IOMMU user API header was introduced to support nested DMA translation and
related fault handling. The current UAPI data structures consist of three
areas that cover the interactions between host kernel and guest:
 - fault handling
 - cache invalidation
 - bind guest page tables, i.e. guest PASID

Future extensions are likely to support more architectures and vIOMMU features.

In the previous discussion, using user-filled data size and feature flags is
made a preferred approach over a unified version number.

In addition to introduce argsz field to data structures, this patchset is also
trying to document the UAPI design, usage, and extension rules. VT-d driver
changes to utilize the new argsz field is included, VFIO usage is to follow.



        - Addjusted paddings in UAPI data to be 8 byte aligned
        - Do not clobber argsz in IOMMU core before passing on to vendor driver
        - Removed pr_warn_ for invalid UAPI data check, just return -EINVAL
        - Clarified VFIO responsibility in UAPI data handling
        - Use iommu_uapi prefix to differentiate APIs has in-kernel caller
        - Added comment for unchecked flags of invalidation granularity
        - Added example in doc to show vendor data checking

        - Added checks of UAPI data for reserved fields, version, and flags.
        - Removed version check from vendor driver (vt-d)
        - Relaxed argsz check to match the UAPI struct size instead of variable
          union size
        - Updated documentation

        - Rewrote backward compatibility rule to support existing code
          re-compiled with newer kernel UAPI header that runs on older
          kernel. Based on review comment from Alex W.

        - Take user pointer directly in UAPI functions. Perform argsz check
          and copy_from_user() in IOMMU driver. Eliminate the need for
          VFIO or other upper layer to parse IOMMU data.
        - Create wrapper function for in-kernel users of UAPI functions
        - Removed unified API version and helper
        - Introduced argsz for each UAPI data
        - Introduced UAPI doc

Jacob Pan (5):
  docs: IOMMU user API
  iommu/uapi: Add argsz for user filled data
  iommu/uapi: Use named union for user data
  iommu/uapi: Handle data and argsz filled by users
  iommu/vt-d: Check UAPI data processed by IOMMU core

 Documentation/userspace-api/iommu.rst | 338 ++++++++++++++++++++++++++++++++++
 drivers/iommu/intel/iommu.c           |  27 ++-
 drivers/iommu/intel/svm.c             |   9 +-
 drivers/iommu/iommu.c                 | 192 ++++++++++++++++++-
 include/linux/iommu.h                 |  20 +-
 include/uapi/linux/iommu.h            |  16 +-
 6 files changed, 568 insertions(+), 34 deletions(-)
 create mode 100644 Documentation/userspace-api/iommu.rst


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