Re: [PATCH 1/2] drm/amdgpu: fix start calculation in amdgpu_vram_mgr_new

["Christian König" <christian.koenig@amd.com>]

Am 10.05.22 um 16:42 schrieb Alex Deucher:
> On Tue, May 10, 2022 at 7:36 AM Christian König
> <ckoenig.leichtzumerken@gmail.com> wrote:
>> We still need to calculate a virtual start address for the resource to
>> aid checking of it is visible or not.
> Does this fix a known issue or is it just something you noticed?

Just something I've noticed. Judging from the bug reports we get large 
BAR systems are so common by now that only a few people are left where 
that actually matters.

Christian.

>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 22 +++++++++++++-------
>>   1 file changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> index 49e4092f447f..51d9d3a4456c 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
>> @@ -496,16 +496,22 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>>                          list_splice_tail(trim_list, &vres->blocks);
>>          }
>>
>> -       list_for_each_entry(block, &vres->blocks, link)
>> -               vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
>> +       vres->base.start = 0;
>> +       list_for_each_entry(block, &vres->blocks, link) {
>> +               unsigned long start;
>>
>> -       block = amdgpu_vram_mgr_first_block(&vres->blocks);
>> -       if (!block) {
>> -               r = -EINVAL;
>> -               goto error_fini;
>> -       }
>> +               start = amdgpu_vram_mgr_block_start(block) +
>> +                       amdgpu_vram_mgr_block_size(block);
>> +               start >>= PAGE_SHIFT;
>>
>> -       vres->base.start = amdgpu_vram_mgr_block_start(block) >> PAGE_SHIFT;
>> +               if (start > vres->base.num_pages)
>> +                       start -= vres->base.num_pages;
>> +               else
>> +                       start = 0;
>> +               vres->base.start = max(vres->base.start, start);
>> +
>> +               vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
>> +       }
>>
>>          if (amdgpu_is_vram_mgr_blocks_contiguous(&vres->blocks))
>>                  vres->base.placement |= TTM_PL_FLAG_CONTIGUOUS;
>> --
>> 2.25.1
>>