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

From: Alex Deucher
Date: Wed Jan 18 2023 - 11:33:50 EST

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.

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
> >>>
> >>
> >
>