iommu/amd: Get the maximum number of PASIDs supported

Read the number of PASIDs supported by each IOMMU in the
system and take the smallest number as the maximum value
supported by the IOMMU driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 17e0f77c7da..fb4afd6d357 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -141,6 +141,8 @@ 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;
+
 /*
  * The ACPI table parsing functions set this variable on an error
  */
@@ -699,6 +701,17 @@ static void __init init_iommu_from_pci(struct amd_iommu *iommu)
 
         iommu->features = ((u64)high << 32) | low;
 
+        if (iommu_feature(iommu, FEATURE_GT)) {
+                u32 pasids;
+                u64 shift;
+
+                shift   = iommu->features & FEATURE_PASID_MASK;
+                shift >>= FEATURE_PASID_SHIFT;
+                pasids  = (1 << shift);
+
+                amd_iommu_max_pasids = min(amd_iommu_max_pasids, pasids);
+        }
+
         if (!is_rd890_iommu(iommu->dev))
                 return;