Re: [PATCH v2] drm/amdgpu: Fix size validation for non-exclusive domains

[Luben Tuikov <luben.tuikov@amd.com>]

On 2022-12-12 14:19, Christian König wrote:
> Am 12.12.22 um 18:48 schrieb Luben Tuikov:
>> Fix amdgpu_bo_validate_size() to check whether the TTM domain manager for the
>> requested memory exists, and to allow for non-exclusive domain allocations, as
>> there would be if the domain is a mask, e.g. AMDGPU_GEM_DOMAIN_VRAM |
>> AMDGPU_GEM_DOMAIN_GTT.
>>
>> Cc: Alex Deucher <Alexander.Deucher@amd.com>
>> Cc: Christian König <christian.koenig@amd.com>
>> Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 19 +++++++------------
>>   1 file changed, 7 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> index fd3ab4b5e5bb1f..e0f103f0ec2178 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>> @@ -448,31 +448,26 @@ static bool amdgpu_bo_validate_size(struct amdgpu_device *adev,
>>   
>>   	/*
>>   	 * If GTT is part of requested domains the check must succeed to
>> -	 * allow fall back to GTT
>> +	 * allow fall back to GTT.
>> +	 *
>> +	 * Note that allocations can request from either domain. For
>> +	 * this reason, check either in non-exclusive way, and if
>> +	 * neither satisfies, fail the validation.
> 
> That's not correct, the original logic was completely intentional.
> 
> If both VRAM and GTT are specified it's valid if the size fits only into 
> GTT.

Given that this patch fixes a kernel oops, should this patch then fail the validation,
i.e. return false?

This would then fail, in amdgpu_ttm_reserve_tmr():

	ret = amdgpu_bo_create_kernel_at(adev,
				adev->gmc.real_vram_size - adev->mman.discovery_tmr_size,
				adev->mman.discovery_tmr_size,
				AMDGPU_GEM_DOMAIN_VRAM |
				AMDGPU_GEM_DOMAIN_GTT,
				&adev->mman.discovery_memory,
				NULL);

Regards,
Luben