// SPDX-License-Identifier: GPL-2.0-only /* * acpi_pad.c ACPI Processor Aggregator Driver * * Copyright (c) 2009, Intel Corporation. */ #include <linux/kernel.h> #include <linux/cpumask.h> #include <linux/module.h> #include <linux/init.h> #include <linux/types.h> #include <linux/kthread.h> #include <uapi/linux/sched/types.h> #include <linux/freezer.h> #include <linux/cpu.h> #include <linux/tick.h> #include <linux/slab.h> #include <linux/acpi.h> #include <asm/mwait.h> #include <xen/xen.h> #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 static DEFINE_MUTEX(isolated_cpus_lock); static DEFINE_MUTEX(round_robin_lock); static unsigned long power_saving_mwait_eax; static unsigned char tsc_detected_unstable; static unsigned char tsc_marked_unstable; static void power_saving_mwait_init(void) { unsigned int eax, ebx, ecx, edx; unsigned int highest_cstate = 0; unsigned int highest_subcstate = 0; int i; if (!boot_cpu_has(X86_FEATURE_MWAIT)) return; if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) return; cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) return; edx >>= MWAIT_SUBSTATE_SIZE; for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { if (edx & MWAIT_SUBSTATE_MASK) { highest_cstate = i; highest_subcstate = edx & MWAIT_SUBSTATE_MASK; } } power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | (highest_subcstate - 1); #if defined(CONFIG_X86) switch (boot_cpu_data.x86_vendor) { case X86_VENDOR_HYGON: case X86_VENDOR_AMD: case X86_VENDOR_INTEL: case X86_VENDOR_ZHAOXIN: /* * AMD Fam10h TSC will tick in all * C/P/S0/S1 states when this bit is set. */ if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) tsc_detected_unstable = 1; break; default: /* TSC could halt in idle */ tsc_detected_unstable = 1; } #endif } static unsigned long cpu_weight[NR_CPUS]; static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); static void round_robin_cpu(unsigned int tsk_index) { struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); cpumask_var_t tmp; int cpu; unsigned long min_weight = -1; unsigned long uninitialized_var(preferred_cpu); if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) return; mutex_lock(&round_robin_lock); cpumask_clear(tmp); for_each_cpu(cpu, pad_busy_cpus) cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu)); cpumask_andnot(tmp, cpu_online_mask, tmp); /* avoid HT sibilings if possible */ if (cpumask_empty(tmp)) cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); if (cpumask_empty(tmp)) { mutex_unlock(&round_robin_lock); free_cpumask_var(tmp); return; } for_each_cpu(cpu, tmp) { if (cpu_weight[cpu] < min_weight) { min_weight = cpu_weight[cpu]; preferred_cpu = cpu; } } if (tsk_in_cpu[tsk_index] != -1) cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); tsk_in_cpu[tsk_index] = preferred_cpu; cpumask_set_cpu(preferred_cpu, pad_busy_cpus); cpu_weight[preferred_cpu]++; mutex_unlock(&round_robin_lock); set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); free_cpumask_var(tmp); } static void exit_round_robin(unsigned int tsk_index) { struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); tsk_in_cpu[tsk_index] = -1; } static unsigned int idle_pct = 5; /* percentage */ static unsigned int round_robin_time = 1; /* second */ static int power_saving_thread(void *data) { struct sched_param param = {.sched_priority = 1}; int do_sleep; unsigned int tsk_index = (unsigned long)data; u64 last_jiffies = 0; sched_setscheduler(current, SCHED_RR, ¶m); while (!kthread_should_stop()) { unsigned long expire_time; /* round robin to cpus */ expire_time = last_jiffies + round_robin_time * HZ; if (time_before(expire_time, jiffies)) { last_jiffies = jiffies; round_robin_cpu(tsk_index); } do_sleep = 0; expire_time = jiffies + HZ * (100 - idle_pct) / 100; while (!need_resched()) { if (tsc_detected_unstable && !tsc_marked_unstable) { /* TSC could halt in idle, so notify users */ mark_tsc_unstable("TSC halts in idle"); tsc_marked_unstable = 1; } local_irq_disable(); tick_broadcast_enable(); tick_broadcast_enter(); stop_critical_timings(); mwait_idle_with_hints(power_saving_mwait_eax, 1); start_critical_timings(); tick_broadcast_exit(); local_irq_enable(); if (time_before(expire_time, jiffies)) { do_sleep = 1; break; } } /* * current sched_rt has threshold for rt task running time. * When a rt task uses 95% CPU time, the rt thread will be * scheduled out for 5% CPU time to not starve other tasks. But * the mechanism only works when all CPUs have RT task running, * as if one CPU hasn't RT task, RT task from other CPUs will * borrow CPU time from this CPU and cause RT task use > 95% * CPU time. To make 'avoid starvation' work, takes a nap here. */ if (unlikely(do_sleep)) schedule_timeout_killable(HZ * idle_pct / 100); /* If an external event has set the need_resched flag, then * we need to deal with it, or this loop will continue to * spin without calling __mwait(). */ if (unlikely(need_resched())) schedule(); } exit_round_robin(tsk_index); return 0; } static struct task_struct *ps_tsks[NR_CPUS]; static unsigned int ps_tsk_num; static int create_power_saving_task(void) { int rc; ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, (void *)(unsigned long)ps_tsk_num, "acpi_pad/%d", ps_tsk_num); if (IS_ERR(ps_tsks[ps_tsk_num])) { rc = PTR_ERR(ps_tsks[ps_tsk_num]); ps_tsks[ps_tsk_num] = NULL; } else { rc = 0; ps_tsk_num++; } return rc; } static void destroy_power_saving_task(void) { if (ps_tsk_num > 0) { ps_tsk_num--; kthread_stop(ps_tsks[ps_tsk_num]); ps_tsks[ps_tsk_num] = NULL; } } static void set_power_saving_task_num(unsigned int num) { if (num > ps_tsk_num) { while (ps_tsk_num < num) { if (create_power_saving_task()) return; } } else if (num < ps_tsk_num) { while (ps_tsk_num > num) destroy_power_saving_task(); } } static void acpi_pad_idle_cpus(unsigned int num_cpus) { get_online_cpus(); num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); set_power_saving_task_num(num_cpus); put_online_cpus(); } static uint32_t acpi_pad_idle_cpus_num(void) { return ps_tsk_num; } static ssize_t acpi_pad_rrtime_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { unsigned long num; if (kstrtoul(buf, 0, &num)) return -EINVAL; if (num < 1 || num >= 100) return -EINVAL; mutex_lock(&isolated_cpus_lock); round_robin_time = num; mutex_unlock(&isolated_cpus_lock); return count; } static ssize_t acpi_pad_rrtime_show(struct device *dev, struct device_attribute *attr, char *buf) { return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); } static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, acpi_pad_rrtime_show, acpi_pad_rrtime_store); static ssize_t acpi_pad_idlepct_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { unsigned long num; if (kstrtoul(buf, 0, &num)) return -EINVAL; if (num < 1 || num >= 100) return -EINVAL; mutex_lock(&isolated_cpus_lock); idle_pct = num; mutex_unlock(&isolated_cpus_lock); return count; } static ssize_t acpi_pad_idlepct_show(struct device *dev, struct device_attribute *attr, char *buf) { return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); } static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, acpi_pad_idlepct_show, acpi_pad_idlepct_store); static ssize_t acpi_pad_idlecpus_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { unsigned long num; if (kstrtoul(buf, 0, &num)) return -EINVAL; mutex_lock(&isolated_cpus_lock); acpi_pad_idle_cpus(num); mutex_unlock(&isolated_cpus_lock); return count; } static ssize_t acpi_pad_idlecpus_show(struct device *dev, struct device_attribute *attr, char *buf) { return