diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 541 |
1 files changed, 376 insertions, 165 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 88a7ede322bd..b674fdf96208 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -37,6 +37,7 @@ #include <linux/cpuset.h> #include <linux/random.h> #include <linux/cc_platform.h> +#include <linux/parser.h> #include <trace/events/power.h> #define CREATE_TRACE_POINTS @@ -54,7 +55,6 @@ * @rollback: Perform a rollback * @single: Single callback invocation * @bringup: Single callback bringup or teardown selector - * @cpu: CPU number * @node: Remote CPU node; for multi-instance, do a * single entry callback for install/remove * @last: For multi-instance rollback, remember how far we got @@ -331,7 +331,7 @@ static bool cpuhp_wait_for_sync_state(unsigned int cpu, enum cpuhp_sync_state st /* Poll for one millisecond */ arch_cpuhp_sync_state_poll(); } else { - usleep_range_state(USEC_PER_MSEC, 2 * USEC_PER_MSEC, TASK_UNINTERRUPTIBLE); + usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC); } sync = atomic_read(st); } @@ -484,6 +484,8 @@ static int cpu_hotplug_disabled; DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); +static bool cpu_hotplug_offline_disabled __ro_after_init; + void cpus_read_lock(void) { percpu_down_read(&cpu_hotplug_lock); @@ -525,6 +527,7 @@ void lockdep_assert_cpus_held(void) percpu_rwsem_assert_held(&cpu_hotplug_lock); } +EXPORT_SYMBOL_GPL(lockdep_assert_cpus_held); #ifdef CONFIG_LOCKDEP int lockdep_is_cpus_held(void) @@ -543,6 +546,14 @@ static void lockdep_release_cpus_lock(void) rwsem_release(&cpu_hotplug_lock.dep_map, _THIS_IP_); } +/* Declare CPU offlining not supported */ +void cpu_hotplug_disable_offlining(void) +{ + cpu_maps_update_begin(); + cpu_hotplug_offline_disabled = true; + cpu_maps_update_done(); +} + /* * Wait for currently running CPU hotplug operations to complete (if any) and * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects @@ -592,7 +603,10 @@ static void lockdep_release_cpus_lock(void) void __weak arch_smt_update(void) { } #ifdef CONFIG_HOTPLUG_SMT + enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; +static unsigned int cpu_smt_max_threads __ro_after_init; +unsigned int cpu_smt_num_threads __read_mostly = UINT_MAX; void __init cpu_smt_disable(bool force) { @@ -606,16 +620,33 @@ void __init cpu_smt_disable(bool force) pr_info("SMT: disabled\n"); cpu_smt_control = CPU_SMT_DISABLED; } + cpu_smt_num_threads = 1; } /* * The decision whether SMT is supported can only be done after the full * CPU identification. Called from architecture code. */ -void __init cpu_smt_check_topology(void) +void __init cpu_smt_set_num_threads(unsigned int num_threads, + unsigned int max_threads) { - if (!topology_smt_supported()) + WARN_ON(!num_threads || (num_threads > max_threads)); + + if (max_threads == 1) cpu_smt_control = CPU_SMT_NOT_SUPPORTED; + + cpu_smt_max_threads = max_threads; + + /* + * If SMT has been disabled via the kernel command line or SMT is + * not supported, set cpu_smt_num_threads to 1 for consistency. + * If enabled, take the architecture requested number of threads + * to bring up into account. + */ + if (cpu_smt_control != CPU_SMT_ENABLED) + cpu_smt_num_threads = 1; + else if (num_threads < cpu_smt_num_threads) + cpu_smt_num_threads = num_threads; } static int __init smt_cmdline_disable(char *str) @@ -625,9 +656,31 @@ static int __init smt_cmdline_disable(char *str) } early_param("nosmt", smt_cmdline_disable); -static inline bool cpu_smt_allowed(unsigned