On Thu, Jun 21, 2018 at 04:59:13PM +0200, Cornelia Huck wrote:

On Wed, 20 Jun 2018 22:48:58 +0300
"Michael S. Tsirkin" [off-list ref] wrote:

quoted

On Wed, Jun 20, 2018 at 06:06:19PM +0200, Cornelia Huck wrote:

quoted

In any case, I'm not sure anymore why we'd want the extra uuid.  

It's mostly so we can have e.g. multiple devices with same MAC
(which some people seem to want in order to then use
then with different containers).

But it is also handy for when you assign a PF, since then you
can't set the MAC.

OK, so what about the following:

- introduce a new feature bit, VIRTIO_NET_F_STANDBY_UUID that indicates
  that we have a new uuid field in the virtio-net config space
- in QEMU, add a property for virtio-net that allows to specify a uuid,
  offer VIRTIO_NET_F_STANDBY_UUID if set
- when configuring, set the property to the group UUID of the vfio-pci
  device
- in the guest, use the uuid from the virtio-net device's config space
  if applicable; else, fall back to matching by MAC as done today

That should work for all virtio transports.

True. I'm a bit unhappy that it's virtio net specific though
since down the road I expect we'll have a very similar feature
for scsi (and maybe others).

But we do not have a way to have fields that are portable
both across devices and transports, and I think it would
be a useful addition. How would this work though? Any idea?

-- 
MST