On 2024/11/6 04:04, Nicolin Chen wrote:
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.
It looks to be reasonable to share the viommu_obj between devices behind
the same physical IOMMU. This design seems no enforcement for it. So it's
all up to userspace from what I got. :)
--
Regards,
Yi Liu
