Re: [PATCH 02/13] PCI/P2PDMA: Report ACS ports when the paths share no upstream bridge

From: Logan Gunthorpe

Date: Tue Aug 04 2026 - 15:52:35 EST




On 2026-08-02 09:09, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@xxxxxxxxxx>
>
> A provider and a client below different Root Ports share no upstream
> bridge, so the search ends without a match and the walk takes the
> host-bridge route directly. Neither path is examined for ACS, so no
> redirect diagnostic is emitted and the host-bridge whitelist warning
> stays suppressed.
>
> Examine the paths before taking that route, so every redirecting port is
> named in the pci=disable_acs_redir= hint. The mapping type is unchanged.
>
> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>

Thanks! I vaguely remember I might have got hit by this bug a long time
ago and didn't know why. The fix looks good.

Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>