[PATCH] drm/amdgpu: Raise dma resv usage for created TLB fence

[Christian König]

Am 05.09.24 um 10:58 schrieb Dejan Andjelkovic:
> When using SDMA for PT updates, a TLB fence hooked to a buffer
> objects dma resv object with usage declared as BOOKKEEP leaves a
> chance for TLB flush to occur prematurely. This will lead to a page
> fault. Raising the usage from BOOKKEEP to KERNEL removes this
> possibility.

Well that's complete nonsense. The usage model is for implicit syncing 
and not even remotely related to TLB flushing.

What exactly is the problem you run into?

Regards,
Christian.

>
> Signed-off-by: Dejan Andjelkovic <Dejan.Andjelkovic at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index f93804902fd3..8efc2cf9bbb0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -928,7 +928,7 @@ amdgpu_vm_tlb_flush(struct amdgpu_vm_update_params *params,
>   
>   		/* Makes sure no PD/PT is freed before the flush */
>   		dma_resv_add_fence(vm->root.bo->tbo.base.resv, *fence,
> -				   DMA_RESV_USAGE_BOOKKEEP);
> +				   DMA_RESV_USAGE_KERNEL);
>   	}
>   }
>