Linux 2.6.31.6

[linux/fpc-iii.git] / arch / x86 / kernel / cpu / perfctr-watchdog.c

/*
 * local apic based NMI watchdog for various CPUs.
 *
 * This file also handles reservation of performance counters for coordination
 * with other users (like oprofile).
 *
 * Note that these events normally don't tick when the CPU idles. This means
 * the frequency varies with CPU load.
 *
 * Original code for K7/P6 written by Keith Owens
 *
 */

#include <linux/percpu.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/smp.h>
#include <linux/nmi.h>
#include <linux/kprobes.h>

#include <asm/apic.h>
#include <asm/perf_counter.h>

struct nmi_watchdog_ctlblk {
        unsigned int cccr_msr;
        unsigned int perfctr_msr;  /* the MSR to reset in NMI handler */
        unsigned int evntsel_msr;  /* the MSR to select the events to handle */
};

/* Interface defining a CPU specific perfctr watchdog */
struct wd_ops {
        int (*reserve)(void);
        void (*unreserve)(void);
        int (*setup)(unsigned nmi_hz);
        void (*rearm)(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz);
        void (*stop)(void);
        unsigned perfctr;
        unsigned evntsel;
        u64 checkbit;
};

static const struct wd_ops *wd_ops;

/*
 * this number is calculated from Intel's MSR_P4_CRU_ESCR5 register and it's
 * offset from MSR_P4_BSU_ESCR0.
 *
 * It will be the max for all platforms (for now)
 */
#define NMI_MAX_COUNTER_BITS 66

/*
 * perfctr_nmi_owner tracks the ownership of the perfctr registers:
 * evtsel_nmi_owner tracks the ownership of the event selection
 * - different performance counters/ event selection may be reserved for
 *   different subsystems this reservation system just tries to coordinate
 *   things a little
 */
static DECLARE_BITMAP(perfctr_nmi_owner, NMI_MAX_COUNTER_BITS);
static DECLARE_BITMAP(evntsel_nmi_owner, NMI_MAX_COUNTER_BITS);

static DEFINE_PER_CPU(struct nmi_watchdog_ctlblk, nmi_watchdog_ctlblk);

/* converts an msr to an appropriate reservation bit */
static inline unsigned int nmi_perfctr_msr_to_bit(unsigned int msr)
{
        /* returns the bit offset of the performance counter register */
        switch (boot_cpu_data.x86_vendor) {
        case X86_VENDOR_AMD:
                return (msr - MSR_K7_PERFCTR0);
        case X86_VENDOR_INTEL:
                if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
                        return (msr - MSR_ARCH_PERFMON_PERFCTR0);

                switch (boot_cpu_data.x86) {
                case 6:
                        return (msr - MSR_P6_PERFCTR0);
                case 15:
                        return (msr - MSR_P4_BPU_PERFCTR0);
                }
        }
        return 0;
}

/*
 * converts an msr to an appropriate reservation bit
 * returns the bit offset of the event selection register
 */
static inline unsigned int nmi_evntsel_msr_to_bit(unsigned int msr)
{
        /* returns the bit offset of the event selection register */
        switch (boot_cpu_data.x86_vendor) {
        case X86_VENDOR_AMD:
                return (msr - MSR_K7_EVNTSEL0);
        case X86_VENDOR_INTEL:
                if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON))
                        return (msr - MSR_ARCH_PERFMON_EVENTSEL0);

                switch (boot_cpu_data.x86) {
                case 6:
                        return (msr - MSR_P6_EVNTSEL0);
                case 15:
                        return (msr - MSR_P4_BSU_ESCR0);
                }
        }
        return 0;

}

/* checks for a bit availability (hack for oprofile) */
int avail_to_resrv_perfctr_nmi_bit(unsigned int counter)
{
        BUG_ON(counter > NMI_MAX_COUNTER_BITS);

        return (!test_bit(counter, perfctr_nmi_owner));
}

/* checks the an msr for availability */
int avail_to_resrv_perfctr_nmi(unsigned int msr)
{
        unsigned int counter;

        counter = nmi_perfctr_msr_to_bit(msr);
        BUG_ON(counter > NMI_MAX_COUNTER_BITS);

        return (!test_bit(counter, perfctr_nmi_owner));
}
EXPORT_SYMBOL(avail_to_resrv_perfctr_nmi_bit);

int reserve_perfctr_nmi(unsigned int msr)
{
        unsigned int counter;

        counter = nmi_perfctr_msr_to_bit(msr);
        /* register not managed by the allocator? */
        if (counter > NMI_MAX_COUNTER_BITS)
                return 1;

        if (!test_and_set_bit(counter, perfctr_nmi_owner))
                return 1;
        return 0;
}
EXPORT_SYMBOL(reserve_perfctr_nmi);

void release_perfctr_nmi(unsigned int msr)
{
        unsigned int counter;

        counter = nmi_perfctr_msr_to_bit(msr);
        /* register not managed by the allocator? */
        if (counter > NMI_MAX_COUNTER_BITS)
                return;

        clear_bit(counter, perfctr_nmi_owner);
}
EXPORT_SYMBOL(release_perfctr_nmi);

int reserve_evntsel_nmi(unsigned int msr)
{
        unsigned int counter;

        counter = nmi_evntsel_msr_to_bit(msr);
        /* register not managed by the allocator? */
        if (counter > NMI_MAX_COUNTER_BITS)
                return 1;

        if (!test_and_set_bit(counter, evntsel_nmi_owner))
                return 1;
        return 0;
}
EXPORT_SYMBOL(reserve_evntsel_nmi);

void release_evntsel_nmi(unsigned int msr)
{
        unsigned int counter;

        counter = nmi_evntsel_msr_to_bit(msr);
        /* register not managed by the allocator? */
        if (counter > NMI_MAX_COUNTER_BITS)
                return;

        clear_bit(counter, evntsel_nmi_owner);
}
EXPORT_SYMBOL(release_evntsel_nmi);

void disable_lapic_nmi_watchdog(void)
{
        BUG_ON(nmi_watchdog != NMI_LOCAL_APIC);

        if (atomic_read(&nmi_active) <= 0)
                return;

        on_each_cpu(stop_apic_nmi_watchdog, NULL, 1);

        if (wd_ops)
                wd_ops->unreserve();

        BUG_ON(atomic_read(&nmi_active) != 0);
}

void enable_lapic_nmi_watchdog(void)
{
        BUG_ON(nmi_watchdog != NMI_LOCAL_APIC);

        /* are we already enabled */
        if (atomic_read(&nmi_active) != 0)
                return;

        /* are we lapic aware */
        if (!wd_ops)
                return;
        if (!wd_ops->reserve()) {
                printk(KERN_ERR "NMI watchdog: cannot reserve perfctrs\n");
                return;
        }

        on_each_cpu(setup_apic_nmi_watchdog, NULL, 1);
        touch_nmi_watchdog();
}

/*
 * Activate the NMI watchdog via the local APIC.
 */

static unsigned int adjust_for_32bit_ctr(unsigned int hz)
{
        u64 counter_val;
        unsigned int retval = hz;

        /*
         * On Intel CPUs with P6/ARCH_PERFMON only 32 bits in the counter
         * are writable, with higher bits sign extending from bit 31.
         * So, we can only program the counter with 31 bit values and
         * 32nd bit should be 1, for 33.. to be 1.
         * Find the appropriate nmi_hz
         */
        counter_val = (u64)cpu_khz * 1000;
        do_div(counter_val, retval);
        if (counter_val > 0x7fffffffULL) {
                u64 count = (u64)cpu_khz * 1000;
                do_div(count, 0x7fffffffUL);
                retval = count + 1;
        }
        return retval;
}

static void write_watchdog_counter(unsigned int perfctr_msr,
                                const char *descr, unsigned nmi_hz)
{
        u64 count = (u64)cpu_khz * 1000;

        do_div(count, nmi_hz);
        if(descr)
                pr_debug("setting %s to -0x%08Lx\n", descr, count);
        wrmsrl(perfctr_msr, 0 - count);
}

static void write_watchdog_counter32(unsigned int perfctr_msr,
                                const char *descr, unsigned nmi_hz)
{
        u64 count = (u64)cpu_khz * 1000;

        do_div(count, nmi_hz);
        if(descr)
                pr_debug("setting %s to -0x%08Lx\n", descr, count);
        wrmsr(perfctr_msr, (u32)(-count), 0);
}

/*
 * AMD K7/K8/Family10h/Family11h support.
 * AMD keeps this interface nicely stable so there is not much variety
 */
#define K7_EVNTSEL_ENABLE       (1 << 22)
#define K7_EVNTSEL_INT          (1 << 20)
#define K7_EVNTSEL_OS           (1 << 17)
#define K7_EVNTSEL_USR          (1 << 16)
#define K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING    0x76
#define K7_NMI_EVENT            K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING

static int setup_k7_watchdog(unsigned nmi_hz)
{
        unsigned int perfctr_msr, evntsel_msr;
        unsigned int evntsel;
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

        perfctr_msr = wd_ops->perfctr;
        evntsel_msr = wd_ops->evntsel;

        wrmsrl(perfctr_msr, 0UL);

        evntsel = K7_EVNTSEL_INT
                | K7_EVNTSEL_OS
                | K7_EVNTSEL_USR
                | K7_NMI_EVENT;

        /* setup the timer */
        wrmsr(evntsel_msr, evntsel, 0);
        write_watchdog_counter(perfctr_msr, "K7_PERFCTR0",nmi_hz);

        /* initialize the wd struct before enabling */
        wd->perfctr_msr = perfctr_msr;
        wd->evntsel_msr = evntsel_msr;
        wd->cccr_msr = 0;  /* unused */

        /* ok, everything is initialized, announce that we're set */
        cpu_nmi_set_wd_enabled();

        apic_write(APIC_LVTPC, APIC_DM_NMI);
        evntsel |= K7_EVNTSEL_ENABLE;
        wrmsr(evntsel_msr, evntsel, 0);

        return 1;
}

static void single_msr_stop_watchdog(void)
{
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

        wrmsr(wd->evntsel_msr, 0, 0);
}

static int single_msr_reserve(void)
{
        if (!reserve_perfctr_nmi(wd_ops->perfctr))
                return 0;

        if (!reserve_evntsel_nmi(wd_ops->evntsel)) {
                release_perfctr_nmi(wd_ops->perfctr);
                return 0;
        }
        return 1;
}

static void single_msr_unreserve(void)
{
        release_evntsel_nmi(wd_ops->evntsel);
        release_perfctr_nmi(wd_ops->perfctr);
}

static void __kprobes
single_msr_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
{
        /* start the cycle over again */
        write_watchdog_counter(wd->perfctr_msr, NULL, nmi_hz);
}

static const struct wd_ops k7_wd_ops = {
        .reserve        = single_msr_reserve,
        .unreserve      = single_msr_unreserve,
        .setup          = setup_k7_watchdog,
        .rearm          = single_msr_rearm,
        .stop           = single_msr_stop_watchdog,
        .perfctr        = MSR_K7_PERFCTR0,
        .evntsel        = MSR_K7_EVNTSEL0,
        .checkbit       = 1ULL << 47,
};

/*
 * Intel Model 6 (PPro+,P2,P3,P-M,Core1)
 */
#define P6_EVNTSEL0_ENABLE      (1 << 22)
#define P6_EVNTSEL_INT          (1 << 20)
#define P6_EVNTSEL_OS           (1 << 17)
#define P6_EVNTSEL_USR          (1 << 16)
#define P6_EVENT_CPU_CLOCKS_NOT_HALTED  0x79
#define P6_NMI_EVENT            P6_EVENT_CPU_CLOCKS_NOT_HALTED

static int setup_p6_watchdog(unsigned nmi_hz)
{
        unsigned int perfctr_msr, evntsel_msr;
        unsigned int evntsel;
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

        perfctr_msr = wd_ops->perfctr;
        evntsel_msr = wd_ops->evntsel;

