[PATCH 2/2] drm/msm/a7xx: Call CP_RESET_CONTEXT_STATE

[Connor Abbott]

Calling this packet is necessary when we switch contexts because there
are various pieces of state used by userspace to synchronize between BR
and BV that are persistent across submits and we need to make sure that
they are in a "safe" state when switching contexts. Otherwise a
userspace submission in one context could cause another context to
function incorrectly and hang, effectively a denial of service (although
without leaking data). This was missed during initial a7xx bringup.

Fixes: af66706accdf ("drm/msm/a6xx: Add skeleton A7xx support")
Signed-off-by: Connor Abbott <cwabbott0 at gmail.com>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 06465bc2d0b4b128cddfcfcaf1fe4252632b6777..f776e9ce43a7cdbb4ef769606ec851909b0c4cdd 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -130,6 +130,20 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
 		OUT_RING(ring, lower_32_bits(rbmemptr(ring, fence)));
 		OUT_RING(ring, upper_32_bits(rbmemptr(ring, fence)));
 		OUT_RING(ring, submit->seqno - 1);
+
+		OUT_PKT7(ring, CP_THREAD_CONTROL, 1);
+		OUT_RING(ring, CP_SET_THREAD_BOTH);
+
+		/* Reset state used to synchronize BR and BV */
+		OUT_PKT7(ring, CP_RESET_CONTEXT_STATE, 1);
+		OUT_RING(ring,
+			 CP_RESET_CONTEXT_STATE_0_CLEAR_ON_CHIP_TS |
+			 CP_RESET_CONTEXT_STATE_0_CLEAR_RESOURCE_TABLE |
+			 CP_RESET_CONTEXT_STATE_0_CLEAR_BV_BR_COUNTER |
+			 CP_RESET_CONTEXT_STATE_0_RESET_GLOBAL_LOCAL_TS);
+
+		OUT_PKT7(ring, CP_THREAD_CONTROL, 1);
+		OUT_RING(ring, CP_SET_THREAD_BR);
 	}
 
 	if (!sysprof) {

-- 
2.47.1