| Message ID | 20170209053917.GH22807@lemon.lan |
|---|---|
| State | New |
| Headers | show |
On Thu, 02/09 13:39, Fam Zheng wrote: > On Wed, 02/08 19:44, Ed Swierk wrote: > > On Wed, Feb 8, 2017 at 6:52 PM, Fam Zheng <famz@redhat.com> wrote: > > > This means virtio-scsi event vq handler is returning true but actually no > > > progress is made. Can you try the following patch to see if it's because a > > > stalled cache of VQ index? > > > > > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > > > index 6365706..7f7ab57 100644 > > > --- a/hw/virtio/virtio.c > > > +++ b/hw/virtio/virtio.c > > > @@ -2126,7 +2126,7 @@ static bool virtio_queue_host_notifier_aio_poll(void *opaque) > > > EventNotifier *n = opaque; > > > VirtQueue *vq = container_of(n, VirtQueue, host_notifier); > > > > > > - if (virtio_queue_empty(vq)) { > > > + if (vring_avail_idx(vq) == vq->last_avail_idx) { > > > return false; > > > } > > > > I tried this change but the behavior is the same, unfortunately. > > Hmm, maybe I'm missing something. How about this: > > diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c > index ce19eff..8b23e80 100644 > --- a/hw/scsi/virtio-scsi.c > +++ b/hw/scsi/virtio-scsi.c > @@ -754,9 +754,7 @@ out: > > void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) > { > - if (s->events_dropped) { > - virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); > - } > + virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); > } > > static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq) > Ignore this. It will break the "assert(event == VIRTIO_SCSI_T_EVENTS_MISSED)" in the called function. Anyway I think the cause is virtio_queue_host_notifier_aio_poll() only checks if there is an available req in the virtqueue, but in virtio-scsi, eventq actually contain buffers that are only useful when an event needs to be pushed. It is reproducible with ubuntu LTS 14.04.5. I'll see if I can sort out a proper fix. Fam
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index ce19eff..8b23e80 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -754,9 +754,7 @@ out: void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq) { - if (s->events_dropped) { - virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); - } + virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0); } static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq)