path: root/xen/arch/x86/cpu/common.c

#include <xen/config.h>
#include <xen/init.h>
#include <xen/string.h>
#include <xen/delay.h>
#include <xen/smp.h>
#include <asm/current.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/msr.h>
#include <asm/io.h>
#include <asm/mpspec.h>
#include <asm/apic.h>
#include <mach_apic.h>
#include <asm/setup.h>

#include "cpu.h"

#define tsc_disable 0
#define disable_pse 0

static int cachesize_override __cpuinitdata = -1;
size_param("cachesize", cachesize_override);
static bool_t __cpuinitdata disable_x86_fxsr;
boolean_param("nofxsr", disable_x86_fxsr);
static bool_t __cpuinitdata disable_x86_serial_nr;
boolean_param("noserialnumber", disable_x86_serial_nr);

static bool_t __cpuinitdata use_xsave;
boolean_param("xsave", use_xsave);

unsigned int __devinitdata opt_cpuid_mask_ecx = ~0u;
integer_param("cpuid_mask_ecx", opt_cpuid_mask_ecx);
unsigned int __devinitdata opt_cpuid_mask_edx = ~0u;
integer_param("cpuid_mask_edx", opt_cpuid_mask_edx);

unsigned int __devinitdata opt_cpuid_mask_xsave_eax = ~0u;
integer_param("cpuid_mask_xsave_eax", opt_cpuid_mask_xsave_eax);

unsigned int __devinitdata opt_cpuid_mask_ext_ecx = ~0u;
integer_param("cpuid_mask_ext_ecx", opt_cpuid_mask_ext_ecx);
unsigned int __devinitdata opt_cpuid_mask_ext_edx = ~0u;
integer_param("cpuid_mask_ext_edx", opt_cpuid_mask_ext_edx);

struct cpu_dev * cpu_devs[X86_VENDOR_NUM] = {};

unsigned int paddr_bits __read_mostly = 36;

/*
 * Default host IA32_CR_PAT value to cover all memory types.
 * BIOS usually sets it to 0x07040600070406.
 */
u64 host_pat = 0x050100070406;

static unsigned int __cpuinitdata cleared_caps[NCAPINTS];

void __init setup_clear_cpu_cap(unsigned int cap)
{
	__clear_bit(cap, boot_cpu_data.x86_capability);
	__set_bit(cap, cleared_caps);
}

static void default_init(struct cpuinfo_x86 * c)
{
	/* Not much we can do here... */
	/* Check if at least it has cpuid */
	if (c->cpuid_level == -1) {
		/* No cpuid. It must be an ancient CPU */
		if (c->x86 == 4)
			safe_strcpy(c->x86_model_id, "486");
		else if (c->x86 == 3)
			safe_strcpy(c->x86_model_id, "386");
	}
        __clear_bit(X86_FEATURE_SEP, c->x86_capability);
}

static struct cpu_dev default_cpu = {
	.c_init	= default_init,
	.c_vendor = "Unknown",
};
static struct cpu_dev * this_cpu = &default_cpu;

bool_t __cpuinitdata opt_cpu_info;
boolean_param("cpuinfo", opt_cpu_info);

int __cpuinit get_model_name(struct cpuinfo_x86 *c)
{
	unsigned int *v;
	char *p, *q;

	if (cpuid_eax(0x80000000) < 0x80000004)
		return 0;

	v = (unsigned int *) c->x86_model_id;
	cpuid(0x80000002, &v[0], &v[1], &v[2], &v[3]);
	cpuid(0x80000003, &v[4], &v[5], &v[6], &v[7]);
	cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
	c->x86_model_id[48] = 0;

	/* Intel chips right-justify this string for some dumb reason;
	   undo that brain damage */
	p = q = &c->x86_model_id[0];
	while ( *p == ' ' )
	     p++;
	if ( p != q ) {
	     while ( *p )
		  *q++ = *p++;
	     while ( q <= &c->x86_model_id[48] )
		  *q++ = '\0';	/* Zero-pad the rest */
	}

	return 1;
}


void __cpuinit display_cacheinfo(struct cpuinfo_x86 *c)
{
	unsigned int n, dummy, ecx, edx, l2size;

	n = cpuid_eax(0x80000000);

	if (n >= 0x80000005) {
		cpuid(0x80000005, &dummy, &dummy, &ecx, &edx);
		if (opt_cpu_info)
			printk("CPU: L1 I cache %dK (%d bytes/line),"
			              " D cache %dK (%d bytes/line)\n",
			       edx>>24, edx&0xFF, ecx>>24, ecx&0xFF);
		c->x86_cache_size=(ecx>>24)+(edx>>24);	
	}

	if (n < 0x80000006)	/* Some chips just has a large L1. */
		return;

	ecx = cpuid_ecx(0x80000006);
	l2size = ecx >> 16;
	
	/* do processor-specific cache resizing */
	if (this_cpu->c_size_cache)
		l2size = this_cpu->c_size_cache(c,l2size);

	/* Allow user to override all this if necessary. */
	if (cachesize_override != -1)
		l2size = cachesize_override;

	if ( l2size == 0 )
		return;		/* Again, no L2 cache is possible */

	c->x86_cache_size = l2size;

	if (opt_cpu_info)
		printk("CPU: L2 Cache: %dK (%d bytes/line)\n",
		       l2size, ecx & 0xFF);
}

/* Naming convention should be: <Name> [(<Codename>)] */
/* This table only is used unless init_<vendor>() below doesn't set it; */
/* in particular, if CPUID levels 0x80000002..4 are supported, this isn't used */

/* Look up CPU names by table lookup. */
static char __cpuinit *table_lookup_model(struct cpuinfo_x86 *c)
{
	struct cpu_model_info *info;

	if ( c->x86_model >= 16 )
		return NULL;	/* Range check */

	if (!this_cpu)
		return NULL;

	info = this_cpu->c_models;

	while (info && info->family) {
		if (info->family == c->x86)
			return info->model_names[c->x86_model];
		info++;
	}
	return NULL;		/* Not found */
}


static void __cpuinit get_cpu_vendor(struct cpuinfo_x86 *c, int early)
{
	char *v = c->x86_vendor_id;
	int i;
	static int printed;

	for (i = 0; i < X86_VENDOR_NUM; i++) {
		if (cpu_devs[i]) {
			if (!strcmp(v,cpu_devs[i]->c_ident[0]) ||
			    (cpu_devs[i]->c_ident[1] && 
			     !strcmp(v,cpu_devs[i]->c_ident[1]))) {
				c->x86_vendor = i;
				if (!early)
					this_cpu = cpu_devs[i];
				return;
			}
		}
	}
	if (!printed) {
		printed++;
		printk(KERN_ERR "CPU: Vendor unknown, using generic init.\n");
		printk(KERN_ERR "CPU: Your system may be unstable.\n");
	}
	c->x86_vendor = X86_VENDOR_UNKNOWN;
	this_cpu = &default_cpu;
}


/* Standard macro to see if a specific flag is changeable */
static inline int flag_is_changeable_p(unsigned long flag)
{
	unsigned long f1, f2;

	asm("pushf\n\t"
	    "pushf\n\t"
	    "pop %0\n\t"
	    "mov %0,%1\n\t"
	    "xor %2,%0\n\t"
	    "push %0\n\t"
	    "popf\n\t"
	    "pushf\n\t"
	    "pop %0\n\t"
	    "popf\n\t"
	    : "=&r" (f1), "=&r" (f2)
	    : "ir" (flag));

	return ((f1^f2) & flag) != 0;
}


/* Probe for the CPUID instruction */
static int __cpuinit have_cpuid_p(void)
{
	return flag_is_changeable_p(X86_EFLAGS_ID);
}

/* Do minimum CPU detection early.
   Fields really needed: vendor, cpuid_level, family, model, mask, cache alignment.
   The others are not touched to avoid unwanted side effects.

