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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a4g53Oqo; 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="a4g53Oqo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 734551F0089B; Wed, 7 Oct 2026 11:31:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791372697; bh=Zh2Z9eMDzLLM/mnhB0kR2U8FWPmYZDiC/akWXoko2MI=; h=Date:From:To:Cc:Subject:In-Reply-To; b=a4g53OqoEdPogyxv5cSD3kb3ZWOELARzSSSNDblKciRHB6zNzfGrRAdff7b07NR5D bxAbx6NqswKP3cfnn65pu64Krhg43YkJ6bHoLZ4A8AKBmcHOyy4B2ua56HB/EziKwL uWcysDUBAl/lvTdLr3S1oDVM/C6pzqvYbwlWqabvfOGUqCwyx978TUoy+lQGS4Ac+K o7YYMM7tBllaeVNFRL+OuDOVVJhLn4z/UXxG++MA5nq/QGnsUIkQknbdF19Ka8dHZu Z1esAl4BCMogg/wKurS5dKXUzEBMSHhs8II6zlw0xn5D4xcDEEw53sz/MGDjuDSU/z ct56KEDXPqLjQ== Date: Wed, 7 Oct 2026 06:31:36 -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: <20261007113136.GA755180@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: <20261007105409.GE7822@unreal> On Wed, Oct 07, 2026 at 01:54:09PM +0300, Leon Romanovsky wrote: > On Wed, Oct 07, 2026 at 01:56:44AM -0500, Bjorn Helgaas wrote: > > On Tue, Oct 06, 2026 at 04:36:50PM -0500, Bjorn Helgaas wrote: > > > On Wed, Oct 07, 2026 at 12:22:27AM +0300, Leon Romanovsky wrote: > > > > On Tue, Oct 06, 2026 at 02:29:55PM -0500, Bjorn Helgaas wrote: > > > > > 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. > > > > > > > > So maybe this is related to these trivial updates, my series was based > > > > on the clean p2pdma branch: > > > > https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?h=fix-p2p-acs-v9 > > > > > > Ah, yeah, it must be the allow-list additions that I have but you > > > don't. I wouldn't have thought the offsets would have been a problem. > > > > It applies fine if I move the Haswell and Alibaba allowlist patches t > > to the end so the base matches fix-p2p-acs-v9, thanks. > > Bjorn, > > It is unclear to me if I should to resend. No need.