From: Paolo Bonzini <pbonz...@redhat.com> Commit ad07cd6 ("virtio-scsi: always use dataplane path if ioeventfd is active", 2016-10-30) and 9ffe337 ("virtio-blk: always use dataplane path if ioeventfd is active", 2016-10-30) broke the virtio 1.0 indirect access registers.
The indirect access registers bypass the ioeventfd, so that virtio-blk and virtio-scsi now repeatedly try to initialize dataplane instead of triggering the guest->host EventNotifier. Detect the situation by checking vq->handle_aio_output; if it is not NULL, trigger the EventNotifier, which is how the device expects to get notifications and in fact the only thread-safe manner to deliver them. Fixes: ad07cd6 Fixes: 9ffe337 Cc: qemu-sta...@nongnu.org Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com> --- hw/virtio/virtio.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 82b6060..03592c5 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -1528,7 +1528,18 @@ static void virtio_queue_notify_vq(VirtQueue *vq) void virtio_queue_notify(VirtIODevice *vdev, int n) { - virtio_queue_notify_vq(&vdev->vq[n]); + VirtQueue *vq = &vdev->vq[n]; + + if (unlikely(!vq->vring.desc || vdev->broken)) { + return; + } + + trace_virtio_queue_notify(vdev, vq - vdev->vq, vq); + if (vq->handle_aio_output) { + event_notifier_set(&vq->host_notifier); + } else if (vq->handle_output) { + vq->handle_output(vdev, vq); + } } uint16_t virtio_queue_vector(VirtIODevice *vdev, int n) -- MST