[PATCH v5 0/3] Add sync object UAPI support to VirtIO-GPU driver

From: Dmitry Osipenko
Date: Sun Apr 09 2023 - 08:40:50 EST


We have multiple Vulkan context types that are awaiting for the addition
of the sync object DRM UAPI support to the VirtIO-GPU kernel driver:

1. Venus context
2. Native contexts (virtio-freedreno, virtio-intel, virtio-amdgpu)

Mesa core supports DRM sync object UAPI, providing Vulkan drivers with a
generic fencing implementation that we want to utilize.

This patch adds initial sync objects support. It creates fundament for a
further fencing improvements. Later on we will want to extend the VirtIO-GPU
fencing API with passing fence IDs to host for waiting, it will be a new
additional VirtIO-GPU IOCTL and more. Today we have several VirtIO-GPU context
drivers in works that require VirtIO-GPU to support sync objects UAPI.

The patch is heavily inspired by the sync object UAPI implementation of the
MSM driver.

Changelog:

v5: - Factored out dma-fence unwrap API usage into separate patch as was
suggested by Emil Velikov.

- Improved and documented the job submission reorderings as was
requested by Emil Velikov. Sync file FD is now installed after
job is submitted to virtio to further optimize reorderings.

- Added comment for the kvalloc, as was requested by Emil Velikov.

- The num_in/out_syncobjs now is set only after completed parsing
of pre/post deps, as was requested by Emil Velikov.

v4: - Added r-b from Rob Clark to the "refactoring" patch.

- Replaced for/while(ptr && itr) with if (ptr), like was suggested by
Rob Clark.

- Dropped NOWARN and NORETRY GFP flags and switched syncobj patch
to use kvmalloc.

- Removed unused variables from syncobj patch that were borrowed by
accident from another (upcoming) patch after one of git rebases.

v3: - Switched to use dma_fence_unwrap_for_each(), like was suggested by
Rob Clark.

- Fixed missing dma_fence_put() in error code path that was spotted by
Rob Clark.

- Removed obsoleted comment to virtio_gpu_execbuffer_ioctl(), like was
suggested by Rob Clark.

v2: - Fixed chain-fence context matching by making use of
dma_fence_chain_contained().

- Fixed potential uninitialized var usage in error code patch of
parse_post_deps(). MSM driver had a similar issue that is fixed
already in upstream.

- Added new patch that refactors job submission code path. I found
that it was very difficult to add a new/upcoming host-waits feature
because of how variables are passed around the code, the virtgpu_ioctl.c
also was growing to unmanageable size.

Dmitry Osipenko (3):
drm/virtio: Refactor and optimize job submission code path
drm/virtio: Wait for each dma-fence of in-fence array individually
drm/virtio: Support sync objects

drivers/gpu/drm/virtio/Makefile | 2 +-
drivers/gpu/drm/virtio/virtgpu_drv.c | 3 +-
drivers/gpu/drm/virtio/virtgpu_drv.h | 4 +
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 182 --------
drivers/gpu/drm/virtio/virtgpu_submit.c | 525 ++++++++++++++++++++++++
include/uapi/drm/virtgpu_drm.h | 16 +-
6 files changed, 547 insertions(+), 185 deletions(-)
create mode 100644 drivers/gpu/drm/virtio/virtgpu_submit.c

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2.39.2