RE: [virtio-dev] Re: [PATCH v3 0/3] transport-pci: Introduce legacy registers access using AQ

[Parav Pandit <parav@nvidia.com>]

> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Thursday, June 8, 2023 2:31 PM

> > > I'll do a proper review after the forum. Generally lots of small
> > > things. Went looking just to give you a couple of
> > > examples:
> > > 	  too many mentions of VFs and PFs.
> > > 	  text should talk about owner and member. Minimise
> > > 	  mention of VFs to make it easier to extend to
> > > 	  different group types.
> > >
> > True but most additions are in PCI transport chapter.
> > But will change to member and owner.
> 
> Another thing that bothers me is that it references admin commands that are
> defined later in the spec. I don't like it that we are making the reader jump back
> and forth ...
> Maybe it's better to put this in the admin command chapter.
> 
I considered that before.
In its current form, there is very less back-n-forth jump.
This is because admin chapter mostly enumerates the opcode.

And PCI legacy chapter talks about rest of the theory and command details.

When/if we have more transports for this, probably a generic place will be suitable.

Moving now to admin will surely have more back-n-forth as it needs to talk about PCI part and that PCI part will reside in PCI section.

> > > another example:
> > > 	+The PCI VF device SHOULD NOT expose PCI BAR 0 when it prefers to
> > > support
> > >
> > > VFs don't expose BARs at all. PF exposes VF BARs in SRIOV capability.
> > >
> > Yes, it is exposed by PF, the wording of "PCI VF device exposing" is not right.
> > I will reword it.
> 
> So here's an example wording, I don't insist on it exactly but the point is to show
> how we should use spec terminology whereever
> possible:
> 
> If an owner of an SRIOV group supports all of
> VIRTIO_ADMIN_CMD_LCC_REG_WRITE,
> VIRTIO_ADMIN_CMD_LCC_REG_READ .... then it SHOULD NOT expose VF BAR0
> (of non 0 size) as part of its SRIOV capability; this is to facilitate emulating IO
> BAR0 for the legacy interface in software.
> 
Yes good one. Will use.