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Tue, 28 Jul 2026 15:17:11 -0700 Date: Tue, 28 Jul 2026 15:17:09 -0700 From: Nicolin Chen To: Pranjal Shrivastava CC: , , , , , , , , , , , , , , , , Subject: Re: [PATCH v2 03/11] iommu/arm-smmu-v3: Add arm_smmu_drain_queue_for_iopf() helper Message-ID: References: Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA2PEPF00001509:EE_|MN6PR12MB8565:EE_ X-MS-Office365-Filtering-Correlation-Id: 610209c6-d94b-42d8-6d10-08deecf60736 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|1800799024|376014|7416014|36860700016|82310400026|4143699003|10067099003|11063799006|56012099006|18002099003|22082099003|13003099007; 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)(1800799024)(376014)(7416014)(36860700016)(82310400026)(4143699003)(10067099003)(11063799006)(56012099006)(18002099003)(22082099003)(13003099007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: BqAvGzTkN2sH/jW4JhvIRQK7cwJM9H+cC/sN8ir77aCMOILrcww+onSqFsQSqZqlPrc1e+tYBuDBbgFmfTl4U32o2LLXZxKcJfLnPrxTJKB9skGk0OlK3uHSXkGsURvd294LWRTQip75UHuWEkB1RXFsE3iLGPEP5IaIi1Ez8OoDD5j9XeLGCn334m5CDGwZyotPkM/uFL+9ukF71yFehIUxCgMqyUcVR5eSU6WiwRxhoOnY5LLbvwxl0PGdMg3ucaTVSEaKfbUAvfjhbvF7EOiTneMO+f1kPACVJQTyrqkwSxNkt4I5PXOqAg0xWISRXUBvwajL9/Jh8LpK9M4X15Og9z9jKq1QP+5va1WfWgM5Nv29cRmhyJWRDtauxvaggmF15jowi3UvhrCh4wIhmhHuTjbYlmijpjQRdLn6C5WWwtlJkMmBJKICuJCHQMz7 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jul 2026 22:17:35.5897 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 610209c6-d94b-42d8-6d10-08deecf60736 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: SA2PEPF00001509.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN6PR12MB8565 On Tue, Jul 28, 2026 at 09:16:49PM +0000, Pranjal Shrivastava wrote: > The following is a unified drain_queue helper, that also attempts to > address Sashiko's concerns. This applies on top of my runtime PM v9 > series [1], please see if it works for you: > > Subject: [PATCH] iommu/arm-smmu-v3: Add a unified arm_smmu_drain_queue() helper > > Introduce a unified arm_smmu_drain_queue() helper to replace queue > specific polling loops. The helper handles both snapshot-based cohort > draining (for IOPF) and full queue draining (required for Runtime PM). > > The Runtime PM explicitly gates the CMDQ (via CMDQ_PROD_STOP_FLAG) prior > to draining, this allows a single, snapshot-based target to natively > handle all drain scenarios. [..] > queue_poll_init(smmu, &qp); > + qp.wfe = is_cmdq; The callers of this drain() will be RPM and PRI, either of which needs busy-waiting. So, I have added a different drain() helper. I run Sashiko locally; it also gives a clean result. Commit: https://github.com/nicolinc/iommufd/commit/d10325ff40fd45c476bc98d484d8dd2cdc7fdf95 This will be in my pri-v3 series: https://github.com/nicolinc/iommufd/commits/smmuv3_pri-v3 We have too many SMMUv3 under review now. So, I will post it once some of them are merged. Nicolin