#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/rcupdate.h>
+#include <linux/delay.h>
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/kthread.h>
* @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
* @cb_state: The state for a single callback (install/uninstall)
* @result: Result of the operation
+ * @ap_sync_state: State for AP synchronization
* @done_up: Signal completion to the issuer of the task for cpu-up
* @done_down: Signal completion to the issuer of the task for cpu-down
*/
struct hlist_node *last;
enum cpuhp_state cb_state;
int result;
+ atomic_t ap_sync_state;
struct completion done_up;
struct completion done_down;
#endif
return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;
}
+/* Synchronization state management */
+enum cpuhp_sync_state {
+ SYNC_STATE_DEAD,
+ SYNC_STATE_KICKED,
+ SYNC_STATE_SHOULD_DIE,
+ SYNC_STATE_ALIVE,
+ SYNC_STATE_SHOULD_ONLINE,
+ SYNC_STATE_ONLINE,
+};
+
+#ifdef CONFIG_HOTPLUG_CORE_SYNC
+/**
+ * cpuhp_ap_update_sync_state - Update synchronization state during bringup/teardown
+ * @state: The synchronization state to set
+ *
+ * No synchronization point. Just update of the synchronization state, but implies
+ * a full barrier so that the AP changes are visible before the control CPU proceeds.
+ */
+static inline void cpuhp_ap_update_sync_state(enum cpuhp_sync_state state)
+{
+ atomic_t *st = this_cpu_ptr(&cpuhp_state.ap_sync_state);
+
+ (void)atomic_xchg(st, state);
+}
+
+void __weak arch_cpuhp_sync_state_poll(void) { cpu_relax(); }
+
+static bool cpuhp_wait_for_sync_state(unsigned int cpu, enum cpuhp_sync_state state,
+ enum cpuhp_sync_state next_state)
+{
+ atomic_t *st = per_cpu_ptr(&cpuhp_state.ap_sync_state, cpu);
+ ktime_t now, end, start = ktime_get();
+ int sync;
+
+ end = start + 10ULL * NSEC_PER_SEC;
+
+ sync = atomic_read(st);
+ while (1) {
+ if (sync == state) {
+ if (!atomic_try_cmpxchg(st, &sync, next_state))
+ continue;
+ return true;
+ }
+
+ now = ktime_get();
+ if (now > end) {
+ /* Timeout. Leave the state unchanged */
+ return false;
+ } else if (now - start < NSEC_PER_MSEC) {
+ /* Poll for one millisecond */
+ arch_cpuhp_sync_state_poll();
+ } else {
+ usleep_range_state(USEC_PER_MSEC, 2 * USEC_PER_MSEC, TASK_UNINTERRUPTIBLE);
+ }
+ sync = atomic_read(st);
+ }
+ return true;
+}
+#else /* CONFIG_HOTPLUG_CORE_SYNC */
+static inline void cpuhp_ap_update_sync_state(enum cpuhp_sync_state state) { }
+#endif /* !CONFIG_HOTPLUG_CORE_SYNC */
+
+#ifdef CONFIG_HOTPLUG_CORE_SYNC_DEAD
+/**
+ * cpuhp_ap_report_dead - Update synchronization state to DEAD
+ *
+ * No synchronization point. Just update of the synchronization state.
+ */
+void cpuhp_ap_report_dead(void)
+{
+ cpuhp_ap_update_sync_state(SYNC_STATE_DEAD);
+}
+
+void __weak arch_cpuhp_cleanup_dead_cpu(unsigned int cpu) { }
+
+/*
+ * Late CPU shutdown synchronization point. Cannot use cpuhp_state::done_down
+ * because the AP cannot issue complete() at this stage.
+ */
+static void cpuhp_bp_sync_dead(unsigned int cpu)
+{
+ atomic_t *st = per_cpu_ptr(&cpuhp_state.ap_sync_state, cpu);
+ int sync = atomic_read(st);
+
+ do {
+ /* CPU can have reported dead already. Don't overwrite that! */
+ if (sync == SYNC_STATE_DEAD)
+ break;
+ } while (!atomic_try_cmpxchg(st, &sync, SYNC_STATE_SHOULD_DIE));
+
+ if (cpuhp_wait_for_sync_state(cpu, SYNC_STATE_DEAD, SYNC_STATE_DEAD)) {
+ /* CPU reached dead state. Invoke the cleanup function */
+ arch_cpuhp_cleanup_dead_cpu(cpu);
+ return;
+ }
+
+ /* No further action possible. Emit message and give up. */
+ pr_err("CPU%u failed to report dead state\n", cpu);
+}
+#else /* CONFIG_HOTPLUG_CORE_SYNC_DEAD */
+static inline void cpuhp_bp_sync_dead(unsigned int cpu) { }
+#endif /* !CONFIG_HOTPLUG_CORE_SYNC_DEAD */
+
+#ifdef CONFIG_HOTPLUG_CORE_SYNC_FULL
+/**
+ * cpuhp_ap_sync_alive - Synchronize AP with the control CPU once it is alive
+ *
+ * Updates the AP synchronization state to SYNC_STATE_ALIVE and waits
+ * for the BP to release it.
