drm/amd: check num of link levels when update pcie param

commit 406e8845356d18bdf3d3a23b347faf67706472ec upstream.

In SR-IOV environment, the value of pcie_table->num_of_link_levels will
be 0, and num_of_levels - 1 will cause array index out of bounds

Signed-off-by: Lin.Cao <[email protected]>
Acked-by: Jingwen Chen <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
[ Resolve minor conflicts to fix CVE-2023-52812 ]
Signed-off-by: Bin Lan <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Lin.Cao

drivers/gpu/drm/amd/pm/swsmu/smu13/smu_v13_0.c

@@ -2498,6 +2498,9 @@ int smu_v13_0_update_pcie_parameters(struct smu_context *smu,
 	uint32_t smu_pcie_arg;
 	int ret, i;
 
+	if (!num_of_levels)
+		return 0;
+
 	if (!amdgpu_device_pcie_dynamic_switching_supported()) {
 		if (pcie_table->pcie_gen[num_of_levels - 1] < pcie_gen_cap)
 			pcie_gen_cap = pcie_table->pcie_gen[num_of_levels - 1];