   WARNING: this function is only called on the BP.  Don't add code here
   that is supposed to run on all CPUs. */
static void __init early_cpu_detect(void)
{
	struct cpuinfo_x86 *c = &boot_cpu_data;

	c->x86_cache_alignment = 32;

	if (!have_cpuid_p())
		return;

	/* Get vendor name */
	cpuid(0x00000000, &c->cpuid_level,
	      (int *)&c->x86_vendor_id[0],
	      (int *)&c->x86_vendor_id[8],
	      (int *)&c->x86_vendor_id[4]);

	get_cpu_vendor(c, 1);

	c->x86 = 4;
	if (c->cpuid_level >= 0x00000001) {
		u32 cap4, tfms, cap0, misc;
		cpuid(0x00000001, &tfms, &misc, &cap4, &cap0);
		c->x86 = (tfms >> 8) & 15;
		c->x86_model = (tfms >> 4) & 15;
		if (c->x86 == 0xf)
			c->x86 += (tfms >> 20) & 0xff;
		if (c->x86 >= 0x6)
			c->x86_model += ((tfms >> 16) & 0xF) << 4;
		c->x86_mask = tfms & 15;
		cap0 &= ~cleared_caps[0];
		cap4 &= ~cleared_caps[4];
		if (cap0 & (1<<19))
			c->x86_cache_alignment = ((misc >> 8) & 0xff) * 8;
		/* Leaf 0x1 capabilities filled in early for Xen. */
		c->x86_capability[0] = cap0;
		c->x86_capability[4] = cap4;
	}
}

void __cpuinit generic_identify(struct cpuinfo_x86 * c)
{
	u32 tfms, xlvl;

	if (have_cpuid_p()) {
		/* Get vendor name */
		cpuid(0x00000000, &c->cpuid_level,
		      (int *)&c->x86_vendor_id[0],
		      (int *)&c->x86_vendor_id[8],
		      (int *)&c->x86_vendor_id[4]);
		
		get_cpu_vendor(c, 0);
		/* Initialize the standard set of capabilities */
		/* Note that the vendor-specific code below might override */
	
		/* Intel-defined flags: level 0x00000001 */
		if ( c->cpuid_level >= 0x00000001 ) {
			u32 capability, excap, ebx;
			cpuid(0x00000001, &tfms, &ebx, &excap, &capability);
			c->x86_capability[0] = capability;
			c->x86_capability[4] = excap;
			c->x86 = (tfms >> 8) & 15;
			c->x86_model = (tfms >> 4) & 15;
			if (c->x86 == 0xf)
				c->x86 += (tfms >> 20) & 0xff;
			if (c->x86 >= 0x6)
				c->x86_model += ((tfms >> 16) & 0xF) << 4;
			c->x86_mask = tfms & 15;
			if ( cpu_has(c, X86_FEATURE_CLFLSH) )
				c->x86_clflush_size = ((ebx >> 8) & 0xff) * 8;
		} else {
			/* Have CPUID level 0 only - unheard of */
			c->x86 = 4;
		}

		/* AMD-defined flags: level 0x80000001 */
		xlvl = cpuid_eax(0x80000000);
		if ( (xlvl & 0xffff0000) == 0x80000000 ) {
			if ( xlvl >= 0x80000001 ) {
				c->x86_capability[1] = cpuid_edx(0x80000001);
				c->x86_capability[6] = cpuid_ecx(0x80000001);
			}
			if ( xlvl >= 0x80000004 )
				get_model_name(c); /* Default name */
			if ( xlvl >= 0x80000008 )
				paddr_bits = cpuid_eax(0x80000008) & 0xff;
		}

		/* Intel-defined flags: level 0x00000007 */
		if ( c->cpuid_level >= 0x00000007 ) {
			u32 dummy, ebx;
			cpuid_count(0x7, 0, &dummy, &ebx, &dummy, &dummy);
			c->x86_capability[X86_FEATURE_FSGSBASE / 32] = ebx;
		}
	}

	early_intel_workaround(c);

#ifdef CONFIG_X86_HT
	c->phys_proc_id = (cpuid_ebx(1) >> 24) & 0xff;
#endif
}

static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
{
	if (cpu_has(c, X86_FEATURE_PN) && disable_x86_serial_nr ) {
		/* Disable processor serial number */
		uint64_t msr_content;
		rdmsrl(MSR_IA32_BBL_CR_CTL,msr_content);
		wrmsrl(MSR_IA32_BBL_CR_CTL, msr_content | 0x200000);
		printk(KERN_NOTICE "CPU serial number disabled.\n");
		clear_bit(X86_FEATURE_PN, c->x86_capability);

		/* Disabling the serial number may affect the cpuid level */
		c->cpuid_level = cpuid_eax(0);
	}
}


