[Qemu-devel] [PATCH v4 24/29] vhost-user: Add VHOST_USER_POSTCOPY_END message

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

This message is sent just before the end of postcopy to get the
client to stop using userfault since we wont respond to any more
requests.  It should close userfaultfd so that any other pages
get mapped to the backing file automatically by the kernel, since
at this point we know we've received everything.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 contrib/libvhost-user/libvhost-user.c | 23 +++++++++++++++++++++++
 contrib/libvhost-user/libvhost-user.h |  1 +
 docs/interop/vhost-user.txt           | 11 +++++++++++
 hw/virtio/vhost-user.c                |  1 +
 4 files changed, 36 insertions(+)

diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index 1b224af706..1f988ab787 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -99,6 +99,7 @@ vu_request_to_string(unsigned int req)
         REQ(VHOST_USER_SET_CONFIG),
         REQ(VHOST_USER_POSTCOPY_ADVISE),
         REQ(VHOST_USER_POSTCOPY_LISTEN),
+        REQ(VHOST_USER_POSTCOPY_END),
         REQ(VHOST_USER_MAX),
     };
 #undef REQ
@@ -1095,6 +1096,26 @@ vu_set_postcopy_listen(VuDev *dev, VhostUserMsg *vmsg)
     vmsg->payload.u64 = 0; /* Success */
     return true;
 }
+
+static bool
+vu_set_postcopy_end(VuDev *dev, VhostUserMsg *vmsg)
+{
+    DPRINT("%s: Entry\n", __func__);
+    dev->postcopy_listening = false;
+    if (dev->postcopy_ufd > 0) {
+        close(dev->postcopy_ufd);
+        dev->postcopy_ufd = -1;
+        DPRINT("%s: Done close\n", __func__);
+    }
+
+    vmsg->fd_num = 0;
+    vmsg->payload.u64 = 0;
+    vmsg->size = sizeof(vmsg->payload.u64);
+    vmsg->flags = VHOST_USER_VERSION |  VHOST_USER_REPLY_MASK;
+    DPRINT("%s: exit\n", __func__);
+    return true;
+}
+
 static bool
 vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
 {
@@ -1170,6 +1191,8 @@ vu_process_message(VuDev *dev, VhostUserMsg *vmsg)
         return vu_set_postcopy_advise(dev, vmsg);
     case VHOST_USER_POSTCOPY_LISTEN:
         return vu_set_postcopy_listen(dev, vmsg);
+    case VHOST_USER_POSTCOPY_END:
+        return vu_set_postcopy_end(dev, vmsg);
     default:
         vmsg_close_fds(vmsg);
         vu_panic(dev, "Unhandled request: %d", vmsg->request);
diff --git a/contrib/libvhost-user/libvhost-user.h b/contrib/libvhost-user/libvhost-user.h
index ed505cf0c1..79f7a53ee8 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -87,6 +87,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
     VHOST_USER_POSTCOPY_ADVISE  = 28,
     VHOST_USER_POSTCOPY_LISTEN  = 29,
+    VHOST_USER_POSTCOPY_END     = 30,
     VHOST_USER_MAX
 } VhostUserRequest;
 
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
index cc049196c9..5a31e4234e 100644
--- a/docs/interop/vhost-user.txt
+++ b/docs/interop/vhost-user.txt
@@ -729,6 +729,17 @@ Master message types
       This is always sent sometime after a VHOST_USER_POSTCOPY_ADVISE, and
       thus only when VHOST_USER_PROTOCOL_F_PAGEFAULT is supported.
 
+ * VHOST_USER_POSTCOPY_END
+      Id: 30
+      Slave payload: u64
+
+      Master advises that postcopy migration has now completed.  The
+      slave must disable the userfaultfd. The response is an acknowledgement
+      only.
+      When VHOST_USER_PROTOCOL_F_PAGEFAULT is supported, this message
+      is sent at the end of the migration, after VHOST_USER_POSTCOPY_LISTEN
+      was previously sent
+
 Slave message types
 -------------------
 
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index b304bc475e..45de6d8a53 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -82,6 +82,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
     VHOST_USER_POSTCOPY_ADVISE  = 28,
     VHOST_USER_POSTCOPY_LISTEN  = 29,
+    VHOST_USER_POSTCOPY_END     = 30,
     VHOST_USER_MAX
 } VhostUserRequest;
 
-- 
2.14.3