[PATCH v6 0/3] Add sync object UAPI support to VirtIO-GPU driver

[Dmitry Osipenko]

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:

v6: - Added zeroing out of syncobj_desc, as was suggested by Emil Velikov.

    - Fixed memleak in error code path which was spotted by Emil Velikov.

    - Switched to u32/u64 instead of uint_t. Previously was keeping
      uint_t style of the virtgpu_ioctl.c, in the end decided to change
      it because it's not a proper kernel coding style after all.

    - Kept single drm_virtgpu_execbuffer_syncobj struct for both in/out
      sync objects. There was a little concern about whether it would be
      worthwhile to have separate in/out descriptors, in practice it's
      unlikely that we will extend the descs in a foreseeable future.
      There is no overhead in using same struct since we want to pad it
      to 64b anyways and it shouldn't be a problem to separate the descs
      later on if we will want to do that.

    - Added r-b from Emil Velikov.

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 | 530 ++++++++++++++++++++++++
 include/uapi/drm/virtgpu_drm.h          |  16 +-
 6 files changed, 552 insertions(+), 185 deletions(-)
 create mode 100644 drivers/gpu/drm/virtio/virtgpu_submit.c

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2.39.2