/*
 * This does the hard work of actually picking apart the CPU stuff...
 */
void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
{
	int i;

	c->x86_cache_size = -1;
	c->x86_vendor = X86_VENDOR_UNKNOWN;
	c->cpuid_level = -1;	/* CPUID not detected */
	c->x86_model = c->x86_mask = 0;	/* So far unknown... */
	c->x86_vendor_id[0] = '\0'; /* Unset */
	c->x86_model_id[0] = '\0';  /* Unset */
	c->x86_max_cores = 1;
	c->x86_num_siblings = 1;
	c->x86_clflush_size = 0;
	c->phys_proc_id = BAD_APICID;
	c->cpu_core_id = BAD_APICID;
	c->compute_unit_id = BAD_APICID;
	memset(&c->x86_capability, 0, sizeof c->x86_capability);

	if (!have_cpuid_p()) {
		/* First of all, decide if this is a 486 or higher */
		/* It's a 486 if we can modify the AC flag */
		if ( flag_is_changeable_p(X86_EFLAGS_AC) )
			c->x86 = 4;
		else
			c->x86 = 3;
	}

	generic_identify(c);

#ifdef NOISY_CAPS
	printk(KERN_DEBUG "CPU: After generic identify, caps:");
	for (i = 0; i < NCAPINTS; i++)
		printk(" %08x", c->x86_capability[i]);
	printk("\n");
#endif

	if (this_cpu->c_identify) {
		this_cpu->c_identify(c);

#ifdef NOISY_CAPS
		printk(KERN_DEBUG "CPU: After vendor identify, caps:");
		for (i = 0; i < NCAPINTS; i++)
			printk(" %08x", c->x86_capability[i]);
		printk("\n");
#endif
	}

	/*
	 * Vendor-specific initialization.  In this section we
	 * canonicalize the feature flags, meaning if there are
	 * features a certain CPU supports which CPUID doesn't
	 * tell us, CPUID claiming incorrect flags, or other bugs,
	 * we handle them here.
	 *
	 * At the end of this section, c->x86_capability better
	 * indicate the features this CPU genuinely supports!
	 */
	if (this_cpu->c_init)
		this_cpu->c_init(c);

        /* Initialize xsave/xrstor features */
	if ( !use_xsave )
		clear_bit(X86_FEATURE_XSAVE, boot_cpu_data.x86_capability);

	if ( cpu_has_xsave )
		xsave_init();

	/* Disable the PN if appropriate */
	squash_the_stupid_serial_number(c);

	/*
	 * The vendor-specific functions might have changed features.  Now
	 * we do "generic changes."
	 */

	/* TSC disabled? */
	if ( tsc_disable )
		clear_bit(X86_FEATURE_TSC, c->x86_capability);

	/* FXSR disabled? */
	if (disable_x86_fxsr) {
		clear_bit(X86_FEATURE_FXSR, c->x86_capability);
		clear_bit(X86_FEATURE_XMM, c->x86_capability);
	}

	if (disable_pse)
		clear_bit(X86_FEATURE_PSE, c->x86_capability);

	for (i = 0 ; i < NCAPINTS ; ++i)
		c->x86_capability[i] &= ~cleared_caps[i];

	/* If the model name is still unset, do table lookup. */
	if ( !c->x86_model_id[0] ) {
		char *p;
		p = table_lookup_model(c);
		if ( p )
			safe_strcpy(c->x86_model_id, p);
		else
			/* Last resort... */
			snprintf(c->x86_model_id, sizeof(c->x86_model_id),
				"%02x/%02x", c->x86_vendor, c->x86_model);
	}

	/* Now the feature flags better reflect actual CPU features! */

#ifdef NOISY_CAPS
	printk(KERN_DEBUG "CPU: After all inits, caps:");
	for (i = 0; i < NCAPINTS; i++)
		printk(" %08x", c->x86_capability[i]);
	printk("\n");
#endif

	/*
	 * On SMP, boot_cpu_data holds the common feature set between
	 * all CPUs; so make sure that we indicate which features are
	 * common between the CPUs.  The first time this routine gets
	 * executed, c == &boot_cpu_data.
	 */
	if ( c != &boot_cpu_data ) {
		/* AND the already accumulated flags with these */
		for ( i = 0 ; i < NCAPINTS ; i++ )
			boot_cpu_data.x86_capability[i] &= c->x86_capability[i];

		mcheck_init(c, 0);
	} else {
		mcheck_init(c, 1);

		mtrr_bp_init();
	}
}

/* cpuid returns the value latched in the HW at reset, not the APIC ID
 * register's value.  For any box whose BIOS changes APIC IDs, like
 * clustered APIC systems, we must use hard_smp_processor_id.
 *
 * See Intel's IA-32 SW Dev's Manual Vol2 under CPUID.
 */
static inline u32 phys_pkg_id(u32 cpuid_apic, int index_msb)
{
	return hard_smp_processor_id() >> index_msb;
}

