Mention branches and keyring.

[releases.git] / x86 / kernel / apic / apic.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *      Local APIC handling, local APIC timers
 *
 *      (c) 1999, 2000, 2009 Ingo Molnar <mingo@redhat.com>
 *
 *      Fixes
 *      Maciej W. Rozycki       :       Bits for genuine 82489DX APICs;
 *                                      thanks to Eric Gilmore
 *                                      and Rolf G. Tews
 *                                      for testing these extensively.
 *      Maciej W. Rozycki       :       Various updates and fixes.
 *      Mikael Pettersson       :       Power Management for UP-APIC.
 *      Pavel Machek and
 *      Mikael Pettersson       :       PM converted to driver model.
 */

#include <linux/perf_event.h>
#include <linux/kernel_stat.h>
#include <linux/mc146818rtc.h>
#include <linux/acpi_pmtmr.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/memblock.h>
#include <linux/ftrace.h>
#include <linux/ioport.h>
#include <linux/export.h>
#include <linux/syscore_ops.h>
#include <linux/delay.h>
#include <linux/timex.h>
#include <linux/i8253.h>
#include <linux/dmar.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/dmi.h>
#include <linux/smp.h>
#include <linux/mm.h>

#include <asm/trace/irq_vectors.h>
#include <asm/irq_remapping.h>
#include <asm/pc-conf-reg.h>
#include <asm/perf_event.h>
#include <asm/x86_init.h>
#include <linux/atomic.h>
#include <asm/barrier.h>
#include <asm/mpspec.h>
#include <asm/i8259.h>
#include <asm/proto.h>
#include <asm/traps.h>
#include <asm/apic.h>
#include <asm/acpi.h>
#include <asm/io_apic.h>
#include <asm/desc.h>
#include <asm/hpet.h>
#include <asm/mtrr.h>
#include <asm/time.h>
#include <asm/smp.h>
#include <asm/mce.h>
#include <asm/tsc.h>
#include <asm/hypervisor.h>
#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
#include <asm/irq_regs.h>
#include <asm/cpu.h>

unsigned int num_processors;

unsigned disabled_cpus;

/* Processor that is doing the boot up */
unsigned int boot_cpu_physical_apicid __ro_after_init = -1U;
EXPORT_SYMBOL_GPL(boot_cpu_physical_apicid);

u8 boot_cpu_apic_version __ro_after_init;

/*
 * The highest APIC ID seen during enumeration.
 */
static unsigned int max_physical_apicid;

/*
 * Bitmask of physically existing CPUs:
 */
physid_mask_t phys_cpu_present_map;

/*
 * Processor to be disabled specified by kernel parameter
 * disable_cpu_apicid=<int>, mostly used for the kdump 2nd kernel to
 * avoid undefined behaviour caused by sending INIT from AP to BSP.
 */
static unsigned int disabled_cpu_apicid __ro_after_init = BAD_APICID;

/*
 * This variable controls which CPUs receive external NMIs.  By default,
 * external NMIs are delivered only to the BSP.
 */
static int apic_extnmi __ro_after_init = APIC_EXTNMI_BSP;

/*
 * Hypervisor supports 15 bits of APIC ID in MSI Extended Destination ID
 */
static bool virt_ext_dest_id __ro_after_init;

/*
 * Map cpu index to physical APIC ID
 */
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid, BAD_APICID);
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid, BAD_APICID);
DEFINE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid, U32_MAX);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_bios_cpu_apicid);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_acpiid);

#ifdef CONFIG_X86_32

/*
 * On x86_32, the mapping between cpu and logical apicid may vary
 * depending on apic in use.  The following early percpu variable is
 * used for the mapping.  This is where the behaviors of x86_64 and 32
 * actually diverge.  Let's keep it ugly for now.
 */
DEFINE_EARLY_PER_CPU_READ_MOSTLY(int, x86_cpu_to_logical_apicid, BAD_APICID);

/* Local APIC was disabled by the BIOS and enabled by the kernel */
static int enabled_via_apicbase __ro_after_init;

/*
 * Handle interrupt mode configuration register (IMCR).
 * This register controls whether the interrupt signals
 * that reach the BSP come from the master PIC or from the
 * local APIC. Before entering Symmetric I/O Mode, either
 * the BIOS or the operating system must switch out of
 * PIC Mode by changing the IMCR.
 */
static inline void imcr_pic_to_apic(void)
{
        /* NMI and 8259 INTR go through APIC */
        pc_conf_set(PC_CONF_MPS_IMCR, 0x01);
}

static inline void imcr_apic_to_pic(void)
{
        /* NMI and 8259 INTR go directly to BSP */
        pc_conf_set(PC_CONF_MPS_IMCR, 0x00);
}
#endif

/*
 * Knob to control our willingness to enable the local APIC.
 *
 * +1=force-enable
 */
static int force_enable_local_apic __initdata;

/*
 * APIC command line parameters
 */
static int __init parse_lapic(char *arg)
{
        if (IS_ENABLED(CONFIG_X86_32) && !arg)
                force_enable_local_apic = 1;
        else if (arg && !strncmp(arg, "notscdeadline", 13))
                setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
        return 0;
}
early_param("lapic", parse_lapic);

#ifdef CONFIG_X86_64
static int apic_calibrate_pmtmr __initdata;
static __init int setup_apicpmtimer(char *s)
{
        apic_calibrate_pmtmr = 1;
        notsc_setup(NULL);
        return 1;
}
__setup("apicpmtimer", setup_apicpmtimer);
#endif

unsigned long mp_lapic_addr __ro_after_init;
int disable_apic __ro_after_init;
/* Disable local APIC timer from the kernel commandline or via dmi quirk */
static int disable_apic_timer __initdata;
/* Local APIC timer works in C2 */
int local_apic_timer_c2_ok __ro_after_init;
EXPORT_SYMBOL_GPL(local_apic_timer_c2_ok);

/*
 * Debug level, exported for io_apic.c
 */
int apic_verbosity __ro_after_init;

int pic_mode __ro_after_init;

/* Have we found an MP table */
int smp_found_config __ro_after_init;

static struct resource lapic_resource = {
        .name = "Local APIC",
        .flags = IORESOURCE_MEM | IORESOURCE_BUSY,
};

unsigned int lapic_timer_period = 0;

static void apic_pm_activate(void);

static unsigned long apic_phys __ro_after_init;

/*
 * Get the LAPIC version
 */
static inline int lapic_get_version(void)
{
        return GET_APIC_VERSION(apic_read(APIC_LVR));
}

/*
 * Check, if the APIC is integrated or a separate chip
 */
static inline int lapic_is_integrated(void)
{
        return APIC_INTEGRATED(lapic_get_version());
}

/*
 * Check, whether this is a modern or a first generation APIC
 */
static int modern_apic(void)
{
        /* AMD systems use old APIC versions, so check the CPU */
        if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
            boot_cpu_data.x86 >= 0xf)
                return 1;

        /* Hygon systems use modern APIC */
        if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
                return 1;

        return lapic_get_version() >= 0x14;
}

/*
 * right after this call apic become NOOP driven
 * so apic->write/read doesn't do anything
 */
static void __init apic_disable(void)
{
        pr_info("APIC: switched to apic NOOP\n");
        apic = &apic_noop;
}

void native_apic_wait_icr_idle(void)
{
        while (apic_read(APIC_ICR) & APIC_ICR_BUSY)
                cpu_relax();
}

u32 native_safe_apic_wait_icr_idle(void)
{
        u32 send_status;
        int timeout;

        timeout = 0;
        do {
                send_status = apic_read(APIC_ICR) & APIC_ICR_BUSY;
                if (!send_status)
                        break;
                inc_irq_stat(icr_read_retry_count);
                udelay(100);
        } while (timeout++ < 1000);

        return send_status;
}

void native_apic_icr_write(u32 low, u32 id)
{
        unsigned long flags;

        local_irq_save(flags);
        apic_write(APIC_ICR2, SET_XAPIC_DEST_FIELD(id));
        apic_write(APIC_ICR, low);
        local_irq_restore(flags);
}

u64 native_apic_icr_read(void)
{
        u32 icr1, icr2;

        icr2 = apic_read(APIC_ICR2);
        icr1 = apic_read(APIC_ICR);

        return icr1 | ((u64)icr2 << 32);
}

#ifdef CONFIG_X86_32
/**
 * get_physical_broadcast - Get number of physical broadcast IDs
 */
int get_physical_broadcast(void)
{
        return modern_apic() ? 0xff : 0xf;
}
#endif

/**
 * lapic_get_maxlvt - get the maximum number of local vector table entries
 */
int lapic_get_maxlvt(void)
{
        /*
         * - we always have APIC integrated on 64bit mode
         * - 82489DXs do not report # of LVT entries
         */
        return lapic_is_integrated() ? GET_APIC_MAXLVT(apic_read(APIC_LVR)) : 2;
}

/*
 * Local APIC timer
 */

/* Clock divisor */
#define APIC_DIVISOR 16
#define TSC_DIVISOR  8

/* i82489DX specific */
#define         I82489DX_BASE_DIVIDER           (((0x2) << 18))

/*
 * This function sets up the local APIC timer, with a timeout of
 * 'clocks' APIC bus clock. During calibration we actually call
 * this function twice on the boot CPU, once with a bogus timeout
 * value, second time for real. The other (noncalibrating) CPUs
 * call this function only once, with the real, calibrated value.
 *
 * We do reads before writes even if unnecessary, to get around the
 * P5 APIC double write bug.
 */
static void __setup_APIC_LVTT(unsigned int clocks, int oneshot, int irqen)
{
        unsigned int lvtt_value, tmp_value;

        lvtt_value = LOCAL_TIMER_VECTOR;
        if (!oneshot)
                lvtt_value |= APIC_LVT_TIMER_PERIODIC;
        else if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
                lvtt_value |= APIC_LVT_TIMER_TSCDEADLINE;

        /*
         * The i82489DX APIC uses bit 18 and 19 for the base divider.  This
         * overlaps with bit 18 on integrated APICs, but is not documented
         * in the SDM. No problem though. i82489DX equipped systems do not
         * have TSC deadline timer.
         */
        if (!lapic_is_integrated())
                lvtt_value |= I82489DX_BASE_DIVIDER;

        if (!irqen)
                lvtt_value |= APIC_LVT_MASKED;

        apic_write(APIC_LVTT, lvtt_value);

        if (lvtt_value & APIC_LVT_TIMER_TSCDEADLINE) {
                /*
                 * See Intel SDM: TSC-Deadline Mode chapter. In xAPIC mode,
                 * writing to the APIC LVTT and TSC_DEADLINE MSR isn't serialized.
                 * According to Intel, MFENCE can do the serialization here.
                 */
                asm volatile("mfence" : : : "memory");
                return;
        }

