Re: [PATCH] PCI/ATS: Allow to enable ATS on VFs even if it is not enabled on PF

Joerg Roedel
2023-02-16T10:24:37Z

On Wed, Feb 15, 2023 at 02:57:26PM -0600, Bjorn Helgaas wrote:
> [+cc Will, Robin, Joerg for arm-smmu-v3 page size question]
>
> On Sun, Feb 12, 2023 at 08:14:48PM +0200, Leon Romanovsky wrote:
> > On Wed, Feb 08, 2023 at 10:43:21AM -0800, Ganapatrao Kulkarni wrote:
> > > As per PCIe specification(section 10.5), If a VF implements an
> > > ATS capability, its associated PF must implement an ATS capability.
> > > The ATS Capabilities in VFs and their associated PFs are permitted to
> > > be enabled independently.

Well, the spec is one thing, existing hardware the other. Have you
checked the history of the PF-before-VF requirement before making that
change?

It is possible that early PASID-capable hardware actually required
PF-before-VF enablement of ATS.

Regards,

Joerg