        /* KVM doesn't implement this MSR */
        if (wrmsr_safe(perfctr_msr, 0, 0) < 0)
                return 0;

        evntsel = P6_EVNTSEL_INT
                | P6_EVNTSEL_OS
                | P6_EVNTSEL_USR
                | P6_NMI_EVENT;

        /* setup the timer */
        wrmsr(evntsel_msr, evntsel, 0);
        nmi_hz = adjust_for_32bit_ctr(nmi_hz);
        write_watchdog_counter32(perfctr_msr, "P6_PERFCTR0",nmi_hz);

        /* initialize the wd struct before enabling */
        wd->perfctr_msr = perfctr_msr;
        wd->evntsel_msr = evntsel_msr;
        wd->cccr_msr = 0;  /* unused */

        /* ok, everything is initialized, announce that we're set */
        cpu_nmi_set_wd_enabled();

        apic_write(APIC_LVTPC, APIC_DM_NMI);
        evntsel |= P6_EVNTSEL0_ENABLE;
        wrmsr(evntsel_msr, evntsel, 0);

        return 1;
}

static void __kprobes p6_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
{
        /*
         * P6 based Pentium M need to re-unmask
         * the apic vector but it doesn't hurt
         * other P6 variant.
         * ArchPerfom/Core Duo also needs this
         */
        apic_write(APIC_LVTPC, APIC_DM_NMI);

        /* P6/ARCH_PERFMON has 32 bit counter write */
        write_watchdog_counter32(wd->perfctr_msr, NULL,nmi_hz);
}

static const struct wd_ops p6_wd_ops = {
        .reserve        = single_msr_reserve,
        .unreserve      = single_msr_unreserve,
        .setup          = setup_p6_watchdog,
        .rearm          = p6_rearm,
        .stop           = single_msr_stop_watchdog,
        .perfctr        = MSR_P6_PERFCTR0,
        .evntsel        = MSR_P6_EVNTSEL0,
        .checkbit       = 1ULL << 39,
};

/*
 * Intel P4 performance counters.
 * By far the most complicated of all.
 */
#define MSR_P4_MISC_ENABLE_PERF_AVAIL   (1 << 7)
#define P4_ESCR_EVENT_SELECT(N) ((N) << 25)
#define P4_ESCR_OS              (1 << 3)
#define P4_ESCR_USR             (1 << 2)
#define P4_CCCR_OVF_PMI0        (1 << 26)
#define P4_CCCR_OVF_PMI1        (1 << 27)
#define P4_CCCR_THRESHOLD(N)    ((N) << 20)
#define P4_CCCR_COMPLEMENT      (1 << 19)
#define P4_CCCR_COMPARE         (1 << 18)
#define P4_CCCR_REQUIRED        (3 << 16)
#define P4_CCCR_ESCR_SELECT(N)  ((N) << 13)
#define P4_CCCR_ENABLE          (1 << 12)
#define P4_CCCR_OVF             (1 << 31)

#define P4_CONTROLS 18
static unsigned int p4_controls[18] = {
        MSR_P4_BPU_CCCR0,
        MSR_P4_BPU_CCCR1,
        MSR_P4_BPU_CCCR2,
        MSR_P4_BPU_CCCR3,
        MSR_P4_MS_CCCR0,
        MSR_P4_MS_CCCR1,
        MSR_P4_MS_CCCR2,
        MSR_P4_MS_CCCR3,
        MSR_P4_FLAME_CCCR0,
        MSR_P4_FLAME_CCCR1,
        MSR_P4_FLAME_CCCR2,
        MSR_P4_FLAME_CCCR3,
        MSR_P4_IQ_CCCR0,
        MSR_P4_IQ_CCCR1,
        MSR_P4_IQ_CCCR2,
        MSR_P4_IQ_CCCR3,
        MSR_P4_IQ_CCCR4,
        MSR_P4_IQ_CCCR5,
};
/*
 * Set up IQ_COUNTER0 to behave like a clock, by having IQ_CCCR0 filter
 * CRU_ESCR0 (with any non-null event selector) through a complemented
 * max threshold. [IA32-Vol3, Section 14.9.9]
 */
static int setup_p4_watchdog(unsigned nmi_hz)
{
        unsigned int perfctr_msr, evntsel_msr, cccr_msr;
        unsigned int evntsel, cccr_val;
        unsigned int misc_enable, dummy;
        unsigned int ht_num;
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

