[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / kvm.c

/*
 * 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>
#include <asm/idle.h>
#include <asm/apic.h>
#include <asm/apicdef.h>
#include <asm/hypervisor.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;
};

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.halted = idle || preempt_count() > 1;
	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->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 = kzalloc(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();
		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:
		rcu_irq_enter();
		exit_idle();
		kvm_async_pf_task_wake((u32)read_cr2());
		rcu_irq_exit();
		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));
}

static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;

static void kvm_guest_apic_eoi_write(u32 reg, u32 val)
{
	/**
	 * This relies on __test_and_clear_bit to modify the memory
	 * in a way that is atomic with respect to the local CPU.
	 * The hypervisor only accesses this memory from the local CPU so
	 * there's no need for lock or memory barriers.
	 * An optimization barrier is implied in apic write.
	 */
	if (__test_and_clear_bit(KVM_PV_EOI_BIT, &__get_cpu_var(kvm_apic_eoi)))
		return;
	apic_write(APIC_EOI, APIC_EOI_ACK);
}

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 (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
		unsigned long pa;
		/* Size alignment is implied but just to make it explicit. */
		BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
		__get_cpu_var(kvm_apic_eoi) = 0;
		pa = __pa(&__get_cpu_var(kvm_apic_eoi)) | KVM_MSR_ENABLED;
		wrmsrl(MSR_KVM_PV_EOI_EN, pa);
	}

	if (has_steal_clock)
		kvm_register_steal_time();
}

static void kvm_pv_disable_apf(void)
{
	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 void kvm_pv_guest_cpu_reboot(void *unused)
{
	/*
	 * We disable PV EOI before we load a new kernel by kexec,
	 * since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
	 * New kernel can re-enable when it boots.
	 */
	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
	kvm_pv_disable_apf();
}

static int kvm_pv_reboot_notify(struct notifier_block *nb,
				unsigned long code, void *unused)
{
	if (code == SYS_RESTART)
		on_each_cpu(kvm_pv_guest_cpu_reboot, 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();
	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
		wrmsrl(MSR_KVM_PV_EOI_EN, 0);
	kvm_pv_disable_apf();
	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;
	}

	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
		apic_set_eoi_write(kvm_guest_apic_eoi_write);

#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 bool __init kvm_detect(void)
{
	if (!kvm_para_available())
		return false;
	return true;
}

const struct hypervisor_x86 x86_hyper_kvm __refconst = {
	.name			= "KVM",
	.detect			= kvm_detect,
};
EXPORT_SYMBOL_GPL(x86_hyper_kvm);

