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Fri, 19 Sep 2025 17:26:15 -0700 Date: Fri, 19 Sep 2025 17:26:14 -0700 From: Nicolin Chen To: , , CC: , , , , , , , , , , , Subject: Re: [PATCH rfcv2 4/8] iommu/arm-smmu-v3: Introduce a per-domain arm_smmu_invs array Message-ID: References: <80310b98efa4bd7e95d7b3ca302f40d4d69e59c5.1757373449.git.nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <80310b98efa4bd7e95d7b3ca302f40d4d69e59c5.1757373449.git.nicolinc@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF00020E63:EE_|DM4PR12MB8560:EE_ X-MS-Office365-Filtering-Correlation-Id: e7073a96-f25f-4675-3820-08ddf7dc9a64 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|7416014|376014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Jli77tq2FP+Dz/H9w8GhELS9XKC/bDuG4oqAQ2VRCEjd5dY74L41h4qm8MA5?= =?us-ascii?Q?HSXikYS650r11GqhuLlCBnDzrHC6cGhx2ljGJusJUMNWVAU2FvNdm4Stg9nT?= =?us-ascii?Q?1OTigp0/dblZmuJOTv5/grCVf0VuBqpqf/PvUTtU9n4ApBOCtTnNzl2eAwjT?= =?us-ascii?Q?WEcy4PtM77Jl5CPHSF1Cfys6euSGk6xRtk0ph38BnNpkdWKOmebh80AD7M0e?= =?us-ascii?Q?4+Y23QtUOOisTt9uAsfahNe6piPjC7qqtxOg106UzX1z3be0SKwzBD+wl+UJ?= =?us-ascii?Q?ZBQPpbdZLVSclhdCh+5pS8dB27joEOFPiWS6vR3eDQwy6jIDab1S7gWPEAHw?= =?us-ascii?Q?Rzr3L3mxvEW+b7yeobx73fS1ut3lQnyl6MzCUP1yZkP9z75rgRtKGWpsssk0?= =?us-ascii?Q?/fnRiflhPrINQ4LrC569zv42eDhATfDV58atBcvmUoS612QUxylC4ZdRl5hY?= =?us-ascii?Q?i/LuDYGYSaHTHCyTW7/Cm+23S52zwB8cFtAgxEj71FpaFkF29k5yXIrpFlj+?= =?us-ascii?Q?LTos23ctp3VNnG63Be//jMfsoOuG+UASN5QnkHfxI/TP/RIFXSkKj4U341uq?= =?us-ascii?Q?66PZjubg2T5LSSePC2Odm4tj9Rpf0PCpWG/UKYCF4xiqwDbe7rD8UFPypnV0?= =?us-ascii?Q?Nucpp2nLhoxCs8zxXQaht9uLLSoAxdZxVrV5TqmW+3rl0t/+UUSioojgs6a3?= =?us-ascii?Q?Z87TfJAQfz0usNiLAAUAWzwH/OwsbUkSN50JseIz7utaeVPvGj53uJTBoJ6I?= =?us-ascii?Q?WfS8od0yjK6Mu2mItbPBIuRY0k+UAMk/XJLFM+DmQeAI9g2PCrqfpIj61Ff6?= =?us-ascii?Q?K5suPqwY0mJQ3HDgzaCLQZpQJ/e6VM2r8HWuC/iufkZV1nu5CmXnT7IiB/hY?= =?us-ascii?Q?dxcjLQNXP1QWbT5/rjTClyjWn2xC+2F4fVYiBfabEjsEPa5TC9Thf8R3rguh?= =?us-ascii?Q?igfavlhL82JnJlHaswToEcSL2Jg9m0/4qBFT4t69jO7H745JXg/4Vp0Bph7c?= =?us-ascii?Q?4IEz4etHQwjPYmpKbPOHnv2dixecZY6VyeWNi0u7BCM+4k0p7eDqsveKK9ZS?= =?us-ascii?Q?TXlR08/n8fQe+VGoIEAQhiVyKzJ1SkMC6ySx7KEP8Y8lFqBQuyATZ00O8fHn?= =?us-ascii?Q?vX6A4eyj4cuyOHu7K4D5izci/2lLknxcg/zAHM0DPfQLN2HsVOIJtmIew8HS?= =?us-ascii?Q?0LcwPc4CsqQwzY1gWxZXKj6uHpeUU8uTi5Juq4SOFp5vLmonokzcyWL3mNqW?= =?us-ascii?Q?VLas+U2R8AysjncHN29LpclK+g2EZrMkMQS93ma500Vgs24q4Idq8EGV1ERU?= =?us-ascii?Q?Ueh/oLxRbYstBHMF3P7Y34kiI30f0xMSSLILHUG1vWGXC+FAtxmCNhgc6Itp?= =?us-ascii?Q?0mJUdd13vQuBI8ZeeQxhz8cIOXx0esx08+2pSiwLC89y0pXe87axPygCQMxN?= =?us-ascii?Q?FPHbS1swgfLRm7ObCdM8BQtmrVOaxVbkL/yKDsC7y2TFELyQmdZ3JEUZ6CVx?= =?us-ascii?Q?3yWmBkcAvytfoTM65r2a8qMQNqWrD5NjrYjU?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(36860700013)(7416014)(376014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Sep 2025 00:28:10.1503 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e7073a96-f25f-4675-3820-08ddf7dc9a64 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF00020E63.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB8560 On Mon, Sep 08, 2025 at 04:26:58PM -0700, Nicolin Chen wrote: > +/** > + * arm_smmu_invs_unref() - Find in @invs for all entries in @to_unref, decrease > + * the user counts without deletions > + * @invs: the base invalidation array > + * @to_unref: an array of invlidations to decrease their user counts > + * > + * Return: the number of trash entries in the array, for arm_smmu_invs_purge() > + * > + * This function will not fail. Any entry with users=0 will be marked as trash. > + * All trash entries will remain in the @invs until being completely deleted by > + * the next arm_smmu_invs_merge() or an arm_smmu_invs_purge() function call. > + * > + * This function must be locked and serialized with arm_smmu_invs_merge() and > + * arm_smmu_invs_purge(), but do not lockdep on any lock for KUNIT test. > + * > + * Note that the @invs->num_invs will not be updated, even if the actual number > + * of invalidations are decreased. Readers should take the read lock to iterate > + * each entry and check its users counter until @inv->num_invs. > + */ > +VISIBLE_IF_KUNIT > +size_t arm_smmu_invs_unref(struct arm_smmu_invs *invs, > + struct arm_smmu_invs *to_unref) > +{ > + size_t num_dels = 0; > + size_t i, j; > + > + for (i = j = 0; i != invs->num_invs || j != to_unref->num_invs;) { > + int cmp; > + > + if (!refcount_read(&invs->inv[i].users)) { > + num_dels++; > + i++; > + continue; > + } Found that this should AND the condition "i < invs->num_invs". Will fix in next version. > + > + cmp = arm_smmu_invs_merge_cmp(invs, i, to_unref, j); > + if (cmp < 0) { > + /* not found in to_unref, leave alone */ > + i++; > + } else if (cmp == 0) { > + /* same item */ > + if (refcount_dec_and_test(&invs->inv[i].users)) > + num_dels++; > + i++; > + j++; > + } else { > + /* item in to_unref is not in invs or already a trash */ > + WARN_ON(true); > + j++; > + } > + } > + return num_dels; > +} Nicolin