arch/x86/kernel/kvm.c - maze/linux - Git at Google

 /*
  * KVM paravirt_ops implementation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  *
  * Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  * Copyright IBM Corporation, 2007
  *   Authors: Anthony Liguori <aliguori@us.ibm.com>
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/kvm_para.h>
 #include <linux/cpu.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
 #include <linux/hardirq.h>
 #include <linux/notifier.h>
 #include <linux/reboot.h>
 #include <linux/hash.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/kprobes.h>
 #include <asm/timer.h>
 #include <asm/cpu.h>
 #include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/tlbflush.h>

 static int kvmapf = 1;

 static int parse_no_kvmapf(char *arg)
 {
         kvmapf = 0;
         return 0;
 }

 early_param("no-kvmapf", parse_no_kvmapf);

 static int steal_acc = 1;
 static int parse_no_stealacc(char *arg)
 {
         steal_acc = 0;
         return 0;
 }

 early_param("no-steal-acc", parse_no_stealacc);

 static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
 static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
 static int has_steal_clock = 0;

 /*
  * No need for any "IO delay" on KVM
  */
 static void kvm_io_delay(void)
 {
 }

 #define KVM_TASK_SLEEP_HASHBITS 8
 #define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)

 struct kvm_task_sleep_node {
 	struct hlist_node link;
 	wait_queue_head_t wq;
 	u32 token;
 	int cpu;
 	bool halted;
 	struct mm_struct *mm;
 };

 static struct kvm_task_sleep_head {
 	spinlock_t lock;
 	struct hlist_head list;
 } async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];

 static struct kvm_task_sleep_node *_find_apf_task(struct kvm_task_sleep_head *b,
 						  u32 token)
 {
 	struct hlist_node *p;

 	hlist_for_each(p, &b->list) {
 		struct kvm_task_sleep_node *n =
 			hlist_entry(p, typeof(*n), link);
 		if (n->token == token)
 			return n;
 	}

 	return NULL;
 }

 void kvm_async_pf_task_wait(u32 token)
 {
 	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 	struct kvm_task_sleep_node n, *e;
 	DEFINE_WAIT(wait);
 	int cpu, idle;

 	cpu = get_cpu();
 	idle = idle_cpu(cpu);
 	put_cpu();

 	spin_lock(&b->lock);
 	e = _find_apf_task(b, token);
 	if (e) {
 		/* dummy entry exist -> wake up was delivered ahead of PF */
 		hlist_del(&e->link);
 		kfree(e);
 		spin_unlock(&b->lock);
 		return;
 	}

 	n.token = token;
 	n.cpu = smp_processor_id();
 	n.mm = current->active_mm;
 	n.halted = idle || preempt_count() > 1;
 	atomic_inc(&n.mm->mm_count);
 	init_waitqueue_head(&n.wq);
 	hlist_add_head(&n.link, &b->list);
 	spin_unlock(&b->lock);

 	for (;;) {
 		if (!n.halted)
 			prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
 		if (hlist_unhashed(&n.link))
 			break;

 		if (!n.halted) {
 			local_irq_enable();
 			schedule();
 			local_irq_disable();
 		} else {
 			/*
 			 * We cannot reschedule. So halt.
 			 */
 			native_safe_halt();
 			local_irq_disable();
 		}
 	}
 	if (!n.halted)
 		finish_wait(&n.wq, &wait);

 	return;
 }
 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);

 static void apf_task_wake_one(struct kvm_task_sleep_node *n)
 {
 	hlist_del_init(&n->link);
 	if (!n->mm)
 		return;
 	mmdrop(n->mm);
 	if (n->halted)
 		smp_send_reschedule(n->cpu);
 	else if (waitqueue_active(&n->wq))
 		wake_up(&n->wq);
 }

 static void apf_task_wake_all(void)
 {
 	int i;

