From a55491015cf9de6295f30d4da4b7edc101550471 Mon Sep 17 00:00:00 2001
From: Martin Radev <mradev@nvidia.com>
Date: Wed, 31 May 2023 12:59:28 +0300
Subject: [PATCH] gpu: nvgpu: exit early in cbc debugfs under hv

This patch updates the logic for the cbc debugfs node
to fail early if running under HV. The reason is that
the CBC region is maintained by HV and cannot be accessed
by nvgpu.

This avoids a subsequent null-ptr deref for Linux + HV.

Bug 4131079

Change-Id: I1ac1919efc1c05fb679f19a189184ca00908856f
Signed-off-by: Martin Radev <mradev@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2913160
Reviewed-by: Sagar Kamble <skamble@nvidia.com>
Reviewed-by: Ankur Kishore <ankkishore@nvidia.com>
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: svc-mobile-cert <svc-mobile-cert@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
---
 drivers/gpu/nvgpu/os/linux/debug_gr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/nvgpu/os/linux/debug_gr.c b/drivers/gpu/nvgpu/os/linux/debug_gr.c
index 1ebb865ff..13f5c6e99 100644
--- a/drivers/gpu/nvgpu/os/linux/debug_gr.c
+++ b/drivers/gpu/nvgpu/os/linux/debug_gr.c
@@ -17,6 +17,7 @@
 #include <nvgpu/gk20a.h>
 #include <nvgpu/gr/ctx.h>
 #include <nvgpu/nvgpu_init.h>
+#include <nvgpu/soc.h>
 
 #include "common/gr/ctx_priv.h"
 #include "common/gr/gr_priv.h"
@@ -84,6 +85,9 @@ static int cbc_status_debug_open(struct inode *inode, struct file *file)
 	if (!capable(CAP_SYS_ADMIN)) {
 		return -EPERM;
 	}
+	if (nvgpu_is_hypervisor_mode(g)) {
+		return -EPERM;
+	}
 	g = nvgpu_get(g);
 	if (!g) {
 		return -ENODEV;