Skip to content
Snippets Groups Projects
Select Git revision
  • fc90ccfd286eabb05ec54521367df8663cf0bbbf
  • openEuler-1.0-LTS default protected
  • openEuler-22.09
  • OLK-5.10
  • openEuler-22.03-LTS
  • openEuler-22.03-LTS-Ascend
  • master
  • openEuler-22.03-LTS-LoongArch-NW
  • openEuler-22.09-HCK
  • openEuler-20.03-LTS-SP3
  • openEuler-21.09
  • openEuler-21.03
  • openEuler-20.09
  • 4.19.90-2210.5.0
  • 5.10.0-123.0.0
  • 5.10.0-60.63.0
  • 5.10.0-60.62.0
  • 4.19.90-2210.4.0
  • 5.10.0-121.0.0
  • 5.10.0-60.61.0
  • 4.19.90-2210.3.0
  • 5.10.0-60.60.0
  • 5.10.0-120.0.0
  • 5.10.0-60.59.0
  • 5.10.0-119.0.0
  • 4.19.90-2210.2.0
  • 4.19.90-2210.1.0
  • 5.10.0-118.0.0
  • 5.10.0-106.19.0
  • 5.10.0-60.58.0
  • 4.19.90-2209.6.0
  • 5.10.0-106.18.0
  • 5.10.0-106.17.0
33 results

apic.c

Blame
  • apic.c 67.16 KiB
    /*
     *	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/bootmem.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/perf_event.h>
    #include <asm/x86_init.h>
    #include <asm/pgalloc.h>
    #include <linux/atomic.h>
    #include <asm/mpspec.h>
    #include <asm/i8259.h>
    #include <asm/proto.h>
    #include <asm/apic.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>
    
    unsigned int num_processors;
    
    unsigned disabled_cpus;
    
    /* Processor that is doing the boot up */
    unsigned int boot_cpu_physical_apicid = -1U;
    EXPORT_SYMBOL_GPL(boot_cpu_physical_apicid);
    
    u8 boot_cpu_apic_version;
    
    /*
     * 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 __read_mostly = BAD_APICID;
    
    /*
     * This variable controls which CPUs receive external NMIs.  By default,
     * external NMIs are delivered only to the BSP.
     */
    static int apic_extnmi = APIC_EXTNMI_BSP;
    
    /*
     * 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;
    
    /*
     * 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)
    {
    	/* select IMCR register */
    	outb(0x70, 0x22);
    	/* NMI and 8259 INTR go through APIC */
    	outb(0x01, 0x23);
    }
    
    static inline void imcr_apic_to_pic(void)
    {
    	/* select IMCR register */
    	outb(0x70, 0x22);
    	/* NMI and 8259 INTR go directly to BSP */
    	outb(0x00, 0x23);
    }
    #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 0;
    }
    __setup("apicpmtimer", setup_apicpmtimer);
    #endif
    
    unsigned long mp_lapic_addr;
    int disable_apic;
    /* 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;
    EXPORT_SYMBOL_GPL(local_apic_timer_c2_ok);
    
    /*
     * Debug level, exported for io_apic.c
     */
    unsigned int apic_verbosity;
    
    int pic_mode;
    
    /* Have we found an MP table */
    int smp_found_config;
    
    static struct resource lapic_resource = {
    	.name = "Local APIC",
    	.flags = IORESOURCE_MEM | IORESOURCE_BUSY,
    };
    
    unsigned int lapic_timer_frequency = 0;
    
    static void apic_pm_activate(void);
    
    static unsigned long apic_phys;
    
    /*
     * 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;
    	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_APIC_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
    
    /*
     * 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;
    
    	if (!lapic_is_integrated())
    		lvtt_value |= SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV);
    
    	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");
    
    		printk_once(KERN_DEBUG "TSC deadline timer enabled\n");
    		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;
    		rsvd = atomic_cmpxchg(&eilvt_offsets[offset], rsvd, new);
    	} while (rsvd != new);
    
    	rsvd &= ~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;
    
    	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_frequency, 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);
    
    #define DEADLINE_MODEL_MATCH_FUNC(model, func)	\
    	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, (unsigned long)&func }
    
