From: Gurchetan Singh <gurchetansi...@google.com> Rationale:
- gfxstream [a] is good for the Android Emulator/upstream QEMU alignment - Wayland passhthrough [b] via the cross-domain context type is good for Linux on Linux display virtualization - rutabaga_gfx [c] sits on top of gfxstream, cross-domain and even virglrenderer - This series ports rutabaga_gfx to QEMU Feedback requested: - How is everyone feeling about gfxstream/rutabaga_gfx, especially UI maintainers? I've been assuming it is a definite win, so if there's a divergence of opinion on that, we should resolve that quickly. - Need help from memory region API experts on "HACK: use memory region API to inject memory to guest" - Need help from QEMU multi-threaded experts on "HACK: schedule fence return on main AIO context" ---------- | Longer | ---------- Dear all, The people have demanded it, and we have listened. Just the other day, some kids came up to me on the street -- hat in hand, teardrops in their eyes -- and asked "please sir, can you perchance port gfxstream and rutabaga_gfx to upstream QEMU?". I honestly can't take it anymore. In a way, I can understand the fanaticism of the gfxstreamists -- the benefits of gfxstream + rutabaga_gfx in upstream QEMU are massive for all involved: (i) Android Emulator aligned with QEMU The biggest use case is no doubt the Android Emulator. Although used by millions of developers around the world [d][e], the Android Emulator itself uses currently uses a forked QEMU 2.12. The initial fork happened in the early days of Android (circa 2006 [f]) and while the situation has improved, a QEMU update inside the Android Emulator only happens once every 3-5 years. Indeed, most Android Emulator developers aren't even subscribed to qemu-devel@ given this situation. Their task is often to get the next foldable config working or fix that UI bug, but long term technical debt is something that is rarely prioritized. This one of those years when QEMU will be upreved, though. Soon, the emulator will be based on QEMU7.2 and new controls will be instituted to make QEMU modifications harder. Things that can be upstreamed will be upstreamed. One of the biggest downstream pieces of the Android Emulator is the gfxstream graphics stack, and it has some nontrivial features that aren't easy to implement elsewhere [g]. The lore of gfxstream is detailed in patch 10, but suffice to say getting gfxstream mainlined would help move the Android Emulator out of it's downstream mud hut into the light, love and compassion of upstream. (ii) Wayland passthrough For the Linux guest on Linux host use case, we've elected to port rutabaga_gfx into QEMU rather than gfxstream. rutabaga_gfx sits on top of gfxstream, virglrenderer, and the cross-domain context type. With the cross-domain context type, one can avoid a guest compositor pass to display VM windows like host normal windows. It's now possible to run the examples found in the crosvm book [h] with this patchset. There are a few problems [i], but fixing them is O(days). This use case is less strong than the Android Emulator one, since anyone who would play a game in a Linux guest via QEMU would be able to run it natively. But it could be good for developers who need to test code in a virtual machine. ------------------ | Issues | ------------------ The two biggest unsolved issues are the last two "HACK:" patches. Feedback from QEMU memory management and threading experts would be greatly appreciated. ------------------ | UI integration | ------------------ This patchset intentionally uses the simplest KMS display integration possible: framebuffer copies to Pixman. The reason is Linux guests are expected to use Wayland Passthrough, and the Android Emulator UI integration is very complex. gfxstream doesn't have a "context 0" like virglrenderer that can force synchronization between QEMU's and gfxstream's GL code. Initially, we just want to run the Android Emulator in headless mode, and we have a few subsequent followup ideas in mind for UI integration (all of with the goal to be minimally invasive for QEMU). Note: even with Android in headless mode, QEMU upstream will be used in production and not just be a developer toy. -------------------------- | Packaging / Versioning | -------------------------- We have to build QEMU from sources due to compliance reasons, so we haven't created Debian packages for either gfxstream or rutabaga_gfx yet. QEMU is upstream of Debian/Portage anyways. Let us know the standard on packaging and we should be able to follow it. Versioning would be keyed on initial merge into QEMU. -------------------------- | Testing | -------------------------- A document on how to test the patchset is availble on QEMU Gitlab [j]. [a] https://android.googlesource.com/device/generic/vulkan-cereal/ [b] https://www.youtube.com/watch?v=OZJiHMtIQ2M [c] https://github.com/google/crosvm/blob/main/rutabaga_gfx/ffi/src/include/rutabaga_gfx_ffi.h [d] https://www.youtube.com/watch?v=LgRRmgfrFQM [e] https://maltewolfcastle.medium.com/how-to-setup-an-automotive-android-emulator-f287a4061b19 [f] https://groups.google.com/g/android-emulator-dev/c/dltBnUW_HzU [g] https://lists.gnu.org/archive/html/qemu-devel/2023-03/msg04271.html [h] https://crosvm.dev/book/devices/wayland.html [i] https://github.com/talex5/wayland-proxy-virtwl/blob/master/virtio-spec.md#problem [j] https://gitlab.com/qemu-project/qemu/-/issues/1611 Antonio Caggiano (2): virtio-gpu blob prep: improve decoding and add memory region virtio-gpu: CONTEXT_INIT feature Dr. David Alan Gilbert (1): virtio: Add shared memory capability Gerd Hoffmann (1): virtio-gpu: hostmem Gurchetan Singh (9): gfxstream + rutabaga prep: virtio_gpu_gl -> virtio_gpu_virgl gfxstream + rutabaga prep: make GL device more library agnostic gfxstream + rutabaga prep: define callbacks in realize function gfxstream + rutabaga prep: added need defintions, fields, and options gfxstream + rutabaga: add required meson changes gfxstream + rutabaga: add initial support for gfxstream gfxstream + rutabaga: enable rutabaga HACK: use memory region API to inject memory to guest HACK: schedule fence return on main AIO context hw/display/meson.build | 40 +- hw/display/virtio-gpu-base.c | 6 +- hw/display/virtio-gpu-gl.c | 121 +-- hw/display/virtio-gpu-pci.c | 14 + hw/display/virtio-gpu-rutabaga-stubs.c | 8 + hw/display/virtio-gpu-rutabaga.c | 1032 ++++++++++++++++++++++++ hw/display/virtio-gpu-virgl-stubs.c | 8 + hw/display/virtio-gpu-virgl.c | 138 +++- hw/display/virtio-gpu.c | 17 +- hw/display/virtio-vga.c | 33 +- hw/virtio/virtio-pci.c | 18 + include/hw/virtio/virtio-gpu-bswap.h | 18 + include/hw/virtio/virtio-gpu.h | 38 +- include/hw/virtio/virtio-pci.h | 4 + meson.build | 8 + meson_options.txt | 2 + scripts/meson-buildoptions.sh | 3 + 17 files changed, 1356 insertions(+), 152 deletions(-) create mode 100644 hw/display/virtio-gpu-rutabaga-stubs.c create mode 100644 hw/display/virtio-gpu-rutabaga.c create mode 100644 hw/display/virtio-gpu-virgl-stubs.c -- 2.40.0.634.g4ca3ef3211-goog
