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| -rw-r--r-- | Documentation/userspace-api/iommufd.rst | 41 |
1 files changed, 32 insertions, 9 deletions
diff --git a/Documentation/userspace-api/iommufd.rst b/Documentation/userspace-api/iommufd.rst index 5475e066a715..70289d6815d2 100644 --- a/Documentation/userspace-api/iommufd.rst +++ b/Documentation/userspace-api/iommufd.rst @@ -96,6 +96,19 @@ Following IOMMUFD objects are exposed to userspace: backed by corresponding vIOMMU objects, in which case a guest OS would do the "dispatch" naturally instead of VMM trappings. +- IOMMUFD_OBJ_VDEVICE, representing a virtual device for an IOMMUFD_OBJ_DEVICE + against an IOMMUFD_OBJ_VIOMMU. This virtual device holds the device's virtual + information or attributes (related to the vIOMMU) in a VM. An immediate vDATA + example can be the virtual ID of the device on a vIOMMU, which is a unique ID + that VMM assigns to the device for a translation channel/port of the vIOMMU, + e.g. vSID of ARM SMMUv3, vDeviceID of AMD IOMMU, and vRID of Intel VT-d to a + Context Table. Potential use cases of some advanced security information can + be forwarded via this object too, such as security level or realm information + in a Confidential Compute Architecture. A VMM should create a vDEVICE object + to forward all the device information in a VM, when it connects a device to a + vIOMMU, which is a separate ioctl call from attaching the same device to an + HWPT_PAGING that the vIOMMU holds. + All user-visible objects are destroyed via the IOMMU_DESTROY uAPI. The diagrams below show relationships between user-visible objects and kernel @@ -135,16 +148,16 @@ creating the objects and links:: |____________| |____________| |______| _______________________________________________________________________ - | iommufd (with vIOMMU) | + | iommufd (with vIOMMU/vDEVICE) | | | - | [5] | - | _____________ | - | | | | - | |----------------| vIOMMU | | - | | | | | - | | | | | - | | [1] | | [4] [2] | - | | ______ | | _____________ ________ | + | [5] [6] | + | _____________ _____________ | + | | | | | | + | |----------------| vIOMMU |<---| vDEVICE |<----| | + | | | | |_____________| | | + | | | | | | + | | [1] | | [4] | [2] | + | | ______ | | _____________ _|______ | | | | | | [3] | | | | | | | | | IOAS |<---|(HWPT_PAGING)|<---| HWPT_NESTED |<--| DEVICE | | | | |______| |_____________| |_____________| |________| | @@ -217,6 +230,15 @@ creating the objects and links:: 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. +6. IOMMUFD_OBJ_VDEVICE can be only manually created via the IOMMU_VDEVICE_ALLOC + uAPI, provided a viommu_id for an iommufd_viommu object and a dev_id for an + iommufd_device object. The vDEVICE object will be the binding between these + two parent objects. Another @virt_id will be also set via the uAPI providing + the iommufd core an index to store the vDEVICE object to a vDEVICE array per + vIOMMU. If necessary, the IOMMU driver may choose to implement a vdevce_alloc + op to init its HW for virtualization feature related to a vDEVICE. Successful + completion of this operation sets up the linkages between vIOMMU and device. + 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). @@ -230,6 +252,7 @@ User visible objects are backed by following datastructures: - iommufd_hwpt_paging for IOMMUFD_OBJ_HWPT_PAGING. - iommufd_hwpt_nested for IOMMUFD_OBJ_HWPT_NESTED. - iommufd_viommu for IOMMUFD_OBJ_VIOMMU. +- iommufd_vdevice for IOMMUFD_OBJ_VDEVICE. Several terminologies when looking at these datastructures: |