Re: [virtio-comment] [PATCH v1 1/8] admin: Add theory of operation for device migration

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Oct 18, 2023 at 08:16:01AM +0000, Parav Pandit wrote:
> > This doesn't happen yet. For example, a VF with adminq that can be isolated
> > with PASID makes some sense.
> PASID is for the process of user space.
> Kernel space do not consume a PASID.

It could if we need it to.

> Depending on the PASID can work for mediation approach only.
> Last I heard is the cpu or kernel took the support out of it as some special instruction did not work for that cpu.

Are you talking about ENQCMD things? That's nice but I don't think it's
necessary for isolation here.

...

> > The reason why I see it is different from FLR is that
> > 
> > 1) D3cold requires the VF to be off the power
> > 2) State transition might takes more than what FLR did, PCI seems only cover
> > the minimum delay but not maximum which may have implications for
> > downtime
> > 
> D3cold is not controlled by the guest driver.
> PM register can change D0 to D3hot.

It likely makes sense to document how all this interacts with things
like PM and other pci config. maybe you did in v2 didn't look at it yet.