From: Jason Wang <jasowang@redhat.com>
Sent: Tuesday, May 31, 2022 10:42 PM

Well, the ability to query the virtqueue state was proposed as another
feature (Eugenio, please correct me). This should be sufficient for making
virtio-net to be live migrated.

The device is stopped, it won't answer to this special vq config done here.
Programming all of these using cfg registers doesn't scale for on-chip memory and for the speed.

Next would be to program hundreds of statistics of the 64 VQs through giant PCI config space register in some busy polling scheme.

I can clearly see how all these are inefficient for faster LM.
We need an efficient AQ to proceed with at minimum.

https://lists.oasis-open.org/archives/virtio-comment/202103/msg00008.html

quoted

Once the device is stopped, its state cannot be queried further as device

won't respond.

quoted

It has limited use case.
What we need is to stop non admin queue related portion of the device.