gpu: nvgpu: add speculative barrier

Data can be speculativerly stored and
code flow can be hijacked.

To mitigate this problem insert a
speculation barrier.

Bug 200447167

Change-Id: Ia865ff2add8b30de49aa970715625b13e8f71c08
Signed-off-by: Ranjanikar Nikhil Prabhakarrao <rprabhakarra@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1972221
(cherry picked from commit f0762ed4831b3fe6cc953a4a4ec26c2537dcb69f)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/1996052
Reviewed-by: automaticguardword <automaticguardword@nvidia.com>
Reviewed-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit
Tested-by: Deepak Nibade <dnibade@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/fifo/submit.c b/drivers/gpu/nvgpu/common/fifo/submit.c
index d518fbfb..b0f38ff1 100644
--- a/drivers/gpu/nvgpu/common/fifo/submit.c
+++ b/drivers/gpu/nvgpu/common/fifo/submit.c
@@ -212,6 +212,7 @@ static int nvgpu_submit_append_gpfifo_user_direct(struct channel_gk20a *c,
         u32 end = start + len; /* exclusive */
         int err;
 
+        nvgpu_speculation_barrier();
         if (end > gpfifo_size) {
                 /* wrap-around */
                 int length0 = gpfifo_size - start;