        /*
         * Divide PICLK by 16
         */
        tmp_value = apic_read(APIC_TDCR);
        apic_write(APIC_TDCR,
                (tmp_value & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE)) |
                APIC_TDR_DIV_16);

        if (!oneshot)
                apic_write(APIC_TMICT, clocks / APIC_DIVISOR);
}

/*
 * Setup extended LVT, AMD specific
 *
 * Software should use the LVT offsets the BIOS provides.  The offsets
 * are determined by the subsystems using it like those for MCE
 * threshold or IBS.  On K8 only offset 0 (APIC500) and MCE interrupts
 * are supported. Beginning with family 10h at least 4 offsets are
 * available.
 *
 * Since the offsets must be consistent for all cores, we keep track
 * of the LVT offsets in software and reserve the offset for the same
 * vector also to be used on other cores. An offset is freed by
 * setting the entry to APIC_EILVT_MASKED.
 *
 * If the BIOS is right, there should be no conflicts. Otherwise a
 * "[Firmware Bug]: ..." error message is generated. However, if
 * software does not properly determines the offsets, it is not
 * necessarily a BIOS bug.
 */

static atomic_t eilvt_offsets[APIC_EILVT_NR_MAX];

static inline int eilvt_entry_is_changeable(unsigned int old, unsigned int new)
{
        return (old & APIC_EILVT_MASKED)
                || (new == APIC_EILVT_MASKED)
                || ((new & ~APIC_EILVT_MASKED) == old);
}

static unsigned int reserve_eilvt_offset(int offset, unsigned int new)
{
        unsigned int rsvd, vector;

        if (offset >= APIC_EILVT_NR_MAX)
                return ~0;

        rsvd = atomic_read(&eilvt_offsets[offset]);
        do {
                vector = rsvd & ~APIC_EILVT_MASKED;     /* 0: unassigned */
                if (vector && !eilvt_entry_is_changeable(vector, new))
                        /* may not change if vectors are different */
                        return rsvd;
        } while (!atomic_try_cmpxchg(&eilvt_offsets[offset], &rsvd, new));

        rsvd = new & ~APIC_EILVT_MASKED;
        if (rsvd && rsvd != vector)
                pr_info("LVT offset %d assigned for vector 0x%02x\n",
                        offset, rsvd);

        return new;
}

/*
 * If mask=1, the LVT entry does not generate interrupts while mask=0
 * enables the vector. See also the BKDGs. Must be called with
 * preemption disabled.
 */

int setup_APIC_eilvt(u8 offset, u8 vector, u8 msg_type, u8 mask)
{
        unsigned long reg = APIC_EILVTn(offset);
        unsigned int new, old, reserved;

        new = (mask << 16) | (msg_type << 8) | vector;
        old = apic_read(reg);
        reserved = reserve_eilvt_offset(offset, new);

        if (reserved != new) {
                pr_err(FW_BUG "cpu %d, try to use APIC%lX (LVT offset %d) for "
                       "vector 0x%x, but the register is already in use for "
                       "vector 0x%x on another cpu\n",
                       smp_processor_id(), reg, offset, new, reserved);
                return -EINVAL;
        }

        if (!eilvt_entry_is_changeable(old, new)) {
                pr_err(FW_BUG "cpu %d, try to use APIC%lX (LVT offset %d) for "
                       "vector 0x%x, but the register is already in use for "
                       "vector 0x%x on this cpu\n",
                       smp_processor_id(), reg, offset, new, old);
                return -EBUSY;
        }

        apic_write(reg, new);

        return 0;
}
EXPORT_SYMBOL_GPL(setup_APIC_eilvt);

/*
 * Program the next event, relative to now
 */
static int lapic_next_event(unsigned long delta,
                            struct clock_event_device *evt)
{
        apic_write(APIC_TMICT, delta);
        return 0;
}

static int lapic_next_deadline(unsigned long delta,
                               struct clock_event_device *evt)
{
        u64 tsc;

        /* This MSR is special and need a special fence: */
        weak_wrmsr_fence();

        tsc = rdtsc();
        wrmsrl(MSR_IA32_TSC_DEADLINE, tsc + (((u64) delta) * TSC_DIVISOR));
        return 0;
}

static int lapic_timer_shutdown(struct clock_event_device *evt)
{
        unsigned int v;

        /* Lapic used as dummy for broadcast ? */
        if (evt->features & CLOCK_EVT_FEAT_DUMMY)
                return 0;

        v = apic_read(APIC_LVTT);
        v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
        apic_write(APIC_LVTT, v);
        apic_write(APIC_TMICT, 0);
        return 0;
}

static inline int
lapic_timer_set_periodic_oneshot(struct clock_event_device *evt, bool oneshot)
{
        /* Lapic used as dummy for broadcast ? */
        if (evt->features & CLOCK_EVT_FEAT_DUMMY)
                return 0;

        __setup_APIC_LVTT(lapic_timer_period, oneshot, 1);
        return 0;
}

static int lapic_timer_set_periodic(struct clock_event_device *evt)
{
        return lapic_timer_set_periodic_oneshot(evt, false);
}

static int lapic_timer_set_oneshot(struct clock_event_device *evt)
{
        return lapic_timer_set_periodic_oneshot(evt, true);
}

/*
 * Local APIC timer broadcast function
 */
static void lapic_timer_broadcast(const struct cpumask *mask)
{
#ifdef CONFIG_SMP
        apic->send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
#endif
}


/*
 * The local apic timer can be used for any function which is CPU local.
 */
static struct clock_event_device lapic_clockevent = {
        .name                           = "lapic",
        .features                       = CLOCK_EVT_FEAT_PERIODIC |
                                          CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP
                                          | CLOCK_EVT_FEAT_DUMMY,
        .shift                          = 32,
        .set_state_shutdown             = lapic_timer_shutdown,
        .set_state_periodic             = lapic_timer_set_periodic,
        .set_state_oneshot              = lapic_timer_set_oneshot,
        .set_state_oneshot_stopped      = lapic_timer_shutdown,
        .set_next_event                 = lapic_next_event,
        .broadcast                      = lapic_timer_broadcast,
        .rating                         = 100,
        .irq                            = -1,
};
static DEFINE_PER_CPU(struct clock_event_device, lapic_events);

static const struct x86_cpu_id deadline_match[] __initconst = {
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(HASWELL_X, X86_STEPPINGS(0x2, 0x2), 0x3a), /* EP */
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(HASWELL_X, X86_STEPPINGS(0x4, 0x4), 0x0f), /* EX */

        X86_MATCH_INTEL_FAM6_MODEL( BROADWELL_X,        0x0b000020),

        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x2, 0x2), 0x00000011),
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x3, 0x3), 0x0700000e),
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x4, 0x4), 0x0f00000c),
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x5, 0x5), 0x0e000003),

        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(SKYLAKE_X, X86_STEPPINGS(0x3, 0x3), 0x01000136),
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(SKYLAKE_X, X86_STEPPINGS(0x4, 0x4), 0x02000014),
        X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS(SKYLAKE_X, X86_STEPPINGS(0x5, 0xf), 0),

        X86_MATCH_INTEL_FAM6_MODEL( HASWELL,            0x22),
        X86_MATCH_INTEL_FAM6_MODEL( HASWELL_L,          0x20),
        X86_MATCH_INTEL_FAM6_MODEL( HASWELL_G,          0x17),

        X86_MATCH_INTEL_FAM6_MODEL( BROADWELL,          0x25),
        X86_MATCH_INTEL_FAM6_MODEL( BROADWELL_G,        0x17),

        X86_MATCH_INTEL_FAM6_MODEL( SKYLAKE_L,          0xb2),
        X86_MATCH_INTEL_FAM6_MODEL( SKYLAKE,            0xb2),

        X86_MATCH_INTEL_FAM6_MODEL( KABYLAKE_L,         0x52),
        X86_MATCH_INTEL_FAM6_MODEL( KABYLAKE,           0x52),

        {},
};

static __init bool apic_validate_deadline_timer(void)
{
        const struct x86_cpu_id *m;
        u32 rev;

        if (!boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
                return false;
        if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
                return true;

        m = x86_match_cpu(deadline_match);
        if (!m)
                return true;

        rev = (u32)m->driver_data;

        if (boot_cpu_data.microcode >= rev)
                return true;

        setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
        pr_err(FW_BUG "TSC_DEADLINE disabled due to Errata; "
               "/*(DEBLOBBED)*/\n", rev);
        return false;
}

/*
 * Setup the local APIC timer for this CPU. Copy the initialized values
 * of the boot CPU and register the clock event in the framework.
 */
static void setup_APIC_timer(void)
{
        struct clock_event_device *levt = this_cpu_ptr(&lapic_events);

        if (this_cpu_has(X86_FEATURE_ARAT)) {
                lapic_clockevent.features &= ~CLOCK_EVT_FEAT_C3STOP;
                /* Make LAPIC timer preferable over percpu HPET */
                lapic_clockevent.rating = 150;
        }

        memcpy(levt, &lapic_clockevent, sizeof(*levt));
        levt->cpumask = cpumask_of(smp_processor_id());

        if (this_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER)) {
                levt->name = "lapic-deadline";
                levt->features &= ~(CLOCK_EVT_FEAT_PERIODIC |
                                    CLOCK_EVT_FEAT_DUMMY);
                levt->set_next_event = lapic_next_deadline;
                clockevents_config_and_register(levt,
                                                tsc_khz * (1000 / TSC_DIVISOR),
                                                0xF, ~0UL);
        } else
                clockevents_register_device(levt);
}

/*
 * Install the updated TSC frequency from recalibration at the TSC
 * deadline clockevent devices.
 */
static void __lapic_update_tsc_freq(void *info)
{
        struct clock_event_device *levt = this_cpu_ptr(&lapic_events);

        if (!this_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
                return;

        clockevents_update_freq(levt, tsc_khz * (1000 / TSC_DIVISOR));
}

void lapic_update_tsc_freq(void)
{
        /*
         * The clockevent device's ->mult and ->shift can both be
         * changed. In order to avoid races, schedule the frequency
         * update code on each CPU.
         */
        on_each_cpu(__lapic_update_tsc_freq, NULL, 0);
}

/*
 * In this functions we calibrate APIC bus clocks to the external timer.
 *
 * We want to do the calibration only once since we want to have local timer
 * irqs synchronous. CPUs connected by the same APIC bus have the very same bus
 * frequency.
 *
 * This was previously done by reading the PIT/HPET and waiting for a wrap
 * around to find out, that a tick has elapsed. I have a box, where the PIT
 * readout is broken, so it never gets out of the wait loop again. This was
 * also reported by others.
 *
 * Monitoring the jiffies value is inaccurate and the clockevents
 * infrastructure allows us to do a simple substitution of the interrupt
 * handler.
 *
 * The calibration routine also uses the pm_timer when possible, as the PIT
 * happens to run way too slow (factor 2.3 on my VAIO CoreDuo, which goes
 * back to normal later in the boot process).
 */

#define LAPIC_CAL_LOOPS         (HZ/10)

static __initdata int lapic_cal_loops = -1;
static __initdata long lapic_cal_t1, lapic_cal_t2;
static __initdata unsigned long long lapic_cal_tsc1, lapic_cal_tsc2;
static __initdata unsigned long lapic_cal_pm1, lapic_cal_pm2;
static __initdata unsigned long lapic_cal_j1, lapic_cal_j2;

/*
 * Temporary interrupt handler and polled calibration function.
 */
static void __init lapic_cal_handler(struct clock_event_device *dev)
{
        unsigned long long tsc = 0;
        long tapic = apic_read(APIC_TMCCT);
        unsigned long pm = acpi_pm_read_early();

        if (boot_cpu_has(X86_FEATURE_TSC))
                tsc = rdtsc();

        switch (lapic_cal_loops++) {
        case 0:
                lapic_cal_t1 = tapic;
                lapic_cal_tsc1 = tsc;
                lapic_cal_pm1 = pm;
                lapic_cal_j1 = jiffies;
                break;

        case LAPIC_CAL_LOOPS:
                lapic_cal_t2 = tapic;
                lapic_cal_tsc2 = tsc;
                if (pm < lapic_cal_pm1)
                        pm += ACPI_PM_OVRRUN;
                lapic_cal_pm2 = pm;
                lapic_cal_j2 = jiffies;
                break;
        }
}

static int __init
calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)
{
        const long pm_100ms = PMTMR_TICKS_PER_SEC / 10;
        const long pm_thresh = pm_100ms / 100;
        unsigned long mult;
        u64 res;

#ifndef CONFIG_X86_PM_TIMER
        return -1;
#endif

        apic_printk(APIC_VERBOSE, "... PM-Timer delta = %ld\n", deltapm);

