From: Leon Romanovsky <leon@kernel.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: "Bjorn Helgaas" <bhelgaas@google.com>,
"Chaitanya Kulkarni" <kch@nvidia.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jens Axboe" <axboe@kernel.dk>,
"Alex Williamson" <alex@shazbot.org>,
"Ankit Agrawal" <ankita@nvidia.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jonathan Corbet" <corbet@lwn.net>,
"Shuah Khan" <skhan@linuxfoundation.org>,
"Joerg Roedel (AMD)" <joro@8bytes.org>,
"Will Deacon" <will@kernel.org>,
"Robin Murphy" <robin.murphy@arm.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, iommu@lists.linux.dev,
"Tushar Dave" <tdave@nvidia.com>,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-rdma@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH v6 03/18] PCI/P2PDMA: Derive routing from directional ACS controls
Date: Sun, 20 Sep 2026 14:34:20 +0300 [thread overview]
Message-ID: <20260920113420.GA563127@unreal> (raw)
In-Reply-To: <19bee27e-17d7-4b67-b796-ca5bb44e8de7@deltatee.com>
On Fri, Sep 18, 2026 at 01:39:55PM -0600, Logan Gunthorpe wrote:
>
>
> On 2026-09-14 05:22, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > pci_bridge_has_acs_redir() treats Request and Completion Redirect as
> > interchangeable. On asymmetric fabrics, a control for only the reverse TLP
> > direction can unnecessarily force P2PDMA through the host bridge.
> >
> > Evaluate Request Redirect for client Requests and Completion Redirect for
> > provider read Completions. Continue treating enabled Egress Control
> > conservatively as a Request redirect.
> >
> > Fixes: 52916982af48 ("PCI/P2PDMA: Support peer-to-peer memory")
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
>
> Core patch seems fine, minus one minor point below:
>
> Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
>
> > @@ -1132,10 +1173,10 @@ EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
> > /**
> > * pci_p2pdma_map_type - Determine the mapping type for P2PDMA transfers
> > * @provider: P2PDMA provider structure
> > - * @dev: Target device for the transfer
> > + * @dev: Client device that initiates the transfer
> > *
> > * Determines how peer-to-peer DMA transfers should be mapped between
> > - * the provider and the target device. The mapping type indicates whether
> > + * the provider and the client device. The mapping type indicates whether
> > * the transfer can be done directly through PCI switches or must go
> > * through the host bridge.
> > */
> >
>
> This hunk does not seem like it belongs in this patch.
This is the first patch that distinguishes between client and provider
and starts using that terminology instead of target/initiator. Therefore,
the change belongs here.
Thanks
next prev parent reply other threads:[~2026-09-20 11:34 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-14 11:22 [PATCH v6 00/18] PCI/P2PDMA: Route peer-to-peer DMA by TLP class Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 01/18] PCI/P2PDMA: Document pdev->p2pdma lifetime rules Leon Romanovsky
2026-09-18 18:25 ` Logan Gunthorpe
2026-09-19 4:39 ` Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 02/18] PCI/P2PDMA: Document the TLP attribute assumptions Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 03/18] PCI/P2PDMA: Derive routing from directional ACS controls Leon Romanovsky
2026-09-18 19:39 ` Logan Gunthorpe
2026-09-20 11:34 ` Leon Romanovsky [this message]
2026-09-14 11:22 ` [PATCH v6 04/18] PCI: Reject unreadable ACS controls in isolation checks Leon Romanovsky
2026-09-18 19:59 ` Logan Gunthorpe
2026-09-14 11:22 ` [PATCH v6 05/18] PCI/P2PDMA: Evaluate ACS controls at the path divergence Leon Romanovsky
2026-09-18 20:07 ` Logan Gunthorpe
2026-09-14 11:22 ` [PATCH v6 06/18] PCI/P2PDMA: Document directional ACS routing Leon Romanovsky
2026-09-18 20:53 ` Logan Gunthorpe
2026-09-14 11:22 ` [PATCH v6 07/18] PCI/P2PDMA: Collect the path's ACS controls before deciding Leon Romanovsky
2026-09-18 21:11 ` Logan Gunthorpe
2026-09-14 11:22 ` [PATCH v6 08/18] PCI/P2PDMA: Answer routing per TLP class Leon Romanovsky
2026-09-18 21:55 ` Logan Gunthorpe
2026-09-14 11:22 ` [PATCH v6 09/18] PCI/P2PDMA: Route Relaxed Ordering Completions directly Leon Romanovsky
2026-09-18 22:07 ` Logan Gunthorpe
2026-09-14 11:22 ` [PATCH v6 10/18] PCI/P2PDMA: Reject Translated Requests blocked by Translation Blocking Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 11/18] PCI/P2PDMA: Route Translated Requests under Direct Translated P2P Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 12/18] PCI/P2PDMA: Log detailed ACS routing diagnostics Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 13/18] PCI/P2PDMA: Add KUnit tests for the ACS routing decisions Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 14/18] PCI/P2PDMA: Test the ACS P2P routing walk Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 15/18] PCI: Add KUnit coverage for ACS isolation checks Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 16/18] PCI/P2PDMA: Document TLP-class routing Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 17/18] dma-buf: Let importers ask how peer-to-peer traffic is routed Leon Romanovsky
2026-09-14 14:27 ` Christian König
2026-09-14 22:10 ` Jason Gunthorpe
2026-09-15 6:28 ` Leon Romanovsky
2026-09-15 6:23 ` Leon Romanovsky
2026-09-14 11:22 ` [PATCH v6 18/18] RDMA/mlx5: Ask P2PDMA whether ATS takes a direct peer-to-peer route Leon Romanovsky
2026-09-17 13:56 ` Thomas Hellström
2026-09-17 14:00 ` Christian König
2026-09-17 14:28 ` Jason Gunthorpe
2026-09-17 14:02 ` Jason Gunthorpe
2026-09-17 14:16 ` Thomas Hellström
2026-09-17 15:15 ` Jason Gunthorpe
2026-09-18 12:15 ` Leon Romanovsky
2026-09-18 13:42 ` Thomas Hellström
2026-09-18 17:05 ` Jason Gunthorpe
2026-09-19 11:25 ` Leon Romanovsky
2026-09-21 6:43 ` Christian König
2026-09-21 6:57 ` Thomas Hellström
2026-09-21 13:08 ` Jason Gunthorpe
[not found] ` <f9ced8cab6eb929a5f65d789fe6922458c6f3396.camel@linux.intel.com>
[not found] ` <20260921131055.GP11599@ziepe.ca>
2026-09-21 13:27 ` Thomas Hellström
2026-09-21 13:25 ` Jason Gunthorpe
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