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 chose to have a new dedicated channel.
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 ++
MAINTAINERS | 6 +
docs/interop/vhost-user-gpu.txt | 236 ++++++++++++++++++++++++++
docs/interop/vhost-user.txt | 8 +
6 files changed, 263 insertions(+)
create mode 100644 docs/interop/vhost-user-gpu.txt
diff --git a/contrib/libvhost-user/libvhost-user.h
b/contrib/libvhost-user/libvhost-user.h
index 40d7cbfc2a..9899bfda9e 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -92,6 +92,7 @@ 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 1fca321d8a..daf9180c33 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -163,5 +163,6 @@ 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 cbd2900f39..37864bc06a 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -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;
@@ -397,6 +398,16 @@ 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)
{
diff --git a/MAINTAINERS b/MAINTAINERS
index 773624f095..e5dee15967 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1339,6 +1339,12 @@ F: hw/display/virtio-gpu*
F: hw/display/virtio-vga.c
F: include/hw/virtio/virtio-gpu.h
+vhost-user-gpu
+M: Marc-André Lureau <marcandre.lur...@redhat.com>
+M: Gerd Hoffmann <kra...@redhat.com>
+S: Maintained
+F: docs/interop/vhost-user-gpu.txt
+
Cirrus VGA
M: Gerd Hoffmann <kra...@redhat.com>
S: Odd Fixes
diff --git a/docs/interop/vhost-user-gpu.txt b/docs/interop/vhost-user-gpu.txt
new file mode 100644
index 0000000000..309d07fd6d
--- /dev/null
+++ b/docs/interop/vhost-user-gpu.txt
@@ -0,0 +1,236 @@
+=======================
+Vhost-user-gpu Protocol
+=======================
+
+This work is licensed under the terms of the GNU GPL, version 2 or later.
+See the COPYING file in the top-level directory.
+
+Overview
+========
+
+The vhost-user-gpu protocol is aiming at sharing the rendering result
+of a virtio-gpu, done from a vhost-user slave process to a vhost-user
+master process (such as QEMU). It bears a resemblance to a display
+server protocol, if you consider QEMU as the display server and the
+slave as the client, but in a very limited way. Typically, it will
+work by setting a scanout/display configuration, before sending flush
+events for the display updates. It will also update the cursor shape
+and position.
+
+The protocol is sent over a UNIX domain stream socket, since it uses
+socket ancillary data to share opened file descriptors (DMABUF fds or
+shared memory).
+
+Requests are sent by the slave, and the optional replies by the master.
+
+Wire format
+===========
+
+Unless specified differently, numbers are in the machine native byte
+order.
+
+A vhost-user-gpu request consists of 2 header fields and a payload:
+
+::
+
+ ------------------------------------
+ | u32:request | u32:size | payload |
+ ------------------------------------
+
+- request: 32-bit type of the request
+- size: 32-bit size of the payload
+
+A reply consists only of a payload, whose content depends on on the request.
+
+
+Payload types
+-------------
+
+VhostUserGpuCursorPos
+^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+ ----------------------------------
+ | u32:scanout-id | u32:x | u32:y |
+ ----------------------------------
+
+- scanout-id: the scanout where the cursor is located
+- x/y: the cursor postion
+
+VhostUserGpuCursorUpdate
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+
-----------------------------------------------------------------------------
+ | VhostUserGpuCursorPos:pos | u32:hot_x | u32:hot_y | [u32; 64 * 64] cursor
|
+
-----------------------------------------------------------------------------
+
+- pos: the cursor location
+- hot_x/hot_y: the cursor hot location
+- cursor: RGBA cursor data
+
+VhostUserGpuScanout
+^^^^^^^^^^^^^^^^^^^
+
+::
+
+ ----------------------------------
+ | u32:scanout-id | u32:w | u32:h |
+ ----------------------------------
+
+- scanout-id: the scanout configuration to set
+- w/h: the scanout width/height size
+
+
+VhostUserGpuUpdate
+^^^^^^^^^^^^^^^^^^
+
+::
+
+ ---------------------------------------------------------
+ | u32:scanout-id | u32:x | u32:y | u32:w | u32:h | data |
+ ---------------------------------------------------------
+
+- scanout-id: the scanout content to update
+- x/y/w/h: region of the update
+- data: RGBA data (size is computed based on the region size, and request type)
+
+VhostUserGpuDMABUFScanout
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+ ---------------------------------------------------
+ | u32:scanout-id | u32:x | u32:y | u32:w | u32:h | ...