int cpu) +/* + * For Archicture supporting partial SMT states check if the thread is allowed. + * Otherwise this has already been checked through cpu_smt_max_threads when + * setting the SMT level. + */ +static inline bool cpu_smt_thread_allowed(unsigned int cpu) +{ +#ifdef CONFIG_SMT_NUM_THREADS_DYNAMIC + return topology_smt_thread_allowed(cpu); +#else + return true; +#endif +} + +static inline bool cpu_bootable(unsigned int cpu) { - if (cpu_smt_control == CPU_SMT_ENABLED) + if (cpu_smt_control == CPU_SMT_ENABLED && cpu_smt_thread_allowed(cpu)) + return true; + + /* All CPUs are bootable if controls are not configured */ + if (cpu_smt_control == CPU_SMT_NOT_IMPLEMENTED) + return true; + + /* All CPUs are bootable if CPU is not SMT capable */ + if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED) return true; if (topology_is_primary_thread(cpu)) @@ -642,7 +695,7 @@ 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 */ +/* Returns true if SMT is supported and not forcefully (irreversibly) disabled */ bool cpu_smt_possible(void) { return cpu_smt_control != CPU_SMT_FORCE_DISABLED && @@ -650,22 +703,8 @@ bool cpu_smt_possible(void) } EXPORT_SYMBOL_GPL(cpu_smt_possible); -static inline bool cpuhp_smt_aware(void) -{ - return topology_smt_supported(); -} - -static inline const struct cpumask *cpuhp_get_primary_thread_mask(void) -{ - return cpu_primary_thread_mask; -} #else -static inline bool cpu_smt_allowed(unsigned int cpu) { return true; } -static inline bool cpuhp_smt_aware(void) { return false; } -static inline const struct cpumask *cpuhp_get_primary_thread_mask(void) -{ - return cpu_present_mask; -} +static inline bool cpu_bootable(unsigned int cpu) { return true; } #endif static inline enum cpuhp_state @@ -768,10 +807,10 @@ static int bringup_wait_for_ap_online(unsigned int cpu) * 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 notify_cpu_starting() so the - * cpu_smt_allowed() check will now return false if this is not the + * cpu_bootable() check will now return false if this is not the * primary sibling. */ - if (!cpu_smt_allowed(cpu)) + if (!cpu_bootable(cpu)) return -ECANCELED; return 0; } @@ -868,12 +907,13 @@ static int finish_cpu(unsigned int cpu) struct mm_struct *mm = idle->active_mm; /* - * idle_task_exit() will have switched to &init_mm, now - * clean up any remaining active_mm state. + * sched_force_init_mm() ensured the use of &init_mm, + * drop that refcount now that the CPU has stopped. */ - if (mm != &init_mm) - idle->active_mm = &init_mm; + WARN_ON(mm != &init_mm); + idle->active_mm = NULL; mmdrop_lazy_tlb(mm); + return 0; } @@ -1181,52 +1221,6 @@ void __init cpuhp_threads_init(void) kthread_unpark(this_cpu_read(cpuhp_state.thread)); } -/* - * - * Serialize hotplug trainwrecks outside of the cpu_hotplug_lock - * protected region. - * - * The operation is still serialized against concurrent CPU hotplug via - * cpu_add_remove_lock, i.e. CPU map protection. But it is _not_ - * serialized against other hotplug related activity like adding or - * removing of state callbacks and state instances, which invoke either the - * startup or the teardown callback of the affected state. - * - * This is required for subsystems which are unfixable vs. CPU hotplug and - * evade lock inversion problems by scheduling work which has to be - * completed _before_ cpu_up()/_cpu_down() returns. - * - * Don't even think about adding anything to this for any new code or even - * drivers. It's only purpose is to keep existing lock order trainwrecks - * working. - * - * For cpu_down() there might be valid reasons to finish cleanups which are - * not required to be done under cpu_hotplug_lock, but that's a different - * story and would be not invoked via this. - */ -static void cpu_up_down_serialize_trainwrecks(bool tasks_frozen) -{ - /* - * cpusets delegate hotplug operations to a worker to "solve" the - * lock order problems. Wait for the worker, but only if tasks are - * _not_ frozen (suspend, hibernate) as that would wait forever. - * - * The wait is required because otherwise the hotplug operation - * returns with inconsistent state, which could even be observed in - * user space when a new CPU is brought up. The CPU plug uevent - * would be delivered and user space reacting on it would fail to - * move tasks to the newly plugged CPU up to the point where the - * work has finished because up to that point the newly plugged CPU - * is not assignable in cpusets/cgroups. On unplug that's not - * necessarily a visible issue, but it is still inconsistent state, - * which is the real problem which needs to be "fixed". This can't - * prevent the transient state between scheduling the work and - * returning from waiting for it. - */ - if (!tasks_frozen) - cpuset_wait_for_hotplug(); -} - #ifdef CONFIG_HOTPLUG_CPU #ifndef arch_clear_mm_cpumask_cpu #define arch_clear_mm_cpumask_cpu(cpu, mm) cpumask_clear_cpu(cpu, mm_cpumask(mm)) @@ -1296,10 +1290,6 @@ static int take_cpu_down(void *_param) */ cpuhp_invoke_callback_range_nofail(false, cpu, st, target); - /* Give up timekeeping duties */ - tick_handover_do_timer(); - /* Remove CPU from timer broadcasting */ - tick_offline_cpu(cpu); /* Park the stopper thread */ stop_machine_park(cpu); return 0; @@ -1319,9 +1309,6 @@ static int takedown_cpu(unsigned int cpu) */ irq_lock_sparse(); - /* - * So now all preempt/rcu users must observe !cpu_active(). - */ err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu)); if (err) { /* CPU refused to die */ @@ -1351,8 +1338,15 @@ static int takedown_cpu(unsigned int cpu) cpuhp_bp_sync_dead(cpu); - tick_cleanup_dead_cpu(cpu); + lockdep_cleanup_dead_cpu(cpu, idle_thread_get(cpu)); + + /* + * Callbacks must be re-integrated right away to the RCU state machine. + * Otherwise an RCU callback could block a further teardown function + * waiting for its completion. + */ rcutree_migrate_callbacks(cpu); + return 0; } @@ -1368,10 +1362,11 @@ void cpuhp_report_idle_dead(void) struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state); BUG_ON(st->state != CPUHP_AP_OFFLINE); - rcu_report_dead(smp_processor_id()); + tick_assert_timekeeping_handover(); + rcutree_report_cpu_dead(); st->state = CPUHP_AP_IDLE_DEAD; /* - * We cannot call complete after rcu_report_dead() so we delegate it + * We cannot call complete after rcutree_report_cpu_dead() so we delegate it * to an online cpu. */ smp_call_function_single(cpumask_first(cpu_online_mask), @@ -1457,27 +1452,46 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, out: cpus_write_unlock(); - /* - * Do post unplug cleanup. This is still protected against - * concurrent CPU hotplug via cpu_add_remove_lock. - */ - lockup_detector_cleanup(); arch_smt_update(); - cpu_up_down_serialize_trainwrecks(tasks_frozen); return ret; } +struct cpu_down_work { + unsigned int cpu; + enum cpuhp_state target; +}; + +static long __cpu_down_maps_locked(void *arg) +{ + struct cpu_down_work *work = arg; + + return _cpu_down(work->cpu, 0, work->target); +} + static int cpu_down_maps_locked(unsigned int