Revert "iommu/smmuv3: Enforce incompatibility between nested mode and HW MSI regions"

virt inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I61SPO
CVE: NA

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

This reverts commit 85412c04.
Signed-off-by: NKunkun Jiang <jiangkunkun@huawei.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2914,23 +2914,6 @@ static bool arm_smmu_share_msi_domain(struct iommu_domain *domain,
 	return share;
 }
 
-static bool arm_smmu_has_hw_msi_resv_region(struct device *dev)
-{
-	struct iommu_resv_region *region;
-	bool has_msi_resv_region = false;
-	LIST_HEAD(resv_regions);
-
-	iommu_get_resv_regions(dev, &resv_regions);
-	list_for_each_entry(region, &resv_regions, list) {
-		if (region->type == IOMMU_RESV_MSI) {
-			has_msi_resv_region = true;
-			break;
-		}
-	}
-	iommu_put_resv_regions(dev, &resv_regions);
-	return has_msi_resv_region;
-}
-
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
@@ -2995,12 +2978,10 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	/*
 	 * In nested mode we must check all devices belonging to the
 	 * domain share the same physical MSI doorbell. Otherwise nested
-	 * stage MSI binding is not supported. Also nested mode is not
-	 * compatible with MSI HW reserved regions.
+	 * stage MSI binding is not supported.
 	 */
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED &&
-		(!arm_smmu_share_msi_domain(domain, dev) ||
-		 arm_smmu_has_hw_msi_resv_region(dev))) {
+		!arm_smmu_share_msi_domain(domain, dev)) {
 		ret = -EINVAL;
 		goto out_unlock;
 	}

drivers/iommu/iommu.c

@@ -3127,7 +3127,6 @@ void iommu_get_resv_regions(struct device *dev, struct list_head *list)
 	if (ops && ops->get_resv_regions)
 		ops->get_resv_regions(dev, list);
 }
-EXPORT_SYMBOL_GPL(iommu_get_resv_regions);
 
 void iommu_put_resv_regions(struct device *dev, struct list_head *list)
 {
@@ -3136,7 +3135,6 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
 	if (ops && ops->put_resv_regions)
 		ops->put_resv_regions(dev, list);
 }
-EXPORT_SYMBOL_GPL(iommu_put_resv_regions);
 
 /**
  * generic_iommu_put_resv_regions - Reserved region driver helper