * Returns: %true on success, %false on failure.
+ **/
+bool iothread_vq_mapping_apply(
+        IOThreadVirtQueueMappingList *list,
+        AioContext **vq_aio_context,
+        uint16_t num_queues,
+        Error **errp);
+
+/**
+ * iothread_vq_mapping_cleanup:
+ * @list: The mapping of virtqueues to IOThreads.
+ *
+ * Release IOThread object references that were acquired by
+ * iothread_vq_mapping_apply().
+ */
+void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list);
+
+#endif /* HW_VIRTIO_IOTHREAD_VQ_MAPPING_H */
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 @@
 #endif
 #include "hw/virtio/virtio-bus.h"
 #include "migration/qemu-file-types.h"
+#include "hw/virtio/iothread-vq-mapping.h"
 #include "hw/virtio/virtio-access.h"
 #include "hw/virtio/virtio-blk-common.h"
 #include "qemu/coroutine.h"
@@ -XXX,XX +XXX,XX @@ static const BlockDevOps virtio_block_ops = {
     .drained_end   = virtio_blk_drained_end,
 };
 
-static bool
-iothread_vq_mapping_validate(IOThreadVirtQueueMappingList *list, uint16_t
-        num_queues, Error **errp)
-{
-    g_autofree unsigned long *vqs = bitmap_new(num_queues);
-    g_autoptr(GHashTable) iothreads =
-        g_hash_table_new(g_str_hash, g_str_equal);
-
-    for (IOThreadVirtQueueMappingList *node = list; node; node = node->next) {
-        const char *name = node->value->iothread;
-        uint16List *vq;
-
-        if (!iothread_by_id(name)) {
-            error_setg(errp, "IOThread \"%s\" object does not exist", name);
-            return false;
-        }
-
-        if (!g_hash_table_add(iothreads, (gpointer)name)) {
-            error_setg(errp,
-                    "duplicate IOThread name \"%s\" in iothread-vq-mapping",
-                    name);
-            return false;
-        }
-
-        if (node != list) {
-            if (!!node->value->vqs != !!list->value->vqs) {
-                error_setg(errp, "either all items in iothread-vq-mapping "
-                                 "must have vqs or none of them must have it");
-                return false;
-            }
-        }
-
-        for (vq = node->value->vqs; vq; vq = vq->next) {
-            if (vq->value >= num_queues) {
-                error_setg(errp, "vq index %u for IOThread \"%s\" must be "
-                        "less than num_queues %u in iothread-vq-mapping",
-                        vq->value, name, num_queues);
-                return false;
-            }
-
-            if (test_and_set_bit(vq->value, vqs)) {
-                error_setg(errp, "cannot assign vq %u to IOThread \"%s\" "
-                        "because it is already assigned", vq->value, name);
-                return false;
-            }
-        }
-    }
-
-    if (list->value->vqs) {
-        for (uint16_t i = 0; i < num_queues; i++) {
-            if (!test_bit(i, vqs)) {
-                error_setg(errp,
-                        "missing vq %u IOThread assignment in iothread-vq-mapping",
-                        i);
-                return false;
-            }
-        }
-    }
-
-    return true;
-}
-
-/**
- * iothread_vq_mapping_apply:
- * @list: The mapping of virtqueues to IOThreads.
- * @vq_aio_context: The array of AioContext pointers to fill in.
- * @num_queues: The length of @vq_aio_context.
- * @errp: If an error occurs, a pointer to the area to store the error.
- *
- * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
- * the iothread-vq-mapping parameter in @list.
- *
- * iothread_vq_mapping_cleanup() must be called to free IOThread object
- * references after this function returns success.
- *
- * Returns: %true on success, %false on failure.
- **/
-static bool iothread_vq_mapping_apply(
-        IOThreadVirtQueueMappingList *list,
-        AioContext **vq_aio_context,
-        uint16_t num_queues,
-        Error **errp)
-{
-    IOThreadVirtQueueMappingList *node;
-    size_t num_iothreads = 0;
-    size_t cur_iothread = 0;
-
-    if (!iothread_vq_mapping_validate(list, num_queues, errp)) {
-        return false;
-    }
-
-    for (node = list; node; node = node->next) {
-        num_iothreads++;
-    }
-
-    for (node = list; node; node = node->next) {
-        IOThread *iothread = iothread_by_id(node->value->iothread);
-        AioContext *ctx = iothread_get_aio_context(iothread);
-
-        /* Released in virtio_blk_vq_aio_context_cleanup() */
-        object_ref(OBJECT(iothread));
-
-        if (node->value->vqs) {
-            uint16List *vq;
-
-            /* Explicit vq:IOThread assignment */
-            for (vq = node->value->vqs; vq; vq = vq->next) {
-                assert(vq->value < num_queues);
-                vq_aio_context[vq->value] = ctx;
-            }
-        } else {
-            /* Round-robin vq:IOThread assignment */
-            for (unsigned i = cur_iothread; i < num_queues;
-                 i += num_iothreads) {
-                vq_aio_context[i] = ctx;
-            }
-        }
-
-        cur_iothread++;
-    }
-
-    return true;
-}
-
-/**
- * iothread_vq_mapping_cleanup:
- * @list: The mapping of virtqueues to IOThreads.
- *
- * Release IOThread object references that were acquired by
