Re: [PATCH 8/9] vfio/pci: export nvlink2 support into vendor vfio_pci drivers

[Christoph Hellwig]

On Mon, Mar 22, 2021 at 01:44:11PM -0300, Jason Gunthorpe wrote:
> This isn't quite the scenario that needs solving. Lets go back to
> Max's V1 posting:
> 
> The mlx5_vfio_pci.c pci_driver matches this:
> 
> +	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_REDHAT_QUMRANET, 0x1042,
> +			 PCI_VENDOR_ID_MELLANOX, PCI_ANY_ID) }, /* Virtio SNAP controllers */
> 
> This overlaps with the match table in
> drivers/virtio/virtio_pci_common.c:
> 
>         { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },
> 
> So, if we do as you propose we have to add something mellanox specific
> to virtio_pci_common which seems to me to just repeating this whole
> problem except in more drivers.

Oh, yikes.  

> The general thing that that is happening is people are adding VM
> migration capability to existing standard PCI interfaces like VFIO,
> NVMe, etc

Well, if a migration capability is added to virtio (or NVMe) it should
be standardized and not vendor specific.