[PATCH 3/8] vhost-user: add op to enable or disable a single vring

[Kangjie Xu]

There is only vhost_set_dev_enable op in VhostOps. Thus, we introduce
the interface vhost_set_vring_enable to set the enable status for a
single vring.

Resetting a single vq will rely on this interface.

Signed-off-by: Kangjie Xu <kangjie...@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
---
 hw/virtio/vhost-user.c            | 25 ++++++++++++++++++-------
 include/hw/virtio/vhost-backend.h |  3 +++
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 794519359b..3f140d5085 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1198,6 +1198,22 @@ static int vhost_user_set_vring_base(struct vhost_dev 
*dev,
     return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);
 }
 
+static int vhost_user_set_vring_enable(struct vhost_dev *dev,
+                                       int index,
+                                       int enable)
+{
+    if (index < dev->vq_index || index >= dev->vq_index + dev->nvqs) {
+        return -EINVAL;
+    }
+
+    struct vhost_vring_state state = {
+        .index = index,
+        .num   = enable,
+    };
+
+    return vhost_set_vring(dev, VHOST_USER_SET_VRING_ENABLE, &state);
+}
+
 static int vhost_user_set_dev_enable(struct vhost_dev *dev, int enable)
 {
     int i;
@@ -1207,13 +1223,7 @@ static int vhost_user_set_dev_enable(struct vhost_dev 
*dev, int enable)
     }
 
     for (i = 0; i < dev->nvqs; ++i) {
-        int ret;
-        struct vhost_vring_state state = {
-            .index = dev->vq_index + i,
-            .num   = enable,
-        };
-
-        ret = vhost_set_vring(dev, VHOST_USER_SET_VRING_ENABLE, &state);
+        int ret = vhost_user_set_vring_enable(dev, dev->vq_index + i, enable);
         if (ret < 0) {
             /*
              * Restoring the previous state is likely infeasible, as well as
@@ -2627,6 +2637,7 @@ const VhostOps user_ops = {
         .vhost_set_owner = vhost_user_set_owner,
         .vhost_reset_device = vhost_user_reset_device,
         .vhost_get_vq_index = vhost_user_get_vq_index,
+        .vhost_set_vring_enable = vhost_user_set_vring_enable,
         .vhost_set_dev_enable = vhost_user_set_dev_enable,
         .vhost_requires_shm_log = vhost_user_requires_shm_log,
         .vhost_migration_done = vhost_user_migration_done,
diff --git a/include/hw/virtio/vhost-backend.h 
b/include/hw/virtio/vhost-backend.h
index b49432045f..dad7191bac 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -81,6 +81,8 @@ typedef int (*vhost_set_backend_cap_op)(struct vhost_dev 
*dev);
 typedef int (*vhost_set_owner_op)(struct vhost_dev *dev);
 typedef int (*vhost_reset_device_op)(struct vhost_dev *dev);
 typedef int (*vhost_get_vq_index_op)(struct vhost_dev *dev, int idx);
+typedef int (*vhost_set_vring_enable_op)(struct vhost_dev *dev,
+                                         int index, int enable);
 typedef int (*vhost_set_dev_enable_op)(struct vhost_dev *dev,
                                        int enable);
 typedef bool (*vhost_requires_shm_log_op)(struct vhost_dev *dev);
@@ -155,6 +157,7 @@ typedef struct VhostOps {
     vhost_set_owner_op vhost_set_owner;
     vhost_reset_device_op vhost_reset_device;
     vhost_get_vq_index_op vhost_get_vq_index;
+    vhost_set_vring_enable_op vhost_set_vring_enable;
     vhost_set_dev_enable_op vhost_set_dev_enable;
     vhost_requires_shm_log_op vhost_requires_shm_log;
     vhost_migration_done_op vhost_migration_done;
-- 
2.32.0