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

	return 0;
}
arch_initcall(activate_jump_labels);
Commit	Line	Data
0cf1bfd2 MT	1	/*
	2	* KVM paravirt_ops implementation
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write to the Free Software
	16	* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	17	*
	18	* Copyright (C) 2007, Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	19	* Copyright IBM Corporation, 2007
	20	* Authors: Anthony Liguori <aliguori@us.ibm.com>
	21	*/
	22
	23	#include <linux/module.h>
	24	#include <linux/kernel.h>
	25	#include <linux/kvm_para.h>
	26	#include <linux/cpu.h>
	27	#include <linux/mm.h>
1da8a77b	28	#include <linux/highmem.h>
096d14a3	29	#include <linux/hardirq.h>
fd10cde9 GN	30	#include <linux/notifier.h>
fd10cde9 GN	31	#include <linux/reboot.h>
631bc487 GN	32	#include <linux/hash.h>
	33	#include <linux/sched.h>
	34	#include <linux/slab.h>
	35	#include <linux/kprobes.h>
a90ede7b	36	#include <asm/timer.h>
fd10cde9	37	#include <asm/cpu.h>
631bc487 GN	38	#include <asm/traps.h>
631bc487 GN	39	#include <asm/desc.h>
6c047cd9	40	#include <asm/tlbflush.h>
e0875921	41	#include <asm/idle.h>
ab9cf499 MT	42	#include <asm/apic.h>
ab9cf499 MT	43	#include <asm/apicdef.h>
fc73373b	44	#include <asm/hypervisor.h>
096d14a3	45
fd10cde9 GN	46	static int kvmapf = 1;
	47
	48	static int parse_no_kvmapf(char *arg)
	49	{
	50	kvmapf = 0;
	51	return 0;
	52	}
	53
	54	early_param("no-kvmapf", parse_no_kvmapf);
	55
d910f5c1 GC	56	static int steal_acc = 1;
	57	static int parse_no_stealacc(char *arg)
	58	{
	59	steal_acc = 0;
	60	return 0;
	61	}
	62
	63	early_param("no-steal-acc", parse_no_stealacc);
	64
fd10cde9	65	static DEFINE_PER_CPU(struct kvm_vcpu_pv_apf_data, apf_reason) __aligned(64);
d910f5c1 GC	66	static DEFINE_PER_CPU(struct kvm_steal_time, steal_time) __aligned(64);
d910f5c1 GC	67	static int has_steal_clock = 0;
096d14a3	68
0cf1bfd2 MT	69	/*
	70	* No need for any "IO delay" on KVM
	71	*/
	72	static void kvm_io_delay(void)
	73	{
	74	}
	75
631bc487 GN	76	#define KVM_TASK_SLEEP_HASHBITS 8
	77	#define KVM_TASK_SLEEP_HASHSIZE (1<<KVM_TASK_SLEEP_HASHBITS)
	78
	79	struct kvm_task_sleep_node {
	80	struct hlist_node link;
	81	wait_queue_head_t wq;
	82	u32 token;
	83	int cpu;
6c047cd9	84	bool halted;
631bc487 GN	85	};
	86
	87	static struct kvm_task_sleep_head {
	88	spinlock_t lock;
	89	struct hlist_head list;
	90	} async_pf_sleepers[KVM_TASK_SLEEP_HASHSIZE];
	91
	92	static struct kvm_task_sleep_node _find_apf_task(struct kvm_task_sleep_head b,
	93	u32 token)
	94	{
	95	struct hlist_node *p;
	96
	97	hlist_for_each(p, &b->list) {
	98	struct kvm_task_sleep_node *n =
	99	hlist_entry(p, typeof(*n), link);
	100	if (n->token == token)
	101	return n;
	102	}
	103
	104	return NULL;
	105	}
	106
	107	void kvm_async_pf_task_wait(u32 token)
	108	{
	109	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
	110	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
	111	struct kvm_task_sleep_node n, *e;
	112	DEFINE_WAIT(wait);
6c047cd9 GN	113	int cpu, idle;
	114
	115	cpu = get_cpu();
	116	idle = idle_cpu(cpu);
	117	put_cpu();
631bc487 GN	118
	119	spin_lock(&b->lock);
	120	e = _find_apf_task(b, token);
	121	if (e) {
	122	/* dummy entry exist -> wake up was delivered ahead of PF */
	123	hlist_del(&e->link);
	124	kfree(e);
	125	spin_unlock(&b->lock);
	126	return;
	127	}
	128
