Re: [PATCH v8 1/1] vfio/nvgpu: Add vfio pci variant module for grace hopper

[Jason Gunthorpe]

On Thu, Sep 07, 2023 at 01:55:46PM -0600, Alex Williamson wrote:

> There's perhaps an argument whether userspace should compose this
> device itself, for example finding the firmware attributes in sysfs and
> directly mmap'ing the coherent memory via /dev/mem to back a virtual
> BAR or otherwise pass-through this associated region.  

I don't think this works, secure boot turns off /dev/mem and other
things that would let you do this AFAIK.

> I've previously raised the point whether the coherent region here
> might be exposed as a device specific region (such as we do for the
> above IGD regions) rather than a virtual BAR, but the NVIDIA folks feel
> strongly that the BAR approach is correct.

I think it really depends on what the qemu side wants to do..

> Please continue the discussion, but I'm not seeing anything here that
> feels significantly different than what we created vfio-pci variant
> drivers to do.

Right, the driver seems fine for what the infrastructure was created
to do.

Jason