Revert "iommu/smmuv3: Nested mode single MSI doorbell per domain enforcement"

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

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

This reverts commit b4ddfa73.
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

@@ -2883,37 +2883,6 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master)
 	arm_smmu_install_ste_for_dev(master);
 }
 
-static bool arm_smmu_share_msi_domain(struct iommu_domain *domain,
-				      struct device *dev)
-{
-	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
-	struct irq_domain *irqd = dev_get_msi_domain(dev);
-	struct arm_smmu_master *master;
-	unsigned long flags;
-	bool share = false;
-
-	if (!irqd)
-		return true;
-
-	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
-	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
-		struct irq_domain *d = dev_get_msi_domain(master->dev);
-
-		if (!d)
-			continue;
-		if (irqd != d) {
-			dev_info(dev, "Nested mode forbids to attach devices "
-				 "using different physical MSI doorbells "
-				 "to the same iommu_domain");
-			goto unlock;
-		}
-	}
-	share = true;
-unlock:
-	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
-	return share;
-}
-
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
@@ -2975,16 +2944,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 		ret = -EINVAL;
 		goto out_unlock;
 	}
-	/*
-	 * 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.
-	 */
-	if (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED &&
-		!arm_smmu_share_msi_domain(domain, dev)) {
-		ret = -EINVAL;
-		goto out_unlock;
-	}
 
 	master->domain = smmu_domain;