Re: [PATCH drm-misc-next v6 3/6] drm/gpuvm: add an abstraction for a VM / BO combination

[Thomas Hellström]

On Mon, 2023-10-09 at 01:32 +0200, Danilo Krummrich wrote:
> Add an abstraction layer between the drm_gpuva mappings of a
> particular
> drm_gem_object and this GEM object itself. The abstraction represents
> a
> combination of a drm_gem_object and drm_gpuvm. The drm_gem_object
> holds
> a list of drm_gpuvm_bo structures (the structure representing this
> abstraction), while each drm_gpuvm_bo contains list of mappings of
> this
> GEM object.
> 
> This has multiple advantages:
> 
> 1) We can use the drm_gpuvm_bo structure to attach it to various
> lists
>    of the drm_gpuvm. This is useful for tracking external and evicted
>    objects per VM, which is introduced in subsequent patches.
> 
> 2) Finding mappings of a certain drm_gem_object mapped in a certain
>    drm_gpuvm becomes much cheaper.
> 
> 3) Drivers can derive and extend the structure to easily represent
>    driver specific states of a BO for a certain GPUVM.
> 
> The idea of this abstraction was taken from amdgpu, hence the credit
> for
> this idea goes to the developers of amdgpu.
> 
> Cc: Christian König <christian.koenig@xxxxxxx>
> Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
> ---
>  drivers/gpu/drm/drm_gpuvm.c            | 332 +++++++++++++++++++++--
> --
>  drivers/gpu/drm/nouveau/nouveau_uvmm.c |  64 +++--
>  include/drm/drm_gem.h                  |  32 +--
>  include/drm/drm_gpuvm.h                | 177 ++++++++++++-
>  4 files changed, 521 insertions(+), 84 deletions(-)

Forgot to mention, there are a couple of checkpatch.pl --strict issues
with this patch that might need looking at.

Thanks,
Thomas