iommu: dev_bypass: cleanup dev bypass code

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I41AUQ
CVE: NA

-------------------------------------

The device bypass code can be cleanuped to be more readable.
Signed-off-by: NHanjun Guo <guohanjun@huawei.com>
Cc: Guo Hui <guohui@uniontech.com>
Cc: Cheng Jian <cj.chengjian@huawei.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Xiuqi Xie <xiexiuqi@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

drivers/iommu/arm-smmu-v3.c

@@ -3089,10 +3089,10 @@ static struct iommu_ops arm_smmu_ops = {
 	.of_xlate		= arm_smmu_of_xlate,
 	.get_resv_regions	= arm_smmu_get_resv_regions,
 	.put_resv_regions	= arm_smmu_put_resv_regions,
+	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 #ifdef CONFIG_SMMU_BYPASS_DEV
 	.device_domain_type	= arm_smmu_device_domain_type,
 #endif
-	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 };
 
 /* Probing and initialisation functions */

drivers/iommu/iommu.c

@@ -1270,9 +1270,8 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
 	const struct iommu_ops *ops = dev->bus->iommu_ops;
 	struct iommu_group *group;
 	int ret;
-#ifdef CONFIG_SMMU_BYPASS_DEV
 	unsigned int type = iommu_def_domain_type;
-#endif
+
 	group = iommu_group_get(dev);
 	if (group)
 		return group;
@@ -1296,17 +1295,13 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
 
 #ifdef CONFIG_SMMU_BYPASS_DEV
 		/* direct allocate required default domain type for some specific devices. */
-		if (ops->device_domain_type != NULL) {
+		if (ops->device_domain_type) {
 			if (ops->device_domain_type(dev, &type))
 				type = iommu_def_domain_type;
-               }
-
+		}
+#endif
 		dom = __iommu_domain_alloc(dev->bus, type);
 		if (!dom && type != IOMMU_DOMAIN_DMA) {
-#else
-		dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
-		if (!dom && iommu_def_domain_type != IOMMU_DOMAIN_DMA) {
-#endif
 			dev_warn(dev,
 				 "failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA",
 				 iommu_def_domain_type);