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-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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)