[RFC,0/5] Guest announce feature emulation using Shadow VirtQueue

Message

Eugenio Perez Martin Oct. 18, 2022, 3:53 p.m. UTC

A gratuitous ARP is recommended after a live migration to reduce the amount of
time needed by the network links to be aware of the new location. A hypervisor
may not have the knowledge of the guest network configuration, and this is
especially true on passthrough devices, so its simpler to ask the guest to
do it.

However, the device control part of this feature can be totally emulated by
qemu and shadow virtqueue, not needing any special feature from the actual
vdpa device.

Sending as RFC for the moment as VIRTIO_NET_F_STATUS is also needed for the
guest to access the status of virtio net config to check if an announcement
is needed.

Eugenio Pérez (5):
  vdpa: Save emulated features list in vhost_vdpa
  vdpa: Remove shadow CVQ command check
  vdpa: handle VIRTIO_NET_CTRL_ANNOUNCE in
    vhost_vdpa_net_handle_ctrl_avail
  vhost_net: return VIRTIO_NET_S_ANNOUNCE is device model has it set
  vdpa: Offer VIRTIO_NET_F_GUEST_ANNOUNCE feature if SVQ is enabled

 include/hw/virtio/vhost-vdpa.h |  2 +
 hw/net/vhost_net.c             | 30 ++++++++++++++-
 hw/virtio/vhost-vdpa.c         |  8 ++--
 net/vhost-vdpa.c               | 70 +++++++++-------------------------
 4 files changed, 54 insertions(+), 56 deletions(-)