therm_throt.c

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/*
 * Thermal throttle event support code (such as syslog messaging and rate
 * limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
 *
 * This allows consistent reporting of CPU thermal throttle events.
 *
 * Maintains a counter in /sys that keeps track of the number of thermal
 * events, such that the user knows how bad the thermal problem might be
 * (since the logging to syslog and mcelog is rate limited).
 *
 * Author: Dmitriy Zavin ([email protected])
 *
 * Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
 *          Inspired by Ross Biro's and Al Borchers' counter code.
 */
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/percpu.h>
#include <linux/export.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/cpu.h>

#include <asm/processor.h>
#include <asm/apic.h>
#include <asm/idle.h>
#include <asm/mce.h>
#include <asm/msr.h>

/* How long to wait between reporting thermal events */
#define CHECK_INTERVAL      (300 * HZ)

#define THERMAL_THROTTLING_EVENT    0
#define POWER_LIMIT_EVENT       1

/*
 * Current thermal event state:
 */
struct _thermal_state {
    bool            new_event;
    int         event;
    u64         next_check;
    unsigned long       count;
    unsigned long       last_count;
};

struct thermal_state {
    struct _thermal_state core_throttle;
    struct _thermal_state core_power_limit;
    struct _thermal_state package_throttle;
    struct _thermal_state package_power_limit;
    struct _thermal_state core_thresh0;
    struct _thermal_state core_thresh1;
};

/* Callback to handle core threshold interrupts */
int (*platform_thermal_notify)(__u64 msr_val);
EXPORT_SYMBOL(platform_thermal_notify);

static DEFINE_PER_CPU(struct thermal_state, thermal_state);

static atomic_t therm_throt_en  = ATOMIC_INIT(0);

static u32 lvtthmr_init __read_mostly;

#ifdef CONFIG_SYSFS
#define define_therm_throt_device_one_ro(_name)             \
    static DEVICE_ATTR(_name, 0444,                 \
               therm_throt_device_show_##_name,     \
                   NULL)                \

#define define_therm_throt_device_show_func(event, name)        \
                                    \
static ssize_t therm_throt_device_show_##event##_##name(        \
            struct device *dev,             \
            struct device_attribute *attr,          \
            char *buf)                  \
{                                   \
    unsigned int cpu = dev->id;                 \
    ssize_t ret;                            \
                                    \
    preempt_disable();  /* CPU hotplug */           \
    if (cpu_online(cpu)) {                      \
        ret = sprintf(buf, "%lu\n",             \
                  per_cpu(thermal_state, cpu).event.name);  \
    } else                              \
        ret = 0;                        \
    preempt_enable();                       \
                                    \
    return ret;                         \
}

define_therm_throt_device_show_func(core_throttle, count);
define_therm_throt_device_one_ro(core_throttle_count);

define_therm_throt_device_show_func(core_power_limit, count);
define_therm_throt_device_one_ro(core_power_limit_count);

define_therm_throt_device_show_func(package_throttle, count);
define_therm_throt_device_one_ro(package_throttle_count);

define_therm_throt_device_show_func(package_power_limit, count);
define_therm_throt_device_one_ro(package_power_limit_count);

static struct attribute *thermal_throttle_attrs[] = {
    &dev_attr_core_throttle_count.attr,
    NULL
};

static struct attribute_group thermal_attr_group = {
    .attrs  = thermal_throttle_attrs,
    .name   = "thermal_throttle"
};
#endif /* CONFIG_SYSFS */

#define CORE_LEVEL  0
#define PACKAGE_LEVEL   1

/***
 * therm_throt_process - Process thermal throttling event from interrupt
 * @curr: Whether the condition is current or not (boolean), since the
 *        thermal interrupt normally gets called both when the thermal
 *        event begins and once the event has ended.
 *
 * This function is called by the thermal interrupt after the
 * IRQ has been acknowledged.
 *
 * It will take care of rate limiting and printing messages to the syslog.
 *
 * Returns: 0 : Event should NOT be further logged, i.e. still in
 *              "timeout" from previous log message.
 *          1 : Event should be logged further, and a message has been
 *              printed to the syslog.
 */
static int therm_throt_process(bool new_event, int event, int level)
{
    struct _thermal_state *state;
    unsigned int this_cpu = smp_processor_id();
    bool old_event;
    u64 now;
    struct thermal_state *pstate = &per_cpu(thermal_state, this_cpu);

    now = get_jiffies_64();
    if (level == CORE_LEVEL) {
        if (event == THERMAL_THROTTLING_EVENT)
            state = &pstate->core_throttle;
        else if (event == POWER_LIMIT_EVENT)
            state = &pstate->core_power_limit;
        else
             return 0;
    } else if (level == PACKAGE_LEVEL) {
        if (event == THERMAL_THROTTLING_EVENT)
            state = &pstate->package_throttle;
        else if (event == POWER_LIMIT_EVENT)
            state = &pstate->package_power_limit;
        else
            return 0;
    } else
        return 0;

    old_event = state->new_event;
    state->new_event = new_event;

    if (new_event)
        state->count++;

    if (time_before64(now, state->next_check) &&
            state->count != state->last_count)
        return 0;

    state->next_check = now + CHECK_INTERVAL;
    state->last_count = state->count;

    /* if we just entered the thermal event */
    if (new_event) {
        if (event == THERMAL_THROTTLING_EVENT)
            printk(KERN_CRIT "CPU%d: %s temperature above threshold, cpu clock throttled (total events = %lu)\n",
                this_cpu,
                level == CORE_LEVEL ? "Core" : "Package",
                state->count);
        else
            printk(KERN_CRIT "CPU%d: %s power limit notification (total events = %lu)\n",
                this_cpu,
                level == CORE_LEVEL ? "Core" : "Package",
                state->count);
        return 1;
    }
    if (old_event) {
        if (event == THERMAL_THROTTLING_EVENT)
            printk(KERN_INFO "CPU%d: %s temperature/speed normal\n",
                this_cpu,
                level == CORE_LEVEL ? "Core" : "Package");
        else
            printk(KERN_INFO "CPU%d: %s power limit normal\n",
                this_cpu,
                level == CORE_LEVEL ? "Core" : "Package");
        return 1;
    }

    return 0;
}

static int thresh_event_valid(int event)
{
    struct _thermal_state *state;
    unsigned int this_cpu = smp_processor_id();
    struct thermal_state *pstate = &per_cpu(thermal_state, this_cpu);
    u64 now = get_jiffies_64();

    state = (event == 0) ? &pstate->core_thresh0 : &pstate->core_thresh1;

    if (time_before64(now, state->next_check))
        return 0;

    state->next_check = now + CHECK_INTERVAL;
    return 1;
}

#ifdef CONFIG_SYSFS
/* Add/Remove thermal_throttle interface for CPU device: */
static __cpuinit int thermal_throttle_add_dev(struct device *dev,
                unsigned int cpu)
{
    int err;
    struct cpuinfo_x86 *c = &cpu_data(cpu);

    err = sysfs_create_group(&dev->kobj, &thermal_attr_group);
    if (err)
        return err;

    if (cpu_has(c, X86_FEATURE_PLN))
        err = sysfs_add_file_to_group(&dev->kobj,
                          &dev_attr_core_power_limit_count.attr,
                          thermal_attr_group.name);
    if (cpu_has(c, X86_FEATURE_PTS)) {
        err = sysfs_add_file_to_group(&dev->kobj,
                          &dev_attr_package_throttle_count.attr,
                          thermal_attr_group.name);
        if (cpu_has(c, X86_FEATURE_PLN))
            err = sysfs_add_file_to_group(&dev->kobj,
                    &dev_attr_package_power_limit_count.attr,
                    thermal_attr_group.name);
    }

    return err;
}

static __cpuinit void thermal_throttle_remove_dev(struct device *dev)
{
    sysfs_remove_group(&dev->kobj, &thermal_attr_group);
}

/* Mutex protecting device creation against CPU hotplug: */
static DEFINE_MUTEX(therm_cpu_lock);

/* Get notified when a cpu comes on/off. Be hotplug friendly. */
static __cpuinit int
thermal_throttle_cpu_callback(struct notifier_block *nfb,
                  unsigned long action,
                  void *hcpu)
{
    unsigned int cpu = (unsigned long)hcpu;
    struct device *dev;
    int err = 0;

    dev = get_cpu_device(cpu);

    switch (action) {
    case CPU_UP_PREPARE:
    case CPU_UP_PREPARE_FROZEN:
        mutex_lock(&therm_cpu_lock);
        err = thermal_throttle_add_dev(dev, cpu);
        mutex_unlock(&therm_cpu_lock);
        WARN_ON(err);
        break;
    case CPU_UP_CANCELED:
    case CPU_UP_CANCELED_FROZEN:
    case CPU_DEAD:
    case CPU_DEAD_FROZEN:
        mutex_lock(&therm_cpu_lock);
        thermal_throttle_remove_dev(dev);
        mutex_unlock(&therm_cpu_lock);
        break;
    }
    return notifier_from_errno(err);
}

