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Fri, 26 Jun 2026 17:43:51 -0700 Date: Fri, 26 Jun 2026 17:43:49 -0700 From: Nicolin Chen To: CC: , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v2 00/11] iommu/arm-smmu-v3: Add PRI support Message-ID: References: <2a52ecb1-be8a-4522-aa23-f3277f0555fa@oss.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2a52ecb1-be8a-4522-aa23-f3277f0555fa@oss.qualcomm.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS3PEPF0000C37F:EE_|PH8PR12MB6673:EE_ X-MS-Office365-Filtering-Correlation-Id: 9a4498fd-eea9-4242-101b-08ded3e52e89 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|23010399003|376014|7416014|82310400026|1800799024|11063799006|4143699003|56012099006|18002099003|22082099003; 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)(36860700016)(23010399003)(376014)(7416014)(82310400026)(1800799024)(11063799006)(4143699003)(56012099006)(18002099003)(22082099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 8nLKyoPBnQ9IS6Lo1Ql+tFn8b0jkxXDFITCyz2aI0BLbaiphrpsEiNKCq3IN/cKchDJuLR+D67uhrm7GMhPLpNjvBQw+TrGXBbOCOxufeSL7VrYQCyf6n6CMye3RMOX6c/XJ7Ga6qxKTEWJnZ7snlAdwNbITJ8WJASRRW+uaoyGXlrbBbmNwVGpigVF201OBsbDNcCNDDzmynFnSlOcL4mgEeBeGU9laqtEr7UnCJ4B3ecLkr96y3UdLLe/ICClnD8NlSCof642wOfu2m8cPpq1V0a6voW5ACSCeBFcgE3Lpkdobvy2XYEy+FeKN8n13ds4ObLVxcL2sSMl5Yc6in9IcPxhr7KnRV1rHDHE+mX70gLpoNnVMbkqclVB6Hg3u9br94W+Ql84mUr+iiy5UjyHc9q71D7uL9gITTiEl5f44Q1PJdWoln/sh2thRA4iM X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Jun 2026 00:44:01.3749 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9a4498fd-eea9-4242-101b-08ded3e52e89 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: DS3PEPF0000C37F.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB6673 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260626_174411_291058_29D61ADF X-CRM114-Status: GOOD ( 11.21 ) 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, Jun 26, 2026 at 08:24:31PM +0530, harsha.v@oss.qualcomm.com wrote: > One thing I noticed while reviewing: when arm_smmu_priq_thread() detects > PRIQ overflow, partial faults (non-LAST pages stored via > report_partial_fault()) whose LAST page was lost in the overflow remain > permanently in iopf_param->partial. This is a monotonic memory leak — > it grows with each overflow event. > > Intel VT-d handles this in prq_event_thread() (drivers/iommu/intel/prq.c): > if (head == tail) { > iopf_queue_discard_partial(iommu->iopf_queue); > writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG); > } > > iopf_queue_discard_partial() was written for exactly this scenario. > Could we add the same here arm_smmu_priq_thread() > (drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c) ? > > if (queue_sync_prod_in(q) == -EOVERFLOW) { > dev_err(smmu->dev, "PRIQ overflow detected -- requests lost\n"); > + iopf_queue_discard_partial(smmu->evtq.iopf); > } > > At this point all surviving entries have already been consumed by the > loop above, so discarding unconditionally is safe — implicitly matching > Intel's "head == tail" guard. I will fold it in. Thanks! Nicolin