1 files changed, 9 insertions, 7 deletions

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 28b4bea7c109..b76c58dbe30c 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -150,7 +150,7 @@ int amd_iommus_present;
 bool amd_iommu_np_cache __read_mostly;
 bool amd_iommu_iotlb_sup __read_mostly = true;
 
-u32 amd_iommu_max_pasids __read_mostly = ~0;
+u32 amd_iommu_max_pasid __read_mostly = ~0;
 
 bool amd_iommu_v2_present __read_mostly;
 bool amd_iommu_pc_present __read_mostly;
@@ -1231,14 +1231,16 @@ static int iommu_init_pci(struct amd_iommu *iommu)
 
         if (iommu_feature(iommu, FEATURE_GT)) {
                 int glxval;
-                u32 pasids;
-                u64 shift;
+                u32 max_pasid;
+                u64 pasmax;
 
-                shift   = iommu->features & FEATURE_PASID_MASK;
-                shift >>= FEATURE_PASID_SHIFT;
-                pasids  = (1 << shift);
+                pasmax = iommu->features & FEATURE_PASID_MASK;
+                pasmax >>= FEATURE_PASID_SHIFT;
+                max_pasid  = (1 << (pasmax + 1)) - 1;
 
-                amd_iommu_max_pasids = min(amd_iommu_max_pasids, pasids);
+                amd_iommu_max_pasid = min(amd_iommu_max_pasid, max_pasid);
+
+                BUG_ON(amd_iommu_max_pasid & ~PASID_MASK);
 
                 glxval   = iommu->features & FEATURE_GLXVAL_MASK;
                 glxval >>= FEATURE_GLXVAL_SHIFT;