- * iothread_vq_mapping_apply().
- */
-static void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list)
-{
-    IOThreadVirtQueueMappingList *node;
-
-    for (node = list; node; node = node->next) {
-        IOThread *iothread = iothread_by_id(node->value->iothread);
-        object_unref(OBJECT(iothread));
-    }
-}
-
 /* Context: BQL held */
 static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
 {
diff --git a/hw/virtio/iothread-vq-mapping.c b/hw/virtio/iothread-vq-mapping.c
new file mode 100644
index XXXXXXX..XXXXXXX
--- /dev/null
+++ b/hw/virtio/iothread-vq-mapping.c
@@ -XXX,XX +XXX,XX @@
+/*
+ * IOThread Virtqueue Mapping
+ *
+ * Copyright Red Hat, Inc
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ */
+
+#include "qemu/osdep.h"
+#include "system/iothread.h"
+#include "hw/virtio/iothread-vq-mapping.h"
+
+static bool
+iothread_vq_mapping_validate(IOThreadVirtQueueMappingList *list, uint16_t
+        num_queues, Error **errp)
+{
+    g_autofree unsigned long *vqs = bitmap_new(num_queues);
+    g_autoptr(GHashTable) iothreads =
+        g_hash_table_new(g_str_hash, g_str_equal);
+
+    for (IOThreadVirtQueueMappingList *node = list; node; node = node->next) {
+        const char *name = node->value->iothread;
+        uint16List *vq;
+
+        if (!iothread_by_id(name)) {
+            error_setg(errp, "IOThread \"%s\" object does not exist", name);
+            return false;
+        }
+
+        if (!g_hash_table_add(iothreads, (gpointer)name)) {
+            error_setg(errp,
+                    "duplicate IOThread name \"%s\" in iothread-vq-mapping",
+                    name);
+            return false;
+        }
+
+        if (node != list) {
+            if (!!node->value->vqs != !!list->value->vqs) {
+                error_setg(errp, "either all items in iothread-vq-mapping "
+                                 "must have vqs or none of them must have it");
+                return false;
+            }
+        }
+
+        for (vq = node->value->vqs; vq; vq = vq->next) {
+            if (vq->value >= num_queues) {
+                error_setg(errp, "vq index %u for IOThread \"%s\" must be "
+                        "less than num_queues %u in iothread-vq-mapping",
+                        vq->value, name, num_queues);
+                return false;
+            }
+
+            if (test_and_set_bit(vq->value, vqs)) {
+                error_setg(errp, "cannot assign vq %u to IOThread \"%s\" "
+                        "because it is already assigned", vq->value, name);
+                return false;
+            }
+        }
+    }
+
+    if (list->value->vqs) {
+        for (uint16_t i = 0; i < num_queues; i++) {
+            if (!test_bit(i, vqs)) {
+                error_setg(errp,
+                        "missing vq %u IOThread assignment in iothread-vq-mapping",
+                        i);
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+bool iothread_vq_mapping_apply(
+        IOThreadVirtQueueMappingList *list,
+        AioContext **vq_aio_context,
+        uint16_t num_queues,
+        Error **errp)
+{
+    IOThreadVirtQueueMappingList *node;
+    size_t num_iothreads = 0;
+    size_t cur_iothread = 0;
+
+    if (!iothread_vq_mapping_validate(list, num_queues, errp)) {
+        return false;
+    }
+
+    for (node = list; node; node = node->next) {
+        num_iothreads++;
+    }
+
+    for (node = list; node; node = node->next) {
+        IOThread *iothread = iothread_by_id(node->value->iothread);
+        AioContext *ctx = iothread_get_aio_context(iothread);
+
+        /* Released in virtio_blk_vq_aio_context_cleanup() */
+        object_ref(OBJECT(iothread));
+
+        if (node->value->vqs) {
+            uint16List *vq;
+
+            /* Explicit vq:IOThread assignment */
+            for (vq = node->value->vqs; vq; vq = vq->next) {
+                assert(vq->value < num_queues);
+                vq_aio_context[vq->value] = ctx;
+            }
+        } else {
+            /* Round-robin vq:IOThread assignment */
+            for (unsigned i = cur_iothread; i < num_queues;
+                 i += num_iothreads) {
+                vq_aio_context[i] = ctx;
+            }
+        }
+
+        cur_iothread++;
+    }
+
+    return true;
+}
+
+void iothread_vq_mapping_cleanup(IOThreadVirtQueueMappingList *list)
+{
+    IOThreadVirtQueueMappingList *node;
+
+    for (node = list; node; node = node->next) {
+        IOThread *iothread = iothread_by_id(node->value->iothread);
+        object_unref(OBJECT(iothread));
+    }
+}
+
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index XXXXXXX..XXXXXXX 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -XXX,XX +XXX,XX @@
 system_virtio_ss = ss.source_set()
 system_virtio_ss.add(files('virtio-bus.c'))
+system_virtio_ss.add(files('iothread-vq-mapping.c'))
 system_virtio_ss.add(when: 'CONFIG_VIRTIO_PCI', if_true: files('virtio-pci.c'))
 system_virtio_ss.add(when: 'CONFIG_VIRTIO_MMIO', if_true: files('virtio-mmio.c'))
 system_virtio_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('virtio-crypto.c'))
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

