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Thu, 30 Apr 2026 08:24:01 -0700 Date: Thu, 30 Apr 2026 08:24:00 -0700 From: Nicolin Chen To: Jason Gunthorpe CC: , , , , , , , , , , , , , Subject: Re: [PATCH rc v4 1/5] iommu/arm-smmu-v3: Add arm_smmu_kdump_adopt_strtab() for kdump Message-ID: References: <20260430115513.GG3225388@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260430115513.GG3225388@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BY1PEPF0001AE16:EE_|DS0PR12MB8069:EE_ X-MS-Office365-Filtering-Correlation-Id: bc122854-d6c0-4d4d-fa30-08dea6cc9132 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|7416014|376014|1800799024|36860700016|22082099003|18002099003|56012099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(82310400026)(7416014)(376014)(1800799024)(36860700016)(22082099003)(18002099003)(56012099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 6vb41SXAP0tACjvGdh/5rZXbQI3WY/sjaDZkuMET0eH+XVyNY/t0C98zAwot6UxlaYC3U2LB1Lb0EJG5Q9QO1BXeNM/BJ6XGKHBEyFxe2r/N3BTDhmdzDhpg2/hymmFenxzaFcq99eDLKllWrB1TCV4VLq1j9Sc1lvSfDcFfpgxBiX/SzE44MQkrBvkTxva0ewIv7g6di/nRvePMs8S5Q/zJvSiJpm0rRcMglCXyWhonrz+7eSeqpx9w3KzaI1xjgKYPxYtiOd2hEMOzgCB4HzMB6/+yjPMiIfwd0rMGwkNJhGo0SN8XKzxu2T9p8DbPqEyKwxRLEiw5/YeYl2f0/xQaJzIMY+Nz1AN64RsnvnglClTSciZHYFTJUEBTzB6juOAl0O6K9oGbvMfvOmmpfg7346Nyo+HJpmVqDCCOP+rYpZjEG/gO82QMSj/w3j2/ X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Apr 2026 15:24:27.2444 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: bc122854-d6c0-4d4d-fa30-08dea6cc9132 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: BY1PEPF0001AE16.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8069 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260430_082442_969732_59CB5540 X-CRM114-Status: GOOD ( 12.83 ) 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, Apr 30, 2026 at 08:55:13AM -0300, Jason Gunthorpe wrote: > On Wed, Apr 29, 2026 at 02:37:50PM -0700, Nicolin Chen wrote: > > On Wed, Apr 29, 2026 at 12:20:49AM -0700, Nicolin Chen wrote: > > > > > +static int arm_smmu_kdump_adopt_strtab_2lvl(struct arm_smmu_device *smmu, > > > + u32 cfg_reg, dma_addr_t dma) > > [...] > > > + for (i = 0; i < num_l1_ents; i++) { > > > + u64 l2ptr = le64_to_cpu(cfg->l2.l1tab[i].l2ptr); > > > > Sashiko pointed out a missing READ_ON here. > > ?? > > There is no concurrency at this point? You are right. I got confused. I was thinking of an RID-sharing case where some race might happen and adding READ_ONCE could be defensive. A kdump kernel has a very limited use. So, this isn't necessary. Thanks Nicolin