Re: [PATCH v4 12/18] PCI/P2PDMA: Honor ACS egress control vectors

[Logan Gunthorpe]

On 2026-08-21 13:38, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@xxxxxxxxxx>
> 
> An enabled Egress Control bit does not by itself redirect a peer Request.
> The result depends on the vector bit for the target port; a set bit without
> Request Redirect is an ACS Violation, while a clear bit permits direct
> routing.
> 
> Evaluate controls only at the path divergence: Request Redirect and Egress
> Control on the client-side port, and Completion Redirect on the
> provider-side port. Below it, traffic toward the other branch already
> routes upstream.
> 
> Reject unreadable vectors and ACS Violations. Neither condition redirects
> the transaction upstream, so a host-bridge mapping cannot make the path
> usable.
> 
> Tested-by: Tushar Dave <tdave@xxxxxxxxxx>
> Fixes: 52916982af48 ("PCI/P2PDMA: Support peer-to-peer memory")
> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>

Not the easiest patch to follow, but I think it makes sense. It does fix
the nit I posted in my review of the previous patch during the code move.

Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>