static struct notifier_block thermal_throttle_cpu_notifier __cpuinitdata =
{
    .notifier_call = thermal_throttle_cpu_callback,
};

static __init int thermal_throttle_init_device(void)
{
    unsigned int cpu = 0;
    int err;

    if (!atomic_read(&therm_throt_en))
        return 0;

    register_hotcpu_notifier(&thermal_throttle_cpu_notifier);

#ifdef CONFIG_HOTPLUG_CPU
    mutex_lock(&therm_cpu_lock);
#endif
    /* connect live CPUs to sysfs */
    for_each_online_cpu(cpu) {
        err = thermal_throttle_add_dev(get_cpu_device(cpu), cpu);
        WARN_ON(err);
    }
#ifdef CONFIG_HOTPLUG_CPU
    mutex_unlock(&therm_cpu_lock);
#endif

    return 0;
}
device_initcall(thermal_throttle_init_device);

#endif /* CONFIG_SYSFS */

static void notify_thresholds(__u64 msr_val)
{
    /* check whether the interrupt handler is defined;
     * otherwise simply return
     */
    if (!platform_thermal_notify)
        return;

    /* lower threshold reached */
    if ((msr_val & THERM_LOG_THRESHOLD0) && thresh_event_valid(0))
        platform_thermal_notify(msr_val);
    /* higher threshold reached */
    if ((msr_val & THERM_LOG_THRESHOLD1) && thresh_event_valid(1))
        platform_thermal_notify(msr_val);
}

/* Thermal transition interrupt handler */
static void intel_thermal_interrupt(void)
{
    __u64 msr_val;

    rdmsrl(MSR_IA32_THERM_STATUS, msr_val);

    /* Check for violation of core thermal thresholds*/
    notify_thresholds(msr_val);

    if (therm_throt_process(msr_val & THERM_STATUS_PROCHOT,
                THERMAL_THROTTLING_EVENT,
                CORE_LEVEL) != 0)
        mce_log_therm_throt_event(msr_val);

    if (this_cpu_has(X86_FEATURE_PLN))
        therm_throt_process(msr_val & THERM_STATUS_POWER_LIMIT,
                    POWER_LIMIT_EVENT,
                    CORE_LEVEL);

    if (this_cpu_has(X86_FEATURE_PTS)) {
        rdmsrl(MSR_IA32_PACKAGE_THERM_STATUS, msr_val);
        therm_throt_process(msr_val & PACKAGE_THERM_STATUS_PROCHOT,
                    THERMAL_THROTTLING_EVENT,
                    PACKAGE_LEVEL);
        if (this_cpu_has(X86_FEATURE_PLN))
            therm_throt_process(msr_val &
                    PACKAGE_THERM_STATUS_POWER_LIMIT,
                    POWER_LIMIT_EVENT,
                    PACKAGE_LEVEL);
    }
}

static void unexpected_thermal_interrupt(void)
{
    printk(KERN_ERR "CPU%d: Unexpected LVT thermal interrupt!\n",
            smp_processor_id());
}

static void (*smp_thermal_vector)(void) = unexpected_thermal_interrupt;

asmlinkage void smp_thermal_interrupt(struct pt_regs *regs)
{
    irq_enter();
    exit_idle();
    inc_irq_stat(irq_thermal_count);
    smp_thermal_vector();
    irq_exit();
    /* Ack only at the end to avoid potential reentry */
    ack_APIC_irq();
}

/* Thermal monitoring depends on APIC, ACPI and clock modulation */
static int intel_thermal_supported(struct cpuinfo_x86 *c)
{
    if (!cpu_has_apic)
        return 0;
    if (!cpu_has(c, X86_FEATURE_ACPI) || !cpu_has(c, X86_FEATURE_ACC))
        return 0;
    return 1;
}

void __init mcheck_intel_therm_init(void)
{
    /*
     * This function is only called on boot CPU. Save the init thermal
     * LVT value on BSP and use that value to restore APs' thermal LVT
     * entry BIOS programmed later
     */
    if (intel_thermal_supported(&boot_cpu_data))
        lvtthmr_init = apic_read(APIC_LVTTHMR);
}

void intel_init_thermal(struct cpuinfo_x86 *c)
{
    unsigned int cpu = smp_processor_id();
    int tm2 = 0;
    u32 l, h;

    if (!intel_thermal_supported(c))
        return;

