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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


  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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