[PATCH v2 3/3] vdpa: support exposing the count of vqs to userspace

["Longpeng(Mike)" <longpeng2@huawei.com>]

From: Longpeng <longpeng2@huawei.com>

- GET_VQS_COUNT: the count of virtqueues that exposed

Signed-off-by: Longpeng <longpeng2@huawei.com>
---
 drivers/vhost/vdpa.c       | 13 +++++++++++++
 include/uapi/linux/vhost.h |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 0c82eb5..69b3f05 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -370,6 +370,16 @@ static long vhost_vdpa_get_config_size(struct vhost_vdpa *v, u32 __user *argp)
 	return 0;
 }
 
+static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+
+	if (copy_to_user(argp, &vdpa->nvqs, sizeof(vdpa->nvqs)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 				   void __user *argp)
 {
@@ -510,6 +520,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
 	case VHOST_VDPA_GET_CONFIG_SIZE:
 		r = vhost_vdpa_get_config_size(v, argp);
 		break;
+	case VHOST_VDPA_GET_VQS_COUNT:
+		r = vhost_vdpa_get_vqs_count(v, argp);
+		break;
 	default:
 		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
 		if (r == -ENOIOCTLCMD)
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index bc74e95..5d99e7c 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -154,4 +154,7 @@
 /* Get the config size */
 #define VHOST_VDPA_GET_CONFIG_SIZE	_IOR(VHOST_VIRTIO, 0x79, __u32)
 
+/* Get the count of all virtqueues */
+#define VHOST_VDPA_GET_VQS_COUNT	_IOR(VHOST_VIRTIO, 0x80, __u32)
+
 #endif
-- 
1.8.3.1