[PATCH v10 0/7] IOMMU user API enhancement

From: Jacob Pan
Date: Tue Sep 22 2020 - 16:15:35 EST

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.

This set is available at:
https://github.com/jacobpan/linux.git vsva_v5.9_uapi_v10



- Documentation grammar fixes based on Randy's review
- Directly pass PASID value to iommu_sva_unbind_gpasid() without
the superfluous data in struct iommu_gpasid_bind_data.
- Rebased to v5.9-rc2
- Addressed review comments from Eric Auger
1. added a check for the unused vendor flags
2. commit message improvements
- Added PASID data format enum for range checking
- Tidy up based on reviews from Alex W.
- Removed doc section for vIOMMU fault handling
- Renamed all UAPI functions with iommu_uapi_ prefix
- Replaced argsz maxsz checking with flag specific size checks
- Documentation improvements based on suggestions by Eric Auger
Replaced example code with a pointer to the actual code
- Added more checks for illegal flags combinations
- Added doc file to MAINTAINERS
- 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 (7):
docs: IOMMU user API
iommu/uapi: Add argsz for user filled data
iommu/uapi: Introduce enum type for PASID data format
iommu/uapi: Use named union for user data
iommu/uapi: Rename uapi functions
iommu/uapi: Handle data and argsz filled by users
iommu/vt-d: Check UAPI data processed by IOMMU core

Documentation/userspace-api/iommu.rst | 210 ++++++++++++++++++++++++++++++++++
drivers/iommu/intel/iommu.c | 25 ++--
drivers/iommu/intel/svm.c | 13 ++-
drivers/iommu/iommu.c | 201 ++++++++++++++++++++++++++++++--
include/linux/iommu.h | 35 ++++--
include/uapi/linux/iommu.h | 25 ++--
7 files changed, 467 insertions(+), 43 deletions(-)
create mode 100644 Documentation/userspace-api/iommu.rst