[PATCH AUTOSEL 5.4 139/175] drm/amdgpu: Sync with VM root BO when switching VM to CPU update mode

Sasha Levin
2020-06-09T00:03:31Z

From: Felix Kuehling <Felix.Kuehling@amd.com>

[ Upstream commit 90ca78deb004abe75b5024968a199acb96bb70f9 ]

This fixes an intermittent bug where a root PD clear operation still in
progress could overwrite a PDE update done by the CPU, resulting in a
VM fault.

Fixes: 108b4d928c03 ("drm/amd/amdgpu: Update VM function pointer")
Reported-by: Jay Cornwall <Jay.Cornwall@amd.com>
Tested-by: Jay Cornwall <Jay.Cornwall@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index c7514f743409..6335bd4ae374 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2867,10 +2867,17 @@ int amdgpu_vm_make_compute(struct amdgpu_device *adev, struct amdgpu_vm *vm, uns
WARN_ONCE((vm->use_cpu_for_update && !amdgpu_gmc_vram_full_visible(&adev->gmc)),
"CPU update of VM recommended only for large BAR system\n");

- if (vm->use_cpu_for_update)
+ if (vm->use_cpu_for_update) {
+ /* Sync with last SDMA update/clear before switching to CPU */
+ r = amdgpu_bo_sync_wait(vm->root.base.bo,
+ AMDGPU_FENCE_OWNER_UNDEFINED, true);
+ if (r)
+ goto free_idr;
+
vm->update_funcs = &amdgpu_vm_cpu_funcs;
- else
+ } else {
vm->update_funcs = &amdgpu_vm_sdma_funcs;
+ }
dma_fence_put(vm->last_update);
vm->last_update = NULL;

--
2.25.1