[PATCH] drm/amdgpu: Need to set moved to true when evict bo

[Christian König]

Am 29.08.2018 um 04:52 schrieb Zhang, Jerry (Junwei):
> On 08/28/2018 08:40 PM, Emily Deng wrote:
>> Fix the VMC page fault when the running sequence is as below:
>> 1.amdgpu_gem_create_ioctl
>> 2.ttm_bo_swapout->amdgpu_vm_bo_invalidate, as not called
>> amdgpu_vm_bo_base_init, so won't called
>> list_add_tail(&base->bo_list, &bo->va). Even the bo was evicted,
>> it won't set the bo_base->moved.
>
> IMO, the evicted bo should be created previously.
> On BO creation we will add it to the bo->va as below:
>
> amdgpu_gem_create_ioctl
>   drm_gem_handle_create
>     amdgpu_gem_object_open

And here is the problem. Between creating the BO and opening it in the 
client the BO can be evicted.

That's what Emily's patch is handling here.

Christian.

> amdgpu_vm_bo_add
>         amdgpu_vm_bo_base_init
>           list_add_tail(&base->bo_list, &bo->va)
>
> Then it could be set moved in bo invalidate when evicting.
>
> could you provide a bit more backgroud about the issue?
> looks a per vm bo is evicted and a new same bo created.
>
> Jerry
>
>> 3.drm_gem_open_ioctl->amdgpu_vm_bo_base_init, here only called
>> list_move_tail(&base->vm_status, &vm->evicted), but not set the
>> bo_base->moved.
>> 4.amdgpu_vm_bo_map->amdgpu_vm_bo_insert_map, as the bo_base->moved is
>> not set true, the function amdgpu_vm_bo_insert_map will call
>> list_move(&bo_va->base.vm_status, &vm->moved)
>> 5.amdgpu_cs_ioctl won't validate the swapout bo, as it is only in the
>> moved list, not in the evict list. So VMC page fault occurs.
>>
>> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index 1f4b8df..015e20e 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -172,6 +172,7 @@ static void amdgpu_vm_bo_base_init(struct 
>> amdgpu_vm_bo_base *base,
>>        * is validated on next vm use to avoid fault.
>>        * */
>>       list_move_tail(&base->vm_status, &vm->evicted);
>> +    base->moved = true;
>>   }
>>
>>   /**
>>
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