The vq->inuse field is not migrated. Many devices don't hold
VirtQueueElements across migration so it doesn't matter that vq->inuse
starts at 0 on the destination QEMU.
At least virtio-serial, virtio-blk, and virtio-balloon migrate while
holding VirtQueueElements. For these devices we need to recalculate
vq->inuse upon load so the value is correct.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
hw/virtio/virtio.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 15ee3a7..4df8274 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1648,6 +1648,20 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int
version_id)
}
vdev->vq[i].used_idx = vring_used_idx(&vdev->vq[i]);
vdev->vq[i].shadow_avail_idx = vring_avail_idx(&vdev->vq[i]);
+
+ /* Some devices migrate VirtQueueElements that have been popped
+ * from the avail ring but not yet returned to the used ring.
+ */
+ vdev->vq[i].inuse = vdev->vq[i].last_avail_idx -
+ vdev->vq[i].used_idx;
+ if (vdev->vq[i].inuse > vdev->vq[i].vring.num) {
+ error_report("VQ %d size 0x%x < last_avail_idx 0x%x - "
+ "used_idx 0x%x"
+ i, vdev->vq[i].vring.num,
+ vdev->vq[i].last_avail_idx,
+ vdev->vq[i].used_idx);
+ return -1;
+ }
}
}
--
2.7.4