    /*
     * First check if its enabled already, in which case there might
     * be some SMM goo which handles it, so we can't even put a handler
     * since it might be delivered via SMI already:
     */
    rdmsr(MSR_IA32_MISC_ENABLE, l, h);

    h = lvtthmr_init;
    /*
     * The initial value of thermal LVT entries on all APs always reads
     * 0x10000 because APs are woken up by BSP issuing INIT-SIPI-SIPI
     * sequence to them and LVT registers are reset to 0s except for
     * the mask bits which are set to 1s when APs receive INIT IPI.
     * If BIOS takes over the thermal interrupt and sets its interrupt
     * delivery mode to SMI (not fixed), it restores the value that the
     * BIOS has programmed on AP based on BSP's info we saved since BIOS
     * is always setting the same value for all threads/cores.
     */
    if ((h & APIC_DM_FIXED_MASK) != APIC_DM_FIXED)
        apic_write(APIC_LVTTHMR, lvtthmr_init);


    if ((l & MSR_IA32_MISC_ENABLE_TM1) && (h & APIC_DM_SMI)) {
        printk(KERN_DEBUG
               "CPU%d: Thermal monitoring handled by SMI\n", cpu);
        return;
    }

    /* Check whether a vector already exists */
    if (h & APIC_VECTOR_MASK) {
        printk(KERN_DEBUG
               "CPU%d: Thermal LVT vector (%#x) already installed\n",
               cpu, (h & APIC_VECTOR_MASK));
        return;
    }

    /* early Pentium M models use different method for enabling TM2 */
    if (cpu_has(c, X86_FEATURE_TM2)) {
        if (c->x86 == 6 && (c->x86_model == 9 || c->x86_model == 13)) {
            rdmsr(MSR_THERM2_CTL, l, h);
            if (l & MSR_THERM2_CTL_TM_SELECT)
                tm2 = 1;
        } else if (l & MSR_IA32_MISC_ENABLE_TM2)
            tm2 = 1;
    }

    /* We'll mask the thermal vector in the lapic till we're ready: */
    h = THERMAL_APIC_VECTOR | APIC_DM_FIXED | APIC_LVT_MASKED;
    apic_write(APIC_LVTTHMR, h);

    rdmsr(MSR_IA32_THERM_INTERRUPT, l, h);
    if (cpu_has(c, X86_FEATURE_PLN))
        wrmsr(MSR_IA32_THERM_INTERRUPT,
              l | (THERM_INT_LOW_ENABLE
            | THERM_INT_HIGH_ENABLE | THERM_INT_PLN_ENABLE), h);
    else
        wrmsr(MSR_IA32_THERM_INTERRUPT,
              l | (THERM_INT_LOW_ENABLE | THERM_INT_HIGH_ENABLE), h);

    if (cpu_has(c, X86_FEATURE_PTS)) {
        rdmsr(MSR_IA32_PACKAGE_THERM_INTERRUPT, l, h);
        if (cpu_has(c, X86_FEATURE_PLN))
            wrmsr(MSR_IA32_PACKAGE_THERM_INTERRUPT,
                  l | (PACKAGE_THERM_INT_LOW_ENABLE
                | PACKAGE_THERM_INT_HIGH_ENABLE
                | PACKAGE_THERM_INT_PLN_ENABLE), h);
        else
            wrmsr(MSR_IA32_PACKAGE_THERM_INTERRUPT,
                  l | (PACKAGE_THERM_INT_LOW_ENABLE
                | PACKAGE_THERM_INT_HIGH_ENABLE), h);
    }

    smp_thermal_vector = intel_thermal_interrupt;

    rdmsr(MSR_IA32_MISC_ENABLE, l, h);
    wrmsr(MSR_IA32_MISC_ENABLE, l | MSR_IA32_MISC_ENABLE_TM1, h);

    /* Unmask the thermal vector: */
    l = apic_read(APIC_LVTTHMR);
    apic_write(APIC_LVTTHMR, l & ~APIC_LVT_MASKED);

    printk_once(KERN_INFO "CPU0: Thermal monitoring enabled (%s)\n",
               tm2 ? "TM2" : "TM1");

    /* enable thermal throttle processing */
    atomic_set(&therm_throt_en, 1);
}