    #define DEADLINE_MODEL_MATCH_REV(model, rev)	\
    	{ X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, (unsigned long)rev }
    
    static u32 hsx_deadline_rev(void)
    {
    	switch (boot_cpu_data.x86_mask) {
    	case 0x02: return 0x3a; /* EP */
    	case 0x04: return 0x0f; /* EX */
    	}
    
    	return ~0U;
    }
    
    static u32 bdx_deadline_rev(void)
    {
    	switch (boot_cpu_data.x86_mask) {
    	case 0x02: return 0x00000011;
    	case 0x03: return 0x0700000e;
    	case 0x04: return 0x0f00000c;
    	case 0x05: return 0x0e000003;
    	}
    
    	return ~0U;
    }
    
    static u32 skx_deadline_rev(void)
    {
    	switch (boot_cpu_data.x86_mask) {
    	case 0x03: return 0x01000136;
    	case 0x04: return 0x02000014;
    	}
    
    	return ~0U;
    }
    
    static const struct x86_cpu_id deadline_match[] = {
    	DEADLINE_MODEL_MATCH_FUNC( INTEL_FAM6_HASWELL_X,	hsx_deadline_rev),
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_BROADWELL_X,	0x0b000020),
    	DEADLINE_MODEL_MATCH_FUNC( INTEL_FAM6_BROADWELL_XEON_D,	bdx_deadline_rev),
    	DEADLINE_MODEL_MATCH_FUNC( INTEL_FAM6_SKYLAKE_X,	skx_deadline_rev),
    
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_HASWELL_CORE,	0x22),
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_HASWELL_ULT,	0x20),
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_HASWELL_GT3E,	0x17),
    
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_BROADWELL_CORE,	0x25),
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_BROADWELL_GT3E,	0x17),
    
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_SKYLAKE_MOBILE,	0xb2),
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_SKYLAKE_DESKTOP,	0xb2),
    
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_KABYLAKE_MOBILE,	0x52),
    	DEADLINE_MODEL_MATCH_REV ( INTEL_FAM6_KABYLAKE_DESKTOP,	0x52),
    
    	{},
    };
    
    static void apic_check_deadline_errata(void)
    {
    	const struct x86_cpu_id *m;
    	u32 rev;
    
    	if (!boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER) ||
    	    boot_cpu_has(X86_FEATURE_HYPERVISOR))
    		return;
    
    	m = x86_match_cpu(deadline_match);
    	if (!m)
    		return;
    
    	/*
    	 * Function pointers will have the MSB set due to address layout,
    	 * immediate revisions will not.
    	 */
    	if ((long)m->driver_data < 0)
    		rev = ((u32 (*)(void))(m->driver_data))();
    	else
    		rev = (u32)m->driver_data;
    
    	if (boot_cpu_data.microcode >= rev)
    		return;
    
    	setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
    	pr_err(FW_BUG "TSC_DEADLINE disabled due to Errata; "
    	       "please update microcode to version: 0x%x (or later)\n", rev);
    }
    
    /*
     * 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 preferrable 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 syncron. 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.
     */
    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_warning("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 calibrate_APIC_clock(void)
    {
    	struct clock_event_device *levt = this_cpu_ptr(&lapic_events);
    	void (*real_handler)(struct clock_event_device *dev);
    	unsigned long deltaj;
    	long delta, deltatsc;
    	int pm_referenced = 0;
    
    	/**
    	 * check if lapic timer has already been calibrated by platform
    	 * specific routine, such as tsc calibration code. if so, we just fill
    	 * in the clockevent structure and return.
    	 */
    
    	if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER)) {
    		return 0;
    	} else if (lapic_timer_frequency) {
    		apic_printk(APIC_VERBOSE, "lapic timer already calibrated %d\n",
    				lapic_timer_frequency);
    		lapic_clockevent.mult = div_sc(lapic_timer_frequency/APIC_DIVISOR,
    					TICK_NSEC, lapic_clockevent.shift);
    		lapic_clockevent.max_delta_ns =
    			clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
    		lapic_clockevent.max_delta_ticks = 0x7FFFFF;
    		lapic_clockevent.min_delta_ns =
    			clockevent_delta2ns(0xF, &lapic_clockevent);
    		lapic_clockevent.min_delta_ticks = 0xF;
    		lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
    		return 0;
    	}
    
    	apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
    		    "calibrating APIC timer ...\n");
    
    	local_irq_disable();
    
    	/* Replace the global interrupt handler */
    	real_handler = global_clock_event->event_handler;
    	global_clock_event->event_handler = lapic_cal_handler;
    
    	/*
    	 * 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);
    
    	/* Let the interrupts run */
    	local_irq_enable();
    
    	while (lapic_cal_loops <= LAPIC_CAL_LOOPS)
    		cpu_relax();
    
    	local_irq_disable();
    