cpu, enum cpuhp_state target) { + struct cpu_down_work work = { .cpu = cpu, .target = target, }; + /* * If the platform does not support hotplug, report it explicitly to * differentiate it from a transient offlining failure. */ - if (cc_platform_has(CC_ATTR_HOTPLUG_DISABLED)) + if (cpu_hotplug_offline_disabled) return -EOPNOTSUPP; if (cpu_hotplug_disabled) return -EBUSY; - return _cpu_down(cpu, 0, target); + + /* + * Ensure that the control task does not run on the to be offlined + * CPU to prevent a deadlock against cfs_b->period_timer. + * Also keep at least one housekeeping cpu onlined to avoid generating + * an empty sched_domain span. + */ + for_each_cpu_and(cpu, cpu_online_mask, housekeeping_cpumask(HK_TYPE_DOMAIN)) { + if (cpu != work.cpu) + return work_on_cpu(cpu, __cpu_down_maps_locked, &work); + } + return -EBUSY; } static int cpu_down(unsigned int cpu, enum cpuhp_state target) @@ -1575,7 +1589,7 @@ void notify_cpu_starting(unsigned int cpu) struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu); enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE); - rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ + rcutree_report_cpu_starting(cpu); /* Enables RCU usage on this CPU. */ cpumask_set_cpu(cpu, &cpus_booted_once_mask); /* @@ -1672,7 +1686,6 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) out: cpus_write_unlock(); arch_smt_update(); - cpu_up_down_serialize_trainwrecks(tasks_frozen); return ret; } @@ -1683,9 +1696,6 @@ static int cpu_up(unsigned int cpu, enum cpuhp_state target) if (!cpu_possible(cpu)) { pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n", cpu); -#if defined(CONFIG_IA64) - pr_err("please check additional_cpus= boot parameter\n"); -#endif return -EINVAL; } @@ -1699,7 +1709,7 @@ static int cpu_up(unsigned int cpu, enum cpuhp_state target) err = -EBUSY; goto out; } - if (!cpu_smt_allowed(cpu)) { + if (!cpu_bootable(cpu)) { err = -EPERM; goto out; } @@ -1793,6 +1803,32 @@ static int __init parallel_bringup_parse_param(char *arg) } early_param("cpuhp.parallel", parallel_bringup_parse_param); +#ifdef CONFIG_HOTPLUG_SMT +static inline bool cpuhp_smt_aware(void) +{ + return cpu_smt_max_threads > 1; +} + +static inline const struct cpumask *cpuhp_get_primary_thread_mask(void) +{ + return cpu_primary_thread_mask; +} +#else +static inline bool cpuhp_smt_aware(void) +{ + return false; +} +static inline const struct cpumask *cpuhp_get_primary_thread_mask(void) +{ + return cpu_none_mask; +} +#endif + +bool __weak arch_cpuhp_init_parallel_bringup(void) +{ + return true; +} + /* * On architectures which have enabled parallel bringup this invokes all BP * prepare states for each of the to be onlined APs first. The last state @@ -1842,14 +1878,17 @@ static bool __init cpuhp_bringup_cpus_parallel(unsigned int ncpus) static inline bool cpuhp_bringup_cpus_parallel(unsigned int ncpus) { return false; } #endif /* CONFIG_HOTPLUG_PARALLEL */ -void __init bringup_nonboot_cpus(unsigned int setup_max_cpus) +void __init bringup_nonboot_cpus(unsigned int max_cpus) { + if (!max_cpus) + return; + /* Try parallel bringup optimization if enabled */ - if (cpuhp_bringup_cpus_parallel(setup_max_cpus)) + if (cpuhp_bringup_cpus_parallel(max_cpus)) return; /* Full per CPU serialized bringup */ - cpuhp_bringup_mask(cpu_present_mask, setup_max_cpus, CPUHP_ONLINE); + cpuhp_bringup_mask(cpu_present_mask, max_cpus, CPUHP_ONLINE); } #ifdef CONFIG_PM_SLEEP_SMP @@ -1876,8 +1915,8 @@ int freeze_secondary_cpus(int primary) cpumask_clear(frozen_cpus); pr_info("Disabling non-boot CPUs ...