[PATCH v8 0/6] dcc: Create a stream for non-gl/remote clients that want to use dmabuf (v8)

[Michael Scherle]

On 10.06.24 20:34, Vivek Kasireddy wrote:
> For clients that cannot accept a dmabuf fd directly (such as those
> running on a remote system), this patch series provides a way for
> the Spice server to stream the gl/dmabuf data/buffer instead. This
> is mostly done by enabling the creation of Gst memory using a dmabuf
> fd as the source. This ability is useful given that dmabuf is the
> standard mechanism for sharing buffers between various drivers and
> userspace in many Graphics and Media usecases. Currently, this is
> tested with Qemu and remote-viewer using the x264enc/avdec_h264
> and msdkh264enc/dec plugins to stream the Guest/VM desktop but it
> can be easily extended to other plugins and applications.
> 
> Here is roughly how things work:
> - The application (e.g, Qemu) chooses its preferred codec (a Gstreamer
>    one) and calls gl_scanout (to update the fd) followed by gl_draw.
> - In response, the Spice server checks to see if the client is capable
>    of accepting a dmabuf fd directly or not. If yes, the fd is forwarded
>    directly to the client; otherwise, a new stream is created.
> - The Spice server then sends the dmabuf fd to the Gstreamer encoder
>    which uses it as an input for creating an encoded buffer which is then
>    sent to the client.
> - Once the encoding process is done, an async completion cookie is sent
>    to the application.
> 
> Here is a link to the previous version that used a drawable to share
> the dmabuf fd with the Gstreamer encoder:
> https://lists.freedesktop.org/archives/spice-devel/2023-January/052948.html
> 
> This version is tested together with following (required) patches in qemu:
> https://gitlab.freedesktop.org/Vivek/qemu/-/commits/spice_gl_on_v4
> 
> Changelog:
> 
> v8:
> - Added a new gstreamer-encoder patch to this series to convert drm format
>    shared by the VMM to the appropriate Gstreamer format.
> 
> v7:
> - Revert back to the previous design where we do not share fd with the stream
>    and scanout is the sole owner of the fd. This is because sharing fd ownership
>    opens up a lot of corner cases.
> 
> v6: (Frediano)
> - Properly share ownership of the dmabuf fd between stream and scanout
> - Ensure that a newly created stream is associated with all connected clients
> 
> v5:
> - Addressed review comments from Frediano mainly regarding adding autoconf
>    support for gstreamer-allocators dependency and not needing to access
>    scanout as part of gl draw operation
> 
> v4:
> - Test with Virgl enabled
> - Associate dmabuf's y0_top with stream's top_down variable
> 
> v3:
> - Updated the second patch to have a new primary surface created
>    whenever a new stream gets created. This will avoid having to
>    trigger primary surface creation from Qemu. And, this change
>    also fixes the following error seen with v2:
>    ../server/display-channel.cpp:2074:display_channel_create_surface:
>    condition `!display->priv->surfaces[surface_id]' failed
> - Rebase all patches on master
> 
> v2:
> - Update all patches to address review comments from Frediano
> - Tested this series with msdkh264enc/dec plugins that will be added
>    in another patch series
> 
> Cc: Frediano Ziglio <freddy77 at gmail.com>
> Cc: Gerd Hoffmann <kraxel at redhat.com>
> Cc: Marc-André Lureau <marcandre.lureau at redhat.com>
> Cc: Dongwon Kim <dongwon.kim at intel.com>
> 
> Vivek Kasireddy (6):
>    dcc: Check to see if the client supports multiple codecs (v2)
>    dcc: Create a stream associated with gl_draw for non-gl clients (v6)
>    dcc-send: Encode and send gl_draw stream data to the remote client
>      (v4)
>    gstreamer-encoder: Add an encoder function that takes dmabuf fd as
>      input (v3)
>    gstreamer-encoder: Map the drm format to appropriate Gstreamer format
>    video-stream: Don't stop a stream associated with gl_draw (v2)
> 
>   configure.ac                     |   2 +-
>   meson.build                      |   2 +-
>   server/dcc-send.cpp              | 159 ++++++++++++++++----
>   server/dcc.cpp                   |  31 ++--
>   server/dcc.h                     |   6 +
>   server/display-channel-private.h |   1 +
>   server/display-channel.cpp       |   1 +
>   server/gstreamer-encoder.c       | 246 ++++++++++++++++++++++++++-----
>   server/video-encoder.h           |  14 ++
>   server/video-stream.cpp          | 205 ++++++++++++++++++++++----
>   server/video-stream.h            |   4 +
>   11 files changed, 563 insertions(+), 108 deletions(-)
> 

I tested this patchset with several configurations:

- With a passthrough intel gvt-g virtual gpu it works.

- With virtio-vga it works.

- With some extra patches to qemu and an virtualization driver it even 
works with an virtual GPU from an SR-IOV-partitioned Intel Flex
140 GPU. Note this extra patches are related to the gpu and not this 
patchset.

This patch is a significant improvement for handling graphically 
demanding tasks or rapidly changing image content and is crucial for 
SPICE to be a component of a competitive virtual desktop infrastructure.

Tested-by: Michael Scherle <michael.scherle at rz.uni-freiburg.de>

Greetings,
Michael