iommu/amd: Init unity mappings only for dma_ops domains

The default domain for a device might also be
identity-mapped. In this case the kernel would crash when
unity mappings are defined for the device. Fix that by
making sure the domain is a dma_ops domain.

Fixes: 0bb6e243 ('iommu/amd: Support IOMMU_DOMAIN_DMA type allocation')
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -467,9 +467,11 @@ static void init_iommu_group(struct device *dev)
 	if (!domain)
 		goto out;
 
-	dma_domain = to_pdomain(domain)->priv;
+	if (to_pdomain(domain)->flags == PD_DMA_OPS_MASK) {
+		dma_domain = to_pdomain(domain)->priv;
+		init_unity_mappings_for_device(dev, dma_domain);
+	}
 
-	init_unity_mappings_for_device(dev, dma_domain);
 out:
 	iommu_group_put(group);
 }