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Thu, 22 Jan 2026 08:29:12 -0800 Received: from Asurada-Nvidia (10.127.8.12) by mail.nvidia.com (10.126.190.181) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.20 via Frontend Transport; Thu, 22 Jan 2026 08:29:11 -0800 Date: Thu, 22 Jan 2026 08:29:10 -0800 From: Nicolin Chen To: Jason Gunthorpe CC: , Jonathan Cameron , "Tian, Kevin" , "will@kernel.org" , "robin.murphy@arm.com" , "bhelgaas@google.com" , "joro@8bytes.org" , "praan@google.com" , "baolu.lu@linux.intel.com" , "miko.lenczewski@arm.com" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , Subject: Re: [PATCH RFCv1 1/3] PCI: Allow ATS to be always on for CXL.cache capable devices Message-ID: References: <20260121100307.00004e60@huawei.com> <20260121130315.GE1134360@nvidia.com> <6971b9406d069_1d33100df@dwillia2-mobl4.notmuch> <20260122131432.GJ1134360@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; 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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jan 2026 16:29:22.5480 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 51cea509-d37b-4140-3176-08de59d3667e X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.233];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00002318.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS4PR12MB9563 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260122_082930_111010_FEEC06FD X-CRM114-Status: GOOD ( 11.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jan 22, 2026 at 09:14:32AM -0400, Jason Gunthorpe wrote: > On Wed, Jan 21, 2026 at 09:44:32PM -0800, dan.j.williams@intel.com wrote: > > "We have a less than perfect legacy way (PCI untrusted flag) to nod at > > ATS security problems. Let us ignore even that for a new class of > > devices that advertise they can trigger all the old security problems > > plus new ones." > > Ah, I missed that we are already force disabling ATS in this untrusted > case, so we should ensure that continues to be the case here > too. Nicolin does it need a change? pci_ats_always_on() validates against !pci_ats_supported(pdev), so we ensured that untrusted devices would not be always on. Perhaps we should highlight in the commit message, as it's a topic? Nicolin