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Documentation: userspace-api: iommufd: Update vDEVICE

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With the introduction of the new object and its infrastructure, update the
doc and the vIOMMU graph to reflect that.

Link: https://patch.msgid.link/r/e1ff278b7163909b2641ae04ff364bb41d2a2a2e.1730836308.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Nicolin Chen 2024-11-05 12:05:18 -08:00 committed by Jason Gunthorpe
parent 49ad127719
commit b047c0644f
1 changed files with 32 additions and 9 deletions
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41
Documentation/userspace-api/iommufd.rst
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@ -96,6 +96,19 @@ Following IOMMUFD objects are exposed to userspace:
backed by corresponding vIOMMU objects, in which case a guest OS would do backed by corresponding vIOMMU objects, in which case a guest OS would do
the "dispatch" naturally instead of VMM trappings. 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. All user-visible objects are destroyed via the IOMMU_DESTROY uAPI.
The diagrams below show relationships between user-visible objects and kernel 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] | | [5] [6] |
| _____________ | | _____________ _____________ |
| | | | | | | | | |
| |----------------| vIOMMU | | | |----------------| vIOMMU |<---| vDEVICE |<----| |
| | | | | | | | | |_____________| | |
| | | | | | | | | | |
| | [1] | | [4] [2] | | | [1] | | [4] | [2] |
| | ______ | | _____________ ________ | | | ______ | | _____________ _|______ |
| | | | | [3] | | | | | | | | | | | [3] | | | | | |
| | | IOAS |<---|(HWPT_PAGING)|<---| HWPT_NESTED |<--| DEVICE | | | | | 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 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. 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 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). 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_paging for IOMMUFD_OBJ_HWPT_PAGING.
- iommufd_hwpt_nested for IOMMUFD_OBJ_HWPT_NESTED. - iommufd_hwpt_nested for IOMMUFD_OBJ_HWPT_NESTED.
- iommufd_viommu for IOMMUFD_OBJ_VIOMMU. - iommufd_viommu for IOMMUFD_OBJ_VIOMMU.
- iommufd_vdevice for IOMMUFD_OBJ_VDEVICE.
Several terminologies when looking at these datastructures: Several terminologies when looking at these datastructures: