diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index cfb597751f5bad..38856d542afc35 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -96,8 +96,8 @@ static const char * const iommu_group_resv_type_string[] = {
 static int iommu_bus_notifier(struct notifier_block *nb,
 			      unsigned long action, void *data);
 static void iommu_release_device(struct device *dev);
-static struct iommu_domain *__iommu_domain_alloc(const struct bus_type *bus,
-						 unsigned type);
+static struct iommu_domain *
+__iommu_group_domain_alloc(struct iommu_group *group, unsigned int type);
 static int __iommu_attach_device(struct iommu_domain *domain,
 				 struct device *dev);
 static int __iommu_attach_group(struct iommu_domain *domain,
@@ -1719,12 +1719,11 @@ struct iommu_group *fsl_mc_device_group(struct device *dev)
 EXPORT_SYMBOL_GPL(fsl_mc_device_group);
 
 static struct iommu_domain *
-__iommu_group_alloc_default_domain(const struct bus_type *bus,
-				   struct iommu_group *group, int req_type)
+__iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
 {
 	if (group->default_domain && group->default_domain->type == req_type)
 		return group->default_domain;
-	return __iommu_domain_alloc(bus, req_type);
+	return __iommu_group_domain_alloc(group, req_type);
 }
 
 /*
@@ -1751,9 +1750,7 @@ static const struct iommu_ops *group_iommu_ops(struct iommu_group *group)
 static struct iommu_domain *
 iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
 {
-	const struct bus_type *bus =
-		list_first_entry(&group->devices, struct group_device, list)
-			->dev->bus;
+	const struct iommu_ops *ops = group_iommu_ops(group);
 	struct iommu_domain *dom;
 
 	lockdep_assert_held(&group->mutex);
@@ -1763,24 +1760,24 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
 	 * domain. This should always be either an IDENTITY/BLOCKED/PLATFORM
 	 * domain. Do not use in new drivers.
 	 */
-	if (bus->iommu_ops->default_domain) {
+	if (ops->default_domain) {
 		if (req_type)
 			return ERR_PTR(-EINVAL);
-		return bus->iommu_ops->default_domain;
+		return ops->default_domain;
 	}
 
 	if (req_type)
-		return __iommu_group_alloc_default_domain(bus, group, req_type);
+		return __iommu_group_alloc_default_domain(group, req_type);
 
 	/* The driver gave no guidance on what type to use, try the default */
-	dom = __iommu_group_alloc_default_domain(bus, group, iommu_def_domain_type);
+	dom = __iommu_group_alloc_default_domain(group, iommu_def_domain_type);
 	if (dom)
 		return dom;
 
 	/* Otherwise IDENTITY and DMA_FQ defaults will try DMA */
 	if (iommu_def_domain_type == IOMMU_DOMAIN_DMA)
 		return NULL;
-	dom = __iommu_group_alloc_default_domain(bus, group, IOMMU_DOMAIN_DMA);
+	dom = __iommu_group_alloc_default_domain(group, IOMMU_DOMAIN_DMA);
 	if (!dom)
 		return NULL;
 
@@ -2043,19 +2040,16 @@ void iommu_set_fault_handler(struct iommu_domain *domain,
 }
 EXPORT_SYMBOL_GPL(iommu_set_fault_handler);
 
-static struct iommu_domain *__iommu_domain_alloc(const struct bus_type *bus,
-						 unsigned type)
+static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,
+						 unsigned int type)
 {
 	struct iommu_domain *domain;
 	unsigned int alloc_type = type & IOMMU_DOMAIN_ALLOC_FLAGS;
 
-	if (bus == NULL || bus->iommu_ops == NULL)
-		return NULL;
+	if (alloc_type == IOMMU_DOMAIN_IDENTITY && ops->identity_domain)
+		return ops->identity_domain;
 
-	if (alloc_type == IOMMU_DOMAIN_IDENTITY && bus->iommu_ops->identity_domain)
-		return bus->iommu_ops->identity_domain;
-
-	domain = bus->iommu_ops->domain_alloc(alloc_type);
+	domain = ops->domain_alloc(alloc_type);
 	if (!domain)
 		return NULL;
 
@@ -2065,10 +2059,10 @@ static struct iommu_domain *__iommu_domain_alloc(const struct bus_type *bus,
 	 * may override this later
 	 */
 	if (!domain->pgsize_bitmap)
-		domain->pgsize_bitmap = bus->iommu_ops->pgsize_bitmap;
+		domain->pgsize_bitmap = ops->pgsize_bitmap;
 
 	if (!domain->ops)
-		domain->ops = bus->iommu_ops->default_domain_ops;
+		domain->ops = ops->default_domain_ops;
 
 	if (iommu_is_dma_domain(domain) && iommu_get_dma_cookie(domain)) {
 		iommu_domain_free(domain);
@@ -2077,9 +2071,17 @@ static struct iommu_domain *__iommu_domain_alloc(const struct bus_type *bus,
 	return domain;
 }
 
+static struct iommu_domain *
+__iommu_group_domain_alloc(struct iommu_group *group, unsigned int type)
+{
+	return __iommu_domain_alloc(group_iommu_ops(group), type);
+}
+
 struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
 {
-	return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);
+	if (bus == NULL || bus->iommu_ops == NULL)
+		return NULL;
+	return __iommu_domain_alloc(bus->iommu_ops, IOMMU_DOMAIN_UNMANAGED);
 }
 EXPORT_SYMBOL_GPL(iommu_domain_alloc);
 
@@ -3239,21 +3241,18 @@ void iommu_device_unuse_default_domain(struct device *dev)
 
 static int __iommu_group_alloc_blocking_domain(struct iommu_group *group)
 {
-	struct group_device *dev =
-		list_first_entry(&group->devices, struct group_device, list);
-
 	if (group->blocking_domain)
 		return 0;
 
 	group->blocking_domain =
-		__iommu_domain_alloc(dev->dev->bus, IOMMU_DOMAIN_BLOCKED);
+		__iommu_group_domain_alloc(group, IOMMU_DOMAIN_BLOCKED);
 	if (!group->blocking_domain) {
 		/*
 		 * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED
 		 * create an empty domain instead.
 		 */
-		group->blocking_domain = __iommu_domain_alloc(
-			dev->dev->bus, IOMMU_DOMAIN_UNMANAGED);
+		group->blocking_domain = __iommu_group_domain_alloc(
+			group, IOMMU_DOMAIN_UNMANAGED);
 		if (!group->blocking_domain)
 			return -EINVAL;
 	}
