iommu/amd: Use default domain if available for DMA-API

Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 22d38e3..ae7d636 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2495,12 +2495,19 @@
 static struct protection_domain *get_domain(struct device *dev)
 {
 	struct protection_domain *domain;
+	struct iommu_domain *io_domain;
 	struct dma_ops_domain *dma_dom;
 	u16 devid = get_device_id(dev);
 
 	if (!check_device(dev))
 		return ERR_PTR(-EINVAL);
 
+	io_domain = iommu_get_domain_for_dev(dev);
+	if (io_domain) {
+		domain = to_pdomain(io_domain);
+		return domain;
+	}
+
 	domain = domain_for_device(dev);
 	if (domain != NULL && !dma_ops_domain(domain))
 		return ERR_PTR(-EBUSY);