iommu/vt-d: Fix PASID leak in intel_svm_unbind_mm()

mainline inclusion
from mainline-v5.15
commit a21518cb
category: bugfix
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I596WO


CVE: NA

Intel-SIG: commit a21518cb iommu/vt-d: Fix PASID leak in intel_svm_unbind_mm().
Incremental backporting patches for DSA/IAA on Intel Xeon platform.

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

The mm->pasid will be used in intel_svm_free_pasid() after load_pasid()
during unbinding mm. Clearing it in load_pasid() will cause PASID cannot
be freed in intel_svm_free_pasid().

Additionally mm->pasid was updated already before load_pasid() during pasid
allocation. No need to update it again in load_pasid() during binding mm.
Don't update mm->pasid to avoid the issues in both binding mm and unbinding
mm.

Fixes: 40483774 ("iommu/vt-d: Use iommu_sva_alloc(free)_pasid() helpers")
Reported-and-tested-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20210826215918.4073446-1-fenghua.yu@intel.com


Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210828070622.2437559-2-baolu.lu@linux.intel.com


Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>