[RFC 08/10] vhost: Add x-vhost-enable-shadow-vq qmp

["Eugenio Pérez" <eperezma@redhat.com>]

Command to enable shadow virtqueue looks like:

{ "execute": "x-vhost-enable-shadow-vq", "arguments": { "name": "dev0", "enable": true } }

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 qapi/net.json     | 23 +++++++++++++++++++++++
 hw/virtio/vhost.c |  6 ++++++
 2 files changed, 29 insertions(+)

diff --git a/qapi/net.json b/qapi/net.json
index c31748c87f..6170d69798 100644
--- a/qapi/net.json
+++ b/qapi/net.json
@@ -77,6 +77,29 @@
 ##
 { 'command': 'netdev_del', 'data': {'id': 'str'} }
 
+##
+# @x-vhost-enable-shadow-vq:
+#
+# Use vhost shadow virtqueue.
+#
+# @name: the device name of the virtual network adapter
+#
+# @enable: true to use he alternate shadow VQ notification path
+#
+# Returns: Error if failure, or 'no error' for success
+#
+# Since: 5.3
+#
+# Example:
+#
+# -> { "execute": "x-vhost_enable_shadow_vq", "arguments": {"enable": true} }
+# <- { "return": { "enabled" : true } }
+#
+##
+{ 'command': 'x-vhost-enable-shadow-vq',
+  'data': {'name': 'str', 'enable': 'bool'},
+  'if': 'defined(CONFIG_VHOST_KERNEL)' }
+
 ##
 # @NetLegacyNicOptions:
 #
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 040f68ff2e..42836e45f3 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -15,6 +15,7 @@
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
+#include "qapi/qapi-commands-net.h"
 #include "hw/virtio/vhost.h"
 #include "qemu/atomic.h"
 #include "qemu/range.h"
@@ -1841,3 +1842,8 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
 
     return -1;
 }
+
+void qmp_x_vhost_enable_shadow_vq(const char *name, bool enable, Error **errp)
+{
+    error_setg(errp, "Shadow virtqueue still not implemented.");
+}
-- 
2.27.0