/* leaf 0xb SMT level */
#define SMT_LEVEL       0

/* leaf 0xb sub-leaf types */
#define INVALID_TYPE    0
#define SMT_TYPE        1
#define CORE_TYPE       2

#define LEAFB_SUBTYPE(ecx)          (((ecx) >> 8) & 0xff)
#define BITS_SHIFT_NEXT_LEVEL(eax)  ((eax) & 0x1f)
#define LEVEL_MAX_SIBLINGS(ebx)     ((ebx) & 0xffff)

/*
 * Check for extended topology enumeration cpuid leaf 0xb and if it
 * exists, use it for cpu topology detection.
 */
void __cpuinit detect_extended_topology(struct cpuinfo_x86 *c)
{
	unsigned int eax, ebx, ecx, edx, sub_index;
	unsigned int ht_mask_width, core_plus_mask_width;
	unsigned int core_select_mask, core_level_siblings;
	unsigned int initial_apicid;

	if ( c->cpuid_level < 0xb )
		return;

	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);

	/* Check if the cpuid leaf 0xb is actually implemented */
	if ( ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE) )
		return;

	set_bit(X86_FEATURE_XTOPOLOGY, c->x86_capability);

	initial_apicid = edx;

	/* Populate HT related information from sub-leaf level 0 */
	core_level_siblings = c->x86_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
	core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);

	sub_index = 1;
	do {
		cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);

		/* Check for the Core type in the implemented sub leaves */
		if ( LEAFB_SUBTYPE(ecx) == CORE_TYPE ) {
			core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
			core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
			break;
		}

		sub_index++;
	} while ( LEAFB_SUBTYPE(ecx) != INVALID_TYPE );

	core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;

	c->cpu_core_id = phys_pkg_id(initial_apicid, ht_mask_width)
		& core_select_mask;
	c->phys_proc_id = phys_pkg_id(initial_apicid, core_plus_mask_width);

	c->apicid = phys_pkg_id(initial_apicid, 0);
	c->x86_max_cores = (core_level_siblings / c->x86_num_siblings);

	if ( opt_cpu_info )
	{
		printk("CPU: Physical Processor ID: %d\n",
		       c->phys_proc_id);
		if ( c->x86_max_cores > 1 )
			printk("CPU: Processor Core ID: %d\n",
			       c->cpu_core_id);
	}
}

#ifdef CONFIG_X86_HT
void __cpuinit detect_ht(struct cpuinfo_x86 *c)
{
	u32 	eax, ebx, ecx, edx;
	int 	index_msb, core_bits;

	cpuid(1, &eax, &ebx, &ecx, &edx);

	c->apicid = phys_pkg_id((ebx >> 24) & 0xFF, 0);

	if (!cpu_has(c, X86_FEATURE_HT) || cpu_has(c, X86_FEATURE_CMP_LEGACY)
        || cpu_has(c, X86_FEATURE_XTOPOLOGY))
		return;

	c->x86_num_siblings = (ebx & 0xff0000) >> 16;

	if (c->x86_num_siblings == 1) {
		printk(KERN_INFO  "CPU: Hyper-Threading is disabled\n");
	} else if (c->x86_num_siblings > 1 ) {

		if (c->x86_num_siblings > NR_CPUS) {
			printk(KERN_WARNING "CPU: Unsupported number of the siblings %d", c->x86_num_siblings);
			c->x86_num_siblings = 1;
			return;
		}

		index_msb = get_count_order(c->x86_num_siblings);
		c->phys_proc_id = phys_pkg_id((ebx >> 24) & 0xFF, index_msb);

		if (opt_cpu_info)
			printk("CPU: Physical Processor ID: %d\n",
			       c->phys_proc_id);

		c->x86_num_siblings = c->x86_num_siblings / c->x86_max_cores;

		index_msb = get_count_order(c->x86_num_siblings) ;

