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Mon, 11 Aug 2025 16:00:04 -0700 From: Nicolin Chen To: , , , CC: , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v3 1/5] iommu: Lock group->mutex in iommu_deferred_attach Date: Mon, 11 Aug 2025 15:59:08 -0700 Message-ID: <44783ca52e17a9ca0ce7acfe8daae3edc3d7b45b.1754952762.git.nicolinc@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0002256E:EE_|CY8PR12MB7337:EE_ X-MS-Office365-Filtering-Correlation-Id: b647f384-12a0-4666-7f5e-08ddd92adc08 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|36860700013|376014|7416014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?IJOYiK7sBsD96m2AiPnp+10AgQ4vQ+syKCZNszHCF6cLVm7j19KyLHrsI8Tj?= =?us-ascii?Q?R9BtaWWRbUIiwzkf8wecZLdUNOvcRQFQvxZb1dTu/6bZA//3W23vK/3seeH1?= =?us-ascii?Q?Vbt+5IIfgIeqWeExXzcl99vTnyNp+vo8JVUcVImnaz9sydy2ArKrm7xKDt+r?= =?us-ascii?Q?+ggF/xOpNcZfGWcjHx52I2cf0m9SfqfjHuC/p5faPJAJJPxBLZ3tBi5ZDUEh?= =?us-ascii?Q?IpcZ0u83NsRDUlSD96xgm7OgzFuJsZe/ebvjKuww2064WGx8mfrWfohAPiUH?= =?us-ascii?Q?tp5Lg87UoCISJQQ3kUJOkhEznQguetERgYZ1XyP9mLj8aHGUBDfUpWRWofsO?= =?us-ascii?Q?bhzbzvp6YkLeAvpjP2lgr+//y3PY6Mk8vTKpL/zEMPa4CwAoRFWdl+4yjqke?= =?us-ascii?Q?+tgU0Gbf3qHEABRCPFakrsXOG4ZR3mu7jser45BfZ/jXHzP9KI4Yw/6PMVlL?= =?us-ascii?Q?4Q5xJQ8j8k/A0wDkkE8/1SkG5UrdiVdeRGPbLmL94BN2rzcF0g0RPN3vTlJ5?= =?us-ascii?Q?3MOcRJN/jF8PMiNw5W0JXfaaeo5zHgRR7P8vnMmN1jpHaYcI0JqNry+lS3Df?= =?us-ascii?Q?cdS2aKanisN/Ck4ac8IphhTl379GMq0SRG7IJt+DG291DCe+IgY8BZfYBVvH?= =?us-ascii?Q?CV6LycPQEgz/ZV2WQSx0TPdU6wzeDVIEhu8Z4gFKBMAI4H+k/vqyJT5G6BfY?= =?us-ascii?Q?qkocvh4IFsWFL6gtDuov0ltNHUhJ5oxBReXVMFF2O5ezIS3yw55Jja4gCpQq?= =?us-ascii?Q?2EFt0R/P1tn3y/quAboLosM7dIkJJyiwcPXMFa40eGM+4/vs93WiHqto5C/s?= =?us-ascii?Q?fjmW4XoWSVTKwo1w+8NncXLMYZWti3AwI15+cmCBsKV0bgOe478oDgEHilJG?= =?us-ascii?Q?jV2J6YgbCgHUQOSlpGF8pud8oxh0rnfeF+aSzNyqf8UFo9PYIiWny0In3W6i?= =?us-ascii?Q?yNQbLA8Qif1PTztAv0sZKsCoDOH3Zyns5/v7tt+24blGI7P5Bk8lj50vaVH1?= =?us-ascii?Q?9yYdj/LTTjsrCMS0fUBxzV8p04YOaTdZyjh4f7gVZM2kAMgHkmFC0SCFPZY4?= =?us-ascii?Q?zoHUvYRK3+DrkEbyz9Du+N1EGBifpXx7RtnIFgMVhz/7iQKKBN7724vMoAe8?= =?us-ascii?Q?f6aMmdkde5LoCv9vA0smDjfTdg29YQMODYGyjxbqLv6n/AxHPsQy4p7U2sQc?= =?us-ascii?Q?sQu62RRHnMJozV0xrdXrCb/YS6S6RSgTdJF3iG9Y+p0646tBdAerPBhseEYL?= =?us-ascii?Q?YkzgvDQ0AUkLM+G/CLiIw7gKcgNbO8zlCQu5jpD7zWmfBUfQa5GBAk4kU4xJ?= =?us-ascii?Q?xTBmVQtIiRc4ZWiSkjfCAYLR5ylsiHgo9fX2MwubAv6CnmyEKEJ4XunT314Y?= =?us-ascii?Q?2XkvzhKMUD3IPZ0fJLd9i6VBn4fkrffJEnj2LYuH/cXUrHQOGuAp/b/MqF/G?= =?us-ascii?Q?NqQPicqhIFCI91Dh3g4Hi32jE1opy259IJnCwfeFVkXVD+NS/ZscYdyGdwDK?= =?us-ascii?Q?LETb5o9byqpK+kA3P1yIDpsZ+kWWKPqtwCsI?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(36860700013)(376014)(7416014);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Aug 2025 23:00:25.7946 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b647f384-12a0-4666-7f5e-08ddd92adc08 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0002256E.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB7337 Content-Type: text/plain; charset="utf-8" The iommu_deferred_attach() is a runtime asynchronous function called by iommu-dma function, which could race against other attach functions if it accesses something in the dev->iommu_group. So, grab the mutex to guard __iommu_attach_device() like other callers. Reviewed-by: Jason Gunthorpe Signed-off-by: Nicolin Chen --- drivers/iommu/iommu.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 060ebe330ee16..1e0116bce0762 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -2144,10 +2144,17 @@ EXPORT_SYMBOL_GPL(iommu_attach_device); =20 int iommu_deferred_attach(struct device *dev, struct iommu_domain *domain) { - if (dev->iommu && dev->iommu->attach_deferred) - return __iommu_attach_device(domain, dev); + /* + * This is called on the dma mapping fast path so avoid locking. This is + * racy, but we have an expectation that the driver will setup its DMAs + * inside probe while being single threaded to avoid racing. + */ + if (!dev->iommu || !dev->iommu->attach_deferred) + return 0; =20 - return 0; + guard(mutex)(&dev->iommu_group->mutex); + + return __iommu_attach_device(domain, dev); } =20 void iommu_detach_device(struct iommu_domain *domain, struct device *dev) --=20 2.43.0