	129	n.token = token;
	130	n.cpu = smp_processor_id();
6c047cd9	131	n.halted = idle \|\| preempt_count() > 1;
631bc487 GN	132	init_waitqueue_head(&n.wq);
	133	hlist_add_head(&n.link, &b->list);
	134	spin_unlock(&b->lock);
	135
	136	for (;;) {
6c047cd9 GN	137	if (!n.halted)
6c047cd9 GN	138	prepare_to_wait(&n.wq, &wait, TASK_UNINTERRUPTIBLE);
631bc487 GN	139	if (hlist_unhashed(&n.link))
631bc487 GN	140	break;
6c047cd9 GN	141
	142	if (!n.halted) {
	143	local_irq_enable();
	144	schedule();
	145	local_irq_disable();
	146	} else {
	147	/*
	148	* We cannot reschedule. So halt.
	149	*/
	150	native_safe_halt();
	151	local_irq_disable();
	152	}
631bc487	153	}
6c047cd9 GN	154	if (!n.halted)
6c047cd9 GN	155	finish_wait(&n.wq, &wait);
631bc487 GN	156
	157	return;
	158	}
	159	EXPORT_SYMBOL_GPL(kvm_async_pf_task_wait);
	160
	161	static void apf_task_wake_one(struct kvm_task_sleep_node *n)
	162	{
	163	hlist_del_init(&n->link);
6c047cd9 GN	164	if (n->halted)
	165	smp_send_reschedule(n->cpu);
	166	else if (waitqueue_active(&n->wq))
631bc487 GN	167	wake_up(&n->wq);
	168	}
	169
	170	static void apf_task_wake_all(void)
	171	{
	172	int i;
	173
	174	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) {
	175	struct hlist_node p, next;
	176	struct kvm_task_sleep_head *b = &async_pf_sleepers[i];
	177	spin_lock(&b->lock);
	178	hlist_for_each_safe(p, next, &b->list) {
	179	struct kvm_task_sleep_node *n =
	180	hlist_entry(p, typeof(*n), link);
	181	if (n->cpu == smp_processor_id())
	182	apf_task_wake_one(n);
	183	}
	184	spin_unlock(&b->lock);
	185	}
	186	}
	187
	188	void kvm_async_pf_task_wake(u32 token)
	189	{
	190	u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
	191	struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
	192	struct kvm_task_sleep_node *n;
	193
	194	if (token == ~0) {
	195	apf_task_wake_all();
	196	return;
	197	}
	198
	199	again:
	200	spin_lock(&b->lock);
	201	n = _find_apf_task(b, token);
	202	if (!n) {
	203	/*
	204	* async PF was not yet handled.
	205	* Add dummy entry for the token.
	206	*/
62c49cc9	207	n = kzalloc(sizeof(*n), GFP_ATOMIC);
631bc487 GN	208	if (!n) {
	209	/*
	210	* Allocation failed! Busy wait while other cpu
	211	* handles async PF.
	212	*/
	213	spin_unlock(&b->lock);
	214	cpu_relax();
	215	goto again;
	216	}
	217	n->token = token;
	218	n->cpu = smp_processor_id();
	219	init_waitqueue_head(&n->wq);
	220	hlist_add_head(&n->link, &b->list);
	221	} else
	222	apf_task_wake_one(n);
	223	spin_unlock(&b->lock);
	224	return;
	225	}
	226	EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
	227
	228	u32 kvm_read_and_reset_pf_reason(void)
	229	{
	230	u32 reason = 0;
	231
	232	if (__get_cpu_var(apf_reason).enabled) {
	233	reason = __get_cpu_var(apf_reason).reason;
	234	__get_cpu_var(apf_reason).reason = 0;
	235	}
	236
	237	return reason;
	238	}
	239	EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
	240
	241	dotraplinkage void __kprobes
	242	do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
	243	{
	244	switch (kvm_read_and_reset_pf_reason()) {
	245	default:
	246	do_page_fault(regs, error_code);
	247	break;
	248	case KVM_PV_REASON_PAGE_NOT_PRESENT:
	249	/* page is swapped out by the host. */
	250	kvm_async_pf_task_wait((u32)read_cr2());
	251	break;
	252	case KVM_PV_REASON_PAGE_READY:
e0875921 GN	253	rcu_irq_enter();
e0875921 GN	254	exit_idle();
631bc487	255	kvm_async_pf_task_wake((u32)read_cr2());