 	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
 		struct hlist_node *p, *next;
 		struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
 		spin_lock(&b->lock);
 		hlist_for_each_safe(p, next, &b->list) {
 			struct kvm_task_sleep_node *n =
 				hlist_entry(p, typeof(*n), link);
 			if (n->cpu == smp_processor_id())
 				apf_task_wake_one(n);
 		}
 		spin_unlock(&b->lock);
 	}
 }

 void kvm_async_pf_task_wake(u32 token)
 {
 	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
 	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
 	struct kvm_task_sleep_node *n;

 	if (token == ~0) {
 		apf_task_wake_all();
 		return;
 	}

 again:
 	spin_lock(&b->lock);
 	n = _find_apf_task(b, token);
 	if (!n) {
 		/*
 		 * async PF was not yet handled.
 		 * Add dummy entry for the token.
 		 */
 		n = kmalloc(sizeof(*n), GFP_ATOMIC);
 		if (!n) {
 			/*
 			 * Allocation failed! Busy wait while other cpu
 			 * handles async PF.
 			 */
 			spin_unlock(&b->lock);
 			cpu_relax();
 			goto again;
 		}
 		n->token = token;
 		n->cpu = smp_processor_id();
 		n->mm = NULL;
 		init_waitqueue_head(&n->wq);
 		hlist_add_head(&n->link, &b->list);
 	} else
 		apf_task_wake_one(n);
 	spin_unlock(&b->lock);
 	return;
 }
 EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);

 u32 kvm_read_and_reset_pf_reason(void)
 {
 	u32 reason = 0;

 	if (__get_cpu_var(apf_reason).enabled) {
 		reason = __get_cpu_var(apf_reason).reason;
 		__get_cpu_var(apf_reason).reason = 0;
 	}

 	return reason;
 }
 EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);

 dotraplinkage void __kprobes
 do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
 {
 	switch (kvm_read_and_reset_pf_reason()) {
 	default:
 		do_page_fault(regs, error_code);
 		break;
 	case KVM_PV_REASON_PAGE_NOT_PRESENT:
 		/* page is swapped out by the host. */
 		kvm_async_pf_task_wait((u32)read_cr2());
 		break;
 	case KVM_PV_REASON_PAGE_READY:
 		kvm_async_pf_task_wake((u32)read_cr2());
 		break;
 	}
 }

 static void __init paravirt_ops_setup(void)
 {
 	pv_info.name = "KVM";
 	pv_info.paravirt_enabled = 1;

 	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
 		pv_cpu_ops.io_delay = kvm_io_delay;

 #ifdef CONFIG_X86_IO_APIC
 	no_timer_check = 1;
 #endif
 }

 static void kvm_register_steal_time(void)
 {
 	int cpu = smp_processor_id();
 	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);

 	if (!has_steal_clock)
 		return;

 	memset(st, 0, sizeof(*st));

 	wrmsrl(MSR_KVM_STEAL_TIME, (__pa(st) | KVM_MSR_ENABLED));
 	printk(KERN_INFO "kvm-stealtime: cpu %d, msr %lx\n",
 		cpu, __pa(st));
 }

 void __cpuinit kvm_guest_cpu_init(void)
 {
 	if (!kvm_para_available())
 		return;

 	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
 		u64 pa = __pa(&__get_cpu_var(apf_reason));

 #ifdef CONFIG_PREEMPT
 		pa |= KVM_ASYNC_PF_SEND_ALWAYS;
 #endif
 		wrmsrl(MSR_KVM_ASYNC_PF_EN, pa | KVM_ASYNC_PF_ENABLED);
 		__get_cpu_var(apf_reason).enabled = 1;
 		printk(KERN_INFO"KVM setup async PF for cpu %d\n",
 		       smp_processor_id());
 	}

 	if (has_steal_clock)
 		kvm_register_steal_time();
 }

 static void kvm_pv_disable_apf(void *unused)
 {
 	if (!__get_cpu_var(apf_reason).enabled)
 		return;

 	wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
 	__get_cpu_var(apf_reason).enabled = 0;

 	printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
 	       smp_processor_id());
 }

 static int kvm_pv_reboot_notify(struct notifier_block *nb,
 				unsigned long code, void *unused)
 {
 	if (code == SYS_RESTART)
 		on_each_cpu(kvm_pv_disable_apf, NULL, 1);
 	return NOTIFY_DONE;
 }

 static struct notifier_block kvm_pv_reboot_nb = {
 	.notifier_call = kvm_pv_reboot_notify,
 };

 static u64 kvm_steal_clock(int cpu)
 {
 	u64 steal;
 	struct kvm_steal_time *src;
 	int version;

 	src = &per_cpu(steal_time, cpu);
 	do {
 		version = src->version;
 		rmb();
 		steal = src->steal;
 		rmb();
 	} while ((version & 1) || (version != src->version));

 	return steal;
 }

 void kvm_disable_steal_time(void)
 {
 	if (!has_steal_clock)
 		return;

