[RFC PATCH 14/24] vhost-vdpa: introduce uAPI to get the number of virtqueue groups

[Jason Wang <jasowang@redhat.com>]

Follows the vDPA support for multiple address spaces, this patch
introduce uAPI for the userspace to know the number of virtqueue
groups supported by the vDPA device.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/vdpa.c       | 4 ++++
 include/uapi/linux/vhost.h | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 1ba7e95619b5..4b8882f55bc9 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -528,6 +528,10 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 	case VHOST_VDPA_GET_VRING_NUM:
 		r = vhost_vdpa_get_vring_num(v, argp);
 		break;
+	case VHOST_VDPA_GET_GROUP_NUM:
+		r = copy_to_user(argp, &v->vdpa->ngroups,
+				 sizeof(v->vdpa->ngroups));
+		break;
 	case VHOST_SET_LOG_BASE:
 	case VHOST_SET_LOG_FD:
 		r = -ENOIOCTLCMD;
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index c26452782882..19f1acdfe3ea 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -141,4 +141,8 @@
 
 /* Set event fd for config interrupt*/
 #define VHOST_VDPA_SET_CONFIG_CALL	_IOW(VHOST_VIRTIO, 0x77, int)
+
+/* Get the number of virtqueue groups. */
+#define VHOST_VDPA_GET_GROUP_NUM	_IOR(VHOST_VIRTIO, 0x78, unsigned int)
+
 #endif
-- 
2.20.1