+ */
+void cpuhp_ap_sync_alive(void)
+{
+ atomic_t *st = this_cpu_ptr(&cpuhp_state.ap_sync_state);
+
+ cpuhp_ap_update_sync_state(SYNC_STATE_ALIVE);
+
+ /* Wait for the control CPU to release it. */
+ while (atomic_read(st) != SYNC_STATE_SHOULD_ONLINE)
+ cpu_relax();
+}
+
+static bool cpuhp_can_boot_ap(unsigned int cpu)
+{
+ atomic_t *st = per_cpu_ptr(&cpuhp_state.ap_sync_state, cpu);
+ int sync = atomic_read(st);
+
+again:
+ switch (sync) {
+ case SYNC_STATE_DEAD:
+ /* CPU is properly dead */
+ break;
+ case SYNC_STATE_KICKED:
+ /* CPU did not come up in previous attempt */
+ break;
+ case SYNC_STATE_ALIVE:
+ /* CPU is stuck cpuhp_ap_sync_alive(). */
+ break;
+ default:
+ /* CPU failed to report online or dead and is in limbo state. */
+ return false;
+ }
+
+ /* Prepare for booting */
+ if (!atomic_try_cmpxchg(st, &sync, SYNC_STATE_KICKED))
+ goto again;
+
+ return true;
+}
+
+void __weak arch_cpuhp_cleanup_kick_cpu(unsigned int cpu) { }
+
+/*
+ * Early CPU bringup synchronization point. Cannot use cpuhp_state::done_up
+ * because the AP cannot issue complete() so early in the bringup.
+ */
+static int cpuhp_bp_sync_alive(unsigned int cpu)
+{
+ int ret = 0;
+
+ if (!IS_ENABLED(CONFIG_HOTPLUG_CORE_SYNC_FULL))
+ return 0;
+
+ if (!cpuhp_wait_for_sync_state(cpu, SYNC_STATE_ALIVE, SYNC_STATE_SHOULD_ONLINE)) {
+ pr_err("CPU%u failed to report alive state\n", cpu);
+ ret = -EIO;
+ }
+
+ /* Let the architecture cleanup the kick alive mechanics. */
+ arch_cpuhp_cleanup_kick_cpu(cpu);
+ return ret;
+}
+#else /* CONFIG_HOTPLUG_CORE_SYNC_FULL */
+static inline int cpuhp_bp_sync_alive(unsigned int cpu) { return 0; }
+static inline bool cpuhp_can_boot_ap(unsigned int cpu) { return true; }
+#endif /* !CONFIG_HOTPLUG_CORE_SYNC_FULL */
+
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
bool cpuhp_tasks_frozen;
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)
{
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)
}
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))
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 &&
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; }
+static inline bool cpu_bootable(unsigned int cpu) { return true; }
#endif
static inline enum cpuhp_state
return ret;
}
-static int bringup_wait_for_ap(unsigned int cpu)
+static int bringup_wait_for_ap_online(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, 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;
+}
+
+#ifdef CONFIG_HOTPLUG_SPLIT_STARTUP
+static int cpuhp_kick_ap_alive(unsigned int cpu)
+{
+ if (!cpuhp_can_boot_ap(cpu))
+ return -EAGAIN;
+
+ return arch_cpuhp_kick_ap_alive(cpu, idle_thread_get(cpu));
+}
+
+static int cpuhp_bringup_ap(unsigned int cpu)
+{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+ int ret;
+
+ /*
+ * Some architectures have to walk the irq descriptors to
+ * setup the vector space for the cpu which comes online.
+ * Prevent irq alloc/free across the bringup.
