[PATCH v4 0/5] Simplify vfio_iommu_type1 attach/detach routine

Nicolin Chen
2022-06-30T20:37:13Z

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 as KVM will
not 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
v4:
* Dropped EMEDIUMTYPE change in mtk_v1 driver per Robin's input
* Added Baolu's and Kevin's Reviewed-by lines
v3: https://lore.kernel.org/kvm/20220623200029.26007-1-nicolinc@nvidia.com/
* 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@nvidia.com/
* 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@nvidia.com/

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/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 ++++++++++----------
14 files changed, 224 insertions(+), 210 deletions(-)

--
2.17.1