The net config space is already copied from the device so it can me modified
by qemu. In particular, this is already done to fix cases where the NIC does
not expose the right fields.

It's trivial to emulate _F_STATE with qemu if not supported by the device,
sice a valid approach is to always show the link as up. If the feature is
already supported by the device, no config space modification is needed.

This is a pre requisite to use other features like _F_GUEST_ANNOUNCE, since
_F_STATUS is needed for the guest to access the status.

These patches are sent on top of [1] series, so trivial conflicts could arise
if it is applied directly on master. Future versions can be not based on
it is more convenient.

v2:
* Move feature handling to vhost_net, instead of force depending on the
  backend.

Eugenio Pérez (3):
  virtio_net: Modify virtio_net_get_config to early return
  virtio_net: Handle _F_STATUS emulation in virtio_net_get_config
  vhost_vdpa: move VIRTIO_NET_F_STATUS handling to vhost_net

 hw/net/vhost_net.c  | 13 +++++++++++++
 hw/net/virtio-net.c | 39 ++++++++++++++++++++++++---------------
 net/vhost-vdpa.c    |  1 -
 3 files changed, 37 insertions(+), 16 deletions(-)

-- 
2.31.1