amdgpu_vm_flush() sends commands to the GPU to update the VM page tables
for a job.
When a job uses a GPU virtual address space, the GPU needs to refresh
its address translations after the driver updates the page tables.
A VM flush tells the GPU to forget old address translations and use the
updated page table mappings.
This flush command is not supported on all rings. Only rings that
implement the emit_vm_flush() callback know how to emit the correct
hardware command for this operation.
The function already gates vm_flush_needed on the presence of
ring->funcs->emit_vm_flush earlier in the logic. However, static
analysis tools such as Smatch may not track this relationship through
the vm_flush_needed boolean and warn that emit_vm_flush() could be NULL
when the VM flush command is emitted later.
Fixes the below:
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c:826 amdgpu_vm_flush() error: we
previously assumed 'ring->funcs->emit_vm_flush' could be null (see line 788)
Fixes: b3cd285fa68d ("drm/amdgpu: update the PASID mapping only on demand")
Cc: Dan Carpenter <[email protected]>
Cc: Felix Kuehling <[email protected]>
Cc: Christian König <[email protected]>
Cc: Alex Deucher <[email protected]>
Signed-off-by: Srinivasan Shanmugam <[email protected]>
---
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 b89013a6aa0b..cc79cb7dd4e1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -807,7 +807,7 @@ void amdgpu_vm_flush(struct amdgpu_ring *ring, struct
amdgpu_job *job,
if (cleaner_shader_needed)
ring->funcs->emit_cleaner_shader(ring);
- if (vm_flush_needed) {
+ if (vm_flush_needed && ring->funcs->emit_vm_flush) {
trace_amdgpu_vm_flush(ring, job->vmid, job->vm_pd_addr);
amdgpu_ring_emit_vm_flush(ring, job->vmid, job->vm_pd_addr);
}
--
2.34.1
