The SVQ vring used idx usually match with the guest visible one, as long
as all the guest buffers (GPA) maps to exactly one buffer within qemu's
VA. However, as we can see in virtqueue_map_desc, a single guest buffer
could map to many buffers in SVQ vring.

The solution is to stop using the device's used idx and check for the
last avail idx. Since we cannot report in-flight descriptors with vdpa,
let's rewind all of them.

Also, move this rewind to the destination, so we keep migrating the in-flight
ones in case the destnation backend support them (vhost-kernel, emulated virtio
in qemu, etc.)

Eugenio Pérez (2):
  vhost: Get vring base from vq, not svq
  vhost: Move SVQ queue rewind to the destination

 hw/virtio/vhost-vdpa.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

-- 
2.31.1