 	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
 }

 #ifdef CONFIG_SMP
 static void __init kvm_smp_prepare_boot_cpu(void)
 {
 #ifdef CONFIG_KVM_CLOCK
 	WARN_ON(kvm_register_clock("primary cpu clock"));
 #endif
 	kvm_guest_cpu_init();
 	native_smp_prepare_boot_cpu();
 }

 static void __cpuinit kvm_guest_cpu_online(void *dummy)
 {
 	kvm_guest_cpu_init();
 }

 static void kvm_guest_cpu_offline(void *dummy)
 {
 	kvm_disable_steal_time();
 	kvm_pv_disable_apf(NULL);
 	apf_task_wake_all();
 }

 static int __cpuinit kvm_cpu_notify(struct notifier_block *self,
 				    unsigned long action, void *hcpu)
 {
 	int cpu = (unsigned long)hcpu;
 	switch (action) {
 	case CPU_ONLINE:
 	case CPU_DOWN_FAILED:
 	case CPU_ONLINE_FROZEN:
 		smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
 		break;
 	case CPU_DOWN_PREPARE:
 	case CPU_DOWN_PREPARE_FROZEN:
 		smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
 		break;
 	default:
 		break;
 	}
 	return NOTIFY_OK;
 }

 static struct notifier_block __cpuinitdata kvm_cpu_notifier = {
         .notifier_call  = kvm_cpu_notify,
 };
 #endif

 static void __init kvm_apf_trap_init(void)
 {
 	set_intr_gate(14, &async_page_fault);
 }

 void __init kvm_guest_init(void)
 {
 	int i;

 	if (!kvm_para_available())
 		return;

 	paravirt_ops_setup();
 	register_reboot_notifier(&kvm_pv_reboot_nb);
 	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
 		spin_lock_init(&async_pf_sleepers[i].lock);
 	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
 		x86_init.irqs.trap_init = kvm_apf_trap_init;

 	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
 		has_steal_clock = 1;
 		pv_time_ops.steal_clock = kvm_steal_clock;
 	}

 #ifdef CONFIG_SMP
 	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
 	register_cpu_notifier(&kvm_cpu_notifier);
 #else
 	kvm_guest_cpu_init();
 #endif
 }

 static __init int activate_jump_labels(void)
 {
 	if (has_steal_clock) {
 		jump_label_inc(&paravirt_steal_enabled);
 		if (steal_acc)
 			jump_label_inc(&paravirt_steal_rq_enabled);
 	}

 	return 0;
 }
 arch_initcall(activate_jump_labels);
	/*
	* KVM paravirt_ops implementation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	*
	* Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	* Copyright IBM Corporation, 2007
	* Authors: Anthony Liguori <aliguori@us.ibm.com>
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/kvm_para.h>
	#include <linux/cpu.h>
	#include <linux/mm.h>
	#include <linux/highmem.h>
	#include <linux/hardirq.h>
	#include <linux/notifier.h>
	#include <linux/reboot.h>
	#include <linux/hash.h>
	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <linux/kprobes.h>
	#include <asm/timer.h>
	#include <asm/cpu.h>
	#include <asm/traps.h>
	#include <asm/desc.h>
	#include <asm/tlbflush.h>

	static int kvmapf = 1;

	static int parse_no_kvmapf(char *arg)
	{
	kvmapf = 0;
	return 0;
	}

	early_param("no-kvmapf", parse_no_kvmapf);

	static int steal_acc = 1;
	static int parse_no_stealacc(char *arg)
	{
	steal_acc = 0;
	return 0;
	}

	early_param("no-steal-acc", parse_no_stealacc);

	static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
	static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
	static int has_steal_clock = 0;

	/*
	* No need for any "IO delay" on KVM
	*/
	static void kvm_io_delay(void)
	{
	}

	#define KVM_TASK_SLEEP_HASHBITS 8
	#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)

	struct kvm_task_sleep_node {
	struct hlist_node link;
	wait_queue_head_t wq;
	u32 token;
	int cpu;
	bool halted;
	struct mm_struct *mm;
	};

	static struct kvm_task_sleep_head {
	spinlock_t lock;
	struct hlist_head list;
	} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];

	static struct kvm_task_sleep_node _find_apf_task(struct kvm_task_sleep_head b,
	u32 token)
	{
	struct hlist_node *p;

	hlist_for_each(p, &b->list) {
	struct kvm_task_sleep_node *n =
	hlist_entry(p, typeof(*n), link);
	if (n->token == token)
	return n;
	}

