diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index bfd4f7c..b9df141 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -848,7 +848,8 @@
 	if (!group->default_domain) {
 		group->default_domain = __iommu_domain_alloc(dev->bus,
 							     IOMMU_DOMAIN_DMA);
-		group->domain = group->default_domain;
+		if (!group->domain)
+			group->domain = group->default_domain;
 	}
 
 	ret = iommu_group_add_device(group, dev);