diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 73 |
1 files changed, 66 insertions, 7 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index e84c0873559e..e2cad3ee2ead 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -62,7 +62,6 @@ struct cpuhp_cpu_state { bool rollback; bool single; bool bringup; - bool booted_once; struct hlist_node *node; struct hlist_node *last; enum cpuhp_state cb_state; @@ -76,6 +75,10 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = { .fail = CPUHP_INVALID, }; +#ifdef CONFIG_SMP +cpumask_t cpus_booted_once_mask; +#endif + #if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP) static struct lockdep_map cpuhp_state_up_map = STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map); @@ -389,8 +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) { @@ -433,8 +435,16 @@ static inline bool cpu_smt_allowed(unsigned int cpu) * CPU. Otherwise, a broadacasted MCE observing CR4.MCE=0b on any * core will shutdown the machine. */ - return !per_cpu(cpuhp_state, cpu).booted_once; + 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 @@ -1066,7 +1076,7 @@ void notify_cpu_starting(unsigned int cpu) int ret; rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ - st->booted_once = true; + cpumask_set_cpu(cpu, &cpus_booted_once_mask); while (st->state < target) { st->state++; ret = cpuhp_invoke_callback(cpu, st->state, true, NULL, NULL); @@ -2295,6 +2305,9 @@ EXPORT_SYMBOL(__cpu_present_mask); struct cpumask __cpu_active_mask __read_mostly; EXPORT_SYMBOL(__cpu_active_mask); +atomic_t __num_online_cpus __read_mostly; +EXPORT_SYMBOL(__num_online_cpus); + void init_cpu_present(const struct cpumask *src) { cpumask_copy(&__cpu_present_mask, src); @@ -2310,6 +2323,27 @@ void init_cpu_online(const struct cpumask *src) cpumask_copy(&__cpu_online_mask, src); } +void set_cpu_online(unsigned int cpu, bool online) +{ + /* + * atomic_inc/dec() is required to handle the horrid abuse of this + * function by the reboot and kexec code which invoke it from + * IPI/NMI broadcasts when shutting down CPUs. Invocation from + * regular CPU hotplug is properly serialized. + * + * Note, that the fact that __num_online_cpus is of type atomic_t + * does not protect readers which are not serialized against + * concurrent hotplug operations. + */ + if (online) { + if (!cpumask_test_and_set_cpu(cpu, &__cpu_online_mask)) + atomic_inc(&__num_online_cpus); + } else { + if (cpumask_test_and_clear_cpu(cpu, &__cpu_online_mask)) + atomic_dec(&__num_online_cpus); + } +} + /* * Activate the first processor. */ @@ -2334,12 +2368,23 @@ void __init boot_cpu_init(void) void __init boot_cpu_hotplug_init(void) { #ifdef CONFIG_SMP - this_cpu_write(cpuhp_state.booted_once, true); + cpumask_set_cpu(smp_processor_id(), &cpus_booted_once_mask); #endif this_cpu_write(cpuhp_state.state, CPUHP_ONLINE); } -enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO; +/* + * These are used for a global "mitigations=" cmdline option for toggling + * optional CPU mitigations. + */ +enum cpu_mitigations { + CPU_MITIGATIONS_OFF, + CPU_MITIGATIONS_AUTO, + CPU_MITIGATIONS_AUTO_NOSMT, +}; + +static enum cpu_mitigations cpu_mitigations __ro_after_init = + CPU_MITIGATIONS_AUTO; static int __init mitigations_parse_cmdline(char *arg) { @@ -2356,3 +2401,17 @@ static int __init mitigations_parse_cmdline(char *arg) return 0; } early_param("mitigations", mitigations_parse_cmdline); + +/* mitigations=off */ +bool cpu_mitigations_off(void) +{ + return cpu_mitigations == CPU_MITIGATIONS_OFF; +} +EXPORT_SYMBOL_GPL(cpu_mitigations_off); + +/* mitigations=auto,nosmt */ +bool cpu_mitigations_auto_nosmt(void) +{ + return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT; +} +EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt); |