        rdmsr(MSR_IA32_MISC_ENABLE, misc_enable, dummy);
        if (!(misc_enable & MSR_P4_MISC_ENABLE_PERF_AVAIL))
                return 0;

#ifdef CONFIG_SMP
        /* detect which hyperthread we are on */
        if (smp_num_siblings == 2) {
                unsigned int ebx, apicid;

                ebx = cpuid_ebx(1);
                apicid = (ebx >> 24) & 0xff;
                ht_num = apicid & 1;
        } else
#endif
                ht_num = 0;

        /*
         * performance counters are shared resources
         * assign each hyperthread its own set
         * (re-use the ESCR0 register, seems safe
         * and keeps the cccr_val the same)
         */
        if (!ht_num) {
                /* logical cpu 0 */
                perfctr_msr = MSR_P4_IQ_PERFCTR0;
                evntsel_msr = MSR_P4_CRU_ESCR0;
                cccr_msr = MSR_P4_IQ_CCCR0;
                cccr_val = P4_CCCR_OVF_PMI0 | P4_CCCR_ESCR_SELECT(4);

                /*
                 * If we're on the kdump kernel or other situation, we may
                 * still have other performance counter registers set to
                 * interrupt and they'll keep interrupting forever because
                 * of the P4_CCCR_OVF quirk. So we need to ACK all the
                 * pending interrupts and disable all the registers here,
                 * before reenabling the NMI delivery. Refer to p4_rearm()
                 * about the P4_CCCR_OVF quirk.
                 */
                if (reset_devices) {
                        unsigned int low, high;
                        int i;

                        for (i = 0; i < P4_CONTROLS; i++) {
                                rdmsr(p4_controls[i], low, high);
                                low &= ~(P4_CCCR_ENABLE | P4_CCCR_OVF);
                                wrmsr(p4_controls[i], low, high);
                        }
                }
        } else {
                /* logical cpu 1 */
                perfctr_msr = MSR_P4_IQ_PERFCTR1;
                evntsel_msr = MSR_P4_CRU_ESCR0;
                cccr_msr = MSR_P4_IQ_CCCR1;

                /* Pentium 4 D processors don't support P4_CCCR_OVF_PMI1 */
                if (boot_cpu_data.x86_model == 4 && boot_cpu_data.x86_mask == 4)
                        cccr_val = P4_CCCR_OVF_PMI0;
                else
                        cccr_val = P4_CCCR_OVF_PMI1;
                cccr_val |= P4_CCCR_ESCR_SELECT(4);
        }

        evntsel = P4_ESCR_EVENT_SELECT(0x3F)
                | P4_ESCR_OS
                | P4_ESCR_USR;

        cccr_val |= P4_CCCR_THRESHOLD(15)
                 | P4_CCCR_COMPLEMENT
                 | P4_CCCR_COMPARE
                 | P4_CCCR_REQUIRED;

        wrmsr(evntsel_msr, evntsel, 0);
        wrmsr(cccr_msr, cccr_val, 0);
        write_watchdog_counter(perfctr_msr, "P4_IQ_COUNTER0", nmi_hz);

        wd->perfctr_msr = perfctr_msr;
        wd->evntsel_msr = evntsel_msr;
        wd->cccr_msr = cccr_msr;