        /* Check, if the PM timer is available */
        if (!deltapm)
                return -1;

        mult = clocksource_hz2mult(PMTMR_TICKS_PER_SEC, 22);

        if (deltapm > (pm_100ms - pm_thresh) &&
            deltapm < (pm_100ms + pm_thresh)) {
                apic_printk(APIC_VERBOSE, "... PM-Timer result ok\n");
                return 0;
        }

        res = (((u64)deltapm) *  mult) >> 22;
        do_div(res, 1000000);
        pr_warn("APIC calibration not consistent "
                "with PM-Timer: %ldms instead of 100ms\n", (long)res);

        /* Correct the lapic counter value */
        res = (((u64)(*delta)) * pm_100ms);
        do_div(res, deltapm);
        pr_info("APIC delta adjusted to PM-Timer: "
                "%lu (%ld)\n", (unsigned long)res, *delta);
        *delta = (long)res;

        /* Correct the tsc counter value */
        if (boot_cpu_has(X86_FEATURE_TSC)) {
                res = (((u64)(*deltatsc)) * pm_100ms);
                do_div(res, deltapm);
                apic_printk(APIC_VERBOSE, "TSC delta adjusted to "
                                          "PM-Timer: %lu (%ld)\n",
                                        (unsigned long)res, *deltatsc);
                *deltatsc = (long)res;
        }

        return 0;
}

static int __init lapic_init_clockevent(void)
{
        if (!lapic_timer_period)
                return -1;

        /* Calculate the scaled math multiplication factor */
        lapic_clockevent.mult = div_sc(lapic_timer_period/APIC_DIVISOR,
                                        TICK_NSEC, lapic_clockevent.shift);
        lapic_clockevent.max_delta_ns =
                clockevent_delta2ns(0x7FFFFFFF, &lapic_clockevent);
        lapic_clockevent.max_delta_ticks = 0x7FFFFFFF;
        lapic_clockevent.min_delta_ns =
                clockevent_delta2ns(0xF, &lapic_clockevent);
        lapic_clockevent.min_delta_ticks = 0xF;

        return 0;
}

bool __init apic_needs_pit(void)
{
        /*
         * If the frequencies are not known, PIT is required for both TSC
         * and apic timer calibration.
         */
        if (!tsc_khz || !cpu_khz)
                return true;

        /* Is there an APIC at all or is it disabled? */
        if (!boot_cpu_has(X86_FEATURE_APIC) || disable_apic)
                return true;

        /*
         * If interrupt delivery mode is legacy PIC or virtual wire without
         * configuration, the local APIC timer wont be set up. Make sure
         * that the PIT is initialized.
         */
        if (apic_intr_mode == APIC_PIC ||
            apic_intr_mode == APIC_VIRTUAL_WIRE_NO_CONFIG)
                return true;

        /* Virt guests may lack ARAT, but still have DEADLINE */
        if (!boot_cpu_has(X86_FEATURE_ARAT))
                return true;

        /* Deadline timer is based on TSC so no further PIT action required */
        if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
                return false;

        /* APIC timer disabled? */
        if (disable_apic_timer)
                return true;
        /*
         * The APIC timer frequency is known already, no PIT calibration
         * required. If unknown, let the PIT be initialized.
         */
        return lapic_timer_period == 0;
}

static int __init calibrate_APIC_clock(void)
{
        struct clock_event_device *levt = this_cpu_ptr(&lapic_events);
        u64 tsc_perj = 0, tsc_start = 0;
        unsigned long jif_start;
        unsigned long deltaj;
        long delta, deltatsc;
        int pm_referenced = 0;

        if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
                return 0;

        /*
         * Check if lapic timer has already been calibrated by platform
         * specific routine, such as tsc calibration code. If so just fill
         * in the clockevent structure and return.
         */
        if (!lapic_init_clockevent()) {
                apic_printk(APIC_VERBOSE, "lapic timer already calibrated %d\n",
                            lapic_timer_period);
                /*
                 * Direct calibration methods must have an always running
                 * local APIC timer, no need for broadcast timer.
                 */
                lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
                return 0;
        }

        apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
                    "calibrating APIC timer ...\n");

        /*
         * There are platforms w/o global clockevent devices. Instead of
         * making the calibration conditional on that, use a polling based
         * approach everywhere.
         */
        local_irq_disable();

        /*
         * Setup the APIC counter to maximum. There is no way the lapic
         * can underflow in the 100ms detection time frame
         */
        __setup_APIC_LVTT(0xffffffff, 0, 0);

        /*
         * Methods to terminate the calibration loop:
         *  1) Global clockevent if available (jiffies)
         *  2) TSC if available and frequency is known
         */
        jif_start = READ_ONCE(jiffies);

        if (tsc_khz) {
                tsc_start = rdtsc();
                tsc_perj = div_u64((u64)tsc_khz * 1000, HZ);
        }

        /*
         * Enable interrupts so the tick can fire, if a global
         * clockevent device is available
         */
        local_irq_enable();

        while (lapic_cal_loops <= LAPIC_CAL_LOOPS) {
                /* Wait for a tick to elapse */
                while (1) {
                        if (tsc_khz) {
                                u64 tsc_now = rdtsc();
                                if ((tsc_now - tsc_start) >= tsc_perj) {
                                        tsc_start += tsc_perj;
                                        break;
                                }
                        } else {
                                unsigned long jif_now = READ_ONCE(jiffies);

                                if (time_after(jif_now, jif_start)) {
                                        jif_start = jif_now;
                                        break;
                                }
                        }
                        cpu_relax();
                }

                /* Invoke the calibration routine */
                local_irq_disable();
                lapic_cal_handler(NULL);
                local_irq_enable();
        }

        local_irq_disable();

        /* Build delta t1-t2 as apic timer counts down */
        delta = lapic_cal_t1 - lapic_cal_t2;
        apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);

        deltatsc = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);

        /* we trust the PM based calibration if possible */
        pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
                                        &delta, &deltatsc);

        lapic_timer_period = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
        lapic_init_clockevent();

        apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
        apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
        apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
                    lapic_timer_period);

        if (boot_cpu_has(X86_FEATURE_TSC)) {
                apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
                            "%ld.%04ld MHz.\n",
                            (deltatsc / LAPIC_CAL_LOOPS) / (1000000 / HZ),
                            (deltatsc / LAPIC_CAL_LOOPS) % (1000000 / HZ));
        }

        apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
                    "%u.%04u MHz.\n",
                    lapic_timer_period / (1000000 / HZ),
                    lapic_timer_period % (1000000 / HZ));

        /*
         * Do a sanity check on the APIC calibration result
         */
        if (lapic_timer_period < (1000000 / HZ)) {
                local_irq_enable();
                pr_warn("APIC frequency too slow, disabling apic timer\n");
                return -1;
        }

        levt->features &= ~CLOCK_EVT_FEAT_DUMMY;

        /*
         * PM timer calibration failed or not turned on so lets try APIC
         * timer based calibration, if a global clockevent device is
         * available.
         */
        if (!pm_referenced && global_clock_event) {
                apic_printk(APIC_VERBOSE, "... verify APIC timer\n");

                /*
                 * Setup the apic timer manually
                 */
                levt->event_handler = lapic_cal_handler;
                lapic_timer_set_periodic(levt);
                lapic_cal_loops = -1;

                /* Let the interrupts run */
                local_irq_enable();

                while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
                        cpu_relax();

                /* Stop the lapic timer */
                local_irq_disable();
                lapic_timer_shutdown(levt);

                /* Jiffies delta */
                deltaj = lapic_cal_j2 - lapic_cal_j1;
                apic_printk(APIC_VERBOSE, "... jiffies delta = %lu\n", deltaj);

                /* Check, if the jiffies result is consistent */
                if (deltaj >= LAPIC_CAL_LOOPS-2 && deltaj <= LAPIC_CAL_LOOPS+2)
                        apic_printk(APIC_VERBOSE, "... jiffies result ok\n");
                else
                        levt->features |= CLOCK_EVT_FEAT_DUMMY;
        }
        local_irq_enable();

        if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
                pr_warn("APIC timer disabled due to verification failure\n");
                return -1;
        }

        return 0;
}

/*
 * Setup the boot APIC
 *
 * Calibrate and verify the result.
 */
void __init setup_boot_APIC_clock(void)
{
        /*
         * The local apic timer can be disabled via the kernel
         * commandline or from the CPU detection code. Register the lapic
         * timer as a dummy clock event source on SMP systems, so the
         * broadcast mechanism is used. On UP systems simply ignore it.
         */
        if (disable_apic_timer) {
                pr_info("Disabling APIC timer\n");
                /* No broadcast on UP ! */
                if (num_possible_cpus() > 1) {
                        lapic_clockevent.mult = 1;
                        setup_APIC_timer();
                }
                return;
        }

        if (calibrate_APIC_clock()) {
                /* No broadcast on UP ! */
                if (num_possible_cpus() > 1)
                        setup_APIC_timer();
                return;
        }

        /*
         * If nmi_watchdog is set to IO_APIC, we need the
         * PIT/HPET going.  Otherwise register lapic as a dummy
         * device.
         */
        lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;

        /* Setup the lapic or request the broadcast */
        setup_APIC_timer();
        amd_e400_c1e_apic_setup();
}

void setup_secondary_APIC_clock(void)
{
        setup_APIC_timer();
        amd_e400_c1e_apic_setup();
}

/*
 * The guts of the apic timer interrupt
 */
static void local_apic_timer_interrupt(void)
{
        struct clock_event_device *evt = this_cpu_ptr(&lapic_events);

        /*
         * Normally we should not be here till LAPIC has been initialized but
         * in some cases like kdump, its possible that there is a pending LAPIC
         * timer interrupt from previous kernel's context and is delivered in
         * new kernel the moment interrupts are enabled.
         *
         * Interrupts are enabled early and LAPIC is setup much later, hence
         * its possible that when we get here evt->event_handler is NULL.
         * Check for event_handler being NULL and discard the interrupt as
         * spurious.
         */
        if (!evt->event_handler) {
                pr_warn("Spurious LAPIC timer interrupt on cpu %d\n",
                        smp_processor_id());
                /* Switch it off */
                lapic_timer_shutdown(evt);
                return;
        }

        /*
         * the NMI deadlock-detector uses this.
         */
        inc_irq_stat(apic_timer_irqs);

        evt->event_handler(evt);
}

/*
 * Local APIC timer interrupt. This is the most natural way for doing
 * local interrupts, but local timer interrupts can be emulated by
 * broadcast interrupts too. [in case the hw doesn't support APIC timers]
 *
 * [ if a single-CPU system runs an SMP kernel then we call the local
 *   interrupt as well. Thus we cannot inline the local irq ... ]
 */
DEFINE_IDTENTRY_SYSVEC(sysvec_apic_timer_interrupt)
{
        struct pt_regs *old_regs = set_irq_regs(regs);

        ack_APIC_irq();
        trace_local_timer_entry(LOCAL_TIMER_VECTOR);
        local_apic_timer_interrupt();
        trace_local_timer_exit(LOCAL_TIMER_VECTOR);

        set_irq_regs(old_regs);
}

/*
 * Local APIC start and shutdown
 */

/**
 * clear_local_APIC - shutdown the local APIC
 *
 * This is called, when a CPU is disabled and before rebooting, so the state of
 * the local APIC has no dangling leftovers. Also used to cleanout any BIOS
 * leftovers during boot.
 */
void clear_local_APIC(void)
{
        int maxlvt;
        u32 v;

