[PATCH 0/3] virtio-gpu: Enable virglrenderer backend for rutabaga

[Weifeng Liu <weifeng.liu.z@gmail.com>]

Greetings,

I'd like to introduce you my attempt to enable virglrenderer backend for
rutabaga empowered virtio-gpu device.  I am aware that there have been
effort in supporting venus in virtio-gpu-virgl.c [1], but there is no
reason to prevent us from leveraging the virglrenderer component in
rutabaga_gfx, especially it being not very hard to add this
functionality.

Generally, the gap is the polling capability, i.e., virglrenderer
requires the main thread (namely the GPU command handling thread) to
poll virglrenderer at proper moments, which is not yet supported in
virtio-gpu-rutabaga device. This patch set try to add this so that
virglrenderer backend (including virgl and venus) can work as expected.

Slight change to rutabaga_gfx_ffi is also a requirement, which is
included in [2].

Further effort is required to tune the performance, since copying is
present before the rendered images get displayed. But I still think this
patch set could be a good starting point for the pending work.

For those interested in setting up environment and playing around with
this patch set, here is guideline in brief:

1. Clone the master/main branch of virglrenderer, compile and install it.

	git clone https://gitlab.freedesktop.org/virgl/virglrenderer
	cd virglrenderer
	meson setup builddir \
	  --prefix=$INSTALL_DIR/virglrenderer \
	  -Dvenus=true
	ninja -C builddir install

2. Clone the patched CrosVM, build and install rutabaga_gfx_ffi.

	git clone -b rutabaga_ffi_virgl https://github.com/phreer/crosvm.git
	cd crosvm/rutabaga_gfx/ffi
	export PKG_CONFIG_PATH=$INSTALL_DIR/virglrenderer/lib64/pkgconfig/
	meson setup builddir/ \
	  --prefix $HOME/install/rutabaga_gfx/rutabaga_gfx_ffi/ \
	  -Dvirglrenderer=true
	ninja -C builddir install

3. Applied this patch set to QEMU, build and install it:

	cd qemu	
	# Apply this patch set atop main branch ...
	mkdir builddir; cd builddir
	../configure --prefix=$INSTALL_DIR/qemu \
	  --target-list=x86_64-softmmu \
	  --disable-virglrenderer \
	  --enable-rutabaga_gfx
	ninja -C builddir install

4. If you are lucky and everything goes fine, you are prepared to launch
   VM with virglrenderer backed virtio-gpu-rutabaga device:

	export LD_LIBRARY_PATH=$INSTALL_DIR/virglrenderer/lib64/:$LD_LIBRARY_PATH
	export LD_LIBRARY_PATH=$INSTALL_DIR/rutabaga_gfx_ffi/lib64/:$LD_LIBRARY_PATH
	$INSTALL_DIR/qemu/bin/qemu-system-x86_64
	$QEMU -d guest_errors -enable-kvm -M q35 -smp 4 -m $MEM \
	  -object memory-backend-memfd,id=mem1,size=$MEM \
	  -machine memory-backend=mem1 \
	  -device virtio-vga-rutabaga,venus=on,virgl2=on,wsi=surfaceless,hostmem=$MEM \

Note:

- You might need this patch set [3] to avoid KVM bad address error when
  you are running on a GPU using TTM for memory management.

[1] https://lore.kernel.org/all/dba6eb97-e1d1-4694-bfb6-e72db95715dd@daynix.com/T/
[2] https://chromium-review.googlesource.com/c/crosvm/crosvm/+/5599645/1
[3] https://lore.kernel.org/kvm/20240229025759.1187910-1-stevensd@google.com/

Weifeng Liu (3):
  virtio-gpu: rutabaga: Properly set stride when copying resources
  virtio-gpu: rutabaga: Poll rutabaga upon events
  virtio-gpu: rutabaga: Add options to enable virgl and venus contexts

 hw/display/virtio-gpu-rutabaga.c | 104 ++++++++++++++++++++++++++++++-
 include/hw/virtio/virtio-gpu.h   |   1 +
 2 files changed, 104 insertions(+), 1 deletion(-)

-- 
2.45.0