Re: [Nouveau] [PATCH 3/8] drm/amdgpu: Implement mmap as GEM object function

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 06.04.21 um 14:42 schrieb Christian König:
> Hi Thomas,
> 
> Am 06.04.21 um 13:55 schrieb Thomas Zimmermann:
>> Hi
>>
>> Am 06.04.21 um 12:56 schrieb Christian König:
>>>>
>>>> In the end I went with the semantics I found in amdgpu_mmap() and 
>>>> handled KFD specially. Let me know if this requires to be changed.
>>>
>>> Well the question is where is the call to 
>>> drm_vma_node_verify_access() now? Cause that needs to be skipped for 
>>> KFD BOs.
>>
>> I see. It's now drm_vma_node_is_allowed(); called by drm_gem_mmap(). 
>> [1] So drm_gem_mmap() cannot be used by amdgpu.
>>
>> If I understand the code at [2] correctly, KFD objects don't use the 
>> GEM ioctl interfaces, but they still use the internal GEM object that 
>> is part of the TTM BO. In this case, amdgpu could have its own version 
>> of drm_gem_mmap(), which calls drm_gem_mmap_obj(), [3] which in turn 
>> handles the mmap details via GEM object functions.
> 
> Correct, well we could cleanup the KFD to use the GEM functions as well.

The KFD code already calls amdgpu_gem_object_create(). It should have 
the object-functions pointer set for use with mmap. Not sure what the 
use of drm_vma_node_is_allowed() would involve.

Best regards
Thomas

> 
> Felix what exactly was your objections to using this?
> 
> Regards,
> Christian.
> 
>>
>> drm_gem_prime_mmap() doesn't do any additional verification.
>>
>> Best regards
>> Thomas
>>
>> [1] 
>> https://elixir.bootlin.com/linux/v5.11.11/source/drivers/gpu/drm/drm_gem.c#L1156 
>>
>> [2] 
>> https://elixir.bootlin.com/linux/v5.11.11/source/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c#L1224 
>>
>> [3] 
>> https://elixir.bootlin.com/linux/v5.12-rc6/source/drivers/gpu/drm/drm_gem.c#L1053 
>>
>>
>>
>>>
>>> Regards,
>>> Christian.
>>>
>>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>>>> -
>>>>>>   int amdgpu_copy_buffer(struct amdgpu_ring *ring, uint64_t 
>>>>>> src_offset,
>>>>>>                  uint64_t dst_offset, uint32_t byte_count,
>>>>>>                  struct dma_resv *resv,
>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h 
>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>>>>>> index dec0db8b0b13..6e51faad7371 100644
>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>>>>>> @@ -146,7 +146,6 @@ int amdgpu_fill_buffer(struct amdgpu_bo *bo,
>>>>>>               struct dma_resv *resv,
>>>>>>               struct dma_fence **fence);
>>>>>> -int amdgpu_mmap(struct file *filp, struct vm_area_struct *vma);
>>>>>>   int amdgpu_ttm_alloc_gart(struct ttm_buffer_object *bo);
>>>>>>   int amdgpu_ttm_recover_gart(struct ttm_buffer_object *tbo);
>>>>>>   uint64_t amdgpu_ttm_domain_start(struct amdgpu_device *adev, 
>>>>>> uint32_t type);
>>>>>
>>>>> _______________________________________________
>>>>> dri-devel mailing list
>>>>> dri-devel@lists.freedesktop.org
>>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>>
>>>
>>> _______________________________________________
>>> dri-devel mailing list
>>> dri-devel@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
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-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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