        /* APIC hasn't been mapped yet */
        if (!x2apic_mode && !apic_phys)
                return;

        maxlvt = lapic_get_maxlvt();
        /*
         * Masking an LVT entry can trigger a local APIC error
         * if the vector is zero. Mask LVTERR first to prevent this.
         */
        if (maxlvt >= 3) {
                v = ERROR_APIC_VECTOR; /* any non-zero vector will do */
                apic_write(APIC_LVTERR, v | APIC_LVT_MASKED);
        }
        /*
         * Careful: we have to set masks only first to deassert
         * any level-triggered sources.
         */
        v = apic_read(APIC_LVTT);
        apic_write(APIC_LVTT, v | APIC_LVT_MASKED);
        v = apic_read(APIC_LVT0);
        apic_write(APIC_LVT0, v | APIC_LVT_MASKED);
        v = apic_read(APIC_LVT1);
        apic_write(APIC_LVT1, v | APIC_LVT_MASKED);
        if (maxlvt >= 4) {
                v = apic_read(APIC_LVTPC);
                apic_write(APIC_LVTPC, v | APIC_LVT_MASKED);
        }

        /* lets not touch this if we didn't frob it */
#ifdef CONFIG_X86_THERMAL_VECTOR
        if (maxlvt >= 5) {
                v = apic_read(APIC_LVTTHMR);
                apic_write(APIC_LVTTHMR, v | APIC_LVT_MASKED);
        }
#endif
#ifdef CONFIG_X86_MCE_INTEL
        if (maxlvt >= 6) {
                v = apic_read(APIC_LVTCMCI);
                if (!(v & APIC_LVT_MASKED))
                        apic_write(APIC_LVTCMCI, v | APIC_LVT_MASKED);
        }
#endif

        /*
         * Clean APIC state for other OSs:
         */
        apic_write(APIC_LVTT, APIC_LVT_MASKED);
        apic_write(APIC_LVT0, APIC_LVT_MASKED);
        apic_write(APIC_LVT1, APIC_LVT_MASKED);
        if (maxlvt >= 3)
                apic_write(APIC_LVTERR, APIC_LVT_MASKED);
        if (maxlvt >= 4)
                apic_write(APIC_LVTPC, APIC_LVT_MASKED);

        /* Integrated APIC (!82489DX) ? */
        if (lapic_is_integrated()) {
                if (maxlvt > 3)
                        /* Clear ESR due to Pentium errata 3AP and 11AP */
                        apic_write(APIC_ESR, 0);
                apic_read(APIC_ESR);
        }
}

/**
 * apic_soft_disable - Clears and software disables the local APIC on hotplug
 *
 * Contrary to disable_local_APIC() this does not touch the enable bit in
 * MSR_IA32_APICBASE. Clearing that bit on systems based on the 3 wire APIC
 * bus would require a hardware reset as the APIC would lose track of bus
 * arbitration. On systems with FSB delivery APICBASE could be disabled,
 * but it has to be guaranteed that no interrupt is sent to the APIC while
 * in that state and it's not clear from the SDM whether it still responds
 * to INIT/SIPI messages. Stay on the safe side and use software disable.
 */
void apic_soft_disable(void)
{
        u32 value;

        clear_local_APIC();

        /* Soft disable APIC (implies clearing of registers for 82489DX!). */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_SPIV_APIC_ENABLED;
        apic_write(APIC_SPIV, value);
}

/**
 * disable_local_APIC - clear and disable the local APIC
 */
void disable_local_APIC(void)
{
        /* APIC hasn't been mapped yet */
        if (!x2apic_mode && !apic_phys)
                return;

        apic_soft_disable();

#ifdef CONFIG_X86_32
        /*
         * When LAPIC was disabled by the BIOS and enabled by the kernel,
         * restore the disabled state.
         */
        if (enabled_via_apicbase) {
                unsigned int l, h;

                rdmsr(MSR_IA32_APICBASE, l, h);
                l &= ~MSR_IA32_APICBASE_ENABLE;
                wrmsr(MSR_IA32_APICBASE, l, h);
        }
#endif
}

/*
 * If Linux enabled the LAPIC against the BIOS default disable it down before
 * re-entering the BIOS on shutdown.  Otherwise the BIOS may get confused and
 * not power-off.  Additionally clear all LVT entries before disable_local_APIC
 * for the case where Linux didn't enable the LAPIC.
 */
void lapic_shutdown(void)
{
        unsigned long flags;

        if (!boot_cpu_has(X86_FEATURE_APIC) && !apic_from_smp_config())
                return;

        local_irq_save(flags);

#ifdef CONFIG_X86_32
        if (!enabled_via_apicbase)
                clear_local_APIC();
        else
#endif
                disable_local_APIC();


        local_irq_restore(flags);
}

/**
 * sync_Arb_IDs - synchronize APIC bus arbitration IDs
 */
void __init sync_Arb_IDs(void)
{
        /*
         * Unsupported on P4 - see Intel Dev. Manual Vol. 3, Ch. 8.6.1 And not
         * needed on AMD.
         */
        if (modern_apic() || boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
                return;

        /*
         * Wait for idle.
         */
        apic_wait_icr_idle();

        apic_printk(APIC_DEBUG, "Synchronizing Arb IDs.\n");
        apic_write(APIC_ICR, APIC_DEST_ALLINC |
                        APIC_INT_LEVELTRIG | APIC_DM_INIT);
}

enum apic_intr_mode_id apic_intr_mode __ro_after_init;

static int __init __apic_intr_mode_select(void)
{
        /* Check kernel option */
        if (disable_apic) {
                pr_info("APIC disabled via kernel command line\n");
                return APIC_PIC;
        }

        /* Check BIOS */
#ifdef CONFIG_X86_64
        /* On 64-bit, the APIC must be integrated, Check local APIC only */
        if (!boot_cpu_has(X86_FEATURE_APIC)) {
                disable_apic = 1;
                pr_info("APIC disabled by BIOS\n");
                return APIC_PIC;
        }
#else
        /* On 32-bit, the APIC may be integrated APIC or 82489DX */

        /* Neither 82489DX nor integrated APIC ? */
        if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config) {
                disable_apic = 1;
                return APIC_PIC;
        }

        /* If the BIOS pretends there is an integrated APIC ? */
        if (!boot_cpu_has(X86_FEATURE_APIC) &&
                APIC_INTEGRATED(boot_cpu_apic_version)) {
                disable_apic = 1;
                pr_err(FW_BUG "Local APIC %d not detected, force emulation\n",
                                       boot_cpu_physical_apicid);
                return APIC_PIC;
        }
#endif

        /* Check MP table or ACPI MADT configuration */
        if (!smp_found_config) {
                disable_ioapic_support();
                if (!acpi_lapic) {
                        pr_info("APIC: ACPI MADT or MP tables are not detected\n");
                        return APIC_VIRTUAL_WIRE_NO_CONFIG;
                }
                return APIC_VIRTUAL_WIRE;
        }

#ifdef CONFIG_SMP
        /* If SMP should be disabled, then really disable it! */
        if (!setup_max_cpus) {
                pr_info("APIC: SMP mode deactivated\n");
                return APIC_SYMMETRIC_IO_NO_ROUTING;
        }

        if (read_apic_id() != boot_cpu_physical_apicid) {
                panic("Boot APIC ID in local APIC unexpected (%d vs %d)",
                     read_apic_id(), boot_cpu_physical_apicid);
                /* Or can we switch back to PIC here? */
        }
#endif

        return APIC_SYMMETRIC_IO;
}

/* Select the interrupt delivery mode for the BSP */
void __init apic_intr_mode_select(void)
{
        apic_intr_mode = __apic_intr_mode_select();
}

/*
 * An initial setup of the virtual wire mode.
 */
void __init init_bsp_APIC(void)
{
        unsigned int value;

        /*
         * Don't do the setup now if we have a SMP BIOS as the
         * through-I/O-APIC virtual wire mode might be active.
         */
        if (smp_found_config || !boot_cpu_has(X86_FEATURE_APIC))
                return;

        /*
         * Do not trust the local APIC being empty at bootup.
         */
        clear_local_APIC();

        /*
         * Enable APIC.
         */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_VECTOR_MASK;
        value |= APIC_SPIV_APIC_ENABLED;

#ifdef CONFIG_X86_32
        /* This bit is reserved on P4/Xeon and should be cleared */
        if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
            (boot_cpu_data.x86 == 15))
                value &= ~APIC_SPIV_FOCUS_DISABLED;
        else
#endif
                value |= APIC_SPIV_FOCUS_DISABLED;
        value |= SPURIOUS_APIC_VECTOR;
        apic_write(APIC_SPIV, value);

        /*
         * Set up the virtual wire mode.
         */
        apic_write(APIC_LVT0, APIC_DM_EXTINT);
        value = APIC_DM_NMI;
        if (!lapic_is_integrated())             /* 82489DX */
                value |= APIC_LVT_LEVEL_TRIGGER;
        if (apic_extnmi == APIC_EXTNMI_NONE)
                value |= APIC_LVT_MASKED;
        apic_write(APIC_LVT1, value);
}

static void __init apic_bsp_setup(bool upmode);

/* Init the interrupt delivery mode for the BSP */
void __init apic_intr_mode_init(void)
{
        bool upmode = IS_ENABLED(CONFIG_UP_LATE_INIT);

        switch (apic_intr_mode) {
        case APIC_PIC:
                pr_info("APIC: Keep in PIC mode(8259)\n");
                return;
        case APIC_VIRTUAL_WIRE:
                pr_info("APIC: Switch to virtual wire mode setup\n");
                break;
        case APIC_VIRTUAL_WIRE_NO_CONFIG:
                pr_info("APIC: Switch to virtual wire mode setup with no configuration\n");
                upmode = true;
                break;
        case APIC_SYMMETRIC_IO:
                pr_info("APIC: Switch to symmetric I/O mode setup\n");
                break;
        case APIC_SYMMETRIC_IO_NO_ROUTING:
                pr_info("APIC: Switch to symmetric I/O mode setup in no SMP routine\n");
                break;
        }

        default_setup_apic_routing();

        if (x86_platform.apic_post_init)
                x86_platform.apic_post_init();

        apic_bsp_setup(upmode);
}

static void lapic_setup_esr(void)
{
        unsigned int oldvalue, value, maxlvt;

        if (!lapic_is_integrated()) {
                pr_info("No ESR for 82489DX.\n");
                return;
        }

        if (apic->disable_esr) {
                /*
                 * Something untraceable is creating bad interrupts on
                 * secondary quads ... for the moment, just leave the
                 * ESR disabled - we can't do anything useful with the
                 * errors anyway - mbligh
                 */
                pr_info("Leaving ESR disabled.\n");
                return;
        }

        maxlvt = lapic_get_maxlvt();
        if (maxlvt > 3)         /* Due to the Pentium erratum 3AP. */
                apic_write(APIC_ESR, 0);
        oldvalue = apic_read(APIC_ESR);

        /* enables sending errors */
        value = ERROR_APIC_VECTOR;
        apic_write(APIC_LVTERR, value);

        /*
         * spec says clear errors after enabling vector.
         */
        if (maxlvt > 3)
                apic_write(APIC_ESR, 0);
        value = apic_read(APIC_ESR);
        if (value != oldvalue)
                apic_printk(APIC_VERBOSE, "ESR value before enabling "
                        "vector: 0x%08x  after: 0x%08x\n",
                        oldvalue, value);
}

#define APIC_IR_REGS            APIC_ISR_NR
#define APIC_IR_BITS            (APIC_IR_REGS * 32)
#define APIC_IR_MAPSIZE         (APIC_IR_BITS / BITS_PER_LONG)

union apic_ir {
        unsigned long   map[APIC_IR_MAPSIZE];
        u32             regs[APIC_IR_REGS];
};

static bool apic_check_and_ack(union apic_ir *irr, union apic_ir *isr)
{
        int i, bit;

        /* Read the IRRs */
        for (i = 0; i < APIC_IR_REGS; i++)
                irr->regs[i] = apic_read(APIC_IRR + i * 0x10);