		core_bits = get_count_order(c->x86_max_cores);

		c->cpu_core_id = phys_pkg_id((ebx >> 24) & 0xFF, index_msb) &
					       ((1 << core_bits) - 1);

		if (opt_cpu_info && c->x86_max_cores > 1)
			printk("CPU: Processor Core ID: %d\n",
			       c->cpu_core_id);
	}
}
#endif

void __cpuinit print_cpu_info(unsigned int cpu)
{
	const struct cpuinfo_x86 *c = cpu_data + cpu;
	const char *vendor = NULL;

	if (!opt_cpu_info)
		return;

	printk("CPU%u: ", cpu);

	if (c->x86_vendor < X86_VENDOR_NUM)
		vendor = this_cpu->c_vendor;
	else if (c->cpuid_level >= 0)
		vendor = c->x86_vendor_id;

	if (vendor && strncmp(c->x86_model_id, vendor, strlen(vendor)))
		printk("%s ", vendor);

	if (!c->x86_model_id[0])
		printk("%d86", c->x86);
	else
		printk("%s", c->x86_model_id);

	if (c->x86_mask || c->cpuid_level >= 0) 
		printk(" stepping %02x\n", c->x86_mask);
	else
		printk("\n");
}

static cpumask_t cpu_initialized;

/* This is hacky. :)
 * We're emulating future behavior.
 * In the future, the cpu-specific init functions will be called implicitly
 * via the magic of initcalls.
 * They will insert themselves into the cpu_devs structure.
 * Then, when cpu_init() is called, we can just iterate over that array.
 */

void __init early_cpu_init(void)
{
	intel_cpu_init();
	amd_init_cpu();
#ifdef CONFIG_X86_32
	cyrix_init_cpu();
	nsc_init_cpu();
	centaur_init_cpu();
	transmeta_init_cpu();
#endif
	early_cpu_detect();
}
/*
 * cpu_init() initializes state that is per-CPU. Some data is already
 * initialized (naturally) in the bootstrap process, such as the GDT
 * and IDT. We reload them nevertheless, this function acts as a
 * 'CPU state barrier', nothing should get across.
 */
void __cpuinit cpu_init(void)
{
	int cpu = smp_processor_id();
	struct tss_struct *t = &this_cpu(init_tss);
	struct desc_ptr gdt_desc = {
		.base = (unsigned long)(this_cpu(gdt_table) - FIRST_RESERVED_GDT_ENTRY),
		.limit = LAST_RESERVED_GDT_BYTE
	};

	if (cpu_test_and_set(cpu, cpu_initialized)) {
		printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
		for (;;) local_irq_enable();
	}
	if (opt_cpu_info)
		printk("Initializing CPU#%d\n", cpu);

	if (cpu_has_pat)
		wrmsrl(MSR_IA32_CR_PAT, host_pat);

	/* Install correct page table. */
	write_ptbase(current);

	asm volatile ( "lgdt %0" : : "m" (gdt_desc) );

	/* No nested task. */
	asm volatile ("pushf ; andw $0xbfff,(%"__OP"sp) ; popf" );

	/* Ensure FPU gets initialised for each domain. */
	stts();

	/* Set up and load the per-CPU TSS and LDT. */
	t->bitmap = IOBMP_INVALID_OFFSET;
#if defined(CONFIG_X86_32)
	t->ss0  = __HYPERVISOR_DS;
	t->esp0 = get_stack_bottom();
	if ( cpu_has_sep ) {
	    wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
	    if ( supervisor_mode_kernel )
		wrmsr(MSR_IA32_SYSENTER_ESP, &t->esp1, 0);
	}
#elif defined(CONFIG_X86_64)
	/* Bottom-of-stack must be 16-byte aligned! */
	BUG_ON((get_stack_bottom() & 15) != 0);
	t->rsp0 = get_stack_bottom();
#endif
	load_TR();
	asm volatile ( "lldt %%ax" : : "a" (0) );

	/* Clear all 6 debug registers: */
#define CD(register) asm volatile ( "mov %0,%%db" #register : : "r"(0UL) );
	CD(0); CD(1); CD(2); CD(3); /* no db4 and db5 */; CD(6); CD(7);
#undef CD
}

void cpu_uninit(unsigned int cpu)
{
	cpu_clear(cpu, cpu_initialized);
}