[Qemu-devel] [PATCH 7/7] vhost-user: add a new message to disable/enable a specific virt queue.

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

From: Changchun Ouyang <changchun.ouyang@intel.com>

Add a new message, VHOST_USER_SET_VRING_FLAG, to enable and disable
a specific virt queue, which is similar to attach/detach queue for
tap device.

virtio driver on guest doesn't have to use max virt queue pair, it
could enable any number of virt queue ranging from 1 to max virt
queue pair.

Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
 docs/specs/vhost-user.txt         | 10 ++++++++++
 hw/net/vhost_net.c                | 18 ++++++++++++++++++
 hw/net/virtio-net.c               |  2 ++
 hw/virtio/vhost-user.c            | 32 ++++++++++++++++++++++++++++----
 include/hw/virtio/vhost-backend.h |  2 ++
 include/net/vhost_net.h           |  1 +
 6 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 99d79be..c2c38f3 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -325,3 +325,13 @@ Message types
       Query how many queues the backend supports. This request should be
       sent only when VHOST_USER_PROTOCOL_F_MQ is set in quried protocol
       features by VHOST_USER_GET_PROTOCOL_FEATURES.
+
+ * VHOST_USER_SET_VRING_FLAG
+
+      Id: 18
+      Equivalent ioctl: N/A
+      Master payload: vring state description
+
+      Set the flag(1 for enable and 0 for disable) to signal slave to enable
+      or disable corresponding virt queue. This request should be sent only
+      when the protocol feature bit VHOST_USER_PROTOCOL_F_VRING_FLAG is set.
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 141b557..7d9cc8d 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -418,6 +418,19 @@ VHostNetState *get_vhost_net(NetClientState *nc)
 
     return vhost_net;
 }
+
+int vhost_set_vring_flag(NetClientState *nc, int enable)
+{
+    if (nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
+        VHostNetState *net = get_vhost_net(nc);
+        const VhostOps *vhost_ops = net->dev.vhost_ops;
+        if (vhost_ops->vhost_backend_mq_set_vring_flag)
+            return vhost_ops->vhost_backend_mq_set_vring_flag(&net->dev, enable);
+    }
+
+    return 0;
+}
+
 #else
 struct vhost_net *vhost_net_init(VhostNetOptions *options)
 {
@@ -463,4 +476,9 @@ VHostNetState *get_vhost_net(NetClientState *nc)
 {
     return 0;
 }
+
+int vhost_set_vring_flag(NetClientState *nc, int enable)
+{
+    return 0;
+}
 #endif
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 8d28e45..53f93b1 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -407,6 +407,7 @@ static int peer_attach(VirtIONet *n, int index)
     }
 
     if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
+        vhost_set_vring_flag(nc->peer, 1);
         return 0;
     }
 
@@ -422,6 +423,7 @@ static int peer_detach(VirtIONet *n, int index)
     }
 
     if (nc->peer->info->type !=  NET_CLIENT_OPTIONS_KIND_TAP) {
+        vhost_set_vring_flag(nc->peer, 0);
         return 0;
     }
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 11e46b5..ca6f7fa 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -25,9 +25,10 @@
 
 #define VHOST_MEMORY_MAX_NREGIONS    8
 #define VHOST_USER_F_PROTOCOL_FEATURES 30
-#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x1ULL
+#define VHOST_USER_PROTOCOL_FEATURE_MASK 0xfULL
 
-#define VHOST_USER_PROTOCOL_F_MQ    0
+#define VHOST_USER_PROTOCOL_F_MQ            0
+#define VHOST_USER_PROTOCOL_F_VRING_FLAG    1
 
 typedef enum VhostUserRequest {
     VHOST_USER_NONE = 0,
@@ -48,6 +49,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_GET_PROTOCOL_FEATURES = 15,
     VHOST_USER_SET_PROTOCOL_FEATURES = 16,
     VHOST_USER_GET_QUEUE_NUM = 17,
+    VHOST_USER_SET_VRING_FLAG = 18,
     VHOST_USER_MAX
 } VhostUserRequest;
 
@@ -296,6 +298,11 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
         msg.addr.index += dev->vq_index;
         msg.size = sizeof(m.state);
         break;
+    case VHOST_USER_SET_VRING_FLAG:
+        msg.state.index = dev->vq_index;
+        msg.state.num = *(int*)arg;
+        msg.size = sizeof(msg.state);
+        break;
 
     case VHOST_USER_GET_VRING_BASE:
         memcpy(&msg.state, arg, sizeof(struct vhost_vring_state));
@@ -408,6 +415,22 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
     return 0;
 }
 
+static int vhost_user_set_vring_flag(struct vhost_dev *dev, int enable)
+{
+    int err;
+
+    assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
+
+    if (!(dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_VRING_FLAG)))
+        return -1;
+
+    err = vhost_user_call(dev, VHOST_USER_SET_VRING_FLAG, &enable);
+    if (err < 0)
+        return err;
+
+    return 0;
+}
+
 static int vhost_user_cleanup(struct vhost_dev *dev)
 {
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
@@ -421,5 +444,6 @@ const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_call = vhost_user_call,
         .vhost_backend_init = vhost_user_init,
-        .vhost_backend_cleanup = vhost_user_cleanup
-        };
+        .vhost_backend_cleanup = vhost_user_cleanup,
+        .vhost_backend_mq_set_vring_flag = vhost_user_set_vring_flag,
+};
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index e472f29..6fc76b7 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -24,12 +24,14 @@ typedef int (*vhost_call)(struct vhost_dev *dev, unsigned long int request,
              void *arg);
 typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
 typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
+typedef int (*vhost_backend_mq_set_vring_flag)(struct vhost_dev *dev, int enable);
 
 typedef struct VhostOps {
     VhostBackendType backend_type;
     vhost_call vhost_call;
     vhost_backend_init vhost_backend_init;
     vhost_backend_cleanup vhost_backend_cleanup;
+    vhost_backend_mq_set_vring_flag vhost_backend_mq_set_vring_flag;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index 8db723e..3ec33ff 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -28,4 +28,5 @@ bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
 void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
                               int idx, bool mask);
 VHostNetState *get_vhost_net(NetClientState *nc);
+int vhost_set_vring_flag(NetClientState * nc, int enable);
 #endif
-- 
1.9.0