        /* Read the ISRs */
        for (i = 0; i < APIC_IR_REGS; i++)
                isr->regs[i] = apic_read(APIC_ISR + i * 0x10);

        /*
         * If the ISR map is not empty. ACK the APIC and run another round
         * to verify whether a pending IRR has been unblocked and turned
         * into a ISR.
         */
        if (!bitmap_empty(isr->map, APIC_IR_BITS)) {
                /*
                 * There can be multiple ISR bits set when a high priority
                 * interrupt preempted a lower priority one. Issue an ACK
                 * per set bit.
                 */
                for_each_set_bit(bit, isr->map, APIC_IR_BITS)
                        ack_APIC_irq();
                return true;
        }

        return !bitmap_empty(irr->map, APIC_IR_BITS);
}

/*
 * After a crash, we no longer service the interrupts and a pending
 * interrupt from previous kernel might still have ISR bit set.
 *
 * Most probably by now the CPU has serviced that pending interrupt and it
 * might not have done the ack_APIC_irq() because it thought, interrupt
 * came from i8259 as ExtInt. LAPIC did not get EOI so it does not clear
 * the ISR bit and cpu thinks it has already serviced the interrupt. Hence
 * a vector might get locked. It was noticed for timer irq (vector
 * 0x31). Issue an extra EOI to clear ISR.
 *
 * If there are pending IRR bits they turn into ISR bits after a higher
 * priority ISR bit has been acked.
 */
static void apic_pending_intr_clear(void)
{
        union apic_ir irr, isr;
        unsigned int i;

        /* 512 loops are way oversized and give the APIC a chance to obey. */
        for (i = 0; i < 512; i++) {
                if (!apic_check_and_ack(&irr, &isr))
                        return;
        }
        /* Dump the IRR/ISR content if that failed */
        pr_warn("APIC: Stale IRR: %256pb ISR: %256pb\n", irr.map, isr.map);
}

/**
 * setup_local_APIC - setup the local APIC
 *
 * Used to setup local APIC while initializing BSP or bringing up APs.
 * Always called with preemption disabled.
 */
static void setup_local_APIC(void)
{
        int cpu = smp_processor_id();
        unsigned int value;

        if (disable_apic) {
                disable_ioapic_support();
                return;
        }

        /*
         * If this comes from kexec/kcrash the APIC might be enabled in
         * SPIV. Soft disable it before doing further initialization.
         */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_SPIV_APIC_ENABLED;
        apic_write(APIC_SPIV, value);

#ifdef CONFIG_X86_32
        /* Pound the ESR really hard over the head with a big hammer - mbligh */
        if (lapic_is_integrated() && apic->disable_esr) {
                apic_write(APIC_ESR, 0);
                apic_write(APIC_ESR, 0);
                apic_write(APIC_ESR, 0);
                apic_write(APIC_ESR, 0);
        }
#endif
        /*
         * Double-check whether this APIC is really registered.
         * This is meaningless in clustered apic mode, so we skip it.
         */
        BUG_ON(!apic->apic_id_registered());

        /*
         * Intel recommends to set DFR, LDR and TPR before enabling
         * an APIC.  See e.g. "AP-388 82489DX User's Manual" (Intel
         * document number 292116).  So here it goes...
         */
        apic->init_apic_ldr();

#ifdef CONFIG_X86_32
        if (apic->dest_mode_logical) {
                int logical_apicid, ldr_apicid;

                /*
                 * APIC LDR is initialized.  If logical_apicid mapping was
                 * initialized during get_smp_config(), make sure it matches
                 * the actual value.
                 */
                logical_apicid = early_per_cpu(x86_cpu_to_logical_apicid, cpu);
                ldr_apicid = GET_APIC_LOGICAL_ID(apic_read(APIC_LDR));
                if (logical_apicid != BAD_APICID)
                        WARN_ON(logical_apicid != ldr_apicid);
                /* Always use the value from LDR. */
                early_per_cpu(x86_cpu_to_logical_apicid, cpu) = ldr_apicid;
        }
#endif

        /*
         * Set Task Priority to 'accept all except vectors 0-31'.  An APIC
         * vector in the 16-31 range could be delivered if TPR == 0, but we
         * would think it's an exception and terrible things will happen.  We
         * never change this later on.
         */
        value = apic_read(APIC_TASKPRI);
        value &= ~APIC_TPRI_MASK;
        value |= 0x10;
        apic_write(APIC_TASKPRI, value);

        /* Clear eventually stale ISR/IRR bits */
        apic_pending_intr_clear();

        /*
         * Now that we are all set up, enable the APIC
         */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_VECTOR_MASK;
        /*
         * Enable APIC
         */
        value |= APIC_SPIV_APIC_ENABLED;

#ifdef CONFIG_X86_32
        /*
         * Some unknown Intel IO/APIC (or APIC) errata is biting us with
         * certain networking cards. If high frequency interrupts are
         * happening on a particular IOAPIC pin, plus the IOAPIC routing
         * entry is masked/unmasked at a high rate as well then sooner or
         * later IOAPIC line gets 'stuck', no more interrupts are received
         * from the device. If focus CPU is disabled then the hang goes
         * away, oh well :-(
         *
         * [ This bug can be reproduced easily with a level-triggered
         *   PCI Ne2000 networking cards and PII/PIII processors, dual
         *   BX chipset. ]
         */
        /*
         * Actually disabling the focus CPU check just makes the hang less
         * frequent as it makes the interrupt distribution model be more
         * like LRU than MRU (the short-term load is more even across CPUs).
         */

        /*
         * - enable focus processor (bit==0)
         * - 64bit mode always use processor focus
         *   so no need to set it
         */
        value &= ~APIC_SPIV_FOCUS_DISABLED;
#endif

        /*
         * Set spurious IRQ vector
         */
        value |= SPURIOUS_APIC_VECTOR;
        apic_write(APIC_SPIV, value);

        perf_events_lapic_init();

        /*
         * Set up LVT0, LVT1:
         *
         * set up through-local-APIC on the boot CPU's LINT0. This is not
         * strictly necessary in pure symmetric-IO mode, but sometimes
         * we delegate interrupts to the 8259A.
         */
        /*
         * TODO: set up through-local-APIC from through-I/O-APIC? --macro
         */
        value = apic_read(APIC_LVT0) & APIC_LVT_MASKED;
        if (!cpu && (pic_mode || !value || skip_ioapic_setup)) {
                value = APIC_DM_EXTINT;
                apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu);
        } else {
                value = APIC_DM_EXTINT | APIC_LVT_MASKED;
                apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n", cpu);
        }
        apic_write(APIC_LVT0, value);

        /*
         * Only the BSP sees the LINT1 NMI signal by default. This can be
         * modified by apic_extnmi= boot option.
         */
        if ((!cpu && apic_extnmi != APIC_EXTNMI_NONE) ||
            apic_extnmi == APIC_EXTNMI_ALL)
                value = APIC_DM_NMI;
        else
                value = APIC_DM_NMI | APIC_LVT_MASKED;

        /* Is 82489DX ? */
        if (!lapic_is_integrated())
                value |= APIC_LVT_LEVEL_TRIGGER;
        apic_write(APIC_LVT1, value);

#ifdef CONFIG_X86_MCE_INTEL
        /* Recheck CMCI information after local APIC is up on CPU #0 */
        if (!cpu)
                cmci_recheck();
#endif
}

static void end_local_APIC_setup(void)
{
        lapic_setup_esr();

#ifdef CONFIG_X86_32
        {
                unsigned int value;
                /* Disable the local apic timer */
                value = apic_read(APIC_LVTT);
                value |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
                apic_write(APIC_LVTT, value);
        }
#endif

        apic_pm_activate();
}

/*
 * APIC setup function for application processors. Called from smpboot.c
 */
void apic_ap_setup(void)
{
        setup_local_APIC();
        end_local_APIC_setup();
}

#ifdef CONFIG_X86_X2APIC
int x2apic_mode;
EXPORT_SYMBOL_GPL(x2apic_mode);

enum {
        X2APIC_OFF,
        X2APIC_DISABLED,
        /* All states below here have X2APIC enabled */
        X2APIC_ON,
        X2APIC_ON_LOCKED
};
static int x2apic_state;

static bool x2apic_hw_locked(void)
{
        u64 x86_arch_cap_msr;
        u64 msr;

        x86_arch_cap_msr = x86_read_arch_cap_msr();
        if (x86_arch_cap_msr & ARCH_CAP_XAPIC_DISABLE) {
                rdmsrl(MSR_IA32_XAPIC_DISABLE_STATUS, msr);
                return (msr & LEGACY_XAPIC_DISABLED);
        }
        return false;
}

static void __x2apic_disable(void)
{
        u64 msr;

        if (!boot_cpu_has(X86_FEATURE_APIC))
                return;

        rdmsrl(MSR_IA32_APICBASE, msr);
        if (!(msr & X2APIC_ENABLE))
                return;
        /* Disable xapic and x2apic first and then reenable xapic mode */
        wrmsrl(MSR_IA32_APICBASE, msr & ~(X2APIC_ENABLE | XAPIC_ENABLE));
        wrmsrl(MSR_IA32_APICBASE, msr & ~X2APIC_ENABLE);
        printk_once(KERN_INFO "x2apic disabled\n");
}

static void __x2apic_enable(void)
{
        u64 msr;

        rdmsrl(MSR_IA32_APICBASE, msr);
        if (msr & X2APIC_ENABLE)
                return;
        wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
        printk_once(KERN_INFO "x2apic enabled\n");
}

static int __init setup_nox2apic(char *str)
{
        if (x2apic_enabled()) {
                int apicid = native_apic_msr_read(APIC_ID);

                if (apicid >= 255) {
                        pr_warn("Apicid: %08x, cannot enforce nox2apic\n",
                                apicid);
                        return 0;
                }
                if (x2apic_hw_locked()) {
                        pr_warn("APIC locked in x2apic mode, can't disable\n");
                        return 0;
                }
                pr_warn("x2apic already enabled.\n");
                __x2apic_disable();
        }
        setup_clear_cpu_cap(X86_FEATURE_X2APIC);
        x2apic_state = X2APIC_DISABLED;
        x2apic_mode = 0;
        return 0;
}
early_param("nox2apic", setup_nox2apic);

/* Called from cpu_init() to enable x2apic on (secondary) cpus */
void x2apic_setup(void)
{
        /*
         * Try to make the AP's APIC state match that of the BSP,  but if the
         * BSP is unlocked and the AP is locked then there is a state mismatch.
         * Warn about the mismatch in case a GP fault occurs due to a locked AP
         * trying to be turned off.
         */
        if (x2apic_state != X2APIC_ON_LOCKED && x2apic_hw_locked())
                pr_warn("x2apic lock mismatch between BSP and AP.\n");
        /*
         * If x2apic is not in ON or LOCKED state, disable it if already enabled
         * from BIOS.
         */
        if (x2apic_state < X2APIC_ON) {
                __x2apic_disable();
                return;
        }
        __x2apic_enable();
}

static __init void x2apic_disable(void)
{
        u32 x2apic_id, state = x2apic_state;

        x2apic_mode = 0;
        x2apic_state = X2APIC_DISABLED;

        if (state != X2APIC_ON)
                return;

        x2apic_id = read_apic_id();
        if (x2apic_id >= 255)
                panic("Cannot disable x2apic, id: %08x\n", x2apic_id);

        if (x2apic_hw_locked()) {
                pr_warn("Cannot disable locked x2apic, id: %08x\n", x2apic_id);
                return;
        }

