diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cpu.c | 72 |
1 files changed, 48 insertions, 24 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 0fbf3e59cf14..49acbd2fa81a 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -54,6 +54,7 @@ struct cpuhp_cpu_state { bool rollback; bool single; bool bringup; + bool booted_once; struct hlist_node *node; enum cpuhp_state cb_state; int result; @@ -355,6 +356,40 @@ void cpu_hotplug_enable(void) EXPORT_SYMBOL_GPL(cpu_hotplug_enable); #endif /* CONFIG_HOTPLUG_CPU */ +#ifdef CONFIG_HOTPLUG_SMT +enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; + +static int __init smt_cmdline_disable(char *str) +{ + cpu_smt_control = CPU_SMT_DISABLED; + if (str && !strcmp(str, "force")) { + pr_info("SMT: Force disabled\n"); + cpu_smt_control = CPU_SMT_FORCE_DISABLED; + } + return 0; +} +early_param("nosmt", smt_cmdline_disable); + +static inline bool cpu_smt_allowed(unsigned int cpu) +{ + if (cpu_smt_control == CPU_SMT_ENABLED) + return true; + + if (topology_is_primary_thread(cpu)) + return true; + + /* + * On x86 it's required to boot all logical CPUs at least once so + * that the init code can get a chance to set CR4.MCE on each + * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any + * core will shutdown the machine. + */ + return !per_cpu(cpuhp_state, cpu).booted_once; +} +#else +static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } +#endif + /* Need to know about CPUs going up/down? */ int register_cpu_notifier(struct notifier_block *nb) { @@ -431,6 +466,16 @@ static int bringup_wait_for_ap(unsigned int cpu) stop_machine_unpark(cpu); kthread_unpark(st->thread); + /* + * SMT soft disabling on X86 requires to bring the CPU out of the + * BIOS 'wait for SIPI' state in order to set the CR4.MCE bit. The + * CPU marked itself as booted_once in cpu_notify_starting() so the + * cpu_smt_allowed() check will now return false if this is not the + * primary sibling. + */ + if (!cpu_smt_allowed(cpu)) + return -ECANCELED; + /* Should we go further up ? */ if (st->target > CPUHP_AP_ONLINE_IDLE) { __cpuhp_kick_ap_work(st); @@ -978,29 +1023,6 @@ int cpu_down(unsigned int cpu) EXPORT_SYMBOL(cpu_down); #endif /*CONFIG_HOTPLUG_CPU*/ -#ifdef CONFIG_HOTPLUG_SMT -enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; - -static int __init smt_cmdline_disable(char *str) -{ - cpu_smt_control = CPU_SMT_DISABLED; - if (str && !strcmp(str, "force")) { - pr_info("SMT: Force disabled\n"); - cpu_smt_control = CPU_SMT_FORCE_DISABLED; - } - return 0; -} -early_param("nosmt", smt_cmdline_disable); - -static inline bool cpu_smt_allowed(unsigned int cpu) -{ - return cpu_smt_control == CPU_SMT_ENABLED || - topology_is_primary_thread(cpu); -} -#else -static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } -#endif - /** * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU * @cpu: cpu that just started @@ -1014,6 +1036,7 @@ void notify_cpu_starting(unsigned int cpu) enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ + st->booted_once = true; while (st->state < target) { st->state++; cpuhp_invoke_callback(cpu, st->state, true, NULL); @@ -2114,5 +2137,6 @@ void __init boot_cpu_init(void) */ void __init boot_cpu_hotplug_init(void) { - per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE; + this_cpu_write(cpuhp_state.booted_once, true); + this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); } |