Commit e1572f1d authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
Browse files

cpu/SMT: create and export cpu_smt_possible() 



KVM needs to know if SMT is theoretically possible, this means it is
supported and not forcefully disabled ('nosmt=force'). Create and
export cpu_smt_possible() answering this question.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a073d7e3

include/linux/cpu.h

+2 −0
Original line number Diff line number Diff line
@@ -201,12 +201,14 @@ enum cpuhp_smt_control { 
extern enum cpuhp_smt_control cpu_smt_control;

extern void cpu_smt_disable(bool force);

extern void cpu_smt_check_topology(void);

extern bool cpu_smt_possible(void);

extern int cpuhp_smt_enable(void);

extern int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval);

#else

# define cpu_smt_control		(CPU_SMT_NOT_IMPLEMENTED)

static inline void cpu_smt_disable(bool force) { }

static inline void cpu_smt_check_topology(void) { }

static inline bool cpu_smt_possible(void) { return false; }

static inline int cpuhp_smt_enable(void) { return 0; }

static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }

#endif

kernel/cpu.c

+9 −2
Original line number Diff line number Diff line
@@ -392,8 +392,7 @@ enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; 


void __init cpu_smt_disable(bool force)

{

	if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||

		cpu_smt_control == CPU_SMT_NOT_SUPPORTED)

	if (!cpu_smt_possible())

		return;



	if (force) {
@@ -438,6 +437,14 @@ static inline bool cpu_smt_allowed(unsigned int cpu) 
	 */

	return !cpumask_test_cpu(cpu, &cpus_booted_once_mask);

}



/* Returns true if SMT is not supported of forcefully (irreversibly) disabled */

bool cpu_smt_possible(void)

{

	return cpu_smt_control != CPU_SMT_FORCE_DISABLED &&

		cpu_smt_control != CPU_SMT_NOT_SUPPORTED;

}

EXPORT_SYMBOL_GPL(cpu_smt_possible);

#else

static inline bool cpu_smt_allowed(unsigned int cpu) { return true; }

#endif