+ */
+ irq_lock_sparse();
+
+ ret = cpuhp_bp_sync_alive(cpu);
+ if (ret)
+ goto out_unlock;
+
+ ret = bringup_wait_for_ap_online(cpu);
+ if (ret)
+ goto out_unlock;
+
+ irq_unlock_sparse();
if (st->target <= CPUHP_AP_ONLINE_IDLE)
return 0;
return cpuhp_kick_ap(cpu, st, st->target);
-}
+out_unlock:
+ irq_unlock_sparse();
+ return ret;
+}
+#else
static int bringup_cpu(unsigned int cpu)
{
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
struct task_struct *idle = idle_thread_get(cpu);
int ret;
- /*
- * Reset stale stack state from the last time this CPU was online.
- */
- scs_task_reset(idle);
- kasan_unpoison_task_stack(idle);
+ if (!cpuhp_can_boot_ap(cpu))
+ return -EAGAIN;
/*
* Some architectures have to walk the irq descriptors to
* setup the vector space for the cpu which comes online.
- * Prevent irq alloc/free across the bringup.
+ *
+ * Prevent irq alloc/free across the bringup by acquiring the
+ * sparse irq lock. Hold it until the upcoming CPU completes the
+ * startup in cpuhp_online_idle() which allows to avoid
+ * intermediate synchronization points in the architecture code.
*/
irq_lock_sparse();
- /* Arch-specific enabling code. */
ret = __cpu_up(cpu, idle);
- irq_unlock_sparse();
if (ret)
- return ret;
- return bringup_wait_for_ap(cpu);
+ goto out_unlock;
+
+ ret = cpuhp_bp_sync_alive(cpu);
+ if (ret)
+ goto out_unlock;
+
+ ret = bringup_wait_for_ap_online(cpu);
+ if (ret)
+ goto out_unlock;
+
+ irq_unlock_sparse();
+
+ if (st->target <= CPUHP_AP_ONLINE_IDLE)
+ return 0;
+
+ return cpuhp_kick_ap(cpu, st, st->target);
+
+out_unlock:
+ irq_unlock_sparse();
+ return ret;
}
+#endif
static int finish_cpu(unsigned int cpu)
{
*/
if (mm != &init_mm)
idle->active_mm = &init_mm;
- mmdrop(mm);
+ mmdrop_lazy_tlb(mm);
return 0;
}
return true;
}
-static int cpuhp_invoke_callback_range(bool bringup,
- unsigned int cpu,
- struct cpuhp_cpu_state *st,
- enum cpuhp_state target)
+static int __cpuhp_invoke_callback_range(bool bringup,
+ unsigned int cpu,
+ struct cpuhp_cpu_state *st,
+ enum cpuhp_state target,
+ bool nofail)
{
enum cpuhp_state state;
- int err = 0;
+ int ret = 0;
while (cpuhp_next_state(bringup, &state, st, target)) {
+ int err;
+
err = cpuhp_invoke_callback(cpu, state, bringup, NULL, NULL);
- if (err)
+ if (!err)
+ continue;
+
+ if (nofail) {
+ pr_warn("CPU %u %s state %s (%d) failed (%d)\n",
+ cpu, bringup ? "UP" : "DOWN",
+ cpuhp_get_step(st->state)->name,
+ st->state, err);
+ ret = -1;
+ } else {
+ ret = err;
break;
+ }
}
- return err;
+ return ret;
+}
+
+static inline int cpuhp_invoke_callback_range(bool bringup,
+ unsigned int cpu,
+ struct cpuhp_cpu_state *st,
+ enum cpuhp_state target)
+{
+ return __cpuhp_invoke_callback_range(bringup, cpu, st, target, false);
+}
+
+static inline void cpuhp_invoke_callback_range_nofail(bool bringup,
+ unsigned int cpu,
+ struct cpuhp_cpu_state *st,
+ enum cpuhp_state target)
+{
+ __cpuhp_invoke_callback_range(bringup, cpu, st, target, true);
}
static inline bool can_rollback_cpu(struct cpuhp_cpu_state *st)
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
int err, cpu = smp_processor_id();
- int ret;
/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
*/
WARN_ON(st->state != (CPUHP_TEARDOWN_CPU - 1));
- /* Invoke the former CPU_DYING callbacks */
- ret = cpuhp_invoke_callback_range(false, cpu, st, target);
-
/*
- * DYING must not fail!
+ * Invoke the former CPU_DYING callbacks. DYING must not fail!
*/
- WARN_ON_ONCE(ret);
+ 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;
/* This actually kills the CPU. */
__cpu_die(cpu);
+ cpuhp_bp_sync_dead(cpu);
+
tick_cleanup_dead_cpu(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;
}
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),
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.
