[Intel-gfx] [PATCH v6 0/6] drm/i915/gvt: Dma-buf support for GVT-g

[Xiaoguang Chen]

v5->v6:
1) align the dma-buf life cycle with the vfio device.
2) add the dma-buf releated operations in a separate patch.
3) i915 releated changes.

v4->v5:
1) fix bug while checking whether the gem obj is gvt's dma-buf when user
change caching mode or domains. Add a helper function to do it.
2) add definition for the query plane and create dma-buf.

v3->v4:
1) fix bug while checking whether the gem obj is gvt's dma-buf when set
caching mode or doamins.

v2->v3:
1) add a field gvt_plane_info in the drm_i915_gem_obj structure to save
the decoded plane information to avoid look up while need the plane info.
2) declare a new flag I915_GEM_OBJECT_IS_GVT_DMABUF in drm_i915_gem_object
to represent the gem obj for gvt's dma-buf. The tiling mode, caching mode
and domains can not be changed for this kind of gem object.
3) change dma-buf related information to be more generic. So other vendor
can use the same interface.

v1->v2:
1) create a management fd for dma-buf operations.
2) alloc gem object's backing storage in gem obj's get_pages() callback.

This patch set adds the dma-buf support for intel GVT-g.
dma-buf is a uniform mechanism to share DMA buffers across different
devices and sub-systems.
dma-buf for intel GVT-g is mainly used to share the vgpu's framebuffer
to other users or sub-systems so they can use the dma-buf to show the
desktop of a vm which uses intel vgpu.

The main idea is we create a gem object and set vgpu's framebuffer as
the backing storage of this gem object. And associate this gem obj
to a dma-buf object then export this dma-buf at the meantime
generate a file descriptor for this dma-buf. Finally deliver this file
descriptor to user space. And user can use this dma-buf fd to do render
or other operations.
User need to create a fd(for intel GVT-g dma-buf support it is a:dma-buf
management fd) then user can use this fd to query the plane information
or create a dma-buf. The life cycle of this fd is managed by GVT-g user
do not need to care about that.

We have an example program on how to use the dma-buf. You can download
the program to have a try. Good luck :)
git repo: https://github.com/01org/igvtg-qemu branch:kvmgt_dmabuf_example

Xiaoguang Chen (6):
  drm/i915/gvt: Extend the GVT-g architecture to support vfio device
    region
  drm/i915/gvt: OpRegion support for GVT-g
  drm/i915/gvt: Frame buffer decoder support for GVT-g
  vfio: Define vfio based vgpu's dma-buf operations
  drm/i915/gvt: Dmabuf support for GVT-g
  drm/i915/gvt: Adding interface so user space can get the dma-buf

 drivers/gpu/drm/i915/gvt/Makefile      |   3 +-
 drivers/gpu/drm/i915/gvt/display.c     |   2 +-
 drivers/gpu/drm/i915/gvt/display.h     |   2 +
 drivers/gpu/drm/i915/gvt/dmabuf.c      | 281 +++++++++++++++++++
 drivers/gpu/drm/i915/gvt/dmabuf.h      |  42 +++
 drivers/gpu/drm/i915/gvt/fb_decoder.c  | 479 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/gvt/fb_decoder.h  | 166 ++++++++++++
 drivers/gpu/drm/i915/gvt/gvt.c         |   2 +
 drivers/gpu/drm/i915/gvt/gvt.h         |   7 +
 drivers/gpu/drm/i915/gvt/kvmgt.c       | 262 +++++++++++++++++-
 drivers/gpu/drm/i915/gvt/opregion.c    |   8 +-
 drivers/gpu/drm/i915/gvt/vgpu.c        |   1 +
 drivers/gpu/drm/i915/i915_gem.c        |  26 +-
 drivers/gpu/drm/i915/i915_gem_object.h |   9 +
 include/uapi/linux/vfio.h              |  50 ++++
 15 files changed, 1333 insertions(+), 7 deletions(-)
 create mode 100644 drivers/gpu/drm/i915/gvt/dmabuf.c
 create mode 100644 drivers/gpu/drm/i915/gvt/dmabuf.h
 create mode 100644 drivers/gpu/drm/i915/gvt/fb_decoder.c
 create mode 100644 drivers/gpu/drm/i915/gvt/fb_decoder.h

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2.7.4