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

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

On Thu Oct 2, 2025 at 6:13 AM JST, Zhi Wang wrote:
> On 1.10.2025 17.48, Jason Gunthorpe wrote:
>> On Wed, Oct 01, 2025 at 08:09:37AM +0000, Zhi Wang wrote:
>>>>> 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)?
>>>>
>>>
>>> The guest driver will read PMC_BOOT_1 and check PMC_BOOT_1_VGPU_VF flag
>>> to tell if it is running on a VF or a PF.
>> 
>> Yes exactly, and then novacore should modify its behavior and operate
>> the device in the different mode.
>> 
>> It doesn't matter if a VM is involved or not, a VF driver running side
>> by side wit the PF driver should still work.
>> 
>> There are use cases where people do this, eg they can stick the VF
>> into a linux container and use the SRIOV mechanism as a QOS control.
>> 'This container only gets 1/4 of a GPU'
>> 
>
> Right, I also mentioned the same use cases of NIC/GPU in another reply
> to Danilo. But what I get is NVIDIA doesn't use bare metal VF to support
> linux container, it seems there have been other solutions. IMHO, it is
> not mandatory that we have to support VF driver on bare metal so far
> yet.

For my education, what gets in the way of supporting a VF on the bare
metal if we already support it from inside a VM?