\n"); - for_each_online_cpu(cpu) { - if (cpu == primary) + for (cpu = nr_cpu_ids - 1; cpu >= 0; cpu--) { + if (!cpu_online(cpu) || cpu == primary) continue; if (pm_wakeup_pending()) { @@ -2028,11 +2067,6 @@ static struct cpuhp_step cpuhp_hp_states[] = { .teardown.single = NULL, .cant_stop = true, }, - [CPUHP_PERF_PREPARE] = { - .name = "perf:prepare", - .startup.single = perf_event_init_cpu, - .teardown.single = perf_event_exit_cpu, - }, [CPUHP_RANDOM_PREPARE] = { .name = "random:prepare", .startup.single = random_prepare_cpu, @@ -2046,7 +2080,7 @@ static struct cpuhp_step cpuhp_hp_states[] = { [CPUHP_HRTIMERS_PREPARE] = { .name = "hrtimers:prepare", .startup.single = hrtimers_prepare_cpu, - .teardown.single = hrtimers_dead_cpu, + .teardown.single = NULL, }, [CPUHP_SMPCFD_PREPARE] = { .name = "smpcfd:prepare", @@ -2058,11 +2092,6 @@ static struct cpuhp_step cpuhp_hp_states[] = { .startup.single = relay_prepare_cpu, .teardown.single = NULL, }, - [CPUHP_SLAB_PREPARE] = { - .name = "slab:prepare", - .startup.single = slab_prepare_cpu, - .teardown.single = slab_dead_cpu, - }, [CPUHP_RCUTREE_PREP] = { .name = "RCU/tree:prepare", .startup.single = rcutree_prepare_cpu, @@ -2138,6 +2167,16 @@ static struct cpuhp_step cpuhp_hp_states[] = { .startup.single = NULL, .teardown.single = smpcfd_dying_cpu, }, + [CPUHP_AP_HRTIMERS_DYING] = { + .name = "hrtimers:dying", + .startup.single = hrtimers_cpu_starting, + .teardown.single = hrtimers_cpu_dying, + }, + [CPUHP_AP_TICK_DYING] = { + .name = "tick:dying", + .startup.single = NULL, + .teardown.single = tick_cpu_dying, + }, /* Entry state on starting. Interrupts enabled from here on. Transient * state for synchronsization */ [CPUHP_AP_ONLINE] = { @@ -2426,7 +2465,7 @@ EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance); * The caller needs to hold cpus read locked while calling this function. * Return: * On success: - * Positive state number if @state is CPUHP_AP_ONLINE_DYN; + * Positive state number if @state is CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN; * 0 for all other states * On failure: proper (negative) error code */ @@ -2449,7 +2488,7 @@ int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, ret = cpuhp_store_callbacks(state, name, startup, teardown, multi_instance); - dynstate = state == CPUHP_AP_ONLINE_DYN; + dynstate = state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN; if (ret > 0 && dynstate) { state = ret; ret = 0; @@ -2480,8 +2519,8 @@ int __cpuhp_setup_state_cpuslocked(enum cpuhp_state state, out: mutex_unlock(&cpuhp_state_mutex); /* - * If the requested state is CPUHP_AP_ONLINE_DYN, return the - * dynamically allocated state in case of success. + * If the requested state is CPUHP_AP_ONLINE_DYN or CPUHP_BP_PREPARE_DYN, + * return the dynamically allocated state in case of success. */ if (!ret && dynstate) return state; @@ -2626,6 +2665,12 @@ int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) for_each_online_cpu(cpu) { if (topology_is_primary_thread(cpu)) continue; + /* + * Disable can be called with CPU_SMT_ENABLED when changing + * from a higher to lower number of SMT threads per core. + */ + if (ctrlval == CPU_SMT_ENABLED && cpu_smt_thread_allowed(cpu)) + continue; ret = cpu_down_maps_locked(cpu, CPUHP_OFFLINE); if (ret) break; @@ -2650,6 +2695,14 @@ int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) return ret; } +/* Check if the core a CPU belongs to is online */ +#if !defined(topology_is_core_online) +static inline bool