	return NULL;
	}

	void kvm_async_pf_task_wait(u32 token)
	{
	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
	struct kvm_task_sleep_node n, *e;
	DEFINE_WAIT(wait);
	int cpu, idle;

	cpu = get_cpu();
	idle = idle_cpu(cpu);
	put_cpu();

	spin_lock(&b->lock);
	e = _find_apf_task(b, token);
	if (e) {
	/* dummy entry exist -> wake up was delivered ahead of PF */
	hlist_del(&e->link);
	kfree(e);
	spin_unlock(&b->lock);
	return;
	}

	n.token = token;
	n.cpu = smp_processor_id();
	n.mm = current->active_mm;
	n.halted = idle \|\| preempt_count() > 1;
	atomic_inc(&n.mm->mm_count);
	init_waitqueue_head(&n.wq);
	hlist_add_head(&n.link, &b->list);
	spin_unlock(&b->lock);

	for (;;) {
	if (!n.halted)
	prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
	if (hlist_unhashed(&n.link))
	break;

	if (!n.halted) {
	local_irq_enable();
	schedule();
	local_irq_disable();
	} else {
	/*
	* We cannot reschedule. So halt.
	*/
	native_safe_halt();
	local_irq_disable();
	}
	}
	if (!n.halted)
	finish_wait(&n.wq, &wait);

	return;
	}
	EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);

	static void apf_task_wake_one(struct kvm_task_sleep_node *n)
	{
	hlist_del_init(&n->link);
	if (!n->mm)
	return;
	mmdrop(n->mm);
	if (n->halted)
	smp_send_reschedule(n->cpu);
	else if (waitqueue_active(&n->wq))
	wake_up(&n->wq);
	}

	static void apf_task_wake_all(void)
	{
	int i;

	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
	struct hlist_node p, next;
	struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
	spin_lock(&b->lock);
	hlist_for_each_safe(p, next, &b->list) {
	struct kvm_task_sleep_node *n =
	hlist_entry(p, typeof(*n), link);
	if (n->cpu == smp_processor_id())
	apf_task_wake_one(n);
	}
	spin_unlock(&b->lock);
	}
	}

	void kvm_async_pf_task_wake(u32 token)
	{
	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
	struct kvm_task_sleep_node *n;

	if (token == ~0) {
	apf_task_wake_all();
	return;
	}

	again:
	spin_lock(&b->lock);
	n = _find_apf_task(b, token);
	if (!n) {
	/*
	* async PF was not yet handled.
	* Add dummy entry for the token.
	*/
	n = kmalloc(sizeof(*n), GFP_ATOMIC);
	if (!n) {
	/*
	* Allocation failed! Busy wait while other cpu
	* handles async PF.
	*/
	spin_unlock(&b->lock);
	cpu_relax();
	goto again;
	}
	n->token = token;
	n->cpu = smp_processor_id();
	n->mm = NULL;
	init_waitqueue_head(&n->wq);
	hlist_add_head(&n->link, &b->list);
	} else
	apf_task_wake_one(n);
	spin_unlock(&b->lock);
	return;
	}
	EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);

	u32 kvm_read_and_reset_pf_reason(void)
	{
	u32 reason = 0;

	if (__get_cpu_var(apf_reason).enabled) {
	reason = __get_cpu_var(apf_reason).reason;
	__get_cpu_var(apf_reason).reason = 0;
	}

	return reason;
	}
	EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);

	dotraplinkage void __kprobes
	do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
	{
	switch (kvm_read_and_reset_pf_reason()) {
	default:
	do_page_fault(regs, error_code);
	break;
	case KVM_PV_REASON_PAGE_NOT_PRESENT:
	/* page is swapped out by the host. */
	kvm_async_pf_task_wait((u32)read_cr2());
	break;
	case KVM_PV_REASON_PAGE_READY:
	kvm_async_pf_task_wake((u32)read_cr2());
	break;
	}
	}

	static void __init paravirt_ops_setup(void)
	{
	pv_info.name = "KVM";
	pv_info.paravirt_enabled = 1;

	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
	pv_cpu_ops.io_delay = kvm_io_delay;

