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Wed, 9 Sep 2026 21:23:36 -0700 Date: Wed, 9 Sep 2026 21:23:34 -0700 From: Nicolin Chen To: Jason Gunthorpe , Catalin Marinas , Will Deacon , , Robin Murphy , , Danilo Krummrich , Marek Szyprowski , CC: Mark Rutland , Greg Kroah-Hartman , Suzuki K Poulose , Gavin Shan , Vikram Sethi , "Anshuman Khandual" , Shanker Donthineni , Mostafa Saleh , , Thomas Huth , Marc Zyngier , Ryan Roberts , , Kohei Enju , Shaopeng Tan , Ard Biesheuvel , James Morse , Steven Price , Sang-Heon Jeon , Omar Sandoval , Andrew Morton , Jinjie Ruan , Sam Edwards , Douglas Anderson , "Florian Fainelli" , Chen-Yu Tsai , Huacai Chen , Thomas Zimmermann , Pranjal Shrivastava , Ashish Mhetre , Shameer Kolothum , , , , , Sonang Patel , Ankit Agrawal Subject: Re: [PATCH v1 8/8] iommu/arm-smmu-v3: Probe a guest-level Realm VSMMU via RSI commands Message-ID: References: Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH1PEPF0000AD76:EE_|PH7PR12MB8428:EE_ X-MS-Office365-Filtering-Correlation-Id: 8622a8be-86b3-47af-3b3c-08df0ef35621 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|1800799024|82310400026|7416014|376014|23010399003|18002099003|22082099003|4143699003|56012099006|11063799006|10067099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: LAbdey40vYp7bX9NRE3y0w4lP7WUfJHEyfHTe7IMjC9n9Ppte6FWrr7DERNYPVL1A3MoSvL2bjoj6xoTV1JZ2ZCmFo5aVe2kjGSlpdg+ymL5YNhqg2FxqYedTRjILTQ4+omnQS4qpguv7kzSG96ZAAZBP29pW/IQ0ci8QxvFh3232siXf/r03WFyNRWyQgwERRBEeImDdeHqbSBbNzoq5ed1QN8tuzkW3KBqN9u335VS7onkvwVq65+NsGvJJO4DUb59owdmoymTfpyQ3K881KHjmLl/hM42IUsT1hLQ0ewKPe+15mtkmoLJZd7WiXvnOqXNkyWcWsQuzGzU9pj3TK3GfPboZWq/W4+P7JV8+tKFISbd7UwDcKz7LQSOWw0yULs7rPxgwYch9FYub2uLpvAUHEZAdPtVzvaXwrQjlnXSGLLSsF1Npaee4qaP+I4Y X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Sep 2026 04:23:59.3585 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 8622a8be-86b3-47af-3b3c-08df0ef35621 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CH1PEPF0000AD76.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB8428 On Wed, Sep 09, 2026 at 08:32:51PM -0700, Nicolin Chen wrote: > @@ -5542,6 +5591,12 @@ static int arm_smmu_device_probe(struct platform_device *pdev) > } > ioaddr = res->start; > > + if (is_realm_world()) { > + ret = arm_smmu_probe_realm_vsmmu(smmu, res); > + if (ret) > + return ret; Sashiko pointed out a new finding (didn't appear in my local runs) that arm_smmu_impl_probe() would allow an untrusted hypervisor to provide a malicious ACPI/DT table specifying a vendor extension. I think it's valid, So, we likely need a guard, until impl has RMM level support with additional RSI validation: - smmu = arm_smmu_impl_probe(smmu); - if (IS_ERR(smmu)) - return PTR_ERR(smmu); + if (!is_realm_world()) { + smmu = arm_smmu_impl_probe(smmu); + if (IS_ERR(smmu)) + return PTR_ERR(smmu); + } Nicolin