e0875921	256	rcu_irq_exit();
631bc487 GN	257	break;
	258	}
	259	}
	260
d3ac8815	261	static void __init paravirt_ops_setup(void)
0cf1bfd2 MT	262	{
	263	pv_info.name = "KVM";
	264	pv_info.paravirt_enabled = 1;
	265
	266	if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
	267	pv_cpu_ops.io_delay = kvm_io_delay;
	268
a90ede7b MT	269	#ifdef CONFIG_X86_IO_APIC
	270	no_timer_check = 1;
	271	#endif
0cf1bfd2 MT	272	}
0cf1bfd2 MT	273
d910f5c1 GC	274	static void kvm_register_steal_time(void)
	275	{
	276	int cpu = smp_processor_id();
	277	struct kvm_steal_time *st = &per_cpu(steal_time, cpu);
	278
	279	if (!has_steal_clock)
	280	return;
	281
	282	memset(st, 0, sizeof(*st));
	283
	284	wrmsrl(MSR_KVM_STEAL_TIME, (__pa(st) \| KVM_MSR_ENABLED));
	285	printk(KERN_INFO "kvm-stealtime: cpu %d, msr %lx\n",
	286	cpu, __pa(st));
	287	}
	288
ab9cf499 MT	289	static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED;
	290
	291	static void kvm_guest_apic_eoi_write(u32 reg, u32 val)
	292	{
	293	/**
	294	* This relies on __test_and_clear_bit to modify the memory
	295	* in a way that is atomic with respect to the local CPU.
	296	* The hypervisor only accesses this memory from the local CPU so
	297	* there's no need for lock or memory barriers.
	298	* An optimization barrier is implied in apic write.
	299	*/
	300	if (__test_and_clear_bit(KVM_PV_EOI_BIT, &__get_cpu_var(kvm_apic_eoi)))
	301	return;
90536664	302	apic_write(APIC_EOI, APIC_EOI_ACK);
ab9cf499 MT	303	}
ab9cf499 MT	304
fd10cde9 GN	305	void __cpuinit kvm_guest_cpu_init(void)
	306	{
	307	if (!kvm_para_available())
	308	return;
	309
	310	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) && kvmapf) {
	311	u64 pa = __pa(&__get_cpu_var(apf_reason));
	312
6adba527 GN	313	#ifdef CONFIG_PREEMPT
	314	pa \|= KVM_ASYNC_PF_SEND_ALWAYS;
	315	#endif
fd10cde9 GN	316	wrmsrl(MSR_KVM_ASYNC_PF_EN, pa \| KVM_ASYNC_PF_ENABLED);
	317	__get_cpu_var(apf_reason).enabled = 1;
	318	printk(KERN_INFO"KVM setup async PF for cpu %d\n",
	319	smp_processor_id());
	320	}
d910f5c1	321
ab9cf499 MT	322	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) {
	323	unsigned long pa;
	324	/* Size alignment is implied but just to make it explicit. */
	325	BUILD_BUG_ON(__alignof__(kvm_apic_eoi) < 4);
	326	__get_cpu_var(kvm_apic_eoi) = 0;
	327	pa = __pa(&__get_cpu_var(kvm_apic_eoi)) \| KVM_MSR_ENABLED;
	328	wrmsrl(MSR_KVM_PV_EOI_EN, pa);
	329	}
	330
d910f5c1 GC	331	if (has_steal_clock)
d910f5c1 GC	332	kvm_register_steal_time();
fd10cde9 GN	333	}
fd10cde9 GN	334
ab9cf499	335	static void kvm_pv_disable_apf(void)
fd10cde9 GN	336	{
	337	if (!__get_cpu_var(apf_reason).enabled)
	338	return;
	339
	340	wrmsrl(MSR_KVM_ASYNC_PF_EN, 0);
	341	__get_cpu_var(apf_reason).enabled = 0;
	342
	343	printk(KERN_INFO"Unregister pv shared memory for cpu %d\n",
	344	smp_processor_id());
	345	}
	346
ab9cf499 MT	347	static void kvm_pv_guest_cpu_reboot(void *unused)
	348	{
	349	/*
	350	* We disable PV EOI before we load a new kernel by kexec,
	351	* since MSR_KVM_PV_EOI_EN stores a pointer into old kernel's memory.
	352	* New kernel can re-enable when it boots.
	353	*/
	354	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
	355	wrmsrl(MSR_KVM_PV_EOI_EN, 0);
	356	kvm_pv_disable_apf();
	357	}
	358
fd10cde9 GN	359	static int kvm_pv_reboot_notify(struct notifier_block *nb,
