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Fri, 29 May 2026 18:27:42 -0700 Date: Fri, 29 May 2026 18:27:40 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: Will Deacon , Robin Murphy , "Joerg Roedel" , Bjorn Helgaas , "Rafael J . Wysocki" , Len Brown , "Pranjal Shrivastava" , Mostafa Saleh , Lu Baolu , Kevin Tian , , , , , , , Shuai Xue Subject: Re: [PATCH v4 18/24] iommu/arm-smmu-v3: Introduce master->ats_broken flag Message-ID: References: <49dde0a2e2dc88e421a3010956db33d47cc92aa8.1779161849.git.nicolinc@nvidia.com> <20260519120658.GB3477375@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260519120658.GB3477375@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000C618B:EE_|CH3PR12MB9455:EE_ X-MS-Office365-Filtering-Correlation-Id: add7a66b-d50f-4bac-0e78-08debdeab2e1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|82310400026|7416014|376014|1800799024|11063799006|4143699003|56012099006|18002099003|22082099003; X-Microsoft-Antispam-Message-Info: 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 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)(36860700016)(82310400026)(7416014)(376014)(1800799024)(11063799006)(4143699003)(56012099006)(18002099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: d9rw1vx8ltl25pNvzywCOML/gzute+0rbNg0NfKgCvWm2RXdZj2FTTyujq/aV+Vs8xzK4roWdyzxZuVb1oBeUg9eqawlY6DO1xRnh3dkddjw4+FgEaRhqtx4Sctjtmgu7KRIH7cuXILJUel9d6XElolo4WJyCbKuhfTGko8U91dV3rAYoLXD0l7CFo/pj9DPHLr+8lwL4ypbYMiPhIgvtuUDh3LIt2t3A2wxNhD6SutZmnCl6Nz3mpL86EAJdm8b3yLRRq7SCKXRcvqKKTQ0TCXitk1kzFQrNQxQeZp41xNfI0h02c2o6hNAh8bKSToL8cjpF5jiDqlWIq+D2LHMAkdWsrxAnHhmbmkVl48x6Zk3U+UJJ2/8g6BDWUOfOHoOv5DB8YY/uLPeVYuAehWLeeLxY6FU8Lwd674XMN97Itx8XoRu9GchdhWQ/fZx7ZPY X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 May 2026 01:28:05.3356 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: add7a66b-d50f-4bac-0e78-08debdeab2e1 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: MWH0EPF000C618B.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9455 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260529_182818_884258_1F447979 X-CRM114-Status: GOOD ( 23.09 ) 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 Tue, May 19, 2026 at 09:06:58AM -0300, Jason Gunthorpe wrote: > On Mon, May 18, 2026 at 08:39:01PM -0700, Nicolin Chen wrote: > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > index cde2ff2dcc49b..638956e2535b4 100644 > > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > @@ -2429,6 +2429,10 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master, > > struct arm_smmu_cmd cmd; > > struct arm_smmu_cmdq_batch cmds; > > > > + /* Do not issue ATC_INV that will definitely time out */ > > + if (READ_ONCE(master->ats_broken)) > > + return 0; > > + > > cmd = arm_smmu_make_cmd_atc_inv_all(0, IOMMU_NO_PASID); > > arm_smmu_cmdq_batch_init_cmd(master->smmu, &cmds, &cmd); > > for (i = 0; i < master->num_streams; i++) > > @@ -2651,12 +2655,18 @@ static void __arm_smmu_domain_inv_range(struct arm_smmu_invs *invs, > > cur->id)); > > break; > > case INV_TYPE_ATS: > > + /* Do not issue ATC_INV that will definitely time out */ > > + if (READ_ONCE(cur->master->ats_broken)) > > + break; > > Yuk, this should be a bool in the invs list, not the master. > > If the flow is to have the core code always attach a blocked domain before > reset_done then the invs list will naturally fix itself. So I've tried INV_TYPE_ATS_BROKEN: during per-domain invalidation, each batch is built from domain->invs so it can carry the "invs"; if the batch times out, we can immediately mutate its ATS entries. But I realized a limitation. E.g., if a device attaches to two SVA domains on two SSIDs. An invalidation timing out on one of the SVA domains could mark INV_TYPE_ATS_BROKEN in its own invs, but not in the other SVA domain's invs? So, it seems that master->ats_broken is still a cleaner solution? In the same spirit of "the invs list will naturally fix itself": we could clear master->ats_broken on every attach; if the device has not recovered yet, arm_smmu_atc_inv_master() in commit() will time out and set it back to true. Right? Thanks Nicolin