iommu/vt-d: Unnecessary to handle default identity domain

The iommu default domain framework has been designed to take
care of setting identity default domain type. It's unnecessary
to handle this again in the VT-d driver. Hence, remove it.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu.c

@@ -387,7 +387,6 @@ static int intel_iommu_superpage = 1;
 static int iommu_identity_mapping;
 static int intel_no_bounce;
 
-#define IDENTMAP_ALL		1
 #define IDENTMAP_GFX		2
 #define IDENTMAP_AZALIA		4
 
@@ -3079,8 +3078,7 @@ static int device_def_domain_type(struct device *dev)
 			return IOMMU_DOMAIN_DMA;
 	}
 
-	return (iommu_identity_mapping & IDENTMAP_ALL) ?
-			IOMMU_DOMAIN_IDENTITY : 0;
+	return 0;
 }
 
 static void intel_iommu_init_qi(struct intel_iommu *iommu)
@@ -3424,9 +3422,6 @@ static int __init init_dmars(void)
 		iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
 	}
 
-	if (iommu_default_passthrough())
-		iommu_identity_mapping |= IDENTMAP_ALL;
-
 #ifdef CONFIG_INTEL_IOMMU_BROKEN_GFX_WA
 	dmar_map_gfx = 0;
 #endif
@@ -5038,7 +5033,7 @@ static int __init platform_optin_force_iommu(void)
 	 * map for all devices except those marked as being untrusted.
 	 */
 	if (dmar_disabled)
-		iommu_identity_mapping |= IDENTMAP_ALL;
+		iommu_set_default_passthrough(false);
 
 	dmar_disabled = 0;
 	no_iommu = 0;