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Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging

Pull request

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# gpg: Signature made Wed 12 Jul 2023 08:33:49 PM BST
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]

* tag 'block-pull-request' of https://gitlab.com/stefanha/qemu:
  virtio-blk: fix host notifier issues during dataplane start/stop

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-07-12 20:46:10 +01:00
commit 3dd9e54703
1 changed files with 31 additions and 22 deletions
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53
hw/block/dataplane/virtio-blk.c
View File

@ -219,13 +219,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
memory_region_transaction_commit();
/*
* These fields are visible to the IOThread so we rely on implicit barriers
* in aio_context_acquire() on the write side and aio_notify_accept() on
* the read side.
*/
s->starting = false;
vblk->dataplane_started = true;
trace_virtio_blk_data_plane_start(s);
old_context = blk_get_aio_context(s->conf->conf.blk);
@ -244,6 +237,18 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
event_notifier_set(virtio_queue_get_host_notifier(vq));
}
/*
* These fields must be visible to the IOThread when it processes the
* virtqueue, otherwise it will think dataplane has not started yet.
*
* Make sure ->dataplane_started is false when blk_set_aio_context() is
* called above so that draining does not cause the host notifier to be
* detached/attached prematurely.
*/
s->starting = false;
vblk->dataplane_started = true;
smp_wmb(); /* paired with aio_notify_accept() on the read side */
/* Get this show started by hooking up our callbacks */
if (!blk_in_drain(s->conf->conf.blk)) {
aio_context_acquire(s->ctx);
@ -273,7 +278,6 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
fail_guest_notifiers:
vblk->dataplane_disabled = true;
s->starting = false;
vblk->dataplane_started = true;
return -ENOSYS;
}
@ -327,19 +331,6 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s);
}
aio_context_acquire(s->ctx);
/* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
blk_drain(s->conf->conf.blk);
/*
* Try to switch bs back to the QEMU main loop. If other users keep the
* BlockBackend in the iothread, that's ok
*/
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
aio_context_release(s->ctx);
/*
* Batch all the host notifiers in a single transaction to avoid
* quadratic time complexity in address_space_update_ioeventfds().
@ -360,12 +351,30 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
virtio_bus_cleanup_host_notifier(VIRTIO_BUS(qbus), i);
}
/*
* Set ->dataplane_started to false before draining so that host notifiers
* are not detached/attached anymore.
*/
vblk->dataplane_started = false;
aio_context_acquire(s->ctx);
/* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */
blk_drain(s->conf->conf.blk);
/*
* Try to switch bs back to the QEMU main loop. If other users keep the
* BlockBackend in the iothread, that's ok
*/
blk_set_aio_context(s->conf->conf.blk, qemu_get_aio_context(), NULL);
aio_context_release(s->ctx);
qemu_bh_cancel(s->bh);
notify_guest_bh(s); /* final chance to notify guest */
/* Clean up guest notifier (irq) */
k->set_guest_notifiers(qbus->parent, nvqs, false);
vblk->dataplane_started = false;
s->stopping = false;
}