Re: [PATCH v4 06/17] PCI: add SIOV and IMS capability detection

[Dave Jiang]

On 10/30/2020 3:45 PM, Jason Gunthorpe wrote:
> On Fri, Oct 30, 2020 at 02:20:03PM -0700, Dave Jiang wrote:
> > So the intel-iommu driver checks for the SIOV cap. And the idxd driver
> > checks for SIOV and IMS cap. There will be other upcoming drivers that will
> > check for such cap too. It is Intel vendor specific right now, but SIOV is
> > public and other vendors may implement to the spec. Is there a good place to
> > put the common capability check for that?
>
> I'm still really unhappy with these SIOV caps. It was explained this
> is just a hack to make up for pci_ims_array_create_msi_irq_domain()
> succeeding in VM cases when it doesn't actually work.
>
> Someday this is likely to get fixed, so tying platform behavior to PCI
> caps is completely wrong.
>
> This needs to be solved in the platform code,
> pci_ims_array_create_msi_irq_domain() should not succeed in these
> cases.

That sounds reasonable. Are you asking that the IMS cap check should gate the 
success/failure of pci_ims_array_create_msi_irq_domain() rather than the driver?

> Jason