[PATCH 2/2] amd/amdgpu: force to trigger a no-retry-fault after a retry-fault

[Felix Kuehling]

On 2019-11-19 11:37, Alex Sierra wrote:
> Only for the debugger use case.
>
> [why]
> Avoid endless translation retries, after an invalid address access has
> been issued to the GPU. Instead, the trap handler is forced to enter by
> generating a no-retry-fault.
> A s_trap instruction is inserted in the debugger case to let the wave to
> enter trap handler to save context.
>
> [how]
> Intentionally using an invalid flag combination (F and P set at the same
> time) to trigger a no-retry-fault, after a retry-fault happens. This is
> only valid under compute context.
>
> Change-Id: I4180c30e2631dc0401cbd6171f8a6776e4733c9a
> Signed-off-by: Alex Sierra <alex.sierra at amd.com>

This commit adds some unnecessary empty lines. See inline. With that 
fixed, the series is

Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>

Please also give Christian a chance to review.

Thanks,
   Felix

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 9 ++++++++-
>   1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index d51ac8771ae0..cd36195ff8be 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -3202,11 +3202,18 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, unsigned int pasid,
>   	flags = AMDGPU_PTE_VALID | AMDGPU_PTE_SNOOPED |
>   		AMDGPU_PTE_SYSTEM;
>   
> -	if (amdgpu_vm_fault_stop == AMDGPU_VM_FAULT_STOP_NEVER) {
> +	if (vm->is_compute_context) {
> +		/* Setting PTE flags to trigger a no-retry-fault  */
> +		flags = AMDGPU_PTE_EXECUTABLE | AMDGPU_PDE_PTE |
> +			AMDGPU_PTE_TF;
> +		value = 0;
> +
Unnecessary blank line.
> +	} else if (amdgpu_vm_fault_stop == AMDGPU_VM_FAULT_STOP_NEVER) {
>   		/* Redirect the access to the dummy page */
>   		value = adev->dummy_page_addr;
>   		flags |= AMDGPU_PTE_EXECUTABLE | AMDGPU_PTE_READABLE |
>   			AMDGPU_PTE_WRITEABLE;
> +
Unnecessary blank line.
>   	} else {
>   		/* Let the hw retry silently on the PTE */
>   		value = 0;