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Fri, 28 Aug 2026 09:03:35 -0700 Date: Fri, 28 Aug 2026 09:03:33 -0700 From: Nicolin Chen To: Mostafa Saleh CC: , , , , , , , Subject: Re: [PATCH 1/7] iommu/arm-smmu-v3: Ensure L2 tables are visible before L1 ptrs Message-ID: References: <20260828125409.1921538-1-smostafa@google.com> <20260828125409.1921538-2-smostafa@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260828125409.1921538-2-smostafa@google.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF0000A893:EE_|PH0PR12MB7930:EE_ X-MS-Office365-Filtering-Correlation-Id: a2e2075a-35fe-4c05-28f1-08df051dfece X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|82310400026|36860700016|1800799024|376014|22082099003|18002099003|4143699003|11063799006|56012099006|10067099003; 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)(23010399003)(82310400026)(36860700016)(1800799024)(376014)(22082099003)(18002099003)(4143699003)(11063799006)(56012099006)(10067099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 4fs30RlCE06oZCtKfopkPJ4/C+O7Db9TR9C1j+lUhyUG56hCkm+6QjUO+KJGYnKLH4F0Sn2J/aLLlBgorVgdBcBntO6jXH06iM0/2vYjuVcQinBP97Upy6a+SGTxQIAZPmOEmViDSayqI2cm7fQ5AmRdTDpnsC97HFlZmAao3Zsi2/H5ZJknXQMymD4bOdFriOwo4jZKSP2PxhplLUKtKz1DWmOJ+pL/YDC1WAXaHSnO1wRJAHR7n88RILYWCXGkEUC+QMZBAYwK1m2AbBHApwMO8fYIZsvXCWTaFwOL6Sfhk8BZWjEZpSvDCJ15Waaz8HeG2O/pTfRBKoZqWPDlit431KzvIS6/UD3sGLV1dn0mHzulAl1kU6qjkwH6Z8a7L55axmVYOcFWpnuKuPrPdmyaTU3hhMEW9U6sUAvqhaow96fSjUzEylUqGFNIsoUE X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Aug 2026 16:04:09.3832 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a2e2075a-35fe-4c05-28f1-08df051dfece 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: BN2PEPF0000A893.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7930 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260828_090422_260821_C5D9E59C X-CRM114-Status: GOOD ( 10.60 ) 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 Fri, Aug 28, 2026 at 12:53:36PM +0000, Mostafa Saleh wrote: > Commit 6fabce53f6b9 ("iommu/arm-smmu-v3: Add a missing dma_wmb() for hitless STE update") > adds a dma_wmb() to arm_smmu_write_entry() to make sure stream tables > and context descriptors are observed first. > > However, STE L1 table descriptors are configured directly > via WRITE_ONCE(), where before that they were zeroed with memset() > inside dma_direct_alloc() then written to abort in via memset() also > in arm_smmu_init_initial_stes() without a barrier in both cases which > means that the SMMUv3 can observe the allocated table before the > written descriptors causing it to fetch random data. > > Similarly in arm_smmu_write_cd_l1_desc() where the L1 CD is written > after dma_alloc_coherent() with no barriers. > > Add dma_wmb() in both cases. > > Fixes: 48ec83bcbcf5 ("iommu/arm-smmu: Add initial driver support for ARM SMMUv3 devices") > Reported-by: Sashiko <> > Signed-off-by: Mostafa Saleh Reviewed-by: Nicolin Chen