[PATCH] drm/amdgpu: Check if NBIO funcs are NULL in amdgpu_device_baco_exit

[Alex Deucher <alexander.deucher@amd.com>]

From: Friedrich Vock <friedrich.vock@gmx.de>

The special case for VM passthrough doesn't check adev->nbio.funcs
before dereferencing it. If GPUs that don't have an NBIO block are
passed through, this leads to a NULL pointer dereference on startup.

Signed-off-by: Friedrich Vock <friedrich.vock@gmx.de>
Fixes: 1bece222eabe ("drm/amdgpu: Clear doorbell interrupt status for Sienna Cichlid")
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3558
Cc: stable@vger.kernel.org # 5.15.x
(cherry picked from commit 0cdb3f9740844b9d95ca413e3fcff11f81223ecf)
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 5f6c32ec674d..300d3b236bb3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -5531,7 +5531,7 @@ int amdgpu_device_baco_exit(struct drm_device *dev)
 	    adev->nbio.funcs->enable_doorbell_interrupt)
 		adev->nbio.funcs->enable_doorbell_interrupt(adev, true);
 
-	if (amdgpu_passthrough(adev) &&
+	if (amdgpu_passthrough(adev) && adev->nbio.funcs &&
 	    adev->nbio.funcs->clear_doorbell_interrupt)
 		adev->nbio.funcs->clear_doorbell_interrupt(adev);
 
-- 
2.46.0