[PATCH 06/19] virtio: decrement last_avail_idx with inuse before saving.

Yoshiaki Tamura
2011-01-28T07:23:45Z

For regular migration inuse == 0 always as requests are flushed before
save. However, event-tap log when enabled introduces an extra queue
for requests which is not being flushed, thus the last inuse requests
are left in the event-tap queue. Move the last_avail_idx value sent
to the remote back to make it repeat the last inuse requests.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Yoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>
---
hw/virtio.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/hw/virtio.c b/hw/virtio.c
index 31bd9e3..f05d1b6 100644
--- a/hw/virtio.c
+++ b/hw/virtio.c
@@ -673,12 +673,20 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
qemu_put_be32(f, i);

for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
+ /* For regular migration inuse == 0 always as
+ * requests are flushed before save. However,
+ * event-tap log when enabled introduces an extra
+ * queue for requests which is not being flushed,
+ * thus the last inuse requests are left in the event-tap queue.
+ * Move the last_avail_idx value sent to the remote back
+ * to make it repeat the last inuse requests. */
+ uint16_t last_avail = vdev->vq[i].last_avail_idx - vdev->vq[i].inuse;
if (vdev->vq[i].vring.num == 0)
break;

qemu_put_be32(f, vdev->vq[i].vring.num);
qemu_put_be64(f, vdev->vq[i].pa);
- qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
+ qemu_put_be16s(f, &last_avail);
if (vdev->binding->save_queue)
vdev->binding->save_queue(vdev->binding_opaque, i, f);
}
--
1.7.1.2