Allow virtio-scsi virtqueues to be assigned to different IOThreads. This
makes it possible to take advantage of host multi-queue block layer
scalability by assigning virtqueues that have affinity with vCPUs to
different IOThreads that have affinity with host CPUs. The same feature
was introduced for virtio-blk in the past:
https://developers.redhat.com/articles/2024/09/05/scaling-virtio-blk-disk-io-iothread-virtqueue-mapping

Here are fio randread 4k iodepth=64 results from a 4 vCPU guest with an
Intel P4800X SSD:
iothreads IOPS
------------------------------
1         189576
2         312698
4         346744

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250311132616.1049687-12-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/virtio/virtio-scsi.h |  5 +-
 hw/scsi/virtio-scsi-dataplane.c | 90 ++++++++++++++++++++++++---------
 hw/scsi/virtio-scsi.c           | 63 ++++++++++++++---------
 3 files changed, 107 insertions(+), 51 deletions(-)

diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -XXX,XX +XXX,XX @@
 #include "hw/virtio/virtio.h"
 #include "hw/scsi/scsi.h"
 #include "chardev/char-fe.h"
+#include "qapi/qapi-types-virtio.h"
 #include "system/iothread.h"
 
 #define TYPE_VIRTIO_SCSI_COMMON "virtio-scsi-common"
@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSIConf {
     CharBackend chardev;
     uint32_t boot_tpgt;
     IOThread *iothread;
+    IOThreadVirtQueueMappingList *iothread_vq_mapping_list;
 };
 
 struct VirtIOSCSI;
@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
     QTAILQ_HEAD(, VirtIOSCSIReq) tmf_bh_list;
 
     /* Fields for dataplane below */
-    AioContext *ctx; /* one iothread per virtio-scsi-pci for now */
+    AioContext **vq_aio_context; /* per-virtqueue AioContext pointer */
 
     bool dataplane_started;
     bool dataplane_starting;
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_common_realize(DeviceState *dev,
 void virtio_scsi_common_unrealize(DeviceState *dev);
 
 void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp);
+void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s);
 int virtio_scsi_dataplane_start(VirtIODevice *s);
 void virtio_scsi_dataplane_stop(VirtIODevice *s);
 
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -XXX,XX +XXX,XX @@
 #include "system/block-backend.h"
 #include "hw/scsi/scsi.h"
 #include "scsi/constants.h"
+#include "hw/virtio/iothread-vq-mapping.h"
 #include "hw/virtio/virtio-bus.h"
 
 /* Context: BQL held */
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    uint16_t num_vqs = vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED;
 
