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Tue, 30 Dec 2025 10:52:54 -0800 Date: Tue, 30 Dec 2025 10:52:53 -0800 From: Nicolin Chen To: Jason Gunthorpe CC: , , , , , , , , , Subject: Re: [PATCH v1 2/9] iommu/arm-smmu-v3: Add alloc_id/free_id functions to arm_smmu_invs Message-ID: References: <1541ea4a9e9c935c2f907c0c5f13a4af2bdc2114.1766088962.git.nicolinc@nvidia.com> <20251219170551.GF254720@nvidia.com> Precedence: bulk X-Mailing-List: iommu@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: <20251219170551.GF254720@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000FCC3:EE_|BN5PR12MB9540:EE_ X-MS-Office365-Filtering-Correlation-Id: 279e0896-fa0f-4988-3ffb-08de47d4ad60 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|36860700013|7416014|376014|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Zk9gE4mYl5UnhkDvqBfB/wdvYssr+GysYo0GGzuwI9SdqBXG9pRvPlczXIsc?= =?us-ascii?Q?CA5pbxIuhFpS74QV21uF0Okyqf3aOjyc5YayRGMwAzoIWFGFfqZ/siv4kX7p?= =?us-ascii?Q?pw9JvHKMiIQXZ0YXkbgGqnRKk58B8F2pdUffTjMCfCTrOO23uXMpQ3nYN8uc?= =?us-ascii?Q?BaTmzZz91zv//eK7p4dB9ftCEyt7VE1cqI4X5QEtPi45HzVAusSuCSNf+oJS?= =?us-ascii?Q?qaCpe0xixUZwFz4rTcbDEFFzCYFcPjHHtTPFUGOT0Ke3+yWTmskyoQzKTE6/?= =?us-ascii?Q?B31HI5M1Eo0Fa7e8uA2CjA9aaZ3gts9qVp8GGRwayFTY7RmGUGEAuFad2VEP?= =?us-ascii?Q?Y4aQem5L8w3zOhJvaTdPQwVAR5R/Ro64yMH1O3B5CG9OiFJrOzbKF6kRrZit?= =?us-ascii?Q?m0z+6dFOxLxn4tzG3Ki4UDGf4Mx3+//NwrGTDcGhNRfLpFaXwuAOZG1LeILw?= =?us-ascii?Q?K5csLESHyUl7jYWhMnYxxE3BrgmPefgsrjm81bJoFwoZ70iPoleOrXYzrxYJ?= =?us-ascii?Q?U097M4aboA6xvzxtHIjQA5GM+0eUzmGSfpTpOjIZAD1LlFeCI7LKygqaoqSi?= =?us-ascii?Q?AkrUCov7BGcXFu8NSMaFpw6THlhtdNETXtI/D9XMF+b6F+D9K7jYcV764MpH?= =?us-ascii?Q?aUubPb5pHxGVJ6MU8DI+EikjSa13qsOPUNVja5/WJelwt7l8K/JCGGCPoyXd?= =?us-ascii?Q?jm6aRq56PGRTob+Is2WwqAJUtxESxVlV0mfGY02IdS2XC6LkofxrTGtkffXz?= =?us-ascii?Q?ZkuZtMmb5li6DHGFWooEHsYWzXeovIQNVWp8dzfz4BOGuJIJJMVvWEvNP3jT?= =?us-ascii?Q?131chTkfr1QlkyF6WmnYjKW+yW/Oe/QN4QSyOwDzqKR+htzNb1J+RtrBPVr7?= =?us-ascii?Q?fcUbTMYsDtXk9RE7NhXPoi650Q8zHT+RNvbCaHcbBWjtnDvKJqRCe17BL3oR?= =?us-ascii?Q?UrBl54L5VODuystjE1kwZepjY1GUQpmCy26aafEQFWtjWJVzJMvfAgHowSiX?= =?us-ascii?Q?bdDQ/C4LkBM1xmx00CgeRds/j0X+7PSF5D3fRDxJzP56kNiSMiGnQzk+Sb0x?= =?us-ascii?Q?vI9TIfnCPQXcSbUHesk7CINv826PhZB1FKSzx9qjDTY1yi1D44O1/00FenjC?= =?us-ascii?Q?orB1FanMEGwXFDY6xD5M3eZ7aag58x8/flcWWQAQlXSyzwsGEySoyoeh9Ik2?= =?us-ascii?Q?7ifnv9PMRd8cZOy/UOq48Qk61q05eBKrfA7D8ETGuByDow3EFE9Zd3cFafEI?= =?us-ascii?Q?w318UqUghbzqhUCVI38WcL6TXVqr0MSZI/ASmgqIFnv0HNJ8VFavcTXlgkMj?= =?us-ascii?Q?sldXzPazs+I6MzhPBDwWAbIWSyOIwK8MVL3Q64yvGT1dRambhCR1RVw3C98p?= =?us-ascii?Q?F7p+y8F81WRii3XkNpzBVa/JNnZ4yH6av2zmWO+8jDkUg2FNPzcnA43I3Ok+?= =?us-ascii?Q?IMMuUy5YXOlNqP59olwYXGUl1V/fVQzfFcCrZL/2tDWbkBL6Ttc2Dz9MVjvf?= =?us-ascii?Q?TR9vdMSfrIXMCEIPuEAYLCaVfkE5jhp2v9lO6NnNd6BvM2ukIWWKdDDP1s7i?= =?us-ascii?Q?+RFN5hCtXQkHnh9sjhw=3D?= 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)(82310400026)(36860700013)(7416014)(376014)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Dec 2025 18:53:09.9236 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 279e0896-fa0f-4988-3ffb-08de47d4ad60 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: CY4PEPF0000FCC3.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN5PR12MB9540 Hi Jason, On Fri, Dec 19, 2025 at 01:05:51PM -0400, Jason Gunthorpe wrote: > +static int arm_smmu_get_tag(struct arm_smmu_domain *smmu_domain, > + struct arm_smmu_master *master, > + struct arm_vsmmu *vsmmu, > + struct arm_smmu_iotlb_tag *tag, bool no_alloc) [...] > + case ARM_SMMU_DOMAIN_S2: > + if (smmu_domain->nest_parent) { > + /* FIXME we can support attaching a nest_parent without > + * a vsmmu, but to do that we need to fix > + * arm_smmu_get_id_from_invs() to never return the vmid > + * of a vsmmu. Probably by making a > + * INV_TYPE_S2_VMID_VSMMU */ > + id = vsmmu->vmid; > + return 0; > + } Would you mind elaborating why arm_smmu_get_id_from_invs() can't return vsmmu->vmid to share with a naked S2 STE? I'm having a bit trouble justifying this INV_TYPE_S2_VMID_VSMMU. Since it's the same S2 domain/iopt, if anything that is attached (whether nested or naked) changes the S2 iopt, we should always flush the nested S1 domain too, right? If so, a naked S2 STE should refer to the same VMID in order to allow its following INV_TYPE_S2_VMID_S1_CLEAR to work properly? Thanks Nicolin