    	/* Restore the real event handler */
    	global_clock_event->event_handler = real_handler;
    
    	/* 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);
    
    	/* Calculate the scaled math multiplication factor */
    	lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
    				       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;
    
    	lapic_timer_frequency = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
    
    	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_frequency);
    
    	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_frequency / (1000000 / HZ),
    		    lapic_timer_frequency % (1000000 / HZ));
    
    	/*
    	 * Do a sanity check on the APIC calibration result
    	 */
    	if (lapic_timer_frequency < (1000000 / HZ)) {
    		local_irq_enable();
    		pr_warning("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 (!pm_referenced) {
    		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_warning("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_warning("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 ... ]
     */
    __visible void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
    {
    	struct pt_regs *old_regs = set_irq_regs(regs);
    
    	/*
    	 * NOTE! We'd better ACK the irq immediately,
    	 * because timer handling can be slow.
    	 *
    	 * update_process_times() expects us to have done irq_enter().
    	 * Besides, if we don't timer interrupts ignore the global
    	 * interrupt lock, which is the WrongThing (tm) to do.
    	 */
    	entering_ack_irq();
    	trace_local_timer_entry(LOCAL_TIMER_VECTOR);
    	local_apic_timer_interrupt();
    	trace_local_timer_exit(LOCAL_TIMER_VECTOR);
    	exiting_irq();
    
    	set_irq_regs(old_regs);
    }
    
    int setup_profiling_timer(unsigned int multiplier)
    {
    	return -EINVAL;
    }
    
    /*
     * 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);
    	}
    }
    
    /**
     * disable_local_APIC - clear and disable the local APIC
     */
    void disable_local_APIC(void)
    {
    	unsigned int value;
    
    	/* APIC hasn't been mapped yet */
    	if (!x2apic_mode && !apic_phys)
    		return;
    
    	clear_local_APIC();
    
    	/*
    	 * Disable APIC (implies clearing of registers
    	 * for 82489DX!).
    	 */
    	value = apic_read(APIC_SPIV);
    	value &= ~APIC_SPIV_APIC_ENABLED;
    	apic_write(APIC_SPIV, value);
    
    #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;
    
    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;
    }
    
    /*
     * 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);
    }
    
    /* Init the interrupt delivery mode for the BSP */
    void __init apic_intr_mode_init(void)
    {
    	bool upmode = IS_ENABLED(CONFIG_UP_LATE_INIT);
    
    	apic_intr_mode = apic_intr_mode_select();
    
    	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");
    		default_setup_apic_routing();
    		break;
    	case APIC_VIRTUAL_WIRE_NO_CONFIG:
    		pr_info("APIC: Switch to virtual wire mode setup with no configuration\n");
    		upmode = true;
    		default_setup_apic_routing();
    		break;
    	case APIC_SYMMETRIC_IO:
    		pr_info("APIC: Switch to symmetric I/O mode setup\n");
    		default_setup_apic_routing();
    		break;
    	case APIC_SYMMETRIC_IO_NO_ROUTING:
    		pr_info("APIC: Switch to symmetric I/O mode setup in no SMP routine\n");
    		break;
    	}
    
    	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);
    }
    
    /**
     * setup_local_APIC - setup the local APIC
     *
     * Used to setup local APIC while initializing BSP or bringing up APs.
     * Always called with preemption disabled.
     */
    void setup_local_APIC(void)
    {
    	int cpu = smp_processor_id();
    	unsigned int value, queued;
    	int i, j, acked = 0;
    	unsigned long long tsc = 0, ntsc;
    	long long max_loops = cpu_khz ? cpu_khz : 1000000;
    
    	if (boot_cpu_has(X86_FEATURE_TSC))
    		tsc = rdtsc();
    
    	if (disable_apic) {
    		disable_ioapic_support();
    		return;
    	}
    
    #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
    	perf_events_lapic_init();
    
    	/*
    	 * 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
    	/*
    	 * APIC LDR is initialized.  If logical_apicid mapping was
    	 * initialized during get_smp_config(), make sure it matches the
    	 * actual value.
    	 */
    	i = early_per_cpu(x86_cpu_to_logical_apicid, cpu);
    	WARN_ON(i != BAD_APICID && i != logical_smp_processor_id());
    	/* always use the value from LDR */
    	early_per_cpu(x86_cpu_to_logical_apicid, cpu) =
    		logical_smp_processor_id();
    #endif
    
    	/*
    	 * Set Task Priority to 'accept all'. We never change this
    	 * later on.
    	 */
    	value = apic_read(APIC_TASKPRI);
    	value &= ~APIC_TPRI_MASK;
    	apic_write(APIC_TASKPRI, value);
    
