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/os/linux/dmabuf_vidmem.c b/drivers/gpu/nvgpu/os/linux/dmabuf_vidmem.c
index 8b38a9e1..bada5dc7 100644
--- a/drivers/gpu/nvgpu/os/linux/dmabuf_vidmem.c
+++ b/drivers/gpu/nvgpu/os/linux/dmabuf_vidmem.c
@@ -244,6 +244,7 @@ int nvgpu_vidmem_buf_access_memory(struct gk20a *g, struct dma_buf *dmabuf,
         vidmem_buf = dmabuf->priv;
         mem = vidmem_buf->mem;
 
+        nvgpu_speculation_barrier();
         switch (cmd) {
         case NVGPU_DBG_GPU_IOCTL_ACCESS_FB_MEMORY_CMD_READ:
                 nvgpu_mem_rd_n(g, mem, offset, buffer, size);