linux-kernel - [PATCH v6 0/6] IOMMU user API enhancement

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Message-Id: <1595525140-23899-1-git-send-email-jacob.jun.pan@linux.intel.com>
Date:   Thu, 23 Jul 2020 10:25:34 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>
Cc:     "Lu Baolu" <baolu.lu@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        "Christoph Hellwig" <hch@...radead.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Eric Auger <eric.auger@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH v6 0/6] IOMMU user API enhancement

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.
https://lkml.org/lkml/2020/1/29/45

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_v5.8_uapi_v6

Thanks,

Jacob

Changeog:
v6
	- 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
v5
	- 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

v4
	- 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

v3:
	- 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.
	  https://lore.kernel.org/linux-iommu/20200611094741.6d118fa8@w520.home/
	- 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
v2:
	- Removed unified API version and helper
	- Introduced argsz for each UAPI data
	- Introduced UAPI doc


Jacob Pan (6):
  docs: IOMMU user API
  iommu/uapi: Add argsz for user filled data
  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 | 231 ++++++++++++++++++++++++++++++++++
 MAINTAINERS                           |   1 +
 drivers/iommu/intel/iommu.c           |  25 ++--
 drivers/iommu/intel/svm.c             |   9 +-
 drivers/iommu/iommu.c                 | 206 ++++++++++++++++++++++++++++--
 include/linux/iommu.h                 |  35 ++++--
 include/uapi/linux/iommu.h            |  16 ++-
 7 files changed, 480 insertions(+), 43 deletions(-)
 create mode 100644 Documentation/userspace-api/iommu.rst

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