-    if (vs->conf.iothread) {
+    if (vs->conf.iothread && vs->conf.iothread_vq_mapping_list) {
+        error_setg(errp,
+                   "iothread and iothread-vq-mapping properties cannot be set "
+                   "at the same time");
+        return;
+    }
+
+    if (vs->conf.iothread || vs->conf.iothread_vq_mapping_list) {
         if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
             error_setg(errp,
                        "device is incompatible with iothread "
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
             error_setg(errp, "ioeventfd is required for iothread");
             return;
         }
-        s->ctx = iothread_get_aio_context(vs->conf.iothread);
-    } else {
-        if (!virtio_device_ioeventfd_enabled(vdev)) {
+    }
+
+    s->vq_aio_context = g_new(AioContext *, num_vqs);
+
+    if (vs->conf.iothread_vq_mapping_list) {
+        if (!iothread_vq_mapping_apply(vs->conf.iothread_vq_mapping_list,
+                                       s->vq_aio_context, num_vqs, errp)) {
+            g_free(s->vq_aio_context);
+            s->vq_aio_context = NULL;
             return;
         }
-        s->ctx = qemu_get_aio_context();
+    } else if (vs->conf.iothread) {
+        AioContext *ctx = iothread_get_aio_context(vs->conf.iothread);
+        for (uint16_t i = 0; i < num_vqs; i++) {
+            s->vq_aio_context[i] = ctx;
+        }
+
+        /* Released in virtio_scsi_dataplane_cleanup() */
+        object_ref(OBJECT(vs->conf.iothread));
+    } else {
+        AioContext *ctx = qemu_get_aio_context();
+        for (unsigned i = 0; i < num_vqs; i++) {
+            s->vq_aio_context[i] = ctx;
+        }
+    }
+}
+
+/* Context: BQL held */
+void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s)
+{
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+
+    if (vs->conf.iothread_vq_mapping_list) {
+        iothread_vq_mapping_cleanup(vs->conf.iothread_vq_mapping_list);
     }
+
+    if (vs->conf.iothread) {
+        object_unref(OBJECT(vs->conf.iothread));
+    }
+
+    g_free(s->vq_aio_context);
+    s->vq_aio_context = NULL;
 }
 
 static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
 }
 
 /* Context: BH in IOThread */
-static void virtio_scsi_dataplane_stop_bh(void *opaque)
+static void virtio_scsi_dataplane_stop_vq_bh(void *opaque)
 {
-    VirtIOSCSI *s = opaque;
-    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+    AioContext *ctx = qemu_get_current_aio_context();
+    VirtQueue *vq = opaque;
     EventNotifier *host_notifier;
-    int i;
 
-    virtio_queue_aio_detach_host_notifier(vs->ctrl_vq, s->ctx);
-    host_notifier = virtio_queue_get_host_notifier(vs->ctrl_vq);
+    virtio_queue_aio_detach_host_notifier(vq, ctx);
+    host_notifier = virtio_queue_get_host_notifier(vq);
 
     /*
      * Test and clear notifier after disabling event, in case poll callback
      * didn't have time to run.
      */
     virtio_queue_host_notifier_read(host_notifier);
-
-    virtio_queue_aio_detach_host_notifier(vs->event_vq, s->ctx);
-    host_notifier = virtio_queue_get_host_notifier(vs->event_vq);
-    virtio_queue_host_notifier_read(host_notifier);
-
-    for (i = 0; i < vs->conf.num_queues; i++) {
-        virtio_queue_aio_detach_host_notifier(vs->cmd_vqs[i], s->ctx);
-        host_notifier = virtio_queue_get_host_notifier(vs->cmd_vqs[i]);
-        virtio_queue_host_notifier_read(host_notifier);
-    }
 }
 
