Re: [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND UAPI

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On Wed, Jan 18, 2023 at 11:50 AM Danilo Krummrich <dakr@xxxxxxxxxx> wrote:
>
>
>
> On 1/18/23 17:30, Alex Deucher wrote:
> > On Wed, Jan 18, 2023 at 11:19 AM Danilo Krummrich <dakr@xxxxxxxxxx> wrote:
> >>
> >> On 1/18/23 16:37, Christian König wrote:
> >>> Am 18.01.23 um 16:34 schrieb Danilo Krummrich:
> >>>> Hi Christian,
> >>>>
> >>>> On 1/18/23 09:53, Christian König wrote:
> >>>>> Am 18.01.23 um 07:12 schrieb Danilo Krummrich:
> >>>>>> This patch series provides a new UAPI for the Nouveau driver in
> >>>>>> order to
> >>>>>> support Vulkan features, such as sparse bindings and sparse residency.
> >>>>>>
> >>>>>> Furthermore, with the DRM GPUVA manager it provides a new DRM core
> >>>>>> feature to
> >>>>>> keep track of GPU virtual address (VA) mappings in a more generic way.
> >>>>>>
> >>>>>> The DRM GPUVA manager is indented to help drivers implement
> >>>>>> userspace-manageable
> >>>>>> GPU VA spaces in reference to the Vulkan API. In order to achieve
> >>>>>> this goal it
> >>>>>> serves the following purposes in this context.
> >>>>>>
> >>>>>>       1) Provide a dedicated range allocator to track GPU VA
> >>>>>> allocations and
> >>>>>>          mappings, making use of the drm_mm range allocator.
> >>>>>
> >>>>> This means that the ranges are allocated by the kernel? If yes that's
> >>>>> a really really bad idea.
> >>>>
> >>>> No, it's just for keeping track of the ranges userspace has allocated.
> >>>
> >>> Ok, that makes more sense.
> >>>
> >>> So basically you have an IOCTL which asks kernel for a free range? Or
> >>> what exactly is the drm_mm used for here?
> >>
> >> Not even that, userspace provides both the base address and the range,
> >> the kernel really just keeps track of things. Though, writing a UAPI on
> >> top of the GPUVA manager asking for a free range instead would be
> >> possible by just adding the corresponding wrapper functions to get a
> >> free hole.
> >>
> >> Currently, and that's what I think I read out of your question, the main
> >> benefit of using drm_mm over simply stuffing the entries into a list or
> >> something boils down to easier collision detection and iterating
> >> sub-ranges of the whole VA space.
> >
> > Why not just do this in userspace?  We have a range manager in
> > libdrm_amdgpu that you could lift out into libdrm or some other
> > helper.
>
> The kernel still needs to keep track of the mappings within the various
> VA spaces, e.g. it silently needs to unmap mappings that are backed by
> BOs that get evicted and remap them once they're validated (or swapped
> back in).

Ok, you are just using this for maintaining the GPU VM space in the kernel.

Alex

>
> >
> > Alex
> >
> >
> >>
> >>>
> >>> Regards,
> >>> Christian.
> >>>
> >>>>
> >>>> - Danilo
> >>>>
> >>>>>
> >>>>> Regards,
> >>>>> Christian.
> >>>>>
> >>>>>>
> >>>>>>       2) Generically connect GPU VA mappings to their backing
> >>>>>> buffers, in
> >>>>>>          particular DRM GEM objects.
> >>>>>>
> >>>>>>       3) Provide a common implementation to perform more complex mapping
> >>>>>>          operations on the GPU VA space. In particular splitting and
> >>>>>> merging
> >>>>>>          of GPU VA mappings, e.g. for intersecting mapping requests
> >>>>>> or partial
> >>>>>>          unmap requests.
> >>>>>>
> >>>>>> The new VM_BIND Nouveau UAPI build on top of the DRM GPUVA manager,
> >>>>>> itself
> >>>>>> providing the following new interfaces.
> >>>>>>
> >>>>>>       1) Initialize a GPU VA space via the new
> >>>>>> DRM_IOCTL_NOUVEAU_VM_INIT ioctl
> >>>>>>          for UMDs to specify the portion of VA space managed by the
> >>>>>> kernel and
> >>>>>>          userspace, respectively.
> >>>>>>
> >>>>>>       2) Allocate and free a VA space region as well as bind and
> >>>>>> unbind memory
> >>>>>>          to the GPUs VA space via the new DRM_IOCTL_NOUVEAU_VM_BIND
> >>>>>> ioctl.
> >>>>>>
> >>>>>>       3) Execute push buffers with the new DRM_IOCTL_NOUVEAU_EXEC ioctl.
> >>>>>>
> >>>>>> Both, DRM_IOCTL_NOUVEAU_VM_BIND and DRM_IOCTL_NOUVEAU_EXEC, make use
> >>>>>> of the DRM
> >>>>>> scheduler to queue jobs and support asynchronous processing with DRM
> >>>>>> syncobjs
> >>>>>> as synchronization mechanism.
> >>>>>>
> >>>>>> By default DRM_IOCTL_NOUVEAU_VM_BIND does synchronous processing,
> >>>>>> DRM_IOCTL_NOUVEAU_EXEC supports asynchronous processing only.
> >>>>>>
> >>>>>> The new VM_BIND UAPI for Nouveau makes also use of drm_exec
> >>>>>> (execution context
> >>>>>> for GEM buffers) by Christian König. Since the patch implementing
> >>>>>> drm_exec was
> >>>>>> not yet merged into drm-next it is part of this series, as well as a
> >>>>>> small fix
> >>>>>> for this patch, which was found while testing this series.
> >>>>>>
> >>>>>> This patch series is also available at [1].
> >>>>>>
> >>>>>> There is a Mesa NVK merge request by Dave Airlie [2] implementing the
> >>>>>> corresponding userspace parts for this series.
> >>>>>>
> >>>>>> The Vulkan CTS test suite passes the sparse binding and sparse
> >>>>>> residency test
> >>>>>> cases for the new UAPI together with Dave's Mesa work.
> >>>>>>
> >>>>>> There are also some test cases in the igt-gpu-tools project [3] for
> >>>>>> the new UAPI
> >>>>>> and hence the DRM GPU VA manager. However, most of them are testing
> >>>>>> the DRM GPU
> >>>>>> VA manager's logic through Nouveau's new UAPI and should be
> >>>>>> considered just as
> >>>>>> helper for implementation.
> >>>>>>
> >>>>>> However, I absolutely intend to change those test cases to proper
> >>>>>> kunit test
> >>>>>> cases for the DRM GPUVA manager, once and if we agree on it's
> >>>>>> usefulness and
> >>>>>> design.
> >>>>>>
> >>>>>> [1]
> >>>>>> https://gitlab.freedesktop.org/nouvelles/kernel/-/tree/new-uapi-drm-next /
> >>>>>> https://gitlab.freedesktop.org/nouvelles/kernel/-/merge_requests/1
> >>>>>> [2] https://gitlab.freedesktop.org/nouveau/mesa/-/merge_requests/150/
> >>>>>> [3]
> >>>>>> https://gitlab.freedesktop.org/dakr/igt-gpu-tools/-/tree/wip_nouveau_vm_bind
> >>>>>>
> >>>>>> I also want to give credit to Dave Airlie, who contributed a lot of
> >>>>>> ideas to
> >>>>>> this patch series.
> >>>>>>
> >>>>>> Christian König (1):
> >>>>>>     drm: execution context for GEM buffers
> >>>>>>
> >>>>>> Danilo Krummrich (13):
> >>>>>>     drm/exec: fix memory leak in drm_exec_prepare_obj()
> >>>>>>     drm: manager to keep track of GPUs VA mappings
> >>>>>>     drm: debugfs: provide infrastructure to dump a DRM GPU VA space
> >>>>>>     drm/nouveau: new VM_BIND uapi interfaces
> >>>>>>     drm/nouveau: get vmm via nouveau_cli_vmm()
> >>>>>>     drm/nouveau: bo: initialize GEM GPU VA interface
> >>>>>>     drm/nouveau: move usercopy helpers to nouveau_drv.h
> >>>>>>     drm/nouveau: fence: fail to emit when fence context is killed
> >>>>>>     drm/nouveau: chan: provide nouveau_channel_kill()
> >>>>>>     drm/nouveau: nvkm/vmm: implement raw ops to manage uvmm
> >>>>>>     drm/nouveau: implement uvmm for user mode bindings
> >>>>>>     drm/nouveau: implement new VM_BIND UAPI
> >>>>>>     drm/nouveau: debugfs: implement DRM GPU VA debugfs
> >>>>>>
> >>>>>>    Documentation/gpu/driver-uapi.rst             |   11 +
> >>>>>>    Documentation/gpu/drm-mm.rst                  |   43 +
> >>>>>>    drivers/gpu/drm/Kconfig                       |    6 +
> >>>>>>    drivers/gpu/drm/Makefile                      |    3 +
> >>>>>>    drivers/gpu/drm/amd/amdgpu/Kconfig            |    1 +
> >>>>>>    drivers/gpu/drm/drm_debugfs.c                 |   56 +
> >>>>>>    drivers/gpu/drm/drm_exec.c                    |  294 ++++
> >>>>>>    drivers/gpu/drm/drm_gem.c                     |    3 +
> >>>>>>    drivers/gpu/drm/drm_gpuva_mgr.c               | 1323
> >>>>>> +++++++++++++++++
> >>>>>>    drivers/gpu/drm/nouveau/Kbuild                |    3 +
> >>>>>>    drivers/gpu/drm/nouveau/Kconfig               |    2 +
> >>>>>>    drivers/gpu/drm/nouveau/include/nvif/if000c.h |   23 +-
> >>>>>>    drivers/gpu/drm/nouveau/include/nvif/vmm.h    |   17 +-
> >>>>>>    .../gpu/drm/nouveau/include/nvkm/subdev/mmu.h |   10 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_abi16.c       |   23 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_abi16.h       |    1 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_bo.c          |  152 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_bo.h          |    2 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_chan.c        |   16 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_chan.h        |    1 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_debugfs.c     |   24 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_drm.c         |   25 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_drv.h         |   92 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_exec.c        |  310 ++++
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_exec.h        |   55 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_fence.c       |    7 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_fence.h       |    2 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_gem.c         |   83 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_mem.h         |    5 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_prime.c       |    2 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_sched.c       |  780 ++++++++++
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_sched.h       |   98 ++
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_svm.c         |    2 +-
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_uvmm.c        |  575 +++++++
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_uvmm.h        |   68 +
> >>>>>>    drivers/gpu/drm/nouveau/nouveau_vmm.c         |    4 +-
> >>>>>>    drivers/gpu/drm/nouveau/nvif/vmm.c            |   73 +-
> >>>>>>    .../gpu/drm/nouveau/nvkm/subdev/mmu/uvmm.c    |  168 ++-
> >>>>>>    .../gpu/drm/nouveau/nvkm/subdev/mmu/uvmm.h    |    1 +
> >>>>>>    drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c |   32 +-
> >>>>>>    drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.h |    3 +
> >>>>>>    include/drm/drm_debugfs.h                     |   25 +
> >>>>>>    include/drm/drm_drv.h                         |    6 +
> >>>>>>    include/drm/drm_exec.h                        |  144 ++
> >>>>>>    include/drm/drm_gem.h                         |   75 +
> >>>>>>    include/drm/drm_gpuva_mgr.h                   |  527 +++++++
> >>>>>>    include/uapi/drm/nouveau_drm.h                |  216 +++
> >>>>>>    47 files changed, 5266 insertions(+), 126 deletions(-)
> >>>>>>    create mode 100644 drivers/gpu/drm/drm_exec.c
> >>>>>>    create mode 100644 drivers/gpu/drm/drm_gpuva_mgr.c
> >>>>>>    create mode 100644 drivers/gpu/drm/nouveau/nouveau_exec.c
> >>>>>>    create mode 100644 drivers/gpu/drm/nouveau/nouveau_exec.h
> >>>>>>    create mode 100644 drivers/gpu/drm/nouveau/nouveau_sched.c
> >>>>>>    create mode 100644 drivers/gpu/drm/nouveau/nouveau_sched.h
> >>>>>>    create mode 100644 drivers/gpu/drm/nouveau/nouveau_uvmm.c
> >>>>>>    create mode 100644 drivers/gpu/drm/nouveau/nouveau_uvmm.h
> >>>>>>    create mode 100644 include/drm/drm_exec.h
> >>>>>>    create mode 100644 include/drm/drm_gpuva_mgr.h
> >>>>>>
> >>>>>>
> >>>>>> base-commit: 0b45ac1170ea6416bc1d36798414c04870cd356d
> >>>>>
> >>>>
> >>>
> >>
> >
>




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