topology_is_core_online(unsigned int cpu) +{ + return true; +} +#endif + int cpuhp_smt_enable(void) { int cpu, ret = 0; @@ -2660,6 +2713,8 @@ int cpuhp_smt_enable(void) /* Skip online CPUs and CPUs on offline nodes */ if (cpu_online(cpu) || !node_online(cpu_to_node(cpu))) continue; + if (!cpu_smt_thread_allowed(cpu) || !topology_is_core_online(cpu)) + continue; ret = _cpu_up(cpu, 0, CPUHP_ONLINE); if (ret) break; @@ -2801,7 +2856,6 @@ static struct attribute *cpuhp_cpu_attrs[] = { static const struct attribute_group cpuhp_cpu_attr_group = { .attrs = cpuhp_cpu_attrs, .name = "hotplug", - NULL }; static ssize_t states_show(struct device *dev, @@ -2833,25 +2887,23 @@ static struct attribute *cpuhp_cpu_root_attrs[] = { static const struct attribute_group cpuhp_cpu_root_attr_group = { .attrs = cpuhp_cpu_root_attrs, .name = "hotplug", - NULL }; #ifdef CONFIG_HOTPLUG_SMT +static bool cpu_smt_num_threads_valid(unsigned int threads) +{ + if (IS_ENABLED(CONFIG_SMT_NUM_THREADS_DYNAMIC)) + return threads >= 1 && threads <= cpu_smt_max_threads; + return threads == 1 || threads == cpu_smt_max_threads; +} + static ssize_t __store_smt_control(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { - int ctrlval, ret; - - if (sysfs_streq(buf, "on")) - ctrlval = CPU_SMT_ENABLED; - else if (sysfs_streq(buf, "off")) - ctrlval = CPU_SMT_DISABLED; - else if (sysfs_streq(buf, "forceoff")) - ctrlval = CPU_SMT_FORCE_DISABLED; - else - return -EINVAL; + int ctrlval, ret, num_threads, orig_threads; + bool force_off; if (cpu_smt_control == CPU_SMT_FORCE_DISABLED) return -EPERM; @@ -2859,21 +2911,39 @@ __store_smt_control(struct device *dev, struct device_attribute *attr, if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED) return -ENODEV; + if (sysfs_streq(buf, "on")) { + ctrlval = CPU_SMT_ENABLED; + num_threads = cpu_smt_max_threads; + } else if (sysfs_streq(buf, "off")) { + ctrlval = CPU_SMT_DISABLED; + num_threads = 1; + } else if (sysfs_streq(buf, "forceoff")) { + ctrlval = CPU_SMT_FORCE_DISABLED; + num_threads = 1; + } else if (kstrtoint(buf, 10, &num_threads) == 0) { + if (num_threads == 1) + ctrlval = CPU_SMT_DISABLED; + else if (cpu_smt_num_threads_valid(num_threads)) + ctrlval = CPU_SMT_ENABLED; + else + return -EINVAL; + } else { + return -EINVAL; + } + ret = lock_device_hotplug_sysfs(); if (ret) return ret; - if (ctrlval != cpu_smt_control) { - switch (ctrlval) { - case CPU_SMT_ENABLED: - ret = cpuhp_smt_enable(); - break; - case CPU_SMT_DISABLED: - case CPU_SMT_FORCE_DISABLED: - ret = cpuhp_smt_disable(ctrlval); - break; - } - } + orig_threads = cpu_smt_num_threads; + cpu_smt_num_threads = num_threads; + + force_off = ctrlval != cpu_smt_control && ctrlval == CPU_SMT_FORCE_DISABLED; + + if (num_threads > orig_threads) + ret = cpuhp_smt_enable(); + else if (num_threads < orig_threads || force_off) + ret = cpuhp_smt_disable(ctrlval); unlock_device_hotplug(); return ret ? ret : count; @@ -2901,7 +2971,18 @@ static ssize_t control_show(struct device *dev, { const char *state = smt_states[cpu_smt_control]; - return snprintf(buf, PAGE_SIZE - 2, "%s\n", state); +#ifdef CONFIG_HOTPLUG_SMT + /* + * If SMT is enabled but not all threads are enabled then show the + * number of threads. If all threads are enabled show "on". Otherwise + * show the state name. + */ + if (cpu_smt_control == CPU_SMT_ENABLED && + cpu_smt_num_threads != cpu_smt_max_threads) + return sysfs_emit(buf, "%d\n", cpu_smt_num_threads); +#endif + + return sysfs_emit(buf, "%s\n", state); } static ssize_t control_store(struct