 /* Context: BQL held */
@@ -XXX,XX +XXX,XX @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
     smp_wmb(); /* paired with aio_notify_accept() */
 
     if (s->bus.drain_count == 0) {
-        virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx);
-        virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx);
+        virtio_queue_aio_attach_host_notifier(vs->ctrl_vq,
+                                              s->vq_aio_context[0]);
+        virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq,
+                                                      s->vq_aio_context[1]);
 
         for (i = 0; i < vs->conf.num_queues; i++) {
-            virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx);
+            AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
+            virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], ctx);
         }
     }
     return 0;
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
     s->dataplane_stopping = true;
 
     if (s->bus.drain_count == 0) {
-        aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
+        for (i = 0; i < vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED; i++) {
+            VirtQueue *vq = virtio_get_queue(&vs->parent_obj, i);
+            AioContext *ctx = s->vq_aio_context[i];
+            aio_wait_bh_oneshot(ctx, virtio_scsi_dataplane_stop_vq_bh, vq);
+        }
     }
 
     blk_drain_all(); /* ensure there are no in-flight requests */
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@
 #include "hw/qdev-properties.h"
 #include "hw/scsi/scsi.h"
 #include "scsi/constants.h"
+#include "hw/virtio/iothread-vq-mapping.h"
 #include "hw/virtio/virtio-bus.h"
 #include "hw/virtio/virtio-access.h"
 #include "trace.h"
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
     g_free(n);
 }
 
-static inline void virtio_scsi_ctx_check(VirtIOSCSI *s, SCSIDevice *d)
-{
-    if (s->dataplane_started && d && blk_is_available(d->conf.blk)) {
-        assert(blk_get_aio_context(d->conf.blk) == s->ctx);
-    }
-}
-
 static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
 {
     VirtIOSCSI *s = req->dev;
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_flush_defer_tmf_to_aio_context(VirtIOSCSI *s)
 
     assert(!s->dataplane_started);
 
-    if (s->ctx) {
+    for (uint32_t i = 0; i < s->parent_obj.conf.num_queues; i++) {
+        AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
+
         /* Our BH only runs after previously scheduled BHs */
-        aio_wait_bh_oneshot(s->ctx, dummy_bh, NULL);
+        aio_wait_bh_oneshot(ctx, dummy_bh, NULL);
     }
 }
 
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
     AioContext *ctx;
     int ret = 0;
 
-    virtio_scsi_ctx_check(s, d);
     /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
     req->resp.tmf.response = VIRTIO_SCSI_S_OK;
 
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 
     case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
     case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
+        g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
+
         if (!d) {
             goto fail;
         }
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 
         qatomic_inc(&req->remaining);
 
-        ctx = s->ctx ?: qemu_get_aio_context();
-        virtio_scsi_defer_tmf_to_aio_context(req, ctx);
+        for (uint32_t i = 0; i < s->parent_obj.conf.num_queues; i++) {
+            ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
+
+            if (!g_hash_table_add(aio_contexts, ctx)) {
+                continue; /* skip previously added AioContext */
+            }
+
+            virtio_scsi_defer_tmf_to_aio_context(req, ctx);
+        }
 
         virtio_scsi_tmf_dec_remaining(req);
         ret = -EINPROGRESS;
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq)
  */
 static bool virtio_scsi_defer_to_dataplane(VirtIOSCSI *s)
 {
-    if (!s->ctx || s->dataplane_started) {
+    if (s->dataplane_started) {
         return false;
     }
+    if (s->vq_aio_context[0] == qemu_get_aio_context()) {
+        return false; /* not using IOThreads */
+    }
 
     virtio_device_start_ioeventfd(&s->parent_obj.parent_obj);
     return !s->dataplane_fenced;
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
         virtio_scsi_complete_cmd_req(req);
         return -ENOENT;
     }
-    virtio_scsi_ctx_check(s, d);
     req->sreq = scsi_req_new(d, req->req.cmd.tag,
                              virtio_scsi_get_lun(req->req.cmd.lun),
                              req->req.cmd.cdb, vs->cdb_size, req);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+    AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED];
     SCSIDevice *sd = SCSI_DEVICE(dev);
-    int ret;
 
-    if (s->ctx && !s->dataplane_fenced) {
-        ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
-        if (ret < 0) {
-            return;
-        }
+    if (ctx != qemu_get_aio_context() && !s->dataplane_fenced) {
+        /*
+         * Try to make the BlockBackend's AioContext match ours. Ignore failure
+         * because I/O will still work although block jobs and other users
+         * might be slower when multiple AioContexts use a BlockBackend.
+         */
+        blk_set_aio_context(sd->conf.blk, ctx, errp);
     }
 
     if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
 
     qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
 
-    if (s->ctx) {
+    if (s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED] != qemu_get_aio_context()) {
         /* If other users keep the BlockBackend in the iothread, that's ok */
         blk_set_aio_context(sd->conf.blk, qemu_get_aio_context(), NULL);
     }
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_drained_begin(SCSIBus *bus)
 
     for (uint32_t i = 0; i < total_queues; i++) {
         VirtQueue *vq = virtio_get_queue(vdev, i);
-        virtio_queue_aio_detach_host_notifier(vq, s->ctx);
+        virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
     }
 }
 
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_drained_end(SCSIBus *bus)
 
     for (uint32_t i = 0; i < total_queues; i++) {
         VirtQueue *vq = virtio_get_queue(vdev, i);
+        AioContext *ctx = s->vq_aio_context[i];
+
         if (vq == vs->event_vq) {
-            virtio_queue_aio_attach_host_notifier_no_poll(vq, s->ctx);
+            virtio_queue_aio_attach_host_notifier_no_poll(vq, ctx);
         } else {
-            virtio_queue_aio_attach_host_notifier(vq, s->ctx);
+            virtio_queue_aio_attach_host_notifier(vq, ctx);
         }
     }
 }
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_common_unrealize(DeviceState *dev)
     virtio_cleanup(vdev);
 }
 
+/* main loop */
 static void virtio_scsi_device_unrealize(DeviceState *dev)
 {
     VirtIOSCSI *s = VIRTIO_SCSI(dev);
 
     virtio_scsi_reset_tmf_bh(s);
-
+    virtio_scsi_dataplane_cleanup(s);
     qbus_set_hotplug_handler(BUS(&s->bus), NULL);
     virtio_scsi_common_unrealize(dev);
     qemu_mutex_destroy(&s->tmf_bh_lock);
@@ -XXX,XX +XXX,XX @@ static const Property virtio_scsi_properties[] = {
                                                 VIRTIO_SCSI_F_CHANGE, true),
     DEFINE_PROP_LINK("iothread", VirtIOSCSI, parent_obj.conf.iothread,
                      TYPE_IOTHREAD, IOThread *),
+    DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST("iothread-vq-mapping", VirtIOSCSI,
+            parent_obj.conf.iothread_vq_mapping_list),
 };
 
 static const VMStateDescription vmstate_virtio_scsi = {
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

Previously the ctrl virtqueue was handled in the AioContext where SCSI
requests are processed. When IOThread Virtqueue Mapping was added things
become more complicated because SCSI requests could run in other
AioContexts.

Simplify by handling the ctrl virtqueue in the main loop where reset
operations can be performed. Note that BHs are still used canceling SCSI
requests in their AioContexts but at least the mean loop activity
doesn't need BHs anymore.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250311132616.1049687-13-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/hw/virtio/virtio-scsi.h |   8 --
 hw/scsi/virtio-scsi-dataplane.c |   6 ++
 hw/scsi/virtio-scsi.c           | 144 ++++++--------------------------
 3 files changed, 33 insertions(+), 125 deletions(-)

diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index XXXXXXX..XXXXXXX 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -XXX,XX +XXX,XX @@ struct VirtIOSCSI {
 
     QemuMutex ctrl_lock; /* protects ctrl_vq */
 
-    /*
-     * TMFs deferred to main loop BH. These fields are protected by
-     * tmf_bh_lock.
-     */
-    QemuMutex tmf_bh_lock;
-    QEMUBH *tmf_bh;
-    QTAILQ_HEAD(, VirtIOSCSIReq) tmf_bh_list;
-
     /* Fields for dataplane below */
     AioContext **vq_aio_context; /* per-virtqueue AioContext pointer */
 
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
             s->vq_aio_context[i] = ctx;
         }
     }
+
+    /*
+     * Always handle the ctrl virtqueue in the main loop thread where device
+     * resets can be performed.
+     */
+    s->vq_aio_context[0] = qemu_get_aio_context();
 }
 
 /* Context: BQL held */
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
     g_free(n);
 }
 
