mainline inclusion
from mainline-v5.18
commit 701fac40
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO
CVE: NA

Intel-SIG: commit 701fac40 iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit.
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

Deviation from upstream:
Replace ioasid_put() with ioasid_free() in
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c for the change in out of
tree commit: 7ca84842 iommu/arm-smmu-v3: Support auxiliary domains.

--------------------------------

PASIDs are process-wide. It was attempted to use refcounted PASIDs to
free them when the last thread drops the refcount. This turned out to
be complex and error prone. Given the fact that the PASID space is 20
bits, which allows up to 1M processes to have a PASID associated
concurrently, PASID resource exhaustion is not a realistic concern.

Therefore, it was decided to simplify the approach and stick with lazy
on demand PASID allocation, but drop the eager free approach and make an
allocated PASID's lifetime bound to the lifetime of the process.

Get rid of the refcounting mechanisms and replace/rename the interfaces
to reflect this new approach.

  [ bp: Massage commit message. ]
Suggested-by: NDave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NTony Luck <tony.luck@intel.com>
Reviewed-by: NLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: NJacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NJoerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-6-fenghua.yu@intel.comSigned-off-by: NXiaochen Shen <xiaochen.shen@intel.com>