Re: [PATCH 0/2] rust: pci: expose is_virtfn() and reject VFs in nova-core

["Alexandre Courbot" <acourbot@nvidia.com>]

On Wed Oct 1, 2025 at 10:26 AM JST, John Hubbard wrote:
> On 9/30/25 5:26 PM, Alexandre Courbot wrote:
>> On Wed Oct 1, 2025 at 7:07 AM JST, John Hubbard wrote:
>>> Post-Kangrejos, the approach for NovaCore + VFIO has changed a bit: the
>>> idea now is that VFIO drivers, for NVIDIA GPUs that are supported by
>>> NovaCore, should bind directly to the GPU's VFs. (An earlier idea was to
>>> let NovaCore bind to the VFs, and then have NovaCore call into the upper
>>> (VFIO) module via Aux Bus, but this turns out to be awkward and is no
>>> longer in favor.) So, in order to support that:
>>>
>>> Nova-core must only bind to Physical Functions (PFs) and regular PCI
>>> devices, not to Virtual Functions (VFs) created through SR-IOV.
>> 
>> Naive question: will guests also see the passed-through VF as a VF? If
>> so, wouldn't this change also prevents guests from using Nova?
>
> I'm also new to this area. I would expect that guests *must* see
> these as PFs, otherwise...nothing makes any sense.

But if the guest sees the passed-through VF as a PF, won't it try to
do things it is not supposed to do like loading the GSP firmware (which
is managed by the host)?