        __x2apic_disable();
        register_lapic_address(mp_lapic_addr);
}

static __init void x2apic_enable(void)
{
        if (x2apic_state != X2APIC_OFF)
                return;

        x2apic_mode = 1;
        x2apic_state = X2APIC_ON;
        __x2apic_enable();
}

static __init void try_to_enable_x2apic(int remap_mode)
{
        if (x2apic_state == X2APIC_DISABLED)
                return;

        if (remap_mode != IRQ_REMAP_X2APIC_MODE) {
                u32 apic_limit = 255;

                /*
                 * Using X2APIC without IR is not architecturally supported
                 * on bare metal but may be supported in guests.
                 */
                if (!x86_init.hyper.x2apic_available()) {
                        pr_info("x2apic: IRQ remapping doesn't support X2APIC mode\n");
                        x2apic_disable();
                        return;
                }

                /*
                 * If the hypervisor supports extended destination ID in
                 * MSI, that increases the maximum APIC ID that can be
                 * used for non-remapped IRQ domains.
                 */
                if (x86_init.hyper.msi_ext_dest_id()) {
                        virt_ext_dest_id = 1;
                        apic_limit = 32767;
                }

                /*
                 * Without IR, all CPUs can be addressed by IOAPIC/MSI only
                 * in physical mode, and CPUs with an APIC ID that cannot
                 * be addressed must not be brought online.
                 */
                x2apic_set_max_apicid(apic_limit);
                x2apic_phys = 1;
        }
        x2apic_enable();
}

void __init check_x2apic(void)
{
        if (x2apic_enabled()) {
                pr_info("x2apic: enabled by BIOS, switching to x2apic ops\n");
                x2apic_mode = 1;
                if (x2apic_hw_locked())
                        x2apic_state = X2APIC_ON_LOCKED;
                else
                        x2apic_state = X2APIC_ON;
        } else if (!boot_cpu_has(X86_FEATURE_X2APIC)) {
                x2apic_state = X2APIC_DISABLED;
        }
}
#else /* CONFIG_X86_X2APIC */
void __init check_x2apic(void)
{
        if (!apic_is_x2apic_enabled())
                return;
        /*
         * Checkme: Can we simply turn off x2APIC here instead of disabling the APIC?
         */
        pr_err("Kernel does not support x2APIC, please recompile with CONFIG_X86_X2APIC.\n");
        pr_err("Disabling APIC, expect reduced performance and functionality.\n");

        disable_apic = 1;
        setup_clear_cpu_cap(X86_FEATURE_APIC);
}

static inline void try_to_enable_x2apic(int remap_mode) { }
static inline void __x2apic_enable(void) { }
#endif /* !CONFIG_X86_X2APIC */

void __init enable_IR_x2apic(void)
{
        unsigned long flags;
        int ret, ir_stat;

        if (skip_ioapic_setup) {
                pr_info("Not enabling interrupt remapping due to skipped IO-APIC setup\n");
                return;
        }

        ir_stat = irq_remapping_prepare();
        if (ir_stat < 0 && !x2apic_supported())
                return;

        ret = save_ioapic_entries();
        if (ret) {
                pr_info("Saving IO-APIC state failed: %d\n", ret);
                return;
        }

        local_irq_save(flags);
        legacy_pic->mask_all();
        mask_ioapic_entries();

        /* If irq_remapping_prepare() succeeded, try to enable it */
        if (ir_stat >= 0)
                ir_stat = irq_remapping_enable();
        /* ir_stat contains the remap mode or an error code */
        try_to_enable_x2apic(ir_stat);

        if (ir_stat < 0)
                restore_ioapic_entries();
        legacy_pic->restore_mask();
        local_irq_restore(flags);
}

#ifdef CONFIG_X86_64
/*
 * Detect and enable local APICs on non-SMP boards.
 * Original code written by Keir Fraser.
 * On AMD64 we trust the BIOS - if it says no APIC it is likely
 * not correctly set up (usually the APIC timer won't work etc.)
 */
static int __init detect_init_APIC(void)
{
        if (!boot_cpu_has(X86_FEATURE_APIC)) {
                pr_info("No local APIC present\n");
                return -1;
        }

        mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
        return 0;
}
#else

static int __init apic_verify(void)
{
        u32 features, h, l;

        /*
         * The APIC feature bit should now be enabled
         * in `cpuid'
         */
        features = cpuid_edx(1);
        if (!(features & (1 << X86_FEATURE_APIC))) {
                pr_warn("Could not enable APIC!\n");
                return -1;
        }
        set_cpu_cap(&boot_cpu_data, X86_FEATURE_APIC);
        mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;

        /* The BIOS may have set up the APIC at some other address */
        if (boot_cpu_data.x86 >= 6) {
                rdmsr(MSR_IA32_APICBASE, l, h);
                if (l & MSR_IA32_APICBASE_ENABLE)
                        mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;
        }

        pr_info("Found and enabled local APIC!\n");
        return 0;
}

int __init apic_force_enable(unsigned long addr)
{
        u32 h, l;

        if (disable_apic)
                return -1;

        /*
         * Some BIOSes disable the local APIC in the APIC_BASE
         * MSR. This can only be done in software for Intel P6 or later
         * and AMD K7 (Model > 1) or later.
         */
        if (boot_cpu_data.x86 >= 6) {
                rdmsr(MSR_IA32_APICBASE, l, h);
                if (!(l & MSR_IA32_APICBASE_ENABLE)) {
                        pr_info("Local APIC disabled by BIOS -- reenabling.\n");
                        l &= ~MSR_IA32_APICBASE_BASE;
                        l |= MSR_IA32_APICBASE_ENABLE | addr;
                        wrmsr(MSR_IA32_APICBASE, l, h);
                        enabled_via_apicbase = 1;
                }
        }
        return apic_verify();
}

/*
 * Detect and initialize APIC
 */
static int __init detect_init_APIC(void)
{
        /* Disabled by kernel option? */
        if (disable_apic)
                return -1;

        switch (boot_cpu_data.x86_vendor) {
        case X86_VENDOR_AMD:
                if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model > 1) ||
                    (boot_cpu_data.x86 >= 15))
                        break;
                goto no_apic;
        case X86_VENDOR_HYGON:
                break;
        case X86_VENDOR_INTEL:
                if (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15 ||
                    (boot_cpu_data.x86 == 5 && boot_cpu_has(X86_FEATURE_APIC)))
                        break;
                goto no_apic;
        default:
                goto no_apic;
        }

        if (!boot_cpu_has(X86_FEATURE_APIC)) {
                /*
                 * Over-ride BIOS and try to enable the local APIC only if
                 * "lapic" specified.
                 */
                if (!force_enable_local_apic) {
                        pr_info("Local APIC disabled by BIOS -- "
                                "you can enable it with \"lapic\"\n");
                        return -1;
                }
                if (apic_force_enable(APIC_DEFAULT_PHYS_BASE))
                        return -1;
        } else {
                if (apic_verify())
                        return -1;
        }

        apic_pm_activate();

        return 0;

no_apic:
        pr_info("No local APIC present or hardware disabled\n");
        return -1;
}
#endif

/**
 * init_apic_mappings - initialize APIC mappings
 */
void __init init_apic_mappings(void)
{
        unsigned int new_apicid;

        if (apic_validate_deadline_timer())
                pr_info("TSC deadline timer available\n");

        if (x2apic_mode) {
                boot_cpu_physical_apicid = read_apic_id();
                return;
        }

        /* If no local APIC can be found return early */
        if (!smp_found_config && detect_init_APIC()) {
                /* lets NOP'ify apic operations */
                pr_info("APIC: disable apic facility\n");
                apic_disable();
        } else {
                apic_phys = mp_lapic_addr;

                /*
                 * If the system has ACPI MADT tables or MP info, the LAPIC
                 * address is already registered.
                 */
                if (!acpi_lapic && !smp_found_config)
                        register_lapic_address(apic_phys);
        }

        /*
         * Fetch the APIC ID of the BSP in case we have a
         * default configuration (or the MP table is broken).
         */
        new_apicid = read_apic_id();
        if (boot_cpu_physical_apicid != new_apicid) {
                boot_cpu_physical_apicid = new_apicid;
                /*
                 * yeah -- we lie about apic_version
                 * in case if apic was disabled via boot option
                 * but it's not a problem for SMP compiled kernel
                 * since apic_intr_mode_select is prepared for such
                 * a case and disable smp mode
                 */
                boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
        }
}

void __init register_lapic_address(unsigned long address)
{
        mp_lapic_addr = address;

        if (!x2apic_mode) {
                set_fixmap_nocache(FIX_APIC_BASE, address);
                apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
                            APIC_BASE, address);
        }
        if (boot_cpu_physical_apicid == -1U) {
                boot_cpu_physical_apicid  = read_apic_id();
                boot_cpu_apic_version = GET_APIC_VERSION(apic_read(APIC_LVR));
        }
}

/*
 * Local APIC interrupts
 */

/*
 * Common handling code for spurious_interrupt and spurious_vector entry
 * points below. No point in allowing the compiler to inline it twice.
 */
static noinline void handle_spurious_interrupt(u8 vector)
{
        u32 v;

        trace_spurious_apic_entry(vector);

        inc_irq_stat(irq_spurious_count);

        /*
         * If this is a spurious interrupt then do not acknowledge
         */
        if (vector == SPURIOUS_APIC_VECTOR) {
                /* See SDM vol 3 */
                pr_info("Spurious APIC interrupt (vector 0xFF) on CPU#%d, should never happen.\n",
                        smp_processor_id());
                goto out;
        }

        /*
         * If it is a vectored one, verify it's set in the ISR. If set,
         * acknowledge it.
         */
        v = apic_read(APIC_ISR + ((vector & ~0x1f) >> 1));
        if (v & (1 << (vector & 0x1f))) {
                pr_info("Spurious interrupt (vector 0x%02x) on CPU#%d. Acked\n",
                        vector, smp_processor_id());
                ack_APIC_irq();
        } else {
                pr_info("Spurious interrupt (vector 0x%02x) on CPU#%d. Not pending!\n",
                        vector, smp_processor_id());
        }
out:
        trace_spurious_apic_exit(vector);
}

/**
 * spurious_interrupt - Catch all for interrupts raised on unused vectors
 * @regs:       Pointer to pt_regs on stack
 * @vector:     The vector number
 *
 * This is invoked from ASM entry code to catch all interrupts which
 * trigger on an entry which is routed to the common_spurious idtentry
 * point.
 */
DEFINE_IDTENTRY_IRQ(spurious_interrupt)
{
        handle_spurious_interrupt(vector);
}

DEFINE_IDTENTRY_SYSVEC(sysvec_spurious_apic_interrupt)
{
        handle_spurious_interrupt(SPURIOUS_APIC_VECTOR);
}

/*
 * This interrupt should never happen with our APIC/SMP architecture
 */
DEFINE_IDTENTRY_SYSVEC(sysvec_error_interrupt)
{
        static const char * const error_interrupt_reason[] = {
                "Send CS error",                /* APIC Error Bit 0 */
                "Receive CS error",             /* APIC Error Bit 1 */
                "Send accept error",            /* APIC Error Bit 2 */
                "Receive accept error",         /* APIC Error Bit 3 */
                "Redirectable IPI",             /* APIC Error Bit 4 */
                "Send illegal vector",          /* APIC Error Bit 5 */
                "Received illegal vector",      /* APIC Error Bit 6 */
                "Illegal register address",     /* APIC Error Bit 7 */
        };
        u32 v, i = 0;

        trace_error_apic_entry(ERROR_APIC_VECTOR);

