Detach ioeventfds during drained sections to stop I/O submission from the guest. virtio-blk is no longer reliant on aio_disable_external() after this patch. This will allow us to remove the aio_disable_external() API once all other code that relies on it is converted.
Take extra care to avoid attaching/detaching ioeventfds if the data plane is started/stopped during a drained section. This should be rare, but maybe the mirror block job can trigger it. Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> --- hw/block/dataplane/virtio-blk.c | 17 +++++++++------ hw/block/virtio-blk.c | 38 ++++++++++++++++++++++++++++++++- 2 files changed, 48 insertions(+), 7 deletions(-) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 27eafa6c92..c0d2663abc 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -246,13 +246,15 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev) } /* Get this show started by hooking up our callbacks */ - aio_context_acquire(s->ctx); - for (i = 0; i < nvqs; i++) { - VirtQueue *vq = virtio_get_queue(s->vdev, i); + if (!blk_in_drain(s->conf->conf.blk)) { + aio_context_acquire(s->ctx); + for (i = 0; i < nvqs; i++) { + VirtQueue *vq = virtio_get_queue(s->vdev, i); - virtio_queue_aio_attach_host_notifier(vq, s->ctx); + virtio_queue_aio_attach_host_notifier(vq, s->ctx); + } + aio_context_release(s->ctx); } - aio_context_release(s->ctx); return 0; fail_aio_context: @@ -318,7 +320,10 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev) trace_virtio_blk_data_plane_stop(s); aio_context_acquire(s->ctx); - aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s); + + if (!blk_in_drain(s->conf->conf.blk)) { + aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s); + } /* Wait for virtio_blk_dma_restart_bh() and in flight I/O to complete */ blk_drain(s->conf->conf.blk); diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index cefca93b31..d8dedc575c 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -1109,8 +1109,44 @@ static void virtio_blk_resize(void *opaque) aio_bh_schedule_oneshot(qemu_get_aio_context(), virtio_resize_cb, vdev); } +/* Suspend virtqueue ioeventfd processing during drain */ +static void virtio_blk_drained_begin(void *opaque) +{ + VirtIOBlock *s = opaque; + VirtIODevice *vdev = VIRTIO_DEVICE(opaque); + AioContext *ctx = blk_get_aio_context(s->conf.conf.blk); + + if (!s->dataplane || !s->dataplane_started) { + return; + } + + for (uint16_t i = 0; i < s->conf.num_queues; i++) { + VirtQueue *vq = virtio_get_queue(vdev, i); + virtio_queue_aio_detach_host_notifier(vq, ctx); + } +} + +/* Resume virtqueue ioeventfd processing after drain */ +static void virtio_blk_drained_end(void *opaque) +{ + VirtIOBlock *s = opaque; + VirtIODevice *vdev = VIRTIO_DEVICE(opaque); + AioContext *ctx = blk_get_aio_context(s->conf.conf.blk); + + if (!s->dataplane || !s->dataplane_started) { + return; + } + + for (uint16_t i = 0; i < s->conf.num_queues; i++) { + VirtQueue *vq = virtio_get_queue(vdev, i); + virtio_queue_aio_attach_host_notifier(vq, ctx); + } +} + static const BlockDevOps virtio_block_ops = { - .resize_cb = virtio_blk_resize, + .resize_cb = virtio_blk_resize, + .drained_begin = virtio_blk_drained_begin, + .drained_end = virtio_blk_drained_end, }; static void virtio_blk_device_realize(DeviceState *dev, Error **errp) -- 2.40.1