[PATCH v3 0/5] Simplify vfio_iommu_type1 attach/detach routine

[Nicolin Chen]

This is a preparatory series for IOMMUFD v2 patches. It enforces error
code -EMEDIUMTYPE in iommu_attach_device() and iommu_attach_group() when
an IOMMU domain and a device/group are incompatible. It also drops the
useless domain->ops check since it won't fail in current environment.

These allow VFIO iommu code to simplify its group attachment routine, by
avoiding the extra IOMMU domain allocations and attach/detach sequences
of the old code.

Worths mentioning the exact match for enforce_cache_coherency is removed
with this series, since there's very less value in doing that since KVM
won't be able to take advantage of it -- this just wastes domain memory.
Instead, we rely on Intel IOMMU driver taking care of that internally.

This is on github:
https://github.com/nicolinc/iommufd/commits/vfio_iommu_attach

Changelog
v3:
 * Dropped all dev_err since -EMEDIUMTYPE clearly indicates what error.
 * Updated commit message of enforce_cache_coherency removing patch.
 * Updated commit message of domain->ops removing patch.
 * Replaced "goto out_unlock" with simply mutex_unlock() and return.
 * Added a line of comments for -EMEDIUMTYPE return check.
 * Moved iommu_get_msi_cookie() into alloc_attach_domain() as a cookie
   should be logically tied to the lifetime of a domain itself.
 * Added Kevin's "Reviewed-by".
v2: https://lore.kernel.org/kvm/20220616000304.23890-1-nicolinc@xxxxxxxxxx/
 * Added -EMEDIUMTYPE to more IOMMU drivers that fit the category.
 * Changed dev_err to dev_dbg for -EMEDIUMTYPE to avoid kernel log spam.
 * Dropped iommu_ops patch, and removed domain->ops in VFIO directly,
   since there's no mixed-driver use case that would fail the sanity.
 * Updated commit log of the patch removing enforce_cache_coherency.
 * Fixed a misplace of "num_non_pinned_groups--" in detach_group patch.
 * Moved "num_non_pinned_groups++" in PATCH-5 to the common path between
   domain-reusing and new-domain pathways, like the code previously did.
 * Fixed a typo in EMEDIUMTYPE patch.
v1: https://lore.kernel.org/kvm/20220606061927.26049-1-nicolinc@xxxxxxxxxx/

Jason Gunthorpe (1):
  vfio/iommu_type1: Prefer to reuse domains vs match enforced cache
    coherency

Nicolin Chen (4):
  iommu: Return -EMEDIUMTYPE for incompatible domain and device/group
  vfio/iommu_type1: Remove the domain->ops comparison
  vfio/iommu_type1: Clean up update_dirty_scope in detach_group()
  vfio/iommu_type1: Simplify group attachment

 drivers/iommu/amd/iommu.c                   |   2 +-
 drivers/iommu/apple-dart.c                  |   4 +-
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c |  15 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |   6 +-
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |   9 +-
 drivers/iommu/intel/iommu.c                 |  10 +-
 drivers/iommu/iommu.c                       |  28 ++
 drivers/iommu/ipmmu-vmsa.c                  |   4 +-
 drivers/iommu/mtk_iommu_v1.c                |   2 +-
 drivers/iommu/omap-iommu.c                  |   3 +-
 drivers/iommu/s390-iommu.c                  |   2 +-
 drivers/iommu/sprd-iommu.c                  |   6 +-
 drivers/iommu/tegra-gart.c                  |   2 +-
 drivers/iommu/virtio-iommu.c                |   3 +-
 drivers/vfio/vfio_iommu_type1.c             | 340 ++++++++++----------
 15 files changed, 225 insertions(+), 211 deletions(-)

-- 
2.17.1