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Fri, 25 Oct 2024 16:50:18 -0700 From: Nicolin Chen To: , , CC: , , , , , , , , , , , , , , , , , , , Subject: [PATCH v5 12/13] Documentation: userspace-api: iommufd: Update vIOMMU Date: Fri, 25 Oct 2024 16:49:52 -0700 Message-ID: <82a05ca8880c3613120fcf6875d083b25c5478be.1729897352.git.nicolinc@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: MIME-Version: 1.0 X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PEPF000075F0:EE_|BL3PR12MB6426:EE_ X-MS-Office365-Filtering-Correlation-Id: 67734da2-223c-471a-e8d6-08dcf54fd07e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|36860700013|7416014|82310400026; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.233;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge2.nvidia.com;CAT:NONE;SFS:(13230040)(1800799024)(376014)(36860700013)(7416014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Oct 2024 23:50:32.8029 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 67734da2-223c-471a-e8d6-08dcf54fd07e X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.233];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000075F0.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB6426 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241026_005039_427392_0F271A69 X-CRM114-Status: GOOD ( 18.50 ) 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 With the introduction of the new object and its infrastructure, update the doc to reflect that and add a new graph. Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Signed-off-by: Nicolin Chen --- Documentation/userspace-api/iommufd.rst | 69 ++++++++++++++++++++++++- 1 file changed, 68 insertions(+), 1 deletion(-) diff --git a/Documentation/userspace-api/iommufd.rst b/Documentation/userspace-api/iommufd.rst index 2deba93bf159..92d16efad5b0 100644 --- a/Documentation/userspace-api/iommufd.rst +++ b/Documentation/userspace-api/iommufd.rst @@ -63,6 +63,37 @@ Following IOMMUFD objects are exposed to userspace: space usually has mappings from guest-level I/O virtual addresses to guest- level physical addresses. + - IOMMUFD_OBJ_VIOMMU, representing a slice of the physical IOMMU instance, + passed to or shared with a VM. It may be some HW-accelerated virtualization + features and some SW resources used by the VM. For examples: + * Security namespace for guest owned ID, e.g. guest-controlled cache tags + * Access to a sharable nesting parent pagetable across physical IOMMUs + * Virtualization of various platforms IDs, e.g. RIDs and others + * Delivery of paravirtualized invalidation + * Direct assigned invalidation queues + * Direct assigned interrupts + * Non-affiliated event reporting + Such a vIOMMU object generally has the access to a nesting parent pagetable + to support some HW-accelerated virtualization features. So, a vIOMMU object + must be created given a nesting parent HWPT_PAGING object, and then it would + encapsulate that HWPT_PAGING object. Therefore, a vIOMMU object can be used + to allocate an HWPT_NESTED object in place of the encapsulated HWPT_PAGING. + + .. note:: + + The name "vIOMMU" isn't necessarily identical to a virtualized IOMMU in a + VM. A VM can have one giant virtualized IOMMU running on a machine having + multiple physical IOMMUs, in which case the VMM will dispatch the requests + or configurations from this single virtualized IOMMU instance to multiple + vIOMMU objects created for individual slices of different physical IOMMUs. + In other words, a vIOMMU object is always a representation of one physical + IOMMU, not necessarily of a virtualized IOMMU. For VMMs that want the full + virtualization features from physical IOMMUs, it is suggested to build the + same number of virtualized IOMMUs as the number of physical IOMMUs, so the + passed-through devices would be connected to their own virtualized IOMMUs + backed by corresponding vIOMMU objects, in which case a guest OS would do + the "dispatch" naturally instead of VMM trappings. + All user-visible objects are destroyed via the IOMMU_DESTROY uAPI. The diagrams below show relationships between user-visible objects and kernel @@ -101,6 +132,28 @@ creating the objects and links:: |------------>|iommu_domain|<----|iommu_domain|<----|device| |____________| |____________| |______| + _______________________________________________________________________ + | iommufd (with vIOMMU) | + | | + | [5] | + | _____________ | + | | | | + | |----------------| vIOMMU | | + | | | | | + | | | | | + | | [1] | | [4] [2] | + | | ______ | | _____________ ________ | + | | | | | [3] | | | | | | + | | | IOAS |<---|(HWPT_PAGING)|<---| HWPT_NESTED |<--| DEVICE | | + | | |______| |_____________| |_____________| |________| | + | | | | | | | + |______|________|______________|__________________|_______________|_____| + | | | | | + ______v_____ | ______v_____ ______v_____ ___v__ + | struct | | PFN | (paging) | | (nested) | |struct| + |iommu_device| |------>|iommu_domain|<----|iommu_domain|<----|device| + |____________| storage|____________| |____________| |______| + 1. IOMMUFD_OBJ_IOAS is created via the IOMMU_IOAS_ALLOC uAPI. An iommufd can hold multiple IOAS objects. IOAS is the most generic object and does not expose interfaces that are specific to single IOMMU drivers. All operations @@ -132,7 +185,8 @@ creating the objects and links:: flag is set. 4. IOMMUFD_OBJ_HWPT_NESTED can be only manually created via the IOMMU_HWPT_ALLOC - uAPI, provided an hwpt_id via @pt_id to associate the new HWPT_NESTED object + uAPI, provided an hwpt_id or a viommu_id of a vIOMMU object encapsulating a + nesting parent HWPT_PAGING via @pt_id to associate the new HWPT_NESTED object to the corresponding HWPT_PAGING object. The associating HWPT_PAGING object must be a nesting parent manually allocated via the same uAPI previously with an IOMMU_HWPT_ALLOC_NEST_PARENT flag, otherwise the allocation will fail. The @@ -149,6 +203,18 @@ creating the objects and links:: created via the same IOMMU_HWPT_ALLOC uAPI. The difference is at the type of the object passed in via the @pt_id field of struct iommufd_hwpt_alloc. +5. IOMMUFD_OBJ_VIOMMU can be only manually created via the IOMMU_VIOMMU_ALLOC + uAPI, provided a dev_id (for the device's physical IOMMU to back the vIOMMU) + and an hwpt_id (to associate the vIOMMU to a nesting parent HWPT_PAGING). The + iommufd core will link the vIOMMU object to the struct iommu_device that the + struct device is behind. And an IOMMU driver can implement a viommu_alloc op + to allocate its own vIOMMU data structure embedding the core-level structure + iommufd_viommu and some driver-specific data. If necessary, the driver can + also configure its HW virtualization feature for that vIOMMU (and thus for + the VM). Successful completion of this operation sets up the linkages between + the vIOMMU object and the HWPT_PAGING, then this vIOMMU object can be used + as a nesting parent object to allocate an HWPT_NESTED object described above. + A device can only bind to an iommufd due to DMA ownership claim and attach to at most one IOAS object (no support of PASID yet). @@ -161,6 +227,7 @@ User visible objects are backed by following datastructures: - iommufd_device for IOMMUFD_OBJ_DEVICE. - iommufd_hwpt_paging for IOMMUFD_OBJ_HWPT_PAGING. - iommufd_hwpt_nested for IOMMUFD_OBJ_HWPT_NESTED. +- iommufd_viommu for IOMMUFD_OBJ_VIOMMU. Several terminologies when looking at these datastructures: