apic.c 54 KB
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/*
 *	Local APIC handling, local APIC timers
 *
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 *	(c) 1999, 2000, 2009 Ingo Molnar <mingo@redhat.com>
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 *
 *	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.
 */

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#include <linux/perf_event.h>
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#include <linux/kernel_stat.h>
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#include <linux/mc146818rtc.h>
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#include <linux/acpi_pmtmr.h>
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#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/bootmem.h>
#include <linux/ftrace.h>
#include <linux/ioport.h>
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#include <linux/module.h>
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#include <linux/sysdev.h>
#include <linux/delay.h>
#include <linux/timex.h>
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#include <linux/dmar.h>
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#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/dmi.h>
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#include <linux/nmi.h>
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#include <linux/smp.h>
#include <linux/mm.h>
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#include <asm/perf_event.h>
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#include <asm/x86_init.h>
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#include <asm/pgalloc.h>
#include <asm/atomic.h>
#include <asm/mpspec.h>
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#include <asm/i8253.h>
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#include <asm/i8259.h>
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#include <asm/proto.h>
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#include <asm/apic.h>
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#include <asm/desc.h>
#include <asm/hpet.h>
#include <asm/idle.h>
#include <asm/mtrr.h>
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#include <asm/smp.h>
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#include <asm/mce.h>
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#include <asm/kvm_para.h>
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unsigned int num_processors;
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unsigned disabled_cpus __cpuinitdata;
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/* Processor that is doing the boot up */
unsigned int boot_cpu_physical_apicid = -1U;
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/*
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 * The highest APIC ID seen during enumeration.
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 */
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unsigned int max_physical_apicid;
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/*
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 * Bitmask of physically existing CPUs:
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 */
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physid_mask_t phys_cpu_present_map;

/*
 * Map cpu index to physical APIC ID
 */
DEFINE_EARLY_PER_CPU(u16, x86_cpu_to_apicid, BAD_APICID);
DEFINE_EARLY_PER_CPU(u16, x86_bios_cpu_apicid, BAD_APICID);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_cpu_to_apicid);
EXPORT_EARLY_PER_CPU_SYMBOL(x86_bios_cpu_apicid);
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#ifdef CONFIG_X86_32
/*
 * Knob to control our willingness to enable the local APIC.
 *
 * +1=force-enable
 */
static int force_enable_local_apic;
/*
 * APIC command line parameters
 */
static int __init parse_lapic(char *arg)
{
	force_enable_local_apic = 1;
	return 0;
}
early_param("lapic", parse_lapic);
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/* Local APIC was disabled by the BIOS and enabled by the kernel */
static int enabled_via_apicbase;

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/*
 * 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.
 */
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static inline void imcr_pic_to_apic(void)
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{
	/* select IMCR register */
	outb(0x70, 0x22);
	/* NMI and 8259 INTR go through APIC */
	outb(0x01, 0x23);
}

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static inline void imcr_apic_to_pic(void)
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{
	/* select IMCR register */
	outb(0x70, 0x22);
	/* NMI and 8259 INTR go directly to BSP */
	outb(0x00, 0x23);
}
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#endif

#ifdef CONFIG_X86_64
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static int apic_calibrate_pmtmr __initdata;
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static __init int setup_apicpmtimer(char *s)
{
	apic_calibrate_pmtmr = 1;
	notsc_setup(NULL);
	return 0;
}
__setup("apicpmtimer", setup_apicpmtimer);
#endif

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int x2apic_mode;
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#ifdef CONFIG_X86_X2APIC
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/* x2apic enabled before OS handover */
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static int x2apic_preenabled;
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static __init int setup_nox2apic(char *str)
{
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	if (x2apic_enabled()) {
		pr_warning("Bios already enabled x2apic, "
			   "can't enforce nox2apic");
		return 0;
	}

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	setup_clear_cpu_cap(X86_FEATURE_X2APIC);
	return 0;
}
early_param("nox2apic", setup_nox2apic);
#endif
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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 __cpuinitdata;
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/* Local APIC timer works in C2 */
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int local_apic_timer_c2_ok;
EXPORT_SYMBOL_GPL(local_apic_timer_c2_ok);

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int first_system_vector = 0xfe;

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

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

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

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static unsigned int calibration_result;

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static int lapic_next_event(unsigned long delta,
			    struct clock_event_device *evt);
static void lapic_timer_setup(enum clock_event_mode mode,
			      struct clock_event_device *evt);
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static void lapic_timer_broadcast(const struct cpumask *mask);
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static void apic_pm_activate(void);
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/*
 * The local apic timer can be used for any function which is CPU local.
 */
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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_mode	= lapic_timer_setup,
	.set_next_event	= lapic_next_event,
	.broadcast	= lapic_timer_broadcast,
	.rating		= 100,
	.irq		= -1,
};
static DEFINE_PER_CPU(struct clock_event_device, lapic_events);

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static unsigned long apic_phys;

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

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/*
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 * Check, if the APIC is integrated or a separate chip
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 */
static inline int lapic_is_integrated(void)
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{
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#ifdef CONFIG_X86_64
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	return 1;
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#else
	return APIC_INTEGRATED(lapic_get_version());
#endif
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}

/*
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 * Check, whether this is a modern or a first generation APIC
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 */
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static int modern_apic(void)
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{
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	/* 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;
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}

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

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

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

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

	return send_status;
}

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void native_apic_icr_write(u32 low, u32 id)
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{
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	apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(id));
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	apic_write(APIC_ICR, low);
}

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u64 native_apic_icr_read(void)
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{
	u32 icr1, icr2;

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

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

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/**
 * enable_NMI_through_LVT0 - enable NMI through local vector table 0
 */
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void __cpuinit enable_NMI_through_LVT0(void)
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{
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	unsigned int v;
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	/* unmask and set to NMI */
	v = APIC_DM_NMI;
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	/* Level triggered for 82489DX (32bit mode) */
	if (!lapic_is_integrated())
		v |= APIC_LVT_LEVEL_TRIGGER;

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	apic_write(APIC_LVT0, v);
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}

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

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

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/*
 * Local APIC timer
 */

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/* Clock divisor */
#define APIC_DIVISOR 16
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/*
 * 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)
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{
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	unsigned int lvtt_value, tmp_value;
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	lvtt_value = LOCAL_TIMER_VECTOR;
	if (!oneshot)
		lvtt_value |= APIC_LVT_TIMER_PERIODIC;
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	if (!lapic_is_integrated())
		lvtt_value |= SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV);

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	if (!irqen)
		lvtt_value |= APIC_LVT_MASKED;
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	apic_write(APIC_LVTT, lvtt_value);
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	/*
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	 * Divide PICLK by 16
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	 */
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	tmp_value = apic_read(APIC_TDCR);
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	apic_write(APIC_TDCR,
		(tmp_value & ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE)) |
		APIC_TDR_DIV_16);
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	if (!oneshot)
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		apic_write(APIC_TMICT, clocks / APIC_DIVISOR);
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}

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/*
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 * Setup extended LVT, AMD specific (K8, family 10h)
 *
 * Vector mappings are hard coded. On K8 only offset 0 (APIC500) and
 * MCE interrupts are supported. Thus MCE offset must be set to 0.
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 *
 * If mask=1, the LVT entry does not generate interrupts while mask=0
 * enables the vector. See also the BKDGs.
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 */
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#define APIC_EILVT_LVTOFF_MCE 0
#define APIC_EILVT_LVTOFF_IBS 1

static void setup_APIC_eilvt(u8 lvt_off, u8 vector, u8 msg_type, u8 mask)
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{
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	unsigned long reg = (lvt_off << 4) + APIC_EILVTn(0);
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	unsigned int  v   = (mask << 16) | (msg_type << 8) | vector;
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	apic_write(reg, v);
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}

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u8 setup_APIC_eilvt_mce(u8 vector, u8 msg_type, u8 mask)
{
	setup_APIC_eilvt(APIC_EILVT_LVTOFF_MCE, vector, msg_type, mask);
	return APIC_EILVT_LVTOFF_MCE;
}

u8 setup_APIC_eilvt_ibs(u8 vector, u8 msg_type, u8 mask)
{
	setup_APIC_eilvt(APIC_EILVT_LVTOFF_IBS, vector, msg_type, mask);
	return APIC_EILVT_LVTOFF_IBS;
}
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EXPORT_SYMBOL_GPL(setup_APIC_eilvt_ibs);
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/*
 * Program the next event, relative to now
 */
static int lapic_next_event(unsigned long delta,
			    struct clock_event_device *evt)
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{
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	apic_write(APIC_TMICT, delta);
	return 0;
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}

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/*
 * Setup the lapic timer in periodic or oneshot mode
 */
static void lapic_timer_setup(enum clock_event_mode mode,
			      struct clock_event_device *evt)
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{
	unsigned long flags;
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	unsigned int v;
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	/* Lapic used as dummy for broadcast ? */
	if (evt->features & CLOCK_EVT_FEAT_DUMMY)
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		return;

	local_irq_save(flags);

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	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
	case CLOCK_EVT_MODE_ONESHOT:
		__setup_APIC_LVTT(calibration_result,
				  mode != CLOCK_EVT_MODE_PERIODIC, 1);
		break;
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		v = apic_read(APIC_LVTT);
		v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
		apic_write(APIC_LVTT, v);
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		apic_write(APIC_TMICT, 0);
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		break;
	case CLOCK_EVT_MODE_RESUME:
		/* Nothing to do here */
		break;
	}
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	local_irq_restore(flags);
}

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/*
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 * Local APIC timer broadcast function
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 */
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static void lapic_timer_broadcast(const struct cpumask *mask)
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{
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#ifdef CONFIG_SMP
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	apic->send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
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#endif
}
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/*
 * Setup the local APIC timer for this CPU. Copy the initilized values
 * of the boot CPU and register the clock event in the framework.
 */
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static void __cpuinit setup_APIC_timer(void)
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{
	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
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	if (cpu_has(&current_cpu_data, X86_FEATURE_ARAT)) {
		lapic_clockevent.features &= ~CLOCK_EVT_FEAT_C3STOP;
		/* Make LAPIC timer preferrable over percpu HPET */
		lapic_clockevent.rating = 150;
	}

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	memcpy(levt, &lapic_clockevent, sizeof(*levt));
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	levt->cpumask = cpumask_of(smp_processor_id());
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	clockevents_register_device(levt);
}
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/*
 * 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 (cpu_has_tsc)
		rdtscll(tsc);

	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;
	}
}

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static int __init
calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)
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{
	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

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	apic_printk(APIC_VERBOSE, "... PM-Timer delta = %ld\n", deltapm);
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	/* 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)) {
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		apic_printk(APIC_VERBOSE, "... PM-Timer result ok\n");
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		return 0;
	}

	res = (((u64)deltapm) *  mult) >> 22;
	do_div(res, 1000000);
	pr_warning("APIC calibration not consistent "
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		   "with PM-Timer: %ldms instead of 100ms\n",(long)res);
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	/* 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 (cpu_has_tsc) {
		res = (((u64)(*deltatsc)) * pm_100ms);
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		do_div(res, deltapm);
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		apic_printk(APIC_VERBOSE, "TSC delta adjusted to "
					  "PM-Timer: %lu (%ld) \n",
					(unsigned long)res, *deltatsc);
		*deltatsc = (long)res;
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	}

	return 0;
}

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static int __init calibrate_APIC_clock(void)
{
	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
	void (*real_handler)(struct clock_event_device *dev);
	unsigned long deltaj;
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	long delta, deltatsc;
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	int pm_referenced = 0;

	local_irq_disable();

	/* Replace the global interrupt handler */
	real_handler = global_clock_event->event_handler;
	global_clock_event->event_handler = lapic_cal_handler;

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

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	deltatsc = (long)(lapic_cal_tsc2 - lapic_cal_tsc1);

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	/* we trust the PM based calibration if possible */
	pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
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					&delta, &deltatsc);
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	/* 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(0x7FFFFF, &lapic_clockevent);
	lapic_clockevent.min_delta_ns =
		clockevent_delta2ns(0xF, &lapic_clockevent);

	calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;

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

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

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

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

	levt->features &= ~CLOCK_EVT_FEAT_DUMMY;

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	/*
	 * PM timer calibration failed or not turned on
	 * so lets try APIC timer based calibration
	 */
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	if (!pm_referenced) {
		apic_printk(APIC_VERBOSE, "... verify APIC timer\n");

		/*
		 * Setup the apic timer manually
		 */
		levt->event_handler = lapic_cal_handler;
		lapic_timer_setup(CLOCK_EVT_MODE_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 */
		lapic_timer_setup(CLOCK_EVT_MODE_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;
	} else
		local_irq_enable();

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

	return 0;
}

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/*
 * Setup the boot APIC
 *
 * Calibrate and verify the result.
 */
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void __init setup_boot_APIC_clock(void)
{
	/*
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	 * 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.
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	 */
	if (disable_apic_timer) {
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		pr_info("Disabling APIC timer\n");
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		/* No broadcast on UP ! */
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		if (num_possible_cpus() > 1) {
			lapic_clockevent.mult = 1;
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			setup_APIC_timer();
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		}
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		return;
	}

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

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

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	/*
	 * If nmi_watchdog is set to IO_APIC, we need the
	 * PIT/HPET going.  Otherwise register lapic as a dummy
	 * device.
	 */
	if (nmi_watchdog != NMI_IO_APIC)
		lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
	else
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		pr_warning("APIC timer registered as dummy,"
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			" due to nmi_watchdog=%d!\n", nmi_watchdog);
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	/* Setup the lapic or request the broadcast */
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	setup_APIC_timer();
}

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

/*
 * The guts of the apic timer interrupt
 */
static void local_apic_timer_interrupt(void)
{
	int cpu = smp_processor_id();
	struct clock_event_device *evt = &per_cpu(lapic_events, cpu);

	/*
	 * 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) {
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		pr_warning("Spurious LAPIC timer interrupt on cpu %d\n", cpu);
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		/* Switch it off */
		lapic_timer_setup(CLOCK_EVT_MODE_SHUTDOWN, evt);
		return;
	}

	/*
	 * the NMI deadlock-detector uses this.
	 */
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	inc_irq_stat(apic_timer_irqs);
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	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 ... ]
 */
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void __irq_entry smp_apic_timer_interrupt(struct pt_regs *regs)
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{
	struct pt_regs *old_regs = set_irq_regs(regs);

	/*
	 * NOTE! We'd better ACK the irq immediately,
	 * because timer handling can be slow.
	 */
	ack_APIC_irq();
	/*
	 * 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.
	 */
	exit_idle();
	irq_enter();
	local_apic_timer_interrupt();
	irq_exit();
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	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)
{
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	int maxlvt;
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	u32 v;

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

	maxlvt = lapic_get_maxlvt();
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	/*
	 * 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);
	}

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

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	/*
	 * 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);
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	/* 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);
	}
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}

/**
 * disable_local_APIC - clear and disable the local APIC
 */
void disable_local_APIC(void)
{
	unsigned int value;

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

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	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);
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#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
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}

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/*
 * 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.
 */
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void lapic_shutdown(void)
{
	unsigned long flags;

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	if (!cpu_has_apic && !apic_from_smp_config())
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		return;

	local_irq_save(flags);

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

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	local_irq_restore(flags);
}

/*
 * This is to verify that we're looking at a real local APIC.
 * Check these against your board if the CPUs aren't getting
 * started for no apparent reason.
 */
int __init verify_local_APIC(void)
{
	unsigned int reg0, reg1;

	/*
	 * The version register is read-only in a real APIC.
	 */
	reg0 = apic_read(APIC_LVR);
	apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg0);
	apic_write(APIC_LVR, reg0 ^ APIC_LVR_MASK);
	reg1 = apic_read(APIC_LVR);
	apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg1);

