[RFC PATCH 0/6] Share sva domain with all devices bound to a mm

[Tina Zhang]

During a sva domain's life time, which begins with binding a device to a
mm and ends by releasing all the bound devices from that mm, there is only
one PASID assigned for this sva domain. From platform perspective,
supporting 1:1 mapping between mm PASID and sva domain allows a sva domain
to be shared by mm's all bound devices issuing DMA transactions using the
assigned PASID.

To support mm PASID 1:1 with sva domain, each mm needs to keep both a
reference of an allocated sva domain and its corresponding PASID. However,
currently, mm struct only has one pasid field for sva usage, which is used
to keep the info of an assigned PASID. That pasid field cannot provide
sufficient info to build up the 1:1 mapping between sva domain and PASID.

This patch-set fills the gap by adding an mm_iommu field[1], whose type is
mm_iommu_data struct, to replace the old pasid field. The introduced
mm_iommu_data struct keeps info of both a sva domain reference and an
assigned PASID.


[1]: https://lore.kernel.org/linux-iommu/ZIBxPd1%2FJCAle6yP@xxxxxxxxxx/

Tina Zhang (6):
  iommu: Add two pasid helper functions
  iommu: Call helper functions to get/set assigned pasid value
  iommu: Introduce struct iommu_mm_data
  mm: Add iommu_mm field to mm_struct
  iommu: Support mm PASID 1:1 with sva domain
  mm: Deprecate pasid field

 arch/x86/kernel/traps.c                       |  2 +-
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   | 12 ++--
 drivers/iommu/intel/svm.c                     |  8 +--
 drivers/iommu/iommu-sva.c                     | 68 ++++++++++++-------
 drivers/iommu/iommu.c                         |  3 +
 include/linux/iommu.h                         | 25 ++++++-
 include/linux/mm_types.h                      |  2 +
 mm/init-mm.c                                  |  2 +-
 8 files changed, 84 insertions(+), 38 deletions(-)

-- 
2.34.1