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

Logan Gunthorpe <[email protected]> Tue, 4 Aug 2026 13:52:22 -0600
Newsgroups gmane.linux.documentation,gmane.linux.kernel.pci,gmane.linux.kernel
Message-ID <[email protected]>

On 2026-08-02 09:09, Leon Romanovsky wrote:
> From: Leon Romanovsky <[email protected]>
> 
> 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 <[email protected]>

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 <[email protected]>