diff --git a/src/arch/x86/include/arch/cpu.h b/src/arch/x86/include/arch/cpu.h
index 32717ba5b3..293ca02158 100644
--- a/src/arch/x86/include/arch/cpu.h
+++ b/src/arch/x86/include/arch/cpu.h
@@ -203,9 +203,10 @@ static inline unsigned int cpuid_edx(unsigned int op)
 unsigned int cpu_cpuid_extended_level(void);
 int cpu_have_cpuid(void);
 
+/* Only with !PARALLEL_MP. */
 void smm_init(void);
 void smm_init_completion(void);
-void smm_lock(void);
+
 void smm_setup_structures(void *gnvs, void *tcg, void *smi1);
 
 static inline bool cpu_is_amd(void)
diff --git a/src/cpu/intel/haswell/haswell.h b/src/cpu/intel/haswell/haswell.h
index 4ebbe183b7..cd8d5cb52b 100644
--- a/src/cpu/intel/haswell/haswell.h
+++ b/src/cpu/intel/haswell/haswell.h
@@ -166,6 +166,7 @@ void smm_info(uintptr_t *perm_smbase, size_t *perm_smsize,
 		size_t *smm_save_state_size);
 void smm_initialize(void);
 void smm_relocate(void);
+void smm_lock(void);
 struct bus;
 void bsp_init_and_start_aps(struct bus *cpu_bus);
 /* Determine if HyperThreading is disabled. The variable is not valid until
diff --git a/src/cpu/intel/smm/gen1/smi.h b/src/cpu/intel/smm/gen1/smi.h
index 05c507c09c..3d5149a430 100644
--- a/src/cpu/intel/smm/gen1/smi.h
+++ b/src/cpu/intel/smm/gen1/smi.h
@@ -31,3 +31,4 @@ void southbridge_smm_clear_state(void);
 void smm_relocation_handler(int cpu, uintptr_t curr_smbase,
 			uintptr_t staggered_smbase);
 void smm_relocate(void);
+void smm_lock(void);
diff --git a/src/soc/intel/broadwell/include/soc/smm.h b/src/soc/intel/broadwell/include/soc/smm.h
index 75e78337c2..d3e1cddb81 100644
--- a/src/soc/intel/broadwell/include/soc/smm.h
+++ b/src/soc/intel/broadwell/include/soc/smm.h
@@ -59,6 +59,7 @@ void smm_info(uintptr_t *perm_smbase, size_t *perm_smsize,
 		size_t *smm_save_state_size);
 void smm_initialize(void);
 void smm_relocate(void);
+void smm_lock(void);
 
 /* These helpers are for performing SMM relocation. */
 void southbridge_trigger_smi(void);
diff --git a/src/soc/intel/cannonlake/include/soc/smm.h b/src/soc/intel/cannonlake/include/soc/smm.h
index e1c819ba14..c0ab82f0b7 100644
--- a/src/soc/intel/cannonlake/include/soc/smm.h
+++ b/src/soc/intel/cannonlake/include/soc/smm.h
@@ -56,5 +56,6 @@ void smm_info(uintptr_t *perm_smbase, size_t *perm_smsize,
 		size_t *smm_save_state_size);
 void smm_initialize(void);
 void smm_relocate(void);
+void smm_lock(void);
 
 #endif
diff --git a/src/soc/intel/fsp_broadwell_de/include/soc/smm.h b/src/soc/intel/fsp_broadwell_de/include/soc/smm.h
index 505feaf66d..72aa7fa4f2 100644
--- a/src/soc/intel/fsp_broadwell_de/include/soc/smm.h
+++ b/src/soc/intel/fsp_broadwell_de/include/soc/smm.h
@@ -60,6 +60,7 @@ void smm_info(uintptr_t *perm_smbase, size_t *perm_smsize,
 		size_t *smm_save_state_size);
 void smm_initialize(void);
 void smm_relocate(void);
+void smm_lock(void);
 
 /* These helpers are for performing SMM relocation. */
 void southbridge_trigger_smi(void);
diff --git a/src/soc/intel/icelake/include/soc/smm.h b/src/soc/intel/icelake/include/soc/smm.h
index 3c66f57d43..991c593f72 100644
--- a/src/soc/intel/icelake/include/soc/smm.h
+++ b/src/soc/intel/icelake/include/soc/smm.h
@@ -55,5 +55,6 @@ void smm_info(uintptr_t *perm_smbase, size_t *perm_smsize,
 		size_t *smm_save_state_size);
 void smm_initialize(void);
 void smm_relocate(void);
+void smm_lock(void);
 
 #endif
diff --git a/src/soc/intel/skylake/include/soc/smm.h b/src/soc/intel/skylake/include/soc/smm.h
index 7114a80b08..0c5e9766c0 100644
--- a/src/soc/intel/skylake/include/soc/smm.h
+++ b/src/soc/intel/skylake/include/soc/smm.h
@@ -54,5 +54,6 @@ void smm_info(uintptr_t *perm_smbase, size_t *perm_smsize,
 		size_t *smm_save_state_size);
 void smm_initialize(void);
 void smm_relocate(void);
+void smm_lock(void);
 
 #endif