cpumap_print_to_pagebuf(false, buf, to_cpumask(pad_busy_cpus_bits)); } static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, acpi_pad_idlecpus_show, acpi_pad_idlecpus_store); static int acpi_pad_add_sysfs(struct acpi_device *device) { int result; result = device_create_file(&device->dev, &dev_attr_idlecpus); if (result) return -ENODEV; result = device_create_file(&device->dev, &dev_attr_idlepct); if (result) { device_remove_file(&device->dev, &dev_attr_idlecpus); return -ENODEV; } result = device_create_file(&device->dev, &dev_attr_rrtime); if (result) { device_remove_file(&device->dev, &dev_attr_idlecpus); device_remove_file(&device->dev, &dev_attr_idlepct); return -ENODEV; } return 0; } static void acpi_pad_remove_sysfs(struct acpi_device *device) { device_remove_file(&device->dev, &dev_attr_idlecpus); device_remove_file(&device->dev, &dev_attr_idlepct); device_remove_file(&device->dev, &dev_attr_rrtime); } /* * Query firmware how many CPUs should be idle * return -1 on failure */ static int acpi_pad_pur(acpi_handle handle) { struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; union acpi_object *package; int num = -1; if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) return num; if (!buffer.length || !buffer.pointer) return num; package = buffer.pointer; if (package->type == ACPI_TYPE_PACKAGE && package->package.count == 2 && package->package.elements[0].integer.value == 1) /* rev 1 */ num = package->package.elements[1].integer.value; kfree(buffer.pointer); return num; } static void acpi_pad_handle_notify(acpi_handle handle) { int num_cpus; uint32_t idle_cpus; struct acpi_buffer param = { .length = 4, .pointer = (void *)&idle_cpus, }; mutex_lock(&isolated_cpus_lock); num_cpus = acpi_pad_pur(handle); if (num_cpus < 0) { mutex_unlock(&isolated_cpus_lock); return; } acpi_pad_idle_cpus(num_cpus); idle_cpus = acpi_pad_idle_cpus_num(); acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); mutex_unlock(&isolated_cpus_lock); } static void acpi_pad_notify(acpi_handle handle, u32 event, void *data) { struct acpi_device *device = data; switch (event) { case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: acpi_pad_handle_notify(handle); acpi_bus_generate_netlink_event(device->pnp.device_class, dev_name(&device->dev), event, 0); break; default: pr_warn("Unsupported event [0x%x]\n", event); break; } } static int acpi_pad_add(struct acpi_device *device) { acpi_status status; strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); if (acpi_pad_add_sysfs(device)) return -ENODEV; status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); if (ACPI_FAILURE(status)) { acpi_pad_remove_sysfs(device); return -ENODEV; } return 0; } static int acpi_pad_remove(struct acpi_device *device) { mutex_lock(&isolated_cpus_lock); acpi_pad_idle_cpus(0); mutex_unlock(&isolated_cpus_lock); acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY, acpi_pad_notify); acpi_pad_remove_sysfs(device); return 0; } static const struct acpi_device_id pad_device_ids[] = { {"ACPI000C", 0}, {"", 0}, }; MODULE_DEVICE_TABLE(acpi, pad_device_ids); static struct acpi_driver acpi_pad_driver = { .name = "processor_aggregator", .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, .ids = pad_device_ids, .ops = { .add = acpi_pad_add, .remove = acpi_pad_remove, }, }; static int __init acpi_pad_init(void) { /* Xen ACPI PAD is used when running as Xen Dom0. */ if (xen_initial_domain()) return -ENODEV; power_saving_mwait_init(); if (power_saving_mwait_eax == 0) return -EINVAL; return acpi_bus_register_driver(&acpi_pad_driver); } static void __exit acpi_pad_exit(void) { acpi_bus_unregister_driver(&acpi_pad_driver); } module_init(acpi_pad_init); module_exit(acpi_pad_exit); MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); MODULE_LICENSE("GPL");