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.sie...@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index d51ac8771ae0..358a4f50fcfb 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -3207,6 +3207,12 @@ bool amdgpu_vm_handle_fault(struct amdgpu_device *adev, 
unsigned int pasid,
                value = adev->dummy_page_addr;
                flags |= AMDGPU_PTE_EXECUTABLE | AMDGPU_PTE_READABLE |
                        AMDGPU_PTE_WRITEABLE;
+
+               if (vm->is_compute_context) {
+                       /* Setting PTE flags to trigger a no-retry-fault  */
+                       flags = AMDGPU_PTE_EXECUTABLE | AMDGPU_PDE_PTE |
+                               AMDGPU_PTE_TF;
+               }
        } else {
                /* Let the hw retry silently on the PTE */
                value = 0;
-- 
2.17.1

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