[PATCH 1/2] iommu/vt-d: Fix PASID leak in intel_svm_unbind_mm()

[Lu Baolu <baolu.lu@linux.intel.com>]

From: Fenghua Yu <fenghua.yu@intel.com>

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: 4048377414162 ("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>
---
 drivers/iommu/intel/svm.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 2014fe8695ac..a3f84f2ff1ba 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -514,9 +514,6 @@ static void load_pasid(struct mm_struct *mm, u32 pasid)
 {
 	mutex_lock(&mm->context.lock);
 
-	/* Synchronize with READ_ONCE in update_pasid(). */
-	smp_store_release(&mm->pasid, pasid);
-
 	/* Update PASID MSR on all CPUs running the mm's tasks. */
 	on_each_cpu_mask(mm_cpumask(mm), _load_pasid, NULL, true);
 
-- 
2.25.1

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