        /* ok, everything is initialized, announce that we're set */
        cpu_nmi_set_wd_enabled();

        apic_write(APIC_LVTPC, APIC_DM_NMI);
        cccr_val |= P4_CCCR_ENABLE;
        wrmsr(cccr_msr, cccr_val, 0);
        return 1;
}

static void stop_p4_watchdog(void)
{
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
        wrmsr(wd->cccr_msr, 0, 0);
        wrmsr(wd->evntsel_msr, 0, 0);
}

static int p4_reserve(void)
{
        if (!reserve_perfctr_nmi(MSR_P4_IQ_PERFCTR0))
                return 0;
#ifdef CONFIG_SMP
        if (smp_num_siblings > 1 && !reserve_perfctr_nmi(MSR_P4_IQ_PERFCTR1))
                goto fail1;
#endif
        if (!reserve_evntsel_nmi(MSR_P4_CRU_ESCR0))
                goto fail2;
        /* RED-PEN why is ESCR1 not reserved here? */
        return 1;
 fail2:
#ifdef CONFIG_SMP
        if (smp_num_siblings > 1)
                release_perfctr_nmi(MSR_P4_IQ_PERFCTR1);
 fail1:
#endif
        release_perfctr_nmi(MSR_P4_IQ_PERFCTR0);
        return 0;
}

static void p4_unreserve(void)
{
#ifdef CONFIG_SMP
        if (smp_num_siblings > 1)
                release_perfctr_nmi(MSR_P4_IQ_PERFCTR1);
#endif
        release_evntsel_nmi(MSR_P4_CRU_ESCR0);
        release_perfctr_nmi(MSR_P4_IQ_PERFCTR0);
}

static void __kprobes p4_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
{
        unsigned dummy;
        /*
         * P4 quirks:
         * - An overflown perfctr will assert its interrupt
         *   until the OVF flag in its CCCR is cleared.
         * - LVTPC is masked on interrupt and must be
         *   unmasked by the LVTPC handler.
         */
        rdmsrl(wd->cccr_msr, dummy);
        dummy &= ~P4_CCCR_OVF;
        wrmsrl(wd->cccr_msr, dummy);
        apic_write(APIC_LVTPC, APIC_DM_NMI);
        /* start the cycle over again */
        write_watchdog_counter(wd->perfctr_msr, NULL, nmi_hz);
}

static const struct wd_ops p4_wd_ops = {
        .reserve        = p4_reserve,
        .unreserve      = p4_unreserve,
        .setup          = setup_p4_watchdog,
        .rearm          = p4_rearm,
        .stop           = stop_p4_watchdog,
        /* RED-PEN this is wrong for the other sibling */
        .perfctr        = MSR_P4_BPU_PERFCTR0,
        .evntsel        = MSR_P4_BSU_ESCR0,
        .checkbit       = 1ULL << 39,
};

/*
 * Watchdog using the Intel architected PerfMon.
 * Used for Core2 and hopefully all future Intel CPUs.
 */
#define ARCH_PERFMON_NMI_EVENT_SEL      ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL
#define ARCH_PERFMON_NMI_EVENT_UMASK    ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK

static struct wd_ops intel_arch_wd_ops;

static int setup_intel_arch_watchdog(unsigned nmi_hz)
{
        unsigned int ebx;
        union cpuid10_eax eax;
        unsigned int unused;
        unsigned int perfctr_msr, evntsel_msr;
        unsigned int evntsel;
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

        /*
         * Check whether the Architectural PerfMon supports
         * Unhalted Core Cycles Event or not.
         * NOTE: Corresponding bit = 0 in ebx indicates event present.
         */
        cpuid(10, &(eax.full), &ebx, &unused, &unused);
        if ((eax.split.mask_length < (ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX+1)) ||
            (ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT))
                return 0;

        perfctr_msr = wd_ops->perfctr;
        evntsel_msr = wd_ops->evntsel;

        wrmsrl(perfctr_msr, 0UL);

        evntsel = ARCH_PERFMON_EVENTSEL_INT
                | ARCH_PERFMON_EVENTSEL_OS
                | ARCH_PERFMON_EVENTSEL_USR
                | ARCH_PERFMON_NMI_EVENT_SEL
                | ARCH_PERFMON_NMI_EVENT_UMASK;

