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
