!168 SPR: Add vfio_group_iommu_domain interface to support DLB

Merge Pull Request from: @allen-shi 
 
This PR is to add vfio_group_iommu_domain interface to support DLB. Without this patch, OOT DLB kernel driver failed to build with error due to lack of vfio_group_iommu_domain interface support. 

 **Intel-Kernel Issue** 
[#I5BEBU](https://gitee.com/openeuler/intel-kernel/issues/I5BEBU)

 **Test** 
1. Built and run the kernel successfully
2. DLB kernel driver built successfully and insmod dlb2.ko successfully

 **Known Issue** 
N/A

 **Default config change** 
N/A 
 
Link:https://gitee.com/openeuler/kernel/pulls/168 
Reviewed-by: Kevin Zhu <zhukeqian1@huawei.com> 
Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com> 
Reviewed-by: Chen Wei <chenwei@xfusion.com> 
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> 

drivers/vfio/vfio.c

@@ -2331,6 +2331,24 @@ int vfio_unregister_notifier(struct device *dev, enum vfio_notify_type type,
 }
 EXPORT_SYMBOL(vfio_unregister_notifier);
 
+struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group)
+{
+	struct vfio_container *container;
+	struct vfio_iommu_driver *driver;
+
+	if (!group)
+		return ERR_PTR(-EINVAL);
+
+	container = group->container;
+	driver = container->iommu_driver;
+	if (likely(driver && driver->ops->group_iommu_domain))
+		return driver->ops->group_iommu_domain(container->iommu_data,
+						       group->iommu_group);
+
+	return ERR_PTR(-ENOTTY);
+}
+EXPORT_SYMBOL_GPL(vfio_group_iommu_domain);
+
 /**
  * Module/class support
  */

drivers/vfio/vfio_iommu_type1.c

@@ -3769,6 +3769,29 @@ static int vfio_iommu_type1_dma_rw(void *iommu_data, dma_addr_t user_iova,
 	return ret;
 }
 
+static struct iommu_domain *
+vfio_iommu_type1_group_iommu_domain(void *iommu_data,
+				    struct iommu_group *iommu_group)
+{
+	struct iommu_domain *domain = ERR_PTR(-ENODEV);
+	struct vfio_iommu *iommu = iommu_data;
+	struct vfio_domain *d;
+
+	if (!iommu || !iommu_group)
+		return ERR_PTR(-EINVAL);
+
+	mutex_lock(&iommu->lock);
+	list_for_each_entry(d, &iommu->domain_list, next) {
+		if (find_iommu_group(d, iommu_group)) {
+			domain = d->domain;
+			break;
+		}
+	}
+	mutex_unlock(&iommu->lock);
+
+	return domain;
+}
+
 static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
 	.name			= "vfio-iommu-type1",
 	.owner			= THIS_MODULE,
@@ -3782,6 +3805,7 @@ static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
 	.register_notifier	= vfio_iommu_type1_register_notifier,
 	.unregister_notifier	= vfio_iommu_type1_unregister_notifier,
 	.dma_rw			= vfio_iommu_type1_dma_rw,
+	.group_iommu_domain	= vfio_iommu_type1_group_iommu_domain,
 };
 
 static int __init vfio_iommu_type1_init(void)

include/linux/vfio.h

@@ -90,6 +90,8 @@ struct vfio_iommu_driver_ops {
 					       struct notifier_block *nb);
 	int		(*dma_rw)(void *iommu_data, dma_addr_t user_iova,
 				  void *data, size_t count, bool write);
+	KABI_EXTEND(struct iommu_domain *(*group_iommu_domain)(void *iommu_data,
+						               struct iommu_group *group))
 };
 
 extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
@@ -126,6 +128,8 @@ extern int vfio_group_unpin_pages(struct vfio_group *group,
 extern int vfio_dma_rw(struct vfio_group *group, dma_addr_t user_iova,
 		       void *data, size_t len, bool write);
 
+extern struct iommu_domain *vfio_group_iommu_domain(struct vfio_group *group);
+
 /* each type has independent events */
 enum vfio_notify_type {
 	VFIO_IOMMU_NOTIFY = 0,