        /* setup the timer */
        wrmsr(evntsel_msr, evntsel, 0);
        nmi_hz = adjust_for_32bit_ctr(nmi_hz);
        write_watchdog_counter32(perfctr_msr, "INTEL_ARCH_PERFCTR0", nmi_hz);

        wd->perfctr_msr = perfctr_msr;
        wd->evntsel_msr = evntsel_msr;
        wd->cccr_msr = 0;  /* unused */

        /* ok, everything is initialized, announce that we're set */
        cpu_nmi_set_wd_enabled();

        apic_write(APIC_LVTPC, APIC_DM_NMI);
        evntsel |= ARCH_PERFMON_EVENTSEL0_ENABLE;
        wrmsr(evntsel_msr, evntsel, 0);
        intel_arch_wd_ops.checkbit = 1ULL << (eax.split.bit_width - 1);
        return 1;
}

static struct wd_ops intel_arch_wd_ops __read_mostly = {
        .reserve        = single_msr_reserve,
        .unreserve      = single_msr_unreserve,
        .setup          = setup_intel_arch_watchdog,
        .rearm          = p6_rearm,
        .stop           = single_msr_stop_watchdog,
        .perfctr        = MSR_ARCH_PERFMON_PERFCTR1,
        .evntsel        = MSR_ARCH_PERFMON_EVENTSEL1,
};

static void probe_nmi_watchdog(void)
{
        switch (boot_cpu_data.x86_vendor) {
        case X86_VENDOR_AMD:
                if (boot_cpu_data.x86 != 6 && boot_cpu_data.x86 != 15 &&
                    boot_cpu_data.x86 != 16)
                        return;
                wd_ops = &k7_wd_ops;
                break;
        case X86_VENDOR_INTEL:
                /* Work around where perfctr1 doesn't have a working enable
                 * bit as described in the following errata:
                 * AE49 Core Duo and Intel Core Solo 65 nm
                 * AN49 Intel Pentium Dual-Core
                 * AF49 Dual-Core Intel Xeon Processor LV
                 */
                if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 14) ||
                    ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 15 &&
                     boot_cpu_data.x86_mask == 4))) {
                        intel_arch_wd_ops.perfctr = MSR_ARCH_PERFMON_PERFCTR0;
                        intel_arch_wd_ops.evntsel = MSR_ARCH_PERFMON_EVENTSEL0;
                }
                if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
                        wd_ops = &intel_arch_wd_ops;
                        break;
                }
                switch (boot_cpu_data.x86) {
                case 6:
                        if (boot_cpu_data.x86_model > 13)
                                return;

                        wd_ops = &p6_wd_ops;
                        break;
                case 15:
                        wd_ops = &p4_wd_ops;
                        break;
                default:
                        return;
                }
                break;
        }
}

/* Interface to nmi.c */

int lapic_watchdog_init(unsigned nmi_hz)
{
        if (!wd_ops) {
                probe_nmi_watchdog();
                if (!wd_ops) {
                        printk(KERN_INFO "NMI watchdog: CPU not supported\n");
                        return -1;
                }

                if (!wd_ops->reserve()) {
                        printk(KERN_ERR
                                "NMI watchdog: cannot reserve perfctrs\n");
                        return -1;
                }
        }

        if (!(wd_ops->setup(nmi_hz))) {
                printk(KERN_ERR "Cannot setup NMI watchdog on CPU %d\n",
                       raw_smp_processor_id());
                return -1;
        }

        return 0;
}

void lapic_watchdog_stop(void)
{
        if (wd_ops)
                wd_ops->stop();
}

unsigned lapic_adjust_nmi_hz(unsigned hz)
{
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
        if (wd->perfctr_msr == MSR_P6_PERFCTR0 ||
            wd->perfctr_msr == MSR_ARCH_PERFMON_PERFCTR1)
                hz = adjust_for_32bit_ctr(hz);
        return hz;
}

int __kprobes lapic_wd_event(unsigned nmi_hz)
{
        struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
        u64 ctr;

        rdmsrl(wd->perfctr_msr, ctr);
        if (ctr & wd_ops->checkbit) /* perfctr still running? */
                return 0;

        wd_ops->rearm(wd, nmi_hz);
        return 1;
}