    	/*
    	 * 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 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 serivced
    	 * the interrupt. Hence a vector might get locked. It was noticed
    	 * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
    	 */
    	do {
    		queued = 0;
    		for (i = APIC_ISR_NR - 1; i >= 0; i--)
    			queued |= apic_read(APIC_IRR + i*0x10);
    
    		for (i = APIC_ISR_NR - 1; i >= 0; i--) {
    			value = apic_read(APIC_ISR + i*0x10);
    			for (j = 31; j >= 0; j--) {
    				if (value & (1<<j)) {
    					ack_APIC_irq();
    					acked++;
    				}
    			}
    		}
    		if (acked > 256) {
    			printk(KERN_ERR "LAPIC pending interrupts after %d EOI\n",
    			       acked);
    			break;
    		}
    		if (queued) {
    			if (boot_cpu_has(X86_FEATURE_TSC) && cpu_khz) {
    				ntsc = rdtsc();
    				max_loops = (cpu_khz << 10) - (ntsc - tsc);
    			} else
    				max_loops--;
    		}
    	} while (queued && max_loops > 0);
    	WARN_ON(max_loops <= 0);
    
    	/*
    	 * 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 distributon 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);
    
    	/*
    	 * 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)) {
    		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;
    
    enum {
    	X2APIC_OFF,
    	X2APIC_ON,
    	X2APIC_DISABLED,
    };
    static int x2apic_state;
    
    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_warning("Apicid: %08x, cannot enforce nox2apic\n",
    				   apicid);
    			return 0;
    		}
    		pr_warning("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)
    {
    	/*
    	 * If x2apic is not in ON 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);
    
    	__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) {
    		/* IR is required if there is APIC ID > 255 even when running
    		 * under KVM
    		 */
    		if (max_physical_apicid > 255 ||
    		    !x86_init.hyper.x2apic_available()) {
    			pr_info("x2apic: IRQ remapping doesn't support X2APIC mode\n");
    			x2apic_disable();
    			return;
    		}
    
    		/*
    		 * without IR all CPUs can be addressed by IOAPIC/MSI
    		 * only in physical mode
    		 */
    		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;
    		x2apic_state = X2APIC_ON;
    	} else if (!boot_cpu_has(X86_FEATURE_X2APIC)) {
    		x2apic_state = X2APIC_DISABLED;
    	}
    }
    #else /* CONFIG_X86_X2APIC */
    static int __init validate_x2apic(void)
    {
    	if (!apic_is_x2apic_enabled())
    		return 0;
    	/*
    	 * Checkme: Can we simply turn off x2apic here instead of panic?
    	 */
    	panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");
    }
    early_initcall(validate_x2apic);
    
    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_warning("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_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;
    
    	apic_check_deadline_errata();
    
    	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
     */
    
    /*
     * This interrupt should _never_ happen with our APIC/SMP architecture
     */
    __visible void __irq_entry smp_spurious_interrupt(struct pt_regs *regs)
    {
    	u8 vector = ~regs->orig_ax;
    	u32 v;
    
    	entering_irq();
    	trace_spurious_apic_entry(vector);
    
    	/*
    	 * Check if this really is a spurious interrupt and ACK it
    	 * if it is a vectored one.  Just in case...
    	 * Spurious interrupts should not be ACKed.
    	 */
    	v = apic_read(APIC_ISR + ((vector & ~0x1f) >> 1));
    	if (v & (1 << (vector & 0x1f)))
    		ack_APIC_irq();
    
    	inc_irq_stat(irq_spurious_count);
    
    	/* see sw-dev-man vol 3, chapter 7.4.13.5 */
    	pr_info("spurious APIC interrupt through vector %02x on CPU#%d, "
    		"should never happen.\n", vector, smp_processor_id());
    
    	trace_spurious_apic_exit(vector);
    	exiting_irq();
    }
    
    /*
     * This interrupt should never happen with our APIC/SMP architecture
     */
    __visible void __irq_entry smp_error_interrupt(struct pt_regs *regs)
    {
    	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;
    
    	entering_irq();
    	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);
    	exiting_irq();
    }
    
    /**
     * 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,
    };
    
    /*
     * 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_warning("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_warning(
    			"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_warning("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_warning("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_warning("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();
    }
    
    /*
     * 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)
     *
     * Returns:
     * apic_id of BSP APIC
     */
    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();
    }
    
    #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);
    	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_warning("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);