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)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
- int ret;
- 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);
- ret = cpuhp_invoke_callback_range(true, cpu, st, target);
/*
* STARTING must not fail!
*/
- WARN_ON_ONCE(ret);
+ cpuhp_invoke_callback_range_nofail(true, cpu, st, target);
}
/*
if (state != CPUHP_AP_ONLINE_IDLE)
return;
+ cpuhp_ap_update_sync_state(SYNC_STATE_ONLINE);
+
/*
- * Unpart the stopper thread before we start the idle loop (and start
+ * Unpark the stopper thread before we start the idle loop (and start
* scheduling); this ensures the stopper task is always available.
*/
stop_machine_unpark(smp_processor_id());
ret = PTR_ERR(idle);
goto out;
}
+
+ /*
+ * Reset stale stack state from the last time this CPU was online.
+ */
+ scs_task_reset(idle);
+ kasan_unpoison_task_stack(idle);
}
cpuhp_tasks_frozen = tasks_frozen;
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;
}
err = -EBUSY;
goto out;
}
- if (!cpu_smt_allowed(cpu)) {
+ if (!cpu_bootable(cpu)) {
err = -EPERM;
goto out;
}
return 0;
}
-void bringup_nonboot_cpus(unsigned int setup_max_cpus)
+static void __init cpuhp_bringup_mask(const struct cpumask *mask, unsigned int ncpus,
+ enum cpuhp_state target)
{
unsigned int cpu;
- for_each_present_cpu(cpu) {
- if (num_online_cpus() >= setup_max_cpus)
+ for_each_cpu(cpu, mask) {
+ struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
+
+ if (cpu_up(cpu, target) && can_rollback_cpu(st)) {
+ /*
+ * If this failed then cpu_up() might have only
+ * rolled back to CPUHP_BP_KICK_AP for the final
+ * online. Clean it up. NOOP if already rolled back.
+ */
+ WARN_ON(cpuhp_invoke_callback_range(false, cpu, st, CPUHP_OFFLINE));
+ }
+
+ if (!--ncpus)
break;
- if (!cpu_online(cpu))
- cpu_up(cpu, CPUHP_ONLINE);
}
}
+#ifdef CONFIG_HOTPLUG_PARALLEL
+static bool __cpuhp_parallel_bringup __ro_after_init = true;
+
+static int __init parallel_bringup_parse_param(char *arg)
+{
+ return kstrtobool(arg, &__cpuhp_parallel_bringup);
+}
+early_param("cpuhp.parallel", parallel_bringup_parse_param);
+
+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;
+}
+
+/*
+ * 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
+ * sends the startup IPI to the APs. The APs proceed through the low level
+ * bringup code in parallel and then wait for the control CPU to release
+ * them one by one for the final onlining procedure.
+ *
+ * This avoids waiting for each AP to respond to the startup IPI in
+ * CPUHP_BRINGUP_CPU.
+ */
+static bool __init cpuhp_bringup_cpus_parallel(unsigned int ncpus)
+{
+ const struct cpumask *mask = cpu_present_mask;
+
+ if (__cpuhp_parallel_bringup)
+ __cpuhp_parallel_bringup = arch_cpuhp_init_parallel_bringup();
+ if (!__cpuhp_parallel_bringup)
+ return false;
+
+ if (cpuhp_smt_aware()) {
+ const struct cpumask *pmask = cpuhp_get_primary_thread_mask();
+ static struct cpumask tmp_mask __initdata;
+
+ /*
+ * X86 requires to prevent that SMT siblings stopped while
+ * the primary thread does a microcode update for various
+ * reasons. Bring the primary threads up first.
