[PATCH 4.19 059/114] drm/amdgpu: Fix KFD-related kernel oops on Hawaii

[Greg Kroah-Hartman]

From: Felix Kuehling <Felix.Kuehling@xxxxxxx>

[ Upstream commit dcafbd50f2e4d5cc964aae409fb5691b743fba23 ]

Hawaii needs to flush caches explicitly, submitting an IB in a user
VMID from kernel mode. There is no s_fence in this case.

Fixes: eb3961a57424 ("drm/amdgpu: remove fence context from the job")
Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Reviewed-by: Christian KÃnig <christian.koenig@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
index 51b5e977ca885..f4e9d1b10e3ed 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
@@ -139,7 +139,8 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
 	/* ring tests don't use a job */
 	if (job) {
 		vm = job->vm;
-		fence_ctx = job->base.s_fence->scheduled.context;
+		fence_ctx = job->base.s_fence ?
+			job->base.s_fence->scheduled.context : 0;
 	} else {
 		vm = NULL;
 		fence_ctx = 0;
-- 
2.20.1