+ ----------------------------------------------------------
+ u32:fdw | u32:fwh | u32:stride | u32:flags | i32:fourcc |
+ ----------------------------------------------------------
+
+- scanout-id: the scanout configuration to set
+- x/y: the location of the scanout within the DMABUF
+- w/h: the scanout width/height size
+- fdw/fdh/stride/flags/fourcc: the DMABUF width/height/stride/flags/drm-fourcc
+
+
+In QEMU the vhost-user-gpu message is implemented with the following struct:
+
+::
+
+ typedef struct VhostUserGpuMsg {
+ uint32_t request; /* VhostUserGpuRequest */
+ uint32_t size; /* the following payload size */
+ union {
+ VhostUserGpuCursorPos cursor_pos;
+ VhostUserGpuCursorUpdate cursor_update;
+ VhostUserGpuScanout scanout;
+ VhostUserGpuUpdate update;
+ VhostUserGpuDMABUFScanout dmabuf_scanout;
+ uint64_t u64;
+ } payload;
+ } QEMU_PACKED VhostUserGpuMsg;
+
+Protocol features
+=================
+
+None yet.
+
+As the protocol may need to evolve, new messages and communication
+changes are negotiated thanks to preliminary
+VHOST_USER_GPU_GET_PROTOCOL_FEATURES and
+VHOST_USER_GPU_SET_PROTOCOL_FEATURES requests.
+
+Message types
+=============
+
+- VHOST_USER_GPU_GET_PROTOCOL_FEATURES
+
+ Id:1
+ Request payload: N/A
+ Reply payload: uint64_t
+
+ Get the supported protocol features bitmask.
+
+- VHOST_USER_GPU_SET_PROTOCOL_FEATURES
+
+ Id:2
+ Request payload: uint64_t
+ Reply payload: N/A
+
+ Enable protocol features using a bitmask.
+
+- VHOST_USER_GPU_GET_DISPLAY_INFO
+
+ Id:3
+ Request payload: N/A
+ Reply payload: struct virtio_gpu_resp_display_info (numbers in LE,
+ according to the virtio protocol)
+
+ Get the preferred display configuration.
+
+- VHOST_USER_GPU_CURSOR_POS
+
+ Id: 4
+ Request payload: struct VhostUserGpuCursorPos
+ Reply payload: N/A
+
+ Set/show the cursor position.
+
+- VHOST_USER_GPU_CURSOR_POS_HIDE
+
+ Id:5
+ Request payload: struct VhostUserGpuCursorPos
+ Reply payload: N/A
+
+ Set/hide the cursor.
+
+- VHOST_USER_GPU_CURSOR_UPDATE
+
+ Id:6
+ Request payload: struct VhostUserGpuCursorUpdate
+ Reply payload: N/A
+
+ Update the cursor shape and location.
+
+- VHOST_USER_GPU_SCANOUT
+
+ Id:7
+ Request payload: struct VhostUserGpuScanout
+ Reply payload: N/A
+
+ Set the scanout resolution. To disable a scanout, the dimensions
+ width/height are set to 0.
+
+- VHOST_USER_GPU_UPDATE
+
+ Id:8
+ Request payload: struct VhostUserGpuUpdate
+ Reply payload: N/A
+
+ Update the scanout content. The data payload contains the graphical bits.
+ The display should be flushed and presented.
+
+- VHOST_USER_GPU_DMABUF_SCANOUT
+
+ Id:9
+ Request payload: struct VhostUserGpuDMABUFScanout
+ Reply payload: N/A
+
+ Set the scanout resolution/configuration, and share a DMABUF file
+ descriptor for the scanout content, which is passed as ancillary
+ data. To disable a scanout, the dimensions width/height are set
+ to 0, there is no file descriptor passed.
+
+- VHOST_USER_GPU_DMABUF_UPDATE
+
+ Id:10
+ Request payload: struct VhostUserGpuUpdate
+ Reply payload: u32
+
+ The display should be flushed and presented according to updated
+ region from VhostUserGpuUpdate.
+
+ Note: there is no data payload, since the scanout is shared thanks
+ to DMABUF, that must have been set previously with
+ VHOST_USER_GPU_DMABUF_SCANOUT.
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
index 2efa44d124..40ba89675c 100644
--- a/docs/interop/vhost-user.txt
+++ b/docs/interop/vhost-user.txt
@@ -768,6 +768,14 @@ Master message types
Ask vhost user input backend the list of virtio_input_config.
+ * VHOST_USER_GPU_SET_SOCKET
+ Id: TBD
+ Master payload: N/A
+
+ Sets the GPU protocol socket file descriptor, which is passed as
+ ancillary data. The GPU protocol is used to inform the master of
+ rendering state and updates. See vhost-user-gpu.txt for details.
+
Slave message types
-------------------
--
2.18.0.rc1