	360	unsigned long code, void *unused)
	361	{
	362	if (code == SYS_RESTART)
ab9cf499	363	on_each_cpu(kvm_pv_guest_cpu_reboot, NULL, 1);
fd10cde9 GN	364	return NOTIFY_DONE;
	365	}
	366
	367	static struct notifier_block kvm_pv_reboot_nb = {
	368	.notifier_call = kvm_pv_reboot_notify,
	369	};
	370
d910f5c1 GC	371	static u64 kvm_steal_clock(int cpu)
	372	{
	373	u64 steal;
	374	struct kvm_steal_time *src;
	375	int version;
	376
	377	src = &per_cpu(steal_time, cpu);
	378	do {
	379	version = src->version;
	380	rmb();
	381	steal = src->steal;
	382	rmb();
	383	} while ((version & 1) \|\| (version != src->version));
	384
	385	return steal;
	386	}
	387
	388	void kvm_disable_steal_time(void)
	389	{
	390	if (!has_steal_clock)
	391	return;
	392
	393	wrmsr(MSR_KVM_STEAL_TIME, 0, 0);
	394	}
	395
ca3f1017 GN	396	#ifdef CONFIG_SMP
	397	static void __init kvm_smp_prepare_boot_cpu(void)
	398	{
a63512a4	399	#ifdef CONFIG_KVM_CLOCK
ca3f1017	400	WARN_ON(kvm_register_clock("primary cpu clock"));
a63512a4	401	#endif
fd10cde9	402	kvm_guest_cpu_init();
ca3f1017 GN	403	native_smp_prepare_boot_cpu();
ca3f1017 GN	404	}
fd10cde9	405
775077a0	406	static void __cpuinit kvm_guest_cpu_online(void *dummy)
fd10cde9 GN	407	{
	408	kvm_guest_cpu_init();
	409	}
	410
	411	static void kvm_guest_cpu_offline(void *dummy)
	412	{
d910f5c1	413	kvm_disable_steal_time();
ab9cf499 MT	414	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
	415	wrmsrl(MSR_KVM_PV_EOI_EN, 0);
	416	kvm_pv_disable_apf();
631bc487	417	apf_task_wake_all();
fd10cde9 GN	418	}
	419
	420	static int __cpuinit kvm_cpu_notify(struct notifier_block *self,
	421	unsigned long action, void *hcpu)
	422	{
	423	int cpu = (unsigned long)hcpu;
	424	switch (action) {
	425	case CPU_ONLINE:
	426	case CPU_DOWN_FAILED:
	427	case CPU_ONLINE_FROZEN:
	428	smp_call_function_single(cpu, kvm_guest_cpu_online, NULL, 0);
	429	break;
	430	case CPU_DOWN_PREPARE:
	431	case CPU_DOWN_PREPARE_FROZEN:
	432	smp_call_function_single(cpu, kvm_guest_cpu_offline, NULL, 1);
	433	break;
	434	default:
	435	break;
	436	}
	437	return NOTIFY_OK;
	438	}
	439
	440	static struct notifier_block __cpuinitdata kvm_cpu_notifier = {
	441	.notifier_call = kvm_cpu_notify,
	442	};
ca3f1017 GN	443	#endif
ca3f1017 GN	444
631bc487 GN	445	static void __init kvm_apf_trap_init(void)
	446	{
	447	set_intr_gate(14, &async_page_fault);
	448	}
	449
0cf1bfd2 MT	450	void __init kvm_guest_init(void)
0cf1bfd2 MT	451	{
631bc487 GN	452	int i;
631bc487 GN	453
0cf1bfd2 MT	454	if (!kvm_para_available())
	455	return;
	456
	457	paravirt_ops_setup();
fd10cde9	458	register_reboot_notifier(&kvm_pv_reboot_nb);
631bc487 GN	459	for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++)
	460	spin_lock_init(&async_pf_sleepers[i].lock);
	461	if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF))
	462	x86_init.irqs.trap_init = kvm_apf_trap_init;
	463
d910f5c1 GC	464	if (kvm_para_has_feature(KVM_FEATURE_STEAL_TIME)) {
	465	has_steal_clock = 1;
	466	pv_time_ops.steal_clock = kvm_steal_clock;
	467	}
	468
90536664 MT	469	if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
90536664 MT	470	apic_set_eoi_write(kvm_guest_apic_eoi_write);
ab9cf499	471
ca3f1017 GN	472	#ifdef CONFIG_SMP
ca3f1017 GN	473	smp_ops.smp_prepare_boot_cpu = kvm_smp_prepare_boot_cpu;
fd10cde9 GN	474	register_cpu_notifier(&kvm_cpu_notifier);
	475	#else
	476	kvm_guest_cpu_init();
ca3f1