Re: [RFC PATCH 5/5] nvme-vfio: Add a document for the NVMe device

Christoph Hellwig
2022-12-06T14:01:11Z

On Tue, Dec 06, 2022 at 09:52:54AM -0400, Jason Gunthorpe wrote:
> On Tue, Dec 06, 2022 at 02:09:01PM +0100, Christoph Hellwig wrote:
> > On Tue, Dec 06, 2022 at 09:05:05AM -0400, Jason Gunthorpe wrote:
> > > In this case Intel has a real PCI SRIOV VF to expose to the guest,
> > > with a full VF RID.
> >
> > RID?
>
> "Requester ID" - PCI SIG term that in Linux basically means you get to
> assign an iommu_domain to the vfio device.

Yeah I now the Requester ID, I've just never seen that shortcut for it.

> >From what I understood this series basically allows two Intel devices
> to pass a big opaque blob of data. Intel didn't document what is in
> that blob, so I assume it captures everything you mention above.

Which would be just as bad, because it then changes the IDs under
the live OS on a restore. This is not something that can be done
behind the back of the hypervisors / control plane OS.