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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bcJS+scZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bcJS+scZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 231CB1F0089B; Tue, 6 Oct 2026 19:29:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791314997; bh=E3R9izeh7FIJECvgCCVpi1mo2nxrzOBff+skIfgO+Rs=; h=Date:From:To:Cc:Subject:In-Reply-To; b=bcJS+scZy/6Ervd4affik0znYY7JZa8yo9ks/hJ/Wi8kEV6e/KSbN6DLhH4cvTpEi iv1i3WiOGk68dleHJ296gqU0BhMCEJVAVOZytyc3QKyrYEr2/tnG/0UFyIPfrIj3tg SItyEr00wVeaV0//cgD/K4SQvOZOLnemHSI1OJAFgTEBCV+hiT1KtsppspX2evocA7 ZCQ0Wl20EzvOsu1/yNFVx6Xg4cGeVs0hzCrznBNfgOi0wFN/Avs81GC98fmWJ7AFoR B0uvsH9pjMZFUorJQnadwi8SHKWnKBdfcOjggeubITjVyfME5vEDwO1ixmFyhMjfNP GU6veX6QcYM6Q== Date: Tue, 6 Oct 2026 14:29:55 -0500 From: Bjorn Helgaas To: Leon Romanovsky Cc: Bjorn Helgaas , Logan Gunthorpe , Jason Gunthorpe , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , Christian =?utf-8?B?S8O2bmln?= , Thomas =?utf-8?Q?Hellstr=C3=B6m?= , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, iommu@lists.linux.dev, Tushar Dave , 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, Chaitanya Kulkarni , Greg Kroah-Hartman , Jens Axboe , Alex Williamson , Ankit Agrawal , Jonathan Corbet , Shuah Khan , Randy Dunlap , Sumit Semwal Subject: Re: [PATCH v9 00/18] PCI/P2PDMA: Route peer-to-peer DMA by TLP class Message-ID: <20261006192955.GA703309@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261001-fix-p2p-acs-v4-0-v9-0-1a8e0f50ddd9@nvidia.com> On Thu, Oct 01, 2026 at 02:55:08PM +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 client 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. > ... > Leon Romanovsky (18): > 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 | 15 +- > Documentation/driver-api/pci/p2pdma.rst | 80 +++ > drivers/pci/Kconfig | 15 + > drivers/pci/Makefile | 1 + > drivers/pci/p2pdma.c | 719 ++++++++++++++++++-- > drivers/pci/pci.c | 7 +- > drivers/pci/pci.h | 58 ++ > drivers/pci/pci_acs_test.c | 860 ++++++++++++++++++++++++ > drivers/pci/quirks.c | 6 +- > include/linux/pci-p2pdma.h | 12 +- > 10 files changed, 1687 insertions(+), 86 deletions(-) > --- > base-commit: 08dbfad3f5040f5bdb6c529da20d6d4e81fefd72 > change-id: 20260821-fix-p2p-acs-v4-0-e72455e3a261 > prerequisite-message-id: <20260830-batch-p2p-fixes-v1-0-5044e8dfbe2e@nvidia.com> > prerequisite-patch-id: 6b25c7fcf164cdfc14e9fac5b908d97fcf6509d7 > prerequisite-patch-id: 0d083c281001365aae4b35544cf28891a6ab9a96 > prerequisite-patch-id: bfd9dabf271f3cc9a3a61f46387d20c20311363d > prerequisite-patch-id: fad0275efc722830fc591509506c0a5e4f581073 > prerequisite-patch-id: 0c83bee688fec1f6d1564654df7c630fa6a4a978 This seems like material for the PCI tree, but I'm not sure how to apply it. It doesn't apply cleanly on the current pci/p2pdma (https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=p2pdma), which does contain your series from 20260830-batch-p2p-fixes-v1-0-5044e8dfbe2e@nvidia.com. I could probably fix the conflicts but I don't know why there should be conflicts, since the only commits on pci/p2pdma other than yours are a few trivial allow-list updates. Bjorn