device *dev, struct device_attribute *attr, @@ -2914,7 +2995,7 @@ static DEVICE_ATTR_RW(control); static ssize_t active_show(struct device *dev, struct device_attribute *attr, char *buf) { - return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active()); + return sysfs_emit(buf, "%d\n", sched_smt_active()); } static DEVICE_ATTR_RO(active); @@ -2927,7 +3008,6 @@ static struct attribute *cpuhp_smt_attrs[] = { static const struct attribute_group cpuhp_smt_attr_group = { .attrs = cpuhp_smt_attrs, .name = "smt", - NULL }; static int __init cpu_smt_sysfs_init(void) @@ -3003,16 +3083,22 @@ const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL; EXPORT_SYMBOL(cpu_all_bits); #ifdef CONFIG_INIT_ALL_POSSIBLE -struct cpumask __cpu_possible_mask __read_mostly +struct cpumask __cpu_possible_mask __ro_after_init = {CPU_BITS_ALL}; +unsigned int __num_possible_cpus __ro_after_init = NR_CPUS; #else -struct cpumask __cpu_possible_mask __read_mostly; +struct cpumask __cpu_possible_mask __ro_after_init; +unsigned int __num_possible_cpus __ro_after_init; #endif EXPORT_SYMBOL(__cpu_possible_mask); +EXPORT_SYMBOL(__num_possible_cpus); struct cpumask __cpu_online_mask __read_mostly; EXPORT_SYMBOL(__cpu_online_mask); +struct cpumask __cpu_enabled_mask __read_mostly; +EXPORT_SYMBOL(__cpu_enabled_mask); + struct cpumask __cpu_present_mask __read_mostly; EXPORT_SYMBOL(__cpu_present_mask); @@ -3033,11 +3119,7 @@ void init_cpu_present(const struct cpumask *src) void init_cpu_possible(const struct cpumask *src) { cpumask_copy(&__cpu_possible_mask, src); -} - -void init_cpu_online(const struct cpumask *src) -{ - cpumask_copy(&__cpu_online_mask, src); + __num_possible_cpus = cpumask_weight(&__cpu_possible_mask); } void set_cpu_online(unsigned int cpu, bool online) @@ -3062,6 +3144,21 @@ void set_cpu_online(unsigned int cpu, bool online) } /* + * This should be marked __init, but there is a boatload of call sites + * which need to be fixed up to do so. Sigh... + */ +void set_cpu_possible(unsigned int cpu, bool possible) +{ + if (possible) { + if (!cpumask_test_and_set_cpu(cpu, &__cpu_possible_mask)) + __num_possible_cpus++; + } else { + if (cpumask_test_and_clear_cpu(cpu, &__cpu_possible_mask)) + __num_possible_cpus--; + } +} + +/* * Activate the first processor. */ void __init boot_cpu_init(void) @@ -3092,9 +3189,40 @@ void __init boot_cpu_hotplug_init(void) this_cpu_write(cpuhp_state.target, CPUHP_ONLINE); } +#ifdef CONFIG_CPU_MITIGATIONS +/* + * All except the cross-thread attack vector are mitigated by default. + * Cross-thread mitigation often requires disabling SMT which is expensive + * so cross-thread mitigations are only partially enabled by default. + * + * Guest-to-Host and Guest-to-Guest vectors are only needed if KVM support is + * present. + */ +static bool attack_vectors[NR_CPU_ATTACK_VECTORS] __ro_after_init = { + [CPU_MITIGATE_USER_KERNEL] = true, + [CPU_MITIGATE_USER_USER] = true, + [CPU_MITIGATE_GUEST_HOST] = IS_ENABLED(CONFIG_KVM), + [CPU_MITIGATE_GUEST_GUEST] = IS_ENABLED(CONFIG_KVM), +}; + +bool cpu_attack_vector_mitigated(enum cpu_attack_vectors v) +{ + if (v < NR_CPU_ATTACK_VECTORS) + return attack_vectors[v]; + + WARN_ONCE(1, "Invalid attack vector %d\n", v); + return false; +} + /* - * These are used for a global "mitigations=" cmdline option for toggling - * optional CPU mitigations. + * There are 3 global options, 'off', 'auto', 'auto,nosmt'. These may optionally + * be combined with attack-vector disables which follow them. + * + * Examples: + * mitigations=auto,no_user_kernel,no_user_user,no_cross_thread + * mitigations=auto,nosmt,no_guest_host,no_guest_guest + * + * mitigations=off is equivalent to disabling all attack vectors. */ enum cpu_mitigations { CPU_MITIGATIONS_OFF, @@ -3102,24 +3230,99 @@ enum cpu_mitigations { CPU_MITIGATIONS_AUTO_NOSMT, }; -static enum cpu_mitigations cpu_mitigations __ro_after_init = - CPU_MITIGATIONS_AUTO; +enum { + NO_USER_KERNEL, + NO_USER_USER, + NO_GUEST_HOST, + NO_GUEST_GUEST, + NO_CROSS_THREAD, + NR_VECTOR_PARAMS, +}; + +enum smt_mitigations smt_mitigations __ro_after_init = SMT_MITIGATIONS_AUTO; +static enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO; + +static const match_table_t global_mitigations = { + { CPU_MITIGATIONS_AUTO_NOSMT, "auto,nosmt"}, + { CPU_MITIGATIONS_AUTO, "auto"}, + { CPU_MITIGATIONS_OFF, "off"}, +}; + +static const match_table_t vector_mitigations = { + { NO_USER_KERNEL, "no_user_kernel"}, + { NO_USER_USER, "no_user_user"}, + { NO_GUEST_HOST, "no_guest_host"}, + { NO_GUEST_GUEST, "no_guest_guest"}, + { NO_CROSS_THREAD, "no_cross_thread"}, + { NR_VECTOR_PARAMS, NULL}, +}; + +static int __init mitigations_parse_global_opt(char *arg) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(global_mitigations); i++) { + const char *pattern = global_mitigations[i].pattern; + + if (!strncmp(arg, pattern, strlen(pattern))) { + cpu_mitigations = global_mitigations[i].token; + return strlen(pattern); + } + } + + return 0; +} static int __init mitigations_parse_cmdline(char *arg) { - if (!strcmp(arg, "off")) - cpu_mitigations = CPU_MITIGATIONS_OFF; - else if (!strcmp(arg, "auto")) - cpu_mitigations = CPU_MITIGATIONS_AUTO; - else if (!strcmp(arg, "auto,nosmt")) - cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT; - else - pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n", - arg); + char *s, *p; + int len; + + len = mitigations_parse_global_opt(arg); + + if (cpu_mitigations_off()) { + memset(attack_vectors, 0, sizeof(attack_vectors)); + smt_mitigations = SMT_MITIGATIONS_OFF; + } else if (cpu_mitigations_auto_nosmt()) { + smt_mitigations = SMT_MITIGATIONS_ON; + } + + p = arg + len; + + if (!*p) + return 0; + + /* Attack vector controls may come after the ',' */ + if (*p++ != ',' || !IS_ENABLED(CONFIG_ARCH_HAS_CPU_ATTACK_VECTORS)) { + pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n", arg); + return 0; + } + + while ((s = strsep(&p, ",")) != NULL) { + switch (match_token(s, vector_mitigations, NULL)) { + case NO_USER_KERNEL: + attack_vectors[CPU_MITIGATE_USER_KERNEL] = false; + break; + case NO_USER_USER: + attack_vectors[CPU_MITIGATE_USER_USER] = false; + break; + case NO_GUEST_HOST: + attack_vectors[CPU_MITIGATE_GUEST_HOST] = false; + break; + case NO_GUEST_GUEST: + attack_vectors[CPU_MITIGATE_GUEST_GUEST] = false; + break; + case NO_CROSS_THREAD: + smt_mitigations = SMT_MITIGATIONS_OFF; + break; + default: + pr_crit("Unsupported mitigations options %s\n", s); + return 0; + } + } return 0; } -early_param("mitigations", mitigations_parse_cmdline); /* mitigations=off */ bool cpu_mitigations_off(void) @@ -3134,3 +3337,11 @@ bool cpu_mitigations_auto_nosmt(void) return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT; } EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt); +#else +static int __init mitigations_parse_cmdline(char *arg) +{ + pr_crit("Kernel compiled without mitigations, ignoring 'mitigations'; system may still be vulnerable\n"); + return 0; +} +#endif +early_param("mitigations", mitigations_parse_cmdline); |