+ */
+ cpumask_and(&tmp_mask, mask, pmask);
+ cpuhp_bringup_mask(&tmp_mask, ncpus, CPUHP_BP_KICK_AP);
+ cpuhp_bringup_mask(&tmp_mask, ncpus, CPUHP_ONLINE);
+ /* Account for the online CPUs */
+ ncpus -= num_online_cpus();
+ if (!ncpus)
+ return true;
+ /* Create the mask for secondary CPUs */
+ cpumask_andnot(&tmp_mask, mask, pmask);
+ mask = &tmp_mask;
+ }
+
+ /* Bring the not-yet started CPUs up */
+ cpuhp_bringup_mask(mask, ncpus, CPUHP_BP_KICK_AP);
+ cpuhp_bringup_mask(mask, ncpus, CPUHP_ONLINE);
+ return true;
+}
+#else
+static inline bool cpuhp_bringup_cpus_parallel(unsigned int ncpus) { return false; }
+#endif /* CONFIG_HOTPLUG_PARALLEL */
+
+void __init bringup_nonboot_cpus(unsigned int max_cpus)
+{
+ /* Try parallel bringup optimization if enabled */
+ if (cpuhp_bringup_cpus_parallel(max_cpus))
+ return;
+
+ /* Full per CPU serialized bringup */
+ cpuhp_bringup_mask(cpu_present_mask, max_cpus, CPUHP_ONLINE);
+}
+
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;
[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",
.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,
.startup.single = timers_prepare_cpu,
.teardown.single = timers_dead_cpu,
},
- /* Kicks the plugged cpu into life */
+
+#ifdef CONFIG_HOTPLUG_SPLIT_STARTUP
+ /*
+ * Kicks the AP alive. AP will wait in cpuhp_ap_sync_alive() until
+ * the next step will release it.
+ */
+ [CPUHP_BP_KICK_AP] = {
+ .name = "cpu:kick_ap",
+ .startup.single = cpuhp_kick_ap_alive,
+ },
+
+ /*
+ * Waits for the AP to reach cpuhp_ap_sync_alive() and then
+ * releases it for the complete bringup.
+ */
+ [CPUHP_BRINGUP_CPU] = {
+ .name = "cpu:bringup",
+ .startup.single = cpuhp_bringup_ap,
+ .teardown.single = finish_cpu,
+ .cant_stop = true,
+ },
+#else
+ /*
+ * All-in-one CPU bringup state which includes the kick alive.
+ */
[CPUHP_BRINGUP_CPU] = {
.name = "cpu:bringup",
.startup.single = bringup_cpu,
.teardown.single = finish_cpu,
.cant_stop = true,
},
+#endif
/* Final state before CPU kills itself */
[CPUHP_AP_IDLE_DEAD] = {
.name = "idle:dead",
.startup.single = NULL,
.teardown.single = smpcfd_dying_cpu,
},
+ [CPUHP_AP_HRTIMERS_DYING] = {
+ .name = "hrtimers:dying",
+ .startup.single = NULL,
+ .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] = {
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;
/* 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))
+ continue;
ret = _cpu_up(cpu, 0, CPUHP_ONLINE);
if (ret)
break;
if (st->state < target)
ret = cpu_up(dev->id, target);
- else
+ else if (st->state > target)
ret = cpu_down(dev->id, target);
+ else if (WARN_ON(st->target != target))
+ st->target = target;
out:
unlock_device_hotplug();
return ret ? ret : count;
#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;
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;
{
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,
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);
static int __init cpu_smt_sysfs_init(void)
{
- return sysfs_create_group(&cpu_subsys.dev_root->kobj,
- &cpuhp_smt_attr_group);
+ struct device *dev_root;
+ int ret = -ENODEV;
+
+ dev_root = bus_get_dev_root(&cpu_subsys);
+ if (dev_root) {
+ ret = sysfs_create_group(&dev_root->kobj, &cpuhp_smt_attr_group);
+ put_device(dev_root);
+ }
+ return ret;
}
static int __init cpuhp_sysfs_init(void)
{
+ struct device *dev_root;
int cpu, ret;
ret = cpu_smt_sysfs_init();
if (ret)
return ret;
- ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
- &cpuhp_cpu_root_attr_group);
- if (ret)
- return ret;
+ dev_root = bus_get_dev_root(&cpu_subsys);
+ if (dev_root) {
+ ret = sysfs_create_group(&dev_root->kobj, &cpuhp_cpu_root_attr_group);
+ put_device(dev_root);
+ if (ret)
+ return ret;
+ }
for_each_possible_cpu(cpu) {
struct device *dev = get_cpu_device(cpu);
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};
#else
-struct cpumask __cpu_possible_mask __read_mostly;
+struct cpumask __cpu_possible_mask __ro_after_init;
#endif
EXPORT_SYMBOL(__cpu_possible_mask);
{
#ifdef CONFIG_SMP
cpumask_set_cpu(smp_processor_id(), &cpus_booted_once_mask);
+ atomic_set(this_cpu_ptr(&cpuhp_state.ap_sync_state), SYNC_STATE_ONLINE);
#endif
this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
+ this_cpu_write(cpuhp_state.target, CPUHP_ONLINE);
}
/*
projects / linux-2.6-microblaze.git / blobdiff