[Qemu-devel] [RFC v2 10/12] vhost-user: add vhost_user_gpu_set_socket()

[Marc-André Lureau]

Add a new vhost-user message to give a unix socket for gpu updates to
a vhost-user backend.

Back when I started that work, I added a new GPU channel because the
vhost-user protocol wasn't bidirectional. Since then, there is a
vhost-user-slave channel for the slave to send requests to the master.
We could extend it with GPU messages. However, the GPU protocol is
quite orthogonal to vhost-user and may not need the same kind of
stability guarantees, thus I recommend to have a new dedicated
channel.

FIXME: document the GPU protocol.

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
 contrib/libvhost-user/libvhost-user.h |  1 +
 include/hw/virtio/vhost-backend.h     |  1 +
 hw/virtio/vhost-user.c                | 11 +++++++++++
 3 files changed, 13 insertions(+)

diff --git a/contrib/libvhost-user/libvhost-user.h 
b/contrib/libvhost-user/libvhost-user.h
index d6badc8653..57a3a36100 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -90,6 +90,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_POSTCOPY_LISTEN  = 29,
     VHOST_USER_POSTCOPY_END     = 30,
     VHOST_USER_INPUT_GET_CONFIG,
+    VHOST_USER_GPU_SET_SOCKET,
     VHOST_USER_MAX
 } VhostUserRequest;
 
diff --git a/include/hw/virtio/vhost-backend.h 
b/include/hw/virtio/vhost-backend.h
index 6cc2edacc5..a60d278f05 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -159,5 +159,6 @@ int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev,
 
 int vhost_user_input_get_config(struct vhost_dev *dev,
                                 struct virtio_input_config **config);
+int vhost_user_gpu_set_socket(struct vhost_dev *dev, int fd);
 
 #endif /* VHOST_BACKEND_H */
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 19ed87d07c..5cb76f436b 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -85,6 +85,7 @@ typedef enum VhostUserRequest {
     VHOST_USER_POSTCOPY_LISTEN  = 29,
     VHOST_USER_POSTCOPY_END     = 30,
     VHOST_USER_INPUT_GET_CONFIG,
+    VHOST_USER_GPU_SET_SOCKET,
     VHOST_USER_MAX
 } VhostUserRequest;
 
@@ -383,6 +384,16 @@ err:
     return -1;
 }
 
+int vhost_user_gpu_set_socket(struct vhost_dev *dev, int fd)
+{
+    VhostUserMsg msg = {
+        .hdr.request = VHOST_USER_GPU_SET_SOCKET,
+        .hdr.flags = VHOST_USER_VERSION,
+    };
+
+    return vhost_user_write(dev, &msg, &fd, 1);
+}
+
 static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
                                    struct vhost_log *log)
 {
-- 
2.17.1.906.g10fd178552