Re: [PATCH v11 00/19] PCI/P2PDMA: Route peer-to-peer DMA by TLP class

[Leon Romanovsky <leon@kernel.org>]

On Tue, Oct 13, 2026 at 05:25:08PM +0300, Leon Romanovsky wrote:
> PCI P2PDMA applies Request and Completion Redirect throughout both paths.
> This misclassifies asymmetric and nested switches, and reports one answer
> for every kind of TLP.
> 
> Three ACS controls act on TLP attributes the Requester chooses rather
> than on the topology: Translation Blocking and Direct Translated P2P act on
> a Request's Address Type, and Completion Redirect skips Completions carrying
> Relaxed Ordering.
> 
> Evaluate each direction at the path divergence, decide every class from the
> one walk, and treat a client with ATS enabled as translating unless its
> driver declares per-mapping ATS.
> 
> This completes the P2PDMA side; dma-buf and mlx5 follow separately.
> 
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
> Changes in v11:


Bjorn,

Could you please save me from the AI-bot attack? Every rebase seems to
uncover another bizarre pre-existing issue. It never ends.

Thanks

<...>

> ---
> Leon Romanovsky (19):
>       PCI/P2PDMA: Honor device-specific ACS redirection
>       PCI/P2PDMA: Document the TLP attribute assumptions
>       PCI/P2PDMA: Derive routing from directional ACS controls
>       PCI: Reject unreadable ACS controls in isolation checks
>       PCI/P2PDMA: Evaluate ACS controls at the path divergence
>       PCI/P2PDMA: Document directional ACS routing
>       PCI/P2PDMA: Collect the path's ACS controls before deciding
>       PCI/P2PDMA: Answer routing per TLP class
>       PCI/P2PDMA: Route Relaxed Ordering Completions directly
>       PCI/P2PDMA: Reject Translated Requests blocked by Translation Blocking
>       PCI/P2PDMA: Route Translated Requests under Direct Translated P2P
>       PCI/P2PDMA: Log detailed ACS routing diagnostics
>       PCI/P2PDMA: Add KUnit tests for the ACS routing decisions
>       PCI/P2PDMA: Test the ACS P2P routing walk
>       PCI: Add KUnit coverage for ACS isolation checks
>       PCI/P2PDMA: Document TLP-class routing
>       PCI/P2PDMA: Let a client declare that it selects ATS per mapping
>       PCI/P2PDMA: Evaluate the ATS path for clients with ATS enabled
>       PCI/P2PDMA: Test the routing of clients with ATS enabled
> 
>  Documentation/admin-guide/kernel-parameters.txt |   11 +-
>  Documentation/driver-api/pci/p2pdma.rst         |  105 ++
>  drivers/pci/Kconfig                             |   15 +
>  drivers/pci/Makefile                            |    1 +
>  drivers/pci/p2pdma.c                            |  942 +++++++++++++++--
>  drivers/pci/pci.c                               |    8 +-
>  drivers/pci/pci.h                               |   57 ++
>  drivers/pci/pci_acs_test.c                      | 1225 +++++++++++++++++++++++
>  drivers/pci/quirks.c                            |    8 +-
>  include/linux/pci-p2pdma.h                      |   12 +-
>  10 files changed, 2292 insertions(+), 92 deletions(-)
> ---
> base-commit: 36038f0e8377ef316b723d0d85b1510bc64069ab
> change-id: 20260821-fix-p2p-acs-v4-0-e72455e3a261
> 
> Best regards,
> --  
> Leon Romanovsky <leonro@nvidia.com>
>