        /* First tickle the hardware, only then report what went on. -- REW */
        if (lapic_get_maxlvt() > 3)     /* Due to the Pentium erratum 3AP. */
                apic_write(APIC_ESR, 0);
        v = apic_read(APIC_ESR);
        ack_APIC_irq();
        atomic_inc(&irq_err_count);

        apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x",
                    smp_processor_id(), v);

        v &= 0xff;
        while (v) {
                if (v & 0x1)
                        apic_printk(APIC_DEBUG, KERN_CONT " : %s", error_interrupt_reason[i]);
                i++;
                v >>= 1;
        }

        apic_printk(APIC_DEBUG, KERN_CONT "\n");

        trace_error_apic_exit(ERROR_APIC_VECTOR);
}

/**
 * connect_bsp_APIC - attach the APIC to the interrupt system
 */
static void __init connect_bsp_APIC(void)
{
#ifdef CONFIG_X86_32
        if (pic_mode) {
                /*
                 * Do not trust the local APIC being empty at bootup.
                 */
                clear_local_APIC();
                /*
                 * PIC mode, enable APIC mode in the IMCR, i.e.  connect BSP's
                 * local APIC to INT and NMI lines.
                 */
                apic_printk(APIC_VERBOSE, "leaving PIC mode, "
                                "enabling APIC mode.\n");
                imcr_pic_to_apic();
        }
#endif
}

/**
 * disconnect_bsp_APIC - detach the APIC from the interrupt system
 * @virt_wire_setup:    indicates, whether virtual wire mode is selected
 *
 * Virtual wire mode is necessary to deliver legacy interrupts even when the
 * APIC is disabled.
 */
void disconnect_bsp_APIC(int virt_wire_setup)
{
        unsigned int value;

#ifdef CONFIG_X86_32
        if (pic_mode) {
                /*
                 * Put the board back into PIC mode (has an effect only on
                 * certain older boards).  Note that APIC interrupts, including
                 * IPIs, won't work beyond this point!  The only exception are
                 * INIT IPIs.
                 */
                apic_printk(APIC_VERBOSE, "disabling APIC mode, "
                                "entering PIC mode.\n");
                imcr_apic_to_pic();
                return;
        }
#endif

        /* Go back to Virtual Wire compatibility mode */

        /* For the spurious interrupt use vector F, and enable it */
        value = apic_read(APIC_SPIV);
        value &= ~APIC_VECTOR_MASK;
        value |= APIC_SPIV_APIC_ENABLED;
        value |= 0xf;
        apic_write(APIC_SPIV, value);

        if (!virt_wire_setup) {
                /*
                 * For LVT0 make it edge triggered, active high,
                 * external and enabled
                 */
                value = apic_read(APIC_LVT0);
                value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
                        APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
                        APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
                value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
                value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_EXTINT);
                apic_write(APIC_LVT0, value);
        } else {
                /* Disable LVT0 */
                apic_write(APIC_LVT0, APIC_LVT_MASKED);
        }

        /*
         * For LVT1 make it edge triggered, active high,
         * nmi and enabled
         */
        value = apic_read(APIC_LVT1);
        value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
                        APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
                        APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
        value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
        value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_NMI);
        apic_write(APIC_LVT1, value);
}

/*
 * The number of allocated logical CPU IDs. Since logical CPU IDs are allocated
 * contiguously, it equals to current allocated max logical CPU ID plus 1.
 * All allocated CPU IDs should be in the [0, nr_logical_cpuids) range,
 * so the maximum of nr_logical_cpuids is nr_cpu_ids.
 *
 * NOTE: Reserve 0 for BSP.
 */
static int nr_logical_cpuids = 1;

/*
 * Used to store mapping between logical CPU IDs and APIC IDs.
 */
static int cpuid_to_apicid[] = {
        [0 ... NR_CPUS - 1] = -1,
};

bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
{
        return phys_id == cpuid_to_apicid[cpu];
}

#ifdef CONFIG_SMP
/**
 * apic_id_is_primary_thread - Check whether APIC ID belongs to a primary thread
 * @apicid: APIC ID to check
 */
bool apic_id_is_primary_thread(unsigned int apicid)
{
        u32 mask;

        if (smp_num_siblings == 1)
                return true;
        /* Isolate the SMT bit(s) in the APICID and check for 0 */
        mask = (1U << (fls(smp_num_siblings) - 1)) - 1;
        return !(apicid & mask);
}
#endif

/*
 * Should use this API to allocate logical CPU IDs to keep nr_logical_cpuids
 * and cpuid_to_apicid[] synchronized.
 */
static int allocate_logical_cpuid(int apicid)
{
        int i;

        /*
         * cpuid <-> apicid mapping is persistent, so when a cpu is up,
         * check if the kernel has allocated a cpuid for it.
         */
        for (i = 0; i < nr_logical_cpuids; i++) {
                if (cpuid_to_apicid[i] == apicid)
                        return i;
        }

        /* Allocate a new cpuid. */
        if (nr_logical_cpuids >= nr_cpu_ids) {
                WARN_ONCE(1, "APIC: NR_CPUS/possible_cpus limit of %u reached. "
                             "Processor %d/0x%x and the rest are ignored.\n",
                             nr_cpu_ids, nr_logical_cpuids, apicid);
                return -EINVAL;
        }

        cpuid_to_apicid[nr_logical_cpuids] = apicid;
        return nr_logical_cpuids++;
}

int generic_processor_info(int apicid, int version)
{
        int cpu, max = nr_cpu_ids;
        bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid,
                                phys_cpu_present_map);

        /*
         * boot_cpu_physical_apicid is designed to have the apicid
         * returned by read_apic_id(), i.e, the apicid of the
         * currently booting-up processor. However, on some platforms,
         * it is temporarily modified by the apicid reported as BSP
         * through MP table. Concretely:
         *
         * - arch/x86/kernel/mpparse.c: MP_processor_info()
         * - arch/x86/mm/amdtopology.c: amd_numa_init()
         *
         * This function is executed with the modified
         * boot_cpu_physical_apicid. So, disabled_cpu_apicid kernel
         * parameter doesn't work to disable APs on kdump 2nd kernel.
         *
         * Since fixing handling of boot_cpu_physical_apicid requires
         * another discussion and tests on each platform, we leave it
         * for now and here we use read_apic_id() directly in this
         * function, generic_processor_info().
         */
        if (disabled_cpu_apicid != BAD_APICID &&
            disabled_cpu_apicid != read_apic_id() &&
            disabled_cpu_apicid == apicid) {
                int thiscpu = num_processors + disabled_cpus;

                pr_warn("APIC: Disabling requested cpu."
                        " Processor %d/0x%x ignored.\n", thiscpu, apicid);

                disabled_cpus++;
                return -ENODEV;
        }

        /*
         * If boot cpu has not been detected yet, then only allow upto
         * nr_cpu_ids - 1 processors and keep one slot free for boot cpu
         */
        if (!boot_cpu_detected && num_processors >= nr_cpu_ids - 1 &&
            apicid != boot_cpu_physical_apicid) {
                int thiscpu = max + disabled_cpus - 1;

                pr_warn("APIC: NR_CPUS/possible_cpus limit of %i almost"
                        " reached. Keeping one slot for boot cpu."
                        "  Processor %d/0x%x ignored.\n", max, thiscpu, apicid);

                disabled_cpus++;
                return -ENODEV;
        }

        if (num_processors >= nr_cpu_ids) {
                int thiscpu = max + disabled_cpus;

                pr_warn("APIC: NR_CPUS/possible_cpus limit of %i reached. "
                        "Processor %d/0x%x ignored.\n", max, thiscpu, apicid);

                disabled_cpus++;
                return -EINVAL;
        }

        if (apicid == boot_cpu_physical_apicid) {
                /*
                 * x86_bios_cpu_apicid is required to have processors listed
                 * in same order as logical cpu numbers. Hence the first
                 * entry is BSP, and so on.
                 * boot_cpu_init() already hold bit 0 in cpu_present_mask
                 * for BSP.
                 */
                cpu = 0;

                /* Logical cpuid 0 is reserved for BSP. */
                cpuid_to_apicid[0] = apicid;
        } else {
                cpu = allocate_logical_cpuid(apicid);
                if (cpu < 0) {
                        disabled_cpus++;
                        return -EINVAL;
                }
        }

        /*
         * Validate version
         */
        if (version == 0x0) {
                pr_warn("BIOS bug: APIC version is 0 for CPU %d/0x%x, fixing up to 0x10\n",
                        cpu, apicid);
                version = 0x10;
        }

        if (version != boot_cpu_apic_version) {
                pr_warn("BIOS bug: APIC version mismatch, boot CPU: %x, CPU %d: version %x\n",
                        boot_cpu_apic_version, cpu, version);
        }

        if (apicid > max_physical_apicid)
                max_physical_apicid = apicid;

#if defined(CONFIG_SMP) || defined(CONFIG_X86_64)
        early_per_cpu(x86_cpu_to_apicid, cpu) = apicid;
        early_per_cpu(x86_bios_cpu_apicid, cpu) = apicid;
#endif
#ifdef CONFIG_X86_32
        early_per_cpu(x86_cpu_to_logical_apicid, cpu) =
                apic->x86_32_early_logical_apicid(cpu);
#endif
        set_cpu_possible(cpu, true);
        physid_set(apicid, phys_cpu_present_map);
        set_cpu_present(cpu, true);
        num_processors++;

        return cpu;
}

int hard_smp_processor_id(void)
{
        return read_apic_id();
}

void __irq_msi_compose_msg(struct irq_cfg *cfg, struct msi_msg *msg,
                           bool dmar)
{
        memset(msg, 0, sizeof(*msg));

        msg->arch_addr_lo.base_address = X86_MSI_BASE_ADDRESS_LOW;
        msg->arch_addr_lo.dest_mode_logical = apic->dest_mode_logical;
        msg->arch_addr_lo.destid_0_7 = cfg->dest_apicid & 0xFF;

        msg->arch_data.delivery_mode = APIC_DELIVERY_MODE_FIXED;
        msg->arch_data.vector = cfg->vector;

        msg->address_hi = X86_MSI_BASE_ADDRESS_HIGH;
        /*
         * Only the IOMMU itself can use the trick of putting destination
         * APIC ID into the high bits of the address. Anything else would
         * just be writing to memory if it tried that, and needs IR to
         * address APICs which can't be addressed in the normal 32-bit
         * address range at 0xFFExxxxx. That is typically just 8 bits, but
         * some hypervisors allow the extended destination ID field in bits
         * 5-11 to be used, giving support for 15 bits of APIC IDs in total.
         */
        if (dmar)
                msg->arch_addr_hi.destid_8_31 = cfg->dest_apicid >> 8;
        else if (virt_ext_dest_id && cfg->dest_apicid < 0x8000)
                msg->arch_addr_lo.virt_destid_8_14 = cfg->dest_apicid >> 8;
        else
                WARN_ON_ONCE(cfg->dest_apicid > 0xFF);
}

u32 x86_msi_msg_get_destid(struct msi_msg *msg, bool extid)
{
        u32 dest = msg->arch_addr_lo.destid_0_7;

        if (extid)
                dest |= msg->arch_addr_hi.destid_8_31 << 8;
        return dest;
}
EXPORT_SYMBOL_GPL(x86_msi_msg_get_destid);

#ifdef CONFIG_X86_64
void __init acpi_wake_cpu_handler_update(wakeup_cpu_handler handler)
{
        struct apic **drv;

        for (drv = __apicdrivers; drv < __apicdrivers_end; drv++)
                (*drv)->wakeup_secondary_cpu_64 = handler;
}
#endif