	/*
	 * The two version reads above should print the same
	 * numbers.  If the second one is different, then we
	 * poke at a non-APIC.
	 */
	if (reg1 != reg0)
		return 0;

	/*
	 * Check if the version looks reasonably.
	 */
	reg1 = GET_APIC_VERSION(reg0);
	if (reg1 == 0x00 || reg1 == 0xff)
		return 0;
	reg1 = lapic_get_maxlvt();
	if (reg1 < 0x02 || reg1 == 0xff)
		return 0;

	/*
	 * The ID register is read/write in a real APIC.
	 */
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	reg0 = apic_read(APIC_ID);
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	apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg0);
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	apic_write(APIC_ID, reg0 ^ apic->apic_id_mask);
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	reg1 = apic_read(APIC_ID);
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	apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg1);
	apic_write(APIC_ID, reg0);
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	if (reg1 != (reg0 ^ apic->apic_id_mask))
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		return 0;

	/*
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	 * The next two are just to see if we have sane values.
	 * They're only really relevant if we're in Virtual Wire
	 * compatibility mode, but most boxes are anymore.
	 */
	reg0 = apic_read(APIC_LVT0);
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	apic_printk(APIC_DEBUG, "Getting LVT0: %x\n", reg0);
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	reg1 = apic_read(APIC_LVT1);
	apic_printk(APIC_DEBUG, "Getting LVT1: %x\n", reg1);

	return 1;
}

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/**
 * sync_Arb_IDs - synchronize APIC bus arbitration IDs
 */
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void __init sync_Arb_IDs(void)
{
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	/*
	 * 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)
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		return;

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

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

/*
 * An initial setup of the virtual wire mode.
 */
void __init init_bsp_APIC(void)
{
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	unsigned int value;
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	/*
	 * 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 || !cpu_has_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;
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#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;
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	value |= SPURIOUS_APIC_VECTOR;
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	apic_write(APIC_SPIV, value);
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	/*
	 * Set up the virtual wire mode.
	 */
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	apic_write(APIC_LVT0, APIC_DM_EXTINT);
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	value = APIC_DM_NMI;
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	if (!lapic_is_integrated())		/* 82489DX */
		value |= APIC_LVT_LEVEL_TRIGGER;
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	apic_write(APIC_LVT1, value);
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}

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

	if (!lapic_is_integrated()) {
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		pr_info("No ESR for 82489DX.\n");
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		return;
	}
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	if (apic->disable_esr) {
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		/*
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		 * 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
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		 */
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		pr_info("Leaving ESR disabled.\n");
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		return;
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	}
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	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);
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}


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/**
 * setup_local_APIC - setup the local APIC
 */
void __cpuinit setup_local_APIC(void)
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{
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	unsigned int value;
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	int i, j;
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	if (disable_apic) {
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		arch_disable_smp_support();
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		return;
	}

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#ifdef CONFIG_X86_32
	/* Pound the ESR really hard over the head with a big hammer - mbligh */
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	if (lapic_is_integrated() && apic->disable_esr) {
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		apic_write(APIC_ESR, 0);
		apic_write(APIC_ESR, 0);
		apic_write(APIC_ESR, 0);
		apic_write(APIC_ESR, 0);
	}
#endif
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	perf_events_lapic_init();
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	preempt_disable();
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	/*
	 * Double-check whether this APIC is really registered.
	 * This is meaningless in clustered apic mode, so we skip it.
	 */
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	BUG_ON(!apic->apic_id_registered());
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	/*
	 * 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...
	 */
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	apic->init_apic_ldr();
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	/*
	 * Set Task Priority to 'accept all'. We never change this
	 * later on.
	 */
	value = apic_read(APIC_TASKPRI);
	value &= ~APIC_TPRI_MASK;
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	apic_write(APIC_TASKPRI, value);
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	/*
	 * 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.
	 */
	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();
		}
	}

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	/*
	 * 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;

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#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).
	 * See also the comment in end_level_ioapic_irq().  --macro
	 */

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