gpu: nvgpu: add speculative load barrier (ctrl IOCTLs)

Data can be speculatively loaded from memory and stay in cache even
when bound check fails. This can lead to unintended information
disclosure via side-channel analysis.

To mitigate this problem insert a speculation barrier.

bug 2041355

Change-Id: I03fbc81c105632e788d8a0f97fb4e233d1124b49
Signed-off-by: Aparna Das <aparnad@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1652230
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gv11b/gr_gv11b.c b/drivers/gpu/nvgpu/gv11b/gr_gv11b.c
index 46f5ffb5..0d7a3f4d 100644
--- a/drivers/gpu/nvgpu/gv11b/gr_gv11b.c
+++ b/drivers/gpu/nvgpu/gv11b/gr_gv11b.c
@@ -956,6 +956,8 @@ int gr_gv11b_zbc_s_query_table(struct gk20a *g, struct gr_gk20a *gr,
                 nvgpu_err(g, "invalid zbc stencil table index");
                 return -EINVAL;
         }
+
+        nvgpu_speculation_barrier();
         query_params->depth = gr->zbc_s_tbl[index].stencil;
         query_params->format = gr->zbc_s_tbl[index].format;
         query_params->ref_cnt = gr->zbc_s_tbl[index].ref_cnt;