Re: [PATCH v4 10/18] PCI: Account for ACS egress control in isolation checks

[Jason Gunthorpe <jgg@nvidia.com>]

On Sun, Aug 30, 2026 at 12:20:33PM +0300, Leon Romanovsky wrote:
> On Mon, Aug 24, 2026 at 08:22:50PM -0300, Jason Gunthorpe wrote:
> > > pci_acs_enabled() treats P2P Request Redirect as effective whenever its
> > > control bit is set. PCIe r7.0, sec 6.12.3, table 6-11 lets an enabled
> > > Egress Control Vector override it: a clear vector bit routes the request
> > > directly.
> > 
> > This may well all be correct, but I'd prefer not to touch grouping in
> > this series working on p2pdma.. The grouping logic is already not
> > doing a good job with the spec and we can't change it because it
> > creates regression.
> 
> The longer we wait, the harder it will be to address this deviation
> from the PCI specification.

I think it is too late already. People already made HW that probably
doesn't match the intention of the spec because Linux works with that
HW so we are good and properly trapped now.

Jason