vdpa: Buffer CVQ support on shadow virtqueue

Introduce the control virtqueue support for vDPA shadow virtqueue. This
is needed for advanced networking features like rx filtering.

Virtio-net control VQ copies the descriptors to qemu's VA, so we avoid
TOCTOU with the guest's or device's memory every time there is a device
model change.  Otherwise, the guest could change the memory content in
the time between qemu and the device read it.

To demonstrate command handling, VIRTIO_NET_F_CTRL_MACADDR is
implemented.  If the virtio-net driver changes MAC the virtio-net device
model will be updated with the new one, and a rx filtering change event
will be raised.

More cvq commands could be added here straightforwardly but they have
not been tested.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

0 files changed, 0 insertions, 0 deletions