iommu/vt-d: Add device_def_domain_type() helper

This helper returns the default domain type that the device
requires.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu.c

@@ -2930,29 +2930,37 @@ static bool device_is_rmrr_locked(struct device *dev)
 	return true;
 }
 
-static int iommu_should_identity_map(struct device *dev, int startup)
+/*
+ * Return the required default domain type for a specific device.
+ *
+ * @dev: the device in query
+ * @startup: true if this is during early boot
+ *
+ * Returns:
+ *  - IOMMU_DOMAIN_DMA: device requires a dynamic mapping domain
+ *  - IOMMU_DOMAIN_IDENTITY: device requires an identical mapping domain
+ *  - 0: both identity and dynamic domains work for this device
+ */
+static int device_def_domain_type(struct device *dev, int startup)
 {
 	if (dev_is_pci(dev)) {
 		struct pci_dev *pdev = to_pci_dev(dev);
 
 		if (device_is_rmrr_locked(dev))
-			return 0;
+			return IOMMU_DOMAIN_DMA;
 
 		/*
 		 * Prevent any device marked as untrusted from getting
 		 * placed into the statically identity mapping domain.
 		 */
 		if (pdev->untrusted)
-			return 0;
+			return IOMMU_DOMAIN_DMA;
 
 		if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
-			return 1;
+			return IOMMU_DOMAIN_IDENTITY;
 
 		if ((iommu_identity_mapping & IDENTMAP_GFX) && IS_GFX_DEVICE(pdev))
-			return 1;
-
-		if (!(iommu_identity_mapping & IDENTMAP_ALL))
-			return 0;
+			return IOMMU_DOMAIN_IDENTITY;
 
 		/*
 		 * We want to start off with all devices in the 1:1 domain, and
@@ -2973,14 +2981,14 @@ static int iommu_should_identity_map(struct device *dev, int startup)
 		 */
 		if (!pci_is_pcie(pdev)) {
 			if (!pci_is_root_bus(pdev->bus))
-				return 0;
+				return IOMMU_DOMAIN_DMA;
 			if (pdev->class >> 8 == PCI_CLASS_BRIDGE_PCI)
-				return 0;
+				return IOMMU_DOMAIN_DMA;
 		} else if (pci_pcie_type(pdev) == PCI_EXP_TYPE_PCI_BRIDGE)
-			return 0;
+			return IOMMU_DOMAIN_DMA;
 	} else {
 		if (device_has_rmrr(dev))
-			return 0;
+			return IOMMU_DOMAIN_DMA;
 	}
 
 	/*
@@ -3002,7 +3010,13 @@ static int iommu_should_identity_map(struct device *dev, int startup)
 		return dma_mask >= dma_get_required_mask(dev);
 	}
 
-	return 1;
+	return (iommu_identity_mapping & IDENTMAP_ALL) ?
+			IOMMU_DOMAIN_IDENTITY : 0;
+}
+
+static inline int iommu_should_identity_map(struct device *dev, int startup)
+{
+	return device_def_domain_type(dev, startup) == IOMMU_DOMAIN_IDENTITY;
 }
 
 static int __init dev_prepare_static_identity_mapping(struct device *dev, int hw)