[RFC][PATCH v2 04/13] vfio: add set_vmid and get_vmid for vfio_iommu_type1

[Nicolin Chen]

A VMID is generated in an IOMMU driver, being called from this
->attach_group() callback. So call ->get_vmid() right after it
creates a new VMID, and call ->set_vmid() before it, to let it
reuse the same VMID.

Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
---
 drivers/vfio/vfio.c  | 12 ++++++++++++
 include/linux/vfio.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index c17b25c127a2..8b7442deca93 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1080,9 +1080,21 @@ static int __vfio_container_attach_groups(struct vfio_container *container,
 	int ret = -ENODEV;
 
 	list_for_each_entry(group, &container->group_list, container_next) {
+		if (driver->ops->set_vmid && container->vmid != VFIO_IOMMU_VMID_INVALID) {
+			ret = driver->ops->set_vmid(data, container->vmid);
+			if (ret)
+				goto unwind;
+		}
+
 		ret = driver->ops->attach_group(data, group->iommu_group);
 		if (ret)
 			goto unwind;
+
+		if (driver->ops->get_vmid && container->vmid == VFIO_IOMMU_VMID_INVALID) {
+			ret = driver->ops->get_vmid(data, &container->vmid);
+			if (ret)
+				goto unwind;
+		}
 	}
 
 	return ret;
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index b53a9557884a..b43e7cbef4ab 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -126,6 +126,8 @@ struct vfio_iommu_driver_ops {
 						   struct iommu_group *group);
 	void		(*notify)(void *iommu_data,
 				  enum vfio_iommu_notify_type event);
+	int		(*set_vmid)(void *iommu_data, u32 vmid);
+	int		(*get_vmid)(void *iommu_data, u32 *vmid);
 };
 
 extern int vfio_register_iommu_driver(const struct vfio_iommu_driver_ops *ops);
-- 
2.17.1