[Qemu-devel] [PATCH RFC 12/14] vhost-user: add shutdown support

[marcandre . lureau]

From: Marc-André Lureau <marcandre.lur...@redhat.com>

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
 docs/specs/vhost-user.txt | 15 +++++++++++++++
 hw/virtio/vhost-user.c    | 30 +++++++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 5e00bd3..854493e 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -331,6 +331,21 @@ Message types
       This message is only sent if VHOST_USER_PROTOCOL_F_SLAVE_REQ
       feature is available.
 
+Slave message types
+-------------------
+
+ * VHOST_USER_SLAVE_SHUTDOWN:
+      Id: 1
+      Master payload: N/A
+      Slave payload: u64
+
+      Request the master to shutdown the slave. A 0 reply is for
+      success, in which case the slave may close all connections
+      immediately and quit. A non-zero reply cancels the request.
+
+      Before a reply comes, the master may make other requests in
+      order to flush or sync state.
+
 Migration
 ---------
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 49f566c..949382c 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -55,6 +55,7 @@ typedef enum VhostUserRequest {
 
 typedef enum VhostUserSlaveRequest {
     VHOST_USER_SLAVE_NONE = 0,
+    VHOST_USER_SLAVE_SHUTDOWN = 1,
     VHOST_USER_SLAVE_MAX
 }  VhostUserSlaveRequest;
 
@@ -140,7 +141,7 @@ static VhostUserRequest 
vhost_user_request_translate(unsigned long int request)
     case VHOST_SET_VRING_ERR:
         return VHOST_USER_SET_VRING_ERR;
     default:
-        return VHOST_USER_MAX;
+        return request;
     }
 }
 
@@ -375,6 +376,21 @@ static int slave_can_receive(void *opaque)
     return VHOST_USER_HDR_SIZE;
 }
 
+static int vhost_user_slave_write(struct vhost_dev *dev, VhostUserMsg *msg,
+                                  int *fds, int fd_num)
+{
+    struct vhost_user *u = dev->opaque;
+    CharDriverState *chr = u->slave_chr;
+    int size = VHOST_USER_HDR_SIZE + msg->size;
+
+    if (fd_num) {
+        qemu_chr_fe_set_msgfds(chr, fds, fd_num);
+    }
+
+    return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
+        0 : -1;
+}
+
 static void slave_receive(void *opaque, const uint8_t *buf, int size)
 {
     struct vhost_dev *dev = opaque;
@@ -386,6 +402,18 @@ static void slave_receive(void *opaque, const uint8_t 
*buf, int size)
     }
 
     switch (msg->request) {
+    case VHOST_USER_SLAVE_SHUTDOWN: {
+        uint64_t success = 1;
+
+        if (dev->stop) {
+            dev->stop(dev);
+            success = 0;
+        }
+
+        msg->u64 = success;
+        vhost_user_slave_write(dev, msg, NULL, 0);
+        return;
+    }
     default:
         error_report("Received unexpected msg type.");
     }
-- 
2.4.3