iommu: Move def_domain type check for untrusted device into core

So that the vendor iommu drivers are no more required to provide the
def_domain_type callback to always isolate the untrusted devices.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/linux-iommu/243ce89c33fe4b9da4c56ba35acebf81@huawei.com/
Link: https://lore.kernel.org/r/20201124130604.2912899-2-baolu.lu@linux.intel.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/intel/iommu.c

@@ -2916,13 +2916,6 @@ static int device_def_domain_type(struct device *dev)
 	if (dev_is_pci(dev)) {
 		struct pci_dev *pdev = to_pci_dev(dev);
 
-		/*
-		 * Prevent any device marked as untrusted from getting
-		 * placed into the statically identity mapping domain.
-		 */
-		if (pdev->untrusted)
-			return IOMMU_DOMAIN_DMA;
-
 		if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
 			return IOMMU_DOMAIN_IDENTITY;
 

drivers/iommu/iommu.c

@@ -1460,12 +1460,14 @@ EXPORT_SYMBOL_GPL(fsl_mc_device_group);
 static int iommu_get_def_domain_type(struct device *dev)
 {
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
-	unsigned int type = 0;
+
+	if (dev_is_pci(dev) && to_pci_dev(dev)->untrusted)
+		return IOMMU_DOMAIN_DMA;
 
 	if (ops->def_domain_type)
-		type = ops->def_domain_type(dev);
+		return ops->def_domain_type(dev);
 
-	return (type == 0) ? iommu_def_domain_type : type;
+	return 0;
 }
 
 static int iommu_group_alloc_default_domain(struct bus_type *bus,
@@ -1507,7 +1509,7 @@ static int iommu_alloc_default_domain(struct iommu_group *group,
 	if (group->default_domain)
 		return 0;
 
-	type = iommu_get_def_domain_type(dev);
+	type = iommu_get_def_domain_type(dev) ? : iommu_def_domain_type;
 
 	return iommu_group_alloc_default_domain(dev->bus, group, type);
 }
@@ -1645,12 +1647,8 @@ struct __group_domain_type {
 
 static int probe_get_default_domain_type(struct device *dev, void *data)
 {
-	const struct iommu_ops *ops = dev->bus->iommu_ops;
 	struct __group_domain_type *gtype = data;
-	unsigned int type = 0;
-
-	if (ops->def_domain_type)
-		type = ops->def_domain_type(dev);
+	unsigned int type = iommu_get_def_domain_type(dev);
 
 	if (type) {
 		if (gtype->type && gtype->type != type) {