	#ifdef CONFIG_X86_IO_APIC
	no_timer_check = 1;
	#endif
	}

	static void kvm_register_steal_time(void)
	{
	int cpu = smp_processor_id();
	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);

	if (!has_steal_clock)
	return;

	memset(st, 0, sizeof(*st));

	wrmsrl(MSR_KVM_STEAL_TIME, (__pa(st) \| KVM_MSR_ENABLED));
	printk(KERN_INFO "kvm-stealtime: cpu %d, msr %lx\n",
	cpu, __pa(st));
	}

	void __cpuinit kvm_guest_cpu_init(void)
	{
	if (!kvm_para_available())
	return;

	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
	u64 pa = __pa(&__get_cpu_var(apf_reason));

	#ifdef CONFIG_PREEMPT
	pa \|= KVM_ASYNC_PF_SEND_ALWAYS;
	#endif
	wrmsrl(MSR_KVM_ASYNC_PF_EN, pa \| KVM_ASYNC_PF_ENABLED);
	__get_cpu_var(apf_reason).enabled = 1;
	printk(KERN_INFO"KVM setup async PF for cpu %d\n",
	smp_processor_id());
	}

	if (has_steal_clock)
	kvm_register_steal_time();
	}

	static void kvm_pv_disable_apf(void *unused)
	{
	if (!__get_cpu_var(apf_reason).enabled)
	return;

	wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
	__get_cpu_var(apf_reason).enabled = 0;

	printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
	smp_processor_id());
	}

	static int kvm_pv_reboot_notify(struct notifier_block *nb,
	unsigned long code, void *unused)
	{
	if (code == SYS_RESTART)
	on_each_cpu(kvm_pv_disable_apf, NULL, 1);
	return NOTIFY_DONE;
	}

	static struct notifier_block kvm_pv_reboot_nb = {
	.notifier_call = kvm_pv_reboot_notify,
	};

	static u64 kvm_steal_clock(int cpu)
	{
	u64 steal;
	struct kvm_steal_time *src;
	int version;

	src = &per_cpu(steal_time, cpu);
	do {
	version = src->version;
	rmb();
	steal = src->steal;
	rmb();
	} while ((version & 1) \|\| (version != src->version));

	return steal;
	}

	void kvm_disable_steal_time(void)
	{
	if (!has_steal_clock)
	return;

	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
	}

	#ifdef CONFIG_SMP
	static void __init kvm_smp_prepare_boot_cpu(void)
	{
	#ifdef CONFIG_KVM_CLOCK
	WARN_ON(kvm_register_clock("primary cpu clock"));
	#endif
	kvm_guest_cpu_init();
	native_smp_prepare_boot_cpu();
	}

	static void __cpuinit kvm_guest_cpu_online(void *dummy)
	{
	kvm_guest_cpu_init();
	}

	static void kvm_guest_cpu_offline(void *dummy)
	{
	kvm_disable_steal_time();
	kvm_pv_disable_apf(NULL);
	apf_task_wake_all();
	}

	static int __cpuinit kvm_cpu_notify(struct notifier_block *self,
	unsigned long action, void *hcpu)
	{
	int cpu = (unsigned long)hcpu;
	switch (action) {
	case CPU_ONLINE:
	case CPU_DOWN_FAILED:
	case CPU_ONLINE_FROZEN:
	smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
	break;
	case CPU_DOWN_PREPARE:
	case CPU_DOWN_PREPARE_FROZEN:
	smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
	break;
	default:
	break;
	}
	return NOTIFY_OK;
	}

	static struct notifier_block __cpuinitdata kvm_cpu_notifier = {
	.notifier_call = kvm_cpu_notify,
	};
	#endif

	static void __init kvm_apf_trap_init(void)
	{
	set_intr_gate(14, &async_page_fault);
	}

	void __init kvm_guest_init(void)
	{
	int i;

	if (!kvm_para_available())
	return;

	paravirt_ops_setup();
	register_reboot_notifier(&kvm_pv_reboot_nb);
	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
	spin_lock_init(&async_pf_sleepers[i].lock);
	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
	x86_init.irqs.trap_init = kvm_apf_trap_init;

	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
	has_steal_clock = 1;
	pv_time_ops.steal_clock = kvm_steal_clock;
	}

	#ifdef CONFIG_SMP
	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
	register_cpu_notifier(&kvm_cpu_notifier);
	#else
	kvm_guest_cpu_init();
	#endif
	}

	static __init int activate_jump_labels(void)
	{
	if (has_steal_clock) {
	jump_label_inc(&paravirt_steal_enabled);
	if (steal_acc)
	jump_label_inc(&paravirt_steal_rq_enabled);
	}

	return 0;
	}
	arch_initcall(activate_jump_labels);