/*
 * Override the generic EOI implementation with an optimized version.
 * Only called during early boot when only one CPU is active and with
 * interrupts disabled, so we know this does not race with actual APIC driver
 * use.
 */
void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v))
{
        struct apic **drv;

        for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
                /* Should happen once for each apic */
                WARN_ON((*drv)->eoi_write == eoi_write);
                (*drv)->native_eoi_write = (*drv)->eoi_write;
                (*drv)->eoi_write = eoi_write;
        }
}

static void __init apic_bsp_up_setup(void)
{
#ifdef CONFIG_X86_64
        apic_write(APIC_ID, apic->set_apic_id(boot_cpu_physical_apicid));
#else
        /*
         * Hack: In case of kdump, after a crash, kernel might be booting
         * on a cpu with non-zero lapic id. But boot_cpu_physical_apicid
         * might be zero if read from MP tables. Get it from LAPIC.
         */
# ifdef CONFIG_CRASH_DUMP
        boot_cpu_physical_apicid = read_apic_id();
# endif
#endif
        physid_set_mask_of_physid(boot_cpu_physical_apicid, &phys_cpu_present_map);
}

/**
 * apic_bsp_setup - Setup function for local apic and io-apic
 * @upmode:             Force UP mode (for APIC_init_uniprocessor)
 */
static void __init apic_bsp_setup(bool upmode)
{
        connect_bsp_APIC();
        if (upmode)
                apic_bsp_up_setup();
        setup_local_APIC();

        enable_IO_APIC();
        end_local_APIC_setup();
        irq_remap_enable_fault_handling();
        setup_IO_APIC();
        lapic_update_legacy_vectors();
}

#ifdef CONFIG_UP_LATE_INIT
void __init up_late_init(void)
{
        if (apic_intr_mode == APIC_PIC)
                return;

        /* Setup local timer */
        x86_init.timers.setup_percpu_clockev();
}
#endif

/*
 * Power management
 */
#ifdef CONFIG_PM

static struct {
        /*
         * 'active' is true if the local APIC was enabled by us and
         * not the BIOS; this signifies that we are also responsible
         * for disabling it before entering apm/acpi suspend
         */
        int active;
        /* r/w apic fields */
        unsigned int apic_id;
        unsigned int apic_taskpri;
        unsigned int apic_ldr;
        unsigned int apic_dfr;
        unsigned int apic_spiv;
        unsigned int apic_lvtt;
        unsigned int apic_lvtpc;
        unsigned int apic_lvt0;
        unsigned int apic_lvt1;
        unsigned int apic_lvterr;
        unsigned int apic_tmict;
        unsigned int apic_tdcr;
        unsigned int apic_thmr;
        unsigned int apic_cmci;
} apic_pm_state;

static int lapic_suspend(void)
{
        unsigned long flags;
        int maxlvt;

        if (!apic_pm_state.active)
                return 0;

        maxlvt = lapic_get_maxlvt();

        apic_pm_state.apic_id = apic_read(APIC_ID);
        apic_pm_state.apic_taskpri = apic_read(APIC_TASKPRI);
        apic_pm_state.apic_ldr = apic_read(APIC_LDR);
        apic_pm_state.apic_dfr = apic_read(APIC_DFR);
        apic_pm_state.apic_spiv = apic_read(APIC_SPIV);
        apic_pm_state.apic_lvtt = apic_read(APIC_LVTT);
        if (maxlvt >= 4)
                apic_pm_state.apic_lvtpc = apic_read(APIC_LVTPC);
        apic_pm_state.apic_lvt0 = apic_read(APIC_LVT0);
        apic_pm_state.apic_lvt1 = apic_read(APIC_LVT1);
        apic_pm_state.apic_lvterr = apic_read(APIC_LVTERR);
        apic_pm_state.apic_tmict = apic_read(APIC_TMICT);
        apic_pm_state.apic_tdcr = apic_read(APIC_TDCR);
#ifdef CONFIG_X86_THERMAL_VECTOR
        if (maxlvt >= 5)
                apic_pm_state.apic_thmr = apic_read(APIC_LVTTHMR);
#endif
#ifdef CONFIG_X86_MCE_INTEL
        if (maxlvt >= 6)
                apic_pm_state.apic_cmci = apic_read(APIC_LVTCMCI);
#endif

        local_irq_save(flags);

        /*
         * Mask IOAPIC before disabling the local APIC to prevent stale IRR
         * entries on some implementations.
         */
        mask_ioapic_entries();

        disable_local_APIC();

        irq_remapping_disable();

        local_irq_restore(flags);
        return 0;
}

static void lapic_resume(void)
{
        unsigned int l, h;
        unsigned long flags;
        int maxlvt;

        if (!apic_pm_state.active)
                return;

        local_irq_save(flags);

        /*
         * IO-APIC and PIC have their own resume routines.
         * We just mask them here to make sure the interrupt
         * subsystem is completely quiet while we enable x2apic
         * and interrupt-remapping.
         */
        mask_ioapic_entries();
        legacy_pic->mask_all();

        if (x2apic_mode) {
                __x2apic_enable();
        } else {
                /*
                 * Make sure the APICBASE points to the right address
                 *
                 * FIXME! This will be wrong if we ever support suspend on
                 * SMP! We'll need to do this as part of the CPU restore!
                 */
                if (boot_cpu_data.x86 >= 6) {
                        rdmsr(MSR_IA32_APICBASE, l, h);
                        l &= ~MSR_IA32_APICBASE_BASE;
                        l |= MSR_IA32_APICBASE_ENABLE | mp_lapic_addr;
                        wrmsr(MSR_IA32_APICBASE, l, h);
                }
        }

        maxlvt = lapic_get_maxlvt();
        apic_write(APIC_LVTERR, ERROR_APIC_VECTOR | APIC_LVT_MASKED);
        apic_write(APIC_ID, apic_pm_state.apic_id);
        apic_write(APIC_DFR, apic_pm_state.apic_dfr);
        apic_write(APIC_LDR, apic_pm_state.apic_ldr);
        apic_write(APIC_TASKPRI, apic_pm_state.apic_taskpri);
        apic_write(APIC_SPIV, apic_pm_state.apic_spiv);
        apic_write(APIC_LVT0, apic_pm_state.apic_lvt0);
        apic_write(APIC_LVT1, apic_pm_state.apic_lvt1);
#ifdef CONFIG_X86_THERMAL_VECTOR
        if (maxlvt >= 5)
                apic_write(APIC_LVTTHMR, apic_pm_state.apic_thmr);
#endif
#ifdef CONFIG_X86_MCE_INTEL
        if (maxlvt >= 6)
                apic_write(APIC_LVTCMCI, apic_pm_state.apic_cmci);
#endif
        if (maxlvt >= 4)
                apic_write(APIC_LVTPC, apic_pm_state.apic_lvtpc);
        apic_write(APIC_LVTT, apic_pm_state.apic_lvtt);
        apic_write(APIC_TDCR, apic_pm_state.apic_tdcr);
        apic_write(APIC_TMICT, apic_pm_state.apic_tmict);
        apic_write(APIC_ESR, 0);
        apic_read(APIC_ESR);
        apic_write(APIC_LVTERR, apic_pm_state.apic_lvterr);
        apic_write(APIC_ESR, 0);
        apic_read(APIC_ESR);

        irq_remapping_reenable(x2apic_mode);

        local_irq_restore(flags);
}

/*
 * This device has no shutdown method - fully functioning local APICs
 * are needed on every CPU up until machine_halt/restart/poweroff.
 */

static struct syscore_ops lapic_syscore_ops = {
        .resume         = lapic_resume,
        .suspend        = lapic_suspend,
};

static void apic_pm_activate(void)
{
        apic_pm_state.active = 1;
}

static int __init init_lapic_sysfs(void)
{
        /* XXX: remove suspend/resume procs if !apic_pm_state.active? */
        if (boot_cpu_has(X86_FEATURE_APIC))
                register_syscore_ops(&lapic_syscore_ops);

        return 0;
}

/* local apic needs to resume before other devices access its registers. */
core_initcall(init_lapic_sysfs);

#else   /* CONFIG_PM */

static void apic_pm_activate(void) { }

#endif  /* CONFIG_PM */

#ifdef CONFIG_X86_64

static int multi_checked;
static int multi;

static int set_multi(const struct dmi_system_id *d)
{
        if (multi)
                return 0;
        pr_info("APIC: %s detected, Multi Chassis\n", d->ident);
        multi = 1;
        return 0;
}

static const struct dmi_system_id multi_dmi_table[] = {
        {
                .callback = set_multi,
                .ident = "IBM System Summit2",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "IBM"),
                        DMI_MATCH(DMI_PRODUCT_NAME, "Summit2"),
                },
        },
        {}
};

static void dmi_check_multi(void)
{
        if (multi_checked)
                return;

        dmi_check_system(multi_dmi_table);
        multi_checked = 1;
}

/*
 * apic_is_clustered_box() -- Check if we can expect good TSC
 *
 * Thus far, the major user of this is IBM's Summit2 series:
 * Clustered boxes may have unsynced TSC problems if they are
 * multi-chassis.
 * Use DMI to check them
 */
int apic_is_clustered_box(void)
{
        dmi_check_multi();
        return multi;
}
#endif

/*
 * APIC command line parameters
 */
static int __init setup_disableapic(char *arg)
{
        disable_apic = 1;
        setup_clear_cpu_cap(X86_FEATURE_APIC);
        return 0;
}
early_param("disableapic", setup_disableapic);

/* same as disableapic, for compatibility */
static int __init setup_nolapic(char *arg)
{
        return setup_disableapic(arg);
}
early_param("nolapic", setup_nolapic);

static int __init parse_lapic_timer_c2_ok(char *arg)
{
        local_apic_timer_c2_ok = 1;
        return 0;
}
early_param("lapic_timer_c2_ok", parse_lapic_timer_c2_ok);

static int __init parse_disable_apic_timer(char *arg)
{
        disable_apic_timer = 1;
        return 0;
}
early_param("noapictimer", parse_disable_apic_timer);

static int __init parse_nolapic_timer(char *arg)
{
        disable_apic_timer = 1;
        return 0;
}
early_param("nolapic_timer", parse_nolapic_timer);

static int __init apic_set_verbosity(char *arg)
{
        if (!arg)  {
#ifdef CONFIG_X86_64
                skip_ioapic_setup = 0;
                return 0;
#endif
                return -EINVAL;
        }

        if (strcmp("debug", arg) == 0)
                apic_verbosity = APIC_DEBUG;
        else if (strcmp("verbose", arg) == 0)
                apic_verbosity = APIC_VERBOSE;
#ifdef CONFIG_X86_64
        else {
                pr_warn("APIC Verbosity level %s not recognised"
                        " use apic=verbose or apic=debug\n", arg);
                return -EINVAL;
        }
#endif

        return 0;
}
early_param("apic", apic_set_verbosity);

static int __init lapic_insert_resource(void)
{
        if (!apic_phys)
                return -1;

        /* Put local APIC into the resource map. */
        lapic_resource.start = apic_phys;
        lapic_resource.end = lapic_resource.start + PAGE_SIZE - 1;
        insert_resource(&iomem_resource, &lapic_resource);

        return 0;
}

/*
 * need call insert after e820__reserve_resources()
 * that is using request_resource
 */
late_initcall(lapic_insert_resource);

static int __init apic_set_disabled_cpu_apicid(char *arg)
{
        if (!arg || !get_option(&arg, &disabled_cpu_apicid))
                return -EINVAL;

        return 0;
}
early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid);

static int __init apic_set_extnmi(char *arg)
{
        if (!arg)
                return -EINVAL;

        if (!strncmp("all", arg, 3))
                apic_extnmi = APIC_EXTNMI_ALL;
        else if (!strncmp("none", arg, 4))
                apic_extnmi = APIC_EXTNMI_NONE;
        else if (!strncmp("bsp", arg, 3))
                apic_extnmi = APIC_EXTNMI_BSP;
        else {
                pr_warn("Unknown external NMI delivery mode `%s' ignored\n", arg);
                return -EINVAL;
        }

        return 0;
}
early_param("apic_extnmi", apic_set_extnmi);