-static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
-{
-    VirtIOSCSI *s = req->dev;
-    SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
-    BusChild *kid;
-    int target;
-
-    switch (req->req.tmf.subtype) {
-    case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
-        if (!d) {
-            req->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
-            goto out;
-        }
-        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
-            req->resp.tmf.response = VIRTIO_SCSI_S_INCORRECT_LUN;
-            goto out;
-        }
-        qatomic_inc(&s->resetting);
-        device_cold_reset(&d->qdev);
-        qatomic_dec(&s->resetting);
-        break;
-
-    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
-        target = req->req.tmf.lun[1];
-        qatomic_inc(&s->resetting);
-
-        rcu_read_lock();
-        QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
-            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
-            if (d1->channel == 0 && d1->id == target) {
-                device_cold_reset(&d1->qdev);
-            }
-        }
-        rcu_read_unlock();
-
-        qatomic_dec(&s->resetting);
-        break;
-
-    default:
-        g_assert_not_reached();
-    }
-
-out:
-    object_unref(OBJECT(d));
-    virtio_scsi_complete_req(req, &s->ctrl_lock);
-}
-
-/* Some TMFs must be processed from the main loop thread */
-static void virtio_scsi_do_tmf_bh(void *opaque)
-{
-    VirtIOSCSI *s = opaque;
-    QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
-    VirtIOSCSIReq *req;
-    VirtIOSCSIReq *tmp;
-
-    GLOBAL_STATE_CODE();
-
-    WITH_QEMU_LOCK_GUARD(&s->tmf_bh_lock) {
-        QTAILQ_FOREACH_SAFE(req, &s->tmf_bh_list, next, tmp) {
-            QTAILQ_REMOVE(&s->tmf_bh_list, req, next);
-            QTAILQ_INSERT_TAIL(&reqs, req, next);
-        }
-
-        qemu_bh_delete(s->tmf_bh);
-        s->tmf_bh = NULL;
-    }
-
-    QTAILQ_FOREACH_SAFE(req, &reqs, next, tmp) {
-        QTAILQ_REMOVE(&reqs, req, next);
-        virtio_scsi_do_one_tmf_bh(req);
-    }
-}
-
-static void virtio_scsi_reset_tmf_bh(VirtIOSCSI *s)
-{
-    VirtIOSCSIReq *req;
-    VirtIOSCSIReq *tmp;
-
-    GLOBAL_STATE_CODE();
-
-    /* Called after ioeventfd has been stopped, so tmf_bh_lock is not needed */
-    if (s->tmf_bh) {
-        qemu_bh_delete(s->tmf_bh);
-        s->tmf_bh = NULL;
-    }
-
-    QTAILQ_FOREACH_SAFE(req, &s->tmf_bh_list, next, tmp) {
-        QTAILQ_REMOVE(&s->tmf_bh_list, req, next);
-
-        /* SAM-6 6.3.2 Hard reset */
-        req->resp.tmf.response = VIRTIO_SCSI_S_TARGET_FAILURE;
-        virtio_scsi_complete_req(req, &req->dev->ctrl_lock);
-    }
-}
-
-static void virtio_scsi_defer_tmf_to_main_loop(VirtIOSCSIReq *req)
-{
-    VirtIOSCSI *s = req->dev;
-
-    WITH_QEMU_LOCK_GUARD(&s->tmf_bh_lock) {
-        QTAILQ_INSERT_TAIL(&s->tmf_bh_list, req, next);
-
-        if (!s->tmf_bh) {
-            s->tmf_bh = qemu_bh_new(virtio_scsi_do_tmf_bh, s);
-            qemu_bh_schedule(s->tmf_bh);
-        }
-    }
-}
-
 static void virtio_scsi_tmf_cancel_req(VirtIOSCSIReq *tmf, SCSIRequest *r)
 {
     VirtIOSCSICancelNotifier *notifier;
@@ -XXX,XX +XXX,XX @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
         break;
 
     case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
-    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
-        virtio_scsi_defer_tmf_to_main_loop(req);
-        ret = -EINPROGRESS;
+        if (!d) {
+            goto fail;
+        }
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
+            goto incorrect_lun;
+        }
+        qatomic_inc(&s->resetting);
+        device_cold_reset(&d->qdev);
+        qatomic_dec(&s->resetting);
         break;
 
+    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET: {
+        BusChild *kid;
+        int target = req->req.tmf.lun[1];
+        qatomic_inc(&s->resetting);
+
+        rcu_read_lock();
+        QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
+            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
+            if (d1->channel == 0 && d1->id == target) {
+                device_cold_reset(&d1->qdev);
+            }
+        }
+        rcu_read_unlock();
+
+        qatomic_dec(&s->resetting);
+        break;
+    }
+
     case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
     case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
         g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_reset(VirtIODevice *vdev)
 
     assert(!s->dataplane_started);
 
-    virtio_scsi_reset_tmf_bh(s);
     virtio_scsi_flush_defer_tmf_to_aio_context(s);
 
     qatomic_inc(&s->resetting);
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
     VirtIOSCSI *s = VIRTIO_SCSI(dev);
     Error *err = NULL;
 
-    QTAILQ_INIT(&s->tmf_bh_list);
     qemu_mutex_init(&s->ctrl_lock);
     qemu_mutex_init(&s->event_lock);
-    qemu_mutex_init(&s->tmf_bh_lock);
 
     virtio_scsi_common_realize(dev,
                                virtio_scsi_handle_ctrl,
@@ -XXX,XX +XXX,XX @@ static void virtio_scsi_device_unrealize(DeviceState *dev)
 {
     VirtIOSCSI *s = VIRTIO_SCSI(dev);
 
-    virtio_scsi_reset_tmf_bh(s);
     virtio_scsi_dataplane_cleanup(s);
     qbus_set_hotplug_handler(BUS(&s->bus), NULL);
     virtio_scsi_common_unrealize(dev);
-    qemu_mutex_destroy(&s->tmf_bh_lock);
     qemu_mutex_destroy(&s->event_lock);
     qemu_mutex_destroy(&s->ctrl_lock);
 }
-- 
2.48.1

From: Stefan Hajnoczi <stefanha@redhat.com>

Peter Krempa and Kevin Wolf observed that iothread-vq-mapping is
confusing to use because the control and event virtqueues have a fixed
location before the command virtqueues but need to be treated
differently.

Only expose the command virtqueues via iothread-vq-mapping so that the
command-line parameter is intuitive: it controls where SCSI requests are
processed.

The control virtqueue needs to be hardcoded to the main loop thread for
technical reasons anyway. Kevin also pointed out that it's better to
place the event virtqueue in the main loop thread since its no poll
behavior would prevent polling if assigned to an IOThread.

This change is its own commit to avoid squashing the previous commit.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Suggested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250311132616.1049687-14-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/scsi/virtio-scsi-dataplane.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index XXXXXXX..XXXXXXX 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
     VirtIODevice *vdev = VIRTIO_DEVICE(s);
     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
-    uint16_t num_vqs = vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED;
 
     if (vs->conf.iothread && vs->conf.iothread_vq_mapping_list) {
         error_setg(errp,
@@ -XXX,XX +XXX,XX @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
         }
     }
 
-    s->vq_aio_context = g_new(AioContext *, num_vqs);
+    s->vq_aio_context = g_new(AioContext *, vs->conf.num_queues +
+                                            VIRTIO_SCSI_VQ_NUM_FIXED);
+
+    /*
+     * Handle the ctrl virtqueue in the main loop thread where device resets
+     * can be performed.
+     */
+    s->vq_aio_context[0] = qemu_get_aio_context();
+
+    /*
+     * Handle the event virtqueue in the main loop thread where its no_poll
+     * behavior won't stop IOThread polling.
+     */
+    s->vq_aio_context[1] = qemu_get_aio_context();
 
     if (vs->conf.iothread_vq_mapping_list) {
         if (!iothread_vq_mapping_apply(vs->conf.iothread_vq_mapping_list,
-                                       s->vq_aio_context, num_vqs, errp)) {
+                    &s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED],
+                    vs->conf.num_queues, errp)) {
             g_free(s->vq_aio_context);
             s->vq_aio_context = NULL;
             return;
         }
     } else if (vs->conf.iothread) {
         AioContext *ctx = iothread_get_aio_context(vs->conf.iothread);
-        for (uint16_t i = 0; i < num_vqs; i++) {
-            s->vq_aio_context[i] = ctx;
+        for (uint16_t i = 0; i < vs->conf.num_queues; i++) {
+            s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i] = ctx;
         }
 
         /* Released in virtio_scsi_dataplane_cleanup() */
         object_ref(OBJECT(vs->conf.iothread));
     } else {
         AioContext *ctx = qemu_get_aio_context();
-        for (unsigned i = 0; i < num_vqs; i++) {
-            s->vq_aio_context[i] = ctx;
+        for (unsigned i = 0; i < vs->conf.num_queues; i++) {
+            s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i] = ctx;
         }
     }
-
-    /*
-     * Always handle the ctrl virtqueue in the main loop thread where device
-     * resets can be performed.
-     */
-    s->vq_aio_context[0] = qemu_get_aio_context();
 }
 
 /* Context: BQL held */
-- 
2.48.1