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Tue, 27 Jan 2026 08:38:32 -0800 Date: Tue, 27 Jan 2026 08:38:31 -0800 From: Nicolin Chen To: , Pranjal Shrivastava CC: , , , , , , , , , , Subject: Re: [PATCH v9 6/7] iommu/arm-smmu-v3: Add arm_smmu_invs based arm_smmu_domain_inv_range() Message-ID: References: <06999367d001283744fd98eb7c1823afd516ce84.1766174731.git.nicolinc@nvidia.com> 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: SJ5PEPF000001F3:EE_|DS7PR12MB5886:EE_ X-MS-Office365-Filtering-Correlation-Id: 53840c5c-b7e1-4810-8c7e-08de5dc28eef X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|36860700013|376014|1800799024|82310400026|3613699012; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?U6SJG0Pz2FuteLo5gw0vy184JPgXJ3KwG+EEeT0Dhq9MjcM/fyjkcUIEtRuK?= =?us-ascii?Q?rJ8NEyMj3TuxhDzAzyxCa7gJikTI/Ei+ujmc5A0wjKZANsn9PrA5bpCeFAvx?= =?us-ascii?Q?kRsUkiLh7RquMre7PSZss/YbRBJxcRAQ3FLz2ZTOAaiqRFwtaINwqtN5RQ6h?= =?us-ascii?Q?laD5kr1fAliXVfHx0nvf5LDmhpSIlYC7kkp/yWiOuOdcU2vc2Qbp7uNxGsty?= =?us-ascii?Q?0LKgDLzOuwHUhNIyMzCgvm2rGlG7u6+2QfFix1OTaBX0H5P6RmeULy0aBFVl?= =?us-ascii?Q?fCWaUr8CB5IK9Fmn+MTQ6JhTZEUxG8hQxlMDQEp0CmG6DSkbzKPSILRFDQiY?= =?us-ascii?Q?ZNkwqmCjeboyx/zmeE8fGFlHTb9nRzjj1T+F6UiPl7BC5/tUWoMaYD2m6bpT?= =?us-ascii?Q?CfQEOedWLawZ/AITrNWn+4VAA1hNXzuPAj8j1kKbiN/nLLIBfeseuPF6iRMi?= =?us-ascii?Q?QNdx8UrJnZtbCFxKywcQKdFobvT7ObgL73iy9FVrJ8J3tHm+q35/1FR3oxd/?= =?us-ascii?Q?3khFYOQfnGp9PXzcdlGCK4v0aXofl3jBA1BUF2bbOsFPF3QhH6V1eg/uO1V/?= =?us-ascii?Q?katlRg+C+BGc1rPFQRtnbZg6t9ScrKlJrgryV6PvjedklFHHXmdKLMrd97lS?= =?us-ascii?Q?ZtyfIRT05rO6El7DVQQUNWvK/X/KV+fFDcpKWhmhqpBULHAuG/6yT+NApXUv?= =?us-ascii?Q?GME5PwA6dDIUcOUN6Wx/pu+g4PmhFe1b7gUzowYIU9xa+P0IG7Sd6r8TN7bq?= =?us-ascii?Q?OwbI6V8ocedFrpAMODNzKL+MGFe4WQ3tDgsixfbQidnTs/X8atPlFHQGun3G?= =?us-ascii?Q?lAD7/CgGnVJTZ91E5PLfvsg2Qrg+5fM0Td6zKTT/UglR+xu83vJxXVV7sjoc?= =?us-ascii?Q?iYvkRHnkDETmsk0Y44AXh/A+VchDJEjz+s/aVguFbFDoNA0Tas9hBkbWxnhQ?= =?us-ascii?Q?ojGYRybfnjVODEyIv7ZtVg7ZIoB06iaWwVPwnOpGJWLUPwWdPt/SHX31f7pB?= =?us-ascii?Q?sGFFlGgKDCcN0wq6SU1mL++pe5BNbm/EYF4riqZ761ruw63w2CN3kJU0p49c?= =?us-ascii?Q?gDL2onbhaX4NghW8M55pfpWnxa9Dxc26VekM8y+vO/zm2TJvG1011TO/7wjU?= =?us-ascii?Q?r+taNlz3OBUyQv8D3ajrXWddG+9WgVYnhm0h+UfoZeN7Bsj0xx9HRtU7z/o6?= =?us-ascii?Q?/H4tCmqMw/qeQ1sR1Z5GTPMxXW7QH9+awgzHVM7l8P+jwPAQ7gRG6quPaGbw?= =?us-ascii?Q?1g9N/DF86hM3dkPRUXxcP3ZBAZDHhXHC4XGuOURAJAzvz/N+m6yyjpYgHasg?= =?us-ascii?Q?e7Q3hVIZyLnADR9mvfrN83csuwdzh+P1//p1XTFiW1YOARUFDcgsCbLw8+Vm?= =?us-ascii?Q?aL+w2AzrbCWgc67ZuLDwga0eoGxFBAwUhE8fa2qf+C7vHMn4fsrwSMl3dHp5?= =?us-ascii?Q?MWHC9L6EPXvBudx2jTjH48OwbNiyRNiYdX0PSHeau6JsiGg09K2RLOADamrP?= =?us-ascii?Q?WUfuYHoFy1e6AoKGhkOvwhHOo6D2BIT5hIssnJUTuBX5ceaCrkxLWJFxEZYS?= =?us-ascii?Q?N1td0d9FAkY644/NX6A+1mbB46WJfNq+7KtvnSkzcfSnVon39Zq0xGZgIZxF?= =?us-ascii?Q?smYTfBm9i6BOQ937c9W7qj0KTAYbcW5K07gpXSaEZYUgxC2WXiAW/F2oWm1F?= =?us-ascii?Q?v/1QJdz0k+z4/le4O8hn+/5SF5k=3D?= 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)(7416014)(36860700013)(376014)(1800799024)(82310400026)(3613699012);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Jan 2026 16:38:53.5743 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 53840c5c-b7e1-4810-8c7e-08de5dc28eef 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: SJ5PEPF000001F3.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB5886 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260127_083905_935059_C34FF327 X-CRM114-Status: GOOD ( 14.08 ) 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 Hi Pranjal, Sorry, I missed this! On Fri, Jan 23, 2026 at 09:48:37AM +0000, Pranjal Shrivastava wrote: > On Fri, Dec 19, 2025 at 12:11:28PM -0800, Nicolin Chen wrote: > > + /* > > + * Avoid locking unless ATS is being used. No ATC invalidation can be > > + * going on after a domain is detached. > > + */ > > + if (invs->has_ats) { > > + read_lock(&invs->rwlock); > > Shouldn't these be read_lock_irqsave for all rwlock variants here? > Invalidations might happen in IRQ context as well.. > > > + __arm_smmu_domain_inv_range(invs, iova, size, granule, leaf); > > + read_unlock(&invs->rwlock); It was kept from the older versions where we had a trylock. Jason had an insight about this, mainly for less latency on invalidation threads. Yet, now we have a plain locking. TBH, I can't find a good reason justifying this. And it does look a bit unsafe to me. So, I think I will just change to the _irqsave version. (Jason?) Thanks Nicolin