[PATCH] drm/amdgpu: fix max_entries calculation v3

[Christian König]

Am 02.09.20 um 18:15 schrieb Pan, Xinhui:
>
>> 2020年9月2日 23:21，Christian König <ckoenig.leichtzumerken at gmail.com> 写道：
>>
>> Calculate the correct value for max_entries or we might run after the
>> page_address array.
>>
>> v2: Xinhui pointed out we don't need the shift
>> v3: use local copy of start and simplify some calculation
>>
>> Signed-off-by: Christian König <christian.koenig at amd.com>
>> Fixes: 1e691e244487 drm/amdgpu: stop allocating dummy GTT nodes
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index 8bc2253939be..7cbee1a7ec84 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -1697,7 +1697,7 @@ static int amdgpu_vm_bo_split_mapping(struct amdgpu_device *adev,
>> 				AMDGPU_GPU_PAGES_IN_CPU_PAGE;
>> 		} else {
>> 			addr = 0;
>> -			max_entries = S64_MAX;
>> +			max_entries = mapping->last - start + 1;
>> 		}
>>
>> 		if (pages_addr) {
>> @@ -1727,7 +1727,7 @@ static int amdgpu_vm_bo_split_mapping(struct amdgpu_device *adev,
>> 			addr += pfn << PAGE_SHIFT;
>> 		}
>>
>> -		last = min((uint64_t)mapping->last, start + max_entries - 1);
>> +		last = start + max_entries - 1;
> I am not sure if we calculate the max_entries by nodes->size. does it work in that case?

Oh, good point. When the VA range between start and last is smaller than 
the buffer itself we could indeed overrun here. Going to fix that.

Thanks,
Christian.

>
>> 		r = amdgpu_vm_bo_update_mapping(adev, vm, false, false, resv,
>> 						start, last, flags, addr,
>> 						dma_addr, fence);
>> -- 
>> 2.17.1
>>
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