2 files changed, 32 insertions, 0 deletions

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 5f164ff3026e..f5a662a50acb 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -491,6 +491,7 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
         int map_size;
         u32 ver;
         static int iommu_allocated = 0;
+        int agaw;
 
         iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
         if (!iommu)
@@ -506,6 +507,15 @@ int alloc_iommu(struct dmar_drhd_unit *drhd)
         iommu->cap = dmar_readq(iommu->reg + DMAR_CAP_REG);
         iommu->ecap = dmar_readq(iommu->reg + DMAR_ECAP_REG);
 
+        agaw = iommu_calculate_agaw(iommu);
+        if (agaw < 0) {
+                printk(KERN_ERR
+                        "Cannot get a valid agaw for iommu (seq_id = %d)\n",
+                        iommu->seq_id);
+                goto error;
+        }
+        iommu->agaw = agaw;
+
         /* the registers might be more than one page */
         map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
                 cap_max_fault_reg_offset(iommu->cap));
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 9dca689215eb..3ecfa2304c2c 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -362,6 +362,28 @@ void free_iova_mem(struct iova *iova)
         kmem_cache_free(iommu_iova_cache, iova);
 }
 
+
+static inline int width_to_agaw(int width);
+
+/* calculate agaw for each iommu.
+ * "SAGAW" may be different across iommus, use a default agaw, and
+ * get a supported less agaw for iommus that don't support the default agaw.
+ */
+int iommu_calculate_agaw(struct intel_iommu *iommu)
+{
+        unsigned long sagaw;
+        int agaw = -1;
+
+        sagaw = cap_sagaw(iommu->cap);
+        for (agaw = width_to_agaw(DEFAULT_DOMAIN_ADDRESS_WIDTH);
+             agaw >= 0; agaw--) {
+                if (test_bit(agaw, &sagaw))
+                        break;
+        }
+
+        return agaw;
+}
+
 /* in native case, each domain is related to only one iommu */
 static struct intel_iommu *domain_get_iommu(struct dmar_domain *domain)
 {