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Fri, 23 Jan 2026 09:36:01 -0800 Date: Fri, 23 Jan 2026 09:35:58 -0800 From: Nicolin Chen To: Will Deacon CC: , , , , , , , , , , , Subject: Re: [PATCH v9 3/7] iommu/arm-smmu-v3: Introduce a per-domain arm_smmu_invs array Message-ID: References: <8c94c5194871ee1a0f3a6b49e18818b88f51226d.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: BY1PEPF0001AE1D:EE_|MN0PR12MB5740:EE_ X-MS-Office365-Filtering-Correlation-Id: e7dc7c19-611c-42b4-e712-08de5aa5ee89 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|82310400026|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?cwmLwiZJFce3uIQ1oUllUl+KHpFEW0a5PHndOV1JvNX3tJ9jcnzZATAXyHEJ?= =?us-ascii?Q?KJSVfY6jpkBgyLkBiPC20Ajj9qLz0iY54UbYiHgWp8j0QdoyC2svaH5jKBAx?= =?us-ascii?Q?iw8/yK1dq09UCkqC5Fr0eHeiUvrc0yD0bUjfrshzsRA1ZpkACD9mdqarzuOA?= =?us-ascii?Q?D46qRvmjttW32g+x75jFFMIqH5Wvj/EmZkp/HtRrxyl4l5bEFumhOlNL7Qa5?= =?us-ascii?Q?SwIw2cAami1RgRxXrcmiNfGCbyrfciPuW5iUcwqnrAm3vh6MLHb2fnwWFKFt?= =?us-ascii?Q?6VBo0tWGIBdv5eCxQiNppXs+LnPI09iQReyga781xyms7EbO7NnotXobYezc?= =?us-ascii?Q?ORwotq1vdROE7iXYK30rA3/RTAY1PPAi8bviCCsQnydzU3Kyb4iEc2Z18heB?= =?us-ascii?Q?U7ioobAkZSTA/qFd9WvG1qLcpdheExJX4AGvCINcE8/l+k3mDZs8v8XkJjm8?= =?us-ascii?Q?eIL03zu9c/viIEfP7LUcJfpKJ7sG8UMAYymbKTB/ours7ayUekvFDVznR7/p?= =?us-ascii?Q?Hv+S5fQG+nLOK++5FPd8oxYvwT8rhFFRnmRZYht7+JOjAzKmVqvwv2v5fB3M?= =?us-ascii?Q?TLQJQGF4qAvYpo/UwR5DLcOW+SILxwzyCKY7lBOTqfv72OG64VF+UOlEFiyB?= =?us-ascii?Q?FyWithiJ9SncESQUqaZFzstnlRJvjD670ZTi1NjyP8LAa0441UK3+eDJJwbO?= =?us-ascii?Q?tcTh3Y3rBEgPlBlkslb/ff80G7aL8Z/hd+q9eEjtGyH3r8jqgBvk7ZOwM6rb?= =?us-ascii?Q?1WGo5ae6l8w0BGIezFUKZguJ9z5We+p+FwZNn2zMPmqu5kjefcceFRlswT6X?= =?us-ascii?Q?7DnxOhEC7Jb/kGpHKS55oK+vUAUIg++vUn+AoYk9d0+DXaWjZUfvjo7CQnEY?= =?us-ascii?Q?MHu1NXCylswsnK9Uuk0FuwiVj4s/8PeFc+Mk557ThkJe+L3P3G7ImXOUbbzX?= =?us-ascii?Q?AtmLqLH/ggSCSOkeeOjtiy1pyWbfZicCeIVXkPSs8waHDoPK3wVxfRCPpbm0?= =?us-ascii?Q?y9cEX49mdGoBzrg0zPRAAZSob/4gn0O/hOFvBHIVTWZdgU/3rMVPPDsIVttc?= =?us-ascii?Q?uZjWI7DUa55OQrmouzJMLitbhahklp/w/FDm3nBNZZ3SHcKjUWAks6eStYOU?= =?us-ascii?Q?/7RoSULH++hdxnysNTMxUFtFkap5Xtd6lvojMGXdz8+7G9c6xOJzLWGu9Lgw?= =?us-ascii?Q?dg11bKmkJChxO20JMsYTQduk4LgeJxOruZKqq25My4DYEUx2nQTnNUCN+oNv?= =?us-ascii?Q?E1zCBzsBMcWh0BB5hnUFWJU8a+1dhYXDgifhGD+Rjgb63Y70zaAgww12xLTQ?= =?us-ascii?Q?6C56dDK/6yLixKDrqFRf2bYlGSipdXEuviRsZOpkh+quGQ/lzF3nK0yDa2EP?= =?us-ascii?Q?AibqqOreYRsWncVwOjNkE6gMBYHqzd2iqAgIUexGsHVJ31JSxZEW1Fc5H9LW?= =?us-ascii?Q?OZDRfRKT5a/BzTd+2XkEpkqHBvqhS9eZ3qODcDPv0Gf0ZVdYrZLAzaTIm3jY?= =?us-ascii?Q?mFVjVm7ryXIH7i6XiC0EHriL9S1LQJ9wAp5K3JQogbTqVBjSfeuqupPmQuLQ?= =?us-ascii?Q?qbrIQ3W3XoVJH8Ov1my6FD6iQ2L13CGhrRwu6E+P1VAXxQR1TvGcqHxUif0Z?= =?us-ascii?Q?bAziuTyQN4Me2rwoEgRar8g7gwRsgocV7CuCVx7MBZkgA9NENa9kH1FIXzsX?= =?us-ascii?Q?B6b7/g=3D=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)(376014)(82310400026)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Jan 2026 17:36:25.0064 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e7dc7c19-611c-42b4-e712-08de5aa5ee89 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: BY1PEPF0001AE1D.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5740 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260123_093643_587847_01D4032A X-CRM114-Status: GOOD ( 15.53 ) 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, Jan 23, 2026 at 05:03:10PM +0000, Will Deacon wrote: > On Fri, Dec 19, 2025 at 12:11:25PM -0800, Nicolin Chen wrote: > > +struct arm_smmu_inv { > > + struct arm_smmu_device *smmu; > > + u8 type; > > + u8 size_opcode; > > + u8 nsize_opcode; > > + u32 id; /* ASID or VMID or SID */ > > + union { > > + size_t pgsize; /* ARM_SMMU_FEAT_RANGE_INV */ > > + u32 ssid; /* INV_TYPE_ATS */ > > + }; > > + > > + refcount_t users; /* users=0 to mark as a trash to be purged */ > > The refcount_t API uses atomics with barrier semantics. Do we actually > need those properties when updating the refcounts here? The ASID lock > gives us pretty strong serialisation even after this patch series and > we rely heavily on that. But we can't use that mutex in the invalidation function that might be an IRQ context? > > + /* Test6: purge test_b (new array) */ > > + test_a = arm_smmu_invs_purge(test_b); > > + kfree(test_b); > > + arm_smmu_v3_invs_test_verify(test, test_a, ARRAY_SIZE(results6[0]), > > + results6[0], results6[1]); > > + > > + /* Test7: unref invs3 (same array) */ > > + arm_smmu_invs_unref(test_a, &invs3, NULL); > > + KUNIT_EXPECT_EQ(test, test_a->num_invs, 0); > > + KUNIT_EXPECT_EQ(test, test_a->num_trashes, 0); > > Wouldn't we be better off testing num_trashes == 0 after test 6 has > completed? OK. > > +/** > > + * arm_smmu_invs_for_each_entry - Iterate over two sorted arrays computing for > > + * arm_smmu_invs_merge() or arm_smmu_invs_unref() > > + * @invs_l: the base invalidation array > > + * @idx_l: a stack variable of 'size_t', to store the base array index > > + * @invs_r: the build_invs array as to_merge or to_unref > > + * @idx_r: a stack variable of 'size_t', to store the build_invs index > > + * @cmp: a stack variable of 'int', to store return value (-1, 0, or 1) > > + */ > > +#define arm_smmu_invs_for_each_cmp(invs_l, idx_l, invs_r, idx_r, cmp) \ > > nit: the kerneldoc comment doesn't match the name of this function. I will fix this. Thanks Nicolin