[PATCH 1/2] iommu/vt-d: Fix PASID leak

[Fenghua Yu <fenghua.yu@intel.com>]

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.

Please note that load_pasid() and its called functions will be re-written
in upcoming re-enabling ENQCMD series. This patch tries to fix the issues
cleanly before the re-enabling ENQCMD series.

Fixes: 62ef907a045e ("iommu/vt-d: Fix PASID reference leak")

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>
---
 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 4b9b3f35ba0e..ceeca633a5f9 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -516,9 +516,6 @@ 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);
 
-- 
2.33.0

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