vfio/pci: Fix wrong return value when get iommu attribute DOMAIN_ATTR_NESTING

virt inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I46K8O
CVE: NA

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

Some vendor IOMMU drivers doesn't implement their own domain_get_attr
callback or the processing of DOMAIN_ATTR_NESTING. Then
iommu_domain_get_attr may return an error. But it shouldn't affect the
result of vfio_pci_enable. We print a log to indicate the error and
return 0.
Signed-off-by: NKunkun Jiang <jiangkunkun@huawei.com>
Reviewed-by: NXinle Guo <guoxinle1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/vfio/pci/vfio_pci.c

@@ -502,8 +502,12 @@ static int vfio_pci_dma_fault_init(struct vfio_pci_device *vdev)
 		return 0;
 
 	ret = iommu_domain_get_attr(domain, DOMAIN_ATTR_NESTING, &nested);
-	if (ret || !nested)
-		return ret;
+	if (ret || !nested) {
+		if (ret)
+			pr_warn("%s: Get DOMAIN_ATTR_NESTING failed: %d.\n",
+				__func__, ret);
+		return 0;
+	}
 
 	mutex_init(&vdev->fault_queue_lock);
 
@@ -592,8 +596,12 @@ static int vfio_pci_dma_fault_response_init(struct vfio_pci_device *vdev)
 		return 0;
 
 	ret = iommu_domain_get_attr(domain, DOMAIN_ATTR_NESTING, &nested);
-	if (ret || !nested)
-		return ret;
+	if (ret || !nested) {
+		if (ret)
+			pr_warn("%s: Get DOMAIN_ATTR_NESTING failed: %d.\n",
+				__func__, ret);
+		return 0;
+	}
 
 	mutex_init(&vdev->fault_response_queue_lock);