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Message-ID: <bcbef353-f579-4e90-1c77-be36bbe61c0f@redhat.com>
Date: Wed, 18 Jan 2023 17:19:44 +0100
From: Danilo Krummrich <dakr@...hat.com>
To: Christian König <christian.koenig@....com>,
daniel@...ll.ch, airlied@...hat.com, bskeggs@...hat.com,
jason@...kstrand.net, tzimmermann@...e.de, mripard@...nel.org,
corbet@....net
Cc: dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND
UAPI
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.
>
> 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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