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Mon, 24 Feb 2025 14:24:50 -0800 Date: Mon, 24 Feb 2025 14:24:49 -0800 From: Nicolin Chen To: Pranjal Shrivastava CC: , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v7 12/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: AnonymousSubmission X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF0000013E:EE_|DM4PR12MB6208:EE_ X-MS-Office365-Filtering-Correlation-Id: 01744dfd-aef8-4ead-1601-08dd5522145c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|7416014|82310400026|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?cUCYptckUlPsGP6kdARH0Cb3Zn3YoobGhHtUdmNpQLMqufDy+KfvSYM27t9w?= =?us-ascii?Q?4HumY+Lapsv51PBt4+nUzaUfhpzS9wCw6f3EaBUtms6AS58QB+92g7/+zYqI?= =?us-ascii?Q?pIodKVO/fOE+Xdv+gIS078kZiMDJbSFVssa3v79S20FkvGvy11Amsn5ef4sR?= =?us-ascii?Q?2X3RtzXLjv6Oqwb9q86LXnp9E8cMOtd05oVTDdHzVV9ZOBrESR6J3Q99no/i?= =?us-ascii?Q?37cq1uBVikNYTUX5hj0lpuYdYzNTBOyDde2TAgkgTloAaXkM7x3XrctxLKx1?= =?us-ascii?Q?xEg1gZl01yPKN6bu5HC55AymO7zDj0hF52JMdRj4UKUKIyEyLRENPUAQVu9i?= =?us-ascii?Q?sco+Fsa/oJOqMKnUtuRQb8zDv0rhmZGawCuOndmMdzCryBlePKRMrZ9cdQTb?= =?us-ascii?Q?qyI3plySuEk9BtR7ViD/fPqiLUhsKkpGeqhVy+Xwo5LX7wjcx518GouCnHoE?= =?us-ascii?Q?275uTqJONbKtFjDet6ImOIOvhgzRirsjBJy+nw/mAXm76IMFgsIv+erAWXix?= =?us-ascii?Q?JPLg6sf5sc4UPJ5yML21S3zQmSylPTmJcqIDLnjSm+EO1kHNFU0I2xpTP692?= =?us-ascii?Q?7Pv7OCUeHkx62QrduIcbpzvcv3y236+bgVhW8x2nhCv/thlhwVvM065Kq6g/?= =?us-ascii?Q?ozWjic1N0bgJOPsBJgvZe6SZH3WvNDJd0VnxvJsKVOhjAM2E6KUFt4KOpSzY?= =?us-ascii?Q?RGGIxkpLGOVm6W/atwSMkLptGAZJvvRXDZ5K4L62p60Q3OGu5kBPWH2/0YdB?= =?us-ascii?Q?f6wEieX4tBSwFOviGMFJjgshRIlSF0P+LPpft0m3Gq0m3EOboZUD9UzFcBlL?= =?us-ascii?Q?NW6QMQfZhMhAwwNp1glbPe0wYi0p8ezzplc4TQx/FJSKq3nUL1vW9we4E1ZK?= =?us-ascii?Q?GI3Ry77krMaYywPsgK8Js/ar8aoEZgIobCfgeBjtaFQxzP1nywvzqvT1vXce?= =?us-ascii?Q?e7BzaNWrhldR1oC/miiYYoKYexnhCs/bS4cLF6ADD02lqvnZVoZiczJJ1R9e?= =?us-ascii?Q?tUV2D4/H/tcLDg9/Fev0ov27DkIZ2dE8h2DUGAMIGtlbQbTMcTRwLw7/3lGe?= =?us-ascii?Q?WjYWYc30Zn4tYQqG3YnR2sRNlY8ar44IdXI4TCZPZWA+nCcIYuPxF1BEQhut?= =?us-ascii?Q?IBbLOdABNbS3K8rnTksX0MY5MG1pB5ye4B3tb7VPeNNqx7sP64ljgufqPNpy?= =?us-ascii?Q?qv4YRYr7/uU/oDDRJAezY/ig9WArSQP0i2Wt2yYXHNGe8pH0CV0bmSTcYdOs?= =?us-ascii?Q?tf8lH2phUay9Z4RGy1j35gyMK25f4qf9t0MTKocJZcB+ZlfUEBgKqAn2gEx0?= =?us-ascii?Q?vELqmBgdtrpG45ItRrKWKk+SAZVVtuiap/jK+uepjNB5S95o0iPXD8e52UiD?= =?us-ascii?Q?seJmHtSmXbt9TUCTiUWFxqkFY5mACggl+ndy09GBjt3WLqUh79t9Q9vUYP7x?= =?us-ascii?Q?5mFgSH+7EK2XFLycoAONw06S5cnpMrelnEQISFQRneZKjBgYHZ2oexvAGrqY?= =?us-ascii?Q?nIqk6s9HNuQlkmU=3D?= X-Forefront-Antispam-Report: CIP:216.228.118.232;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge1.nvidia.com;CAT:NONE;SFS:(13230040)(376014)(1800799024)(7416014)(82310400026)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Feb 2025 22:25:01.3744 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 01744dfd-aef8-4ead-1601-08dd5522145c X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CH2PEPF0000013E.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6208 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250224_142511_261658_14B8B770 X-CRM114-Status: GOOD ( 20.37 ) 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 Mon, Feb 24, 2025 at 09:53:58PM +0000, Pranjal Shrivastava wrote: > On Mon, Feb 24, 2025 at 01:31:11PM -0800, Nicolin Chen wrote: > > On Mon, Feb 24, 2025 at 08:35:56PM +0000, Pranjal Shrivastava wrote: > > > oN sAt, Feb 22, 2025 at 07:54:09AM -0800, Nicolin Chen wrote: > > > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c > > > > index 5aa2e7af58b4..364d8469a480 100644 > > > > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c > > > > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c > > > > @@ -85,6 +85,59 @@ static void arm_smmu_make_nested_domain_ste( > > > > } > > > > } > > > > > > > > +int arm_smmu_attach_prepare_vmaster(struct arm_smmu_attach_state *state, > > > > + struct iommu_domain *domain) > > > > +{ > > > > + struct arm_smmu_nested_domain *nested_domain; > > > > + struct arm_smmu_vmaster *vmaster; > > > > + unsigned long vsid; > > > > + int ret; > > > > + > > > > + iommu_group_mutex_assert(state->master->dev); > > > > + > > > > + if (domain->type != IOMMU_DOMAIN_NESTED) > > > > + return 0; > > > > + nested_domain = to_smmu_nested_domain(domain); > > > > + > > > > + /* Skip invalid vSTE */ > > > > + if (!(nested_domain->ste[0] & cpu_to_le64(STRTAB_STE_0_V))) > > > > + return 0; > > > > + > > > > + ret = iommufd_viommu_get_vdev_id(&nested_domain->vsmmu->core, > > > > + state->master->dev, &vsid); > > > > + if (ret) > > > > + return ret; > > > > + > > > > + vmaster = kzalloc(sizeof(*vmaster), GFP_KERNEL); > > > > + if (!vmaster) > > > > + return -ENOMEM; > > > > + vmaster->vsmmu = nested_domain->vsmmu; > > > > + vmaster->vsid = vsid; > > > > + state->vmaster = vmaster; > > > > + > > > > + return 0; > > > > +} > > > > + > > > > +void arm_smmu_attach_commit_vmaster(struct arm_smmu_attach_state *state) > > > > +{ > > > > + struct arm_smmu_master *master = state->master; > > > > + > > > > + mutex_lock(&master->smmu->streams_mutex); > > > > + if (state->vmaster != master->vmaster) { > > > > + kfree(master->vmaster); > > > > + master->vmaster = state->vmaster; > > > > + } > > > > > > Does this condition suggest that we might end up calling > > > `arm_smmu_attach_prepare_vmaster()` multiple times before __actually__ > > > commiting to a vmaster? > > > > No. prepare() and commit() are 1:1. How is it interpreted to have > > "multiple times"? > > Ohh alright. I was just confused about why do we need to check: > `if (state->vmaster != master->vmaster)` ? Hmm, it's probably not necessary, since we always allocate a new vmaster pointer to the "state" or set a NULL. I will clean that up a bit. Thanks Nicolin