[Qemu-devel] [PATCH v9 10/20] Gracefully handle ioctl failure in vhost_virtqueue_stop

[Antonios Motakis]

On stopping the vhost, a call to VHOST_GET_VRING_BASE is issued. The
received value is stored as last_avail_idx, so the virtqueue can continue
operating if the connection is resumed. Handle the failure of this call
and use the current avail_idx. Some packets from the avail ring may be
omitted but still we keep a sane value and can continue on reconnect.

Signed-off-by: Antonios Motakis <address@hidden>
Signed-off-by: Nikolay Nikolaev <address@hidden>
---
 hw/virtio/vhost.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 9e336ad..322e2c0 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -758,12 +758,13 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
     assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
     r = ioctl(dev->control, VHOST_GET_VRING_BASE, &state);
     if (r < 0) {
+        state.num = virtio_queue_get_avail_idx(vdev, idx);
         fprintf(stderr, "vhost VQ %d ring restore failed: %d\n", idx, r);
         fflush(stderr);
     }
     virtio_queue_set_last_avail_idx(vdev, idx, state.num);
     virtio_queue_invalidate_signalled_used(vdev, idx);
-    assert (r >= 0);
+
     cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
                               0, virtio_queue_get_ring_size(vdev, idx));
     cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
-- 
1.8.3.2