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Fri, 14 Feb 2025 03:18:47 +0000 Message-ID: <6823aebc-5525-4d4f-bcb0-03e9e8ffaf65@intel.com> Date: Fri, 14 Feb 2025 11:24:07 +0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 09/14] iommu/vt-d: Add IOMMU_HWPT_ALLOC_PASID support To: Jason Gunthorpe CC: Baolu Lu , , , , , , , , , Suravee Suthikulpanit , Robin Murphy References: <20241219132746.16193-1-yi.l.liu@intel.com> <20241219132746.16193-10-yi.l.liu@intel.com> <38e26d9f-0727-4b15-8e1d-03d262c15c8c@linux.intel.com> <5c5180cb-9bbe-4fa7-b109-5dad2ca9516a@linux.intel.com> <20250212125930.GQ3754072@nvidia.com> <2399c639-b9dc-4c7c-bac8-3776cf6a88f5@intel.com> <20250213125618.GX3754072@nvidia.com> Content-Language: en-US From: Yi Liu In-Reply-To: <20250213125618.GX3754072@nvidia.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SI2PR06CA0009.apcprd06.prod.outlook.com (2603:1096:4:186::17) To DS0PR11MB7529.namprd11.prod.outlook.com (2603:10b6:8:141::20) Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR11MB7529:EE_|IA1PR11MB6219:EE_ X-MS-Office365-Filtering-Correlation-Id: c8fc56fc-488a-4dda-5afb-08dd4ca64ba0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|1800799024|376014|366016; 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Ideally this would cause no PRI > into the guest and the VMM would fault the device. yes, malicious guest can surely do it. >> However, PRIs on S2 might occur due to insufficient permissions, >> potentially caused by userspace. Nonetheless, I am skeptical about the >> existence of such use cases. What do you think about it? > > I suspect it is "OK", we already have to be safe against a misbehaving > guest creating a PRI storm, if a misbehaving guest does it via > pointing to the wrong S2 or just not updating the S1 doesn't seem to > make much difference.. ok, given these facts, we can consider iommufd does not support valid PRI on S2 for now. Hence adding the aforementioned enforcement is acceptable. > IMHO it is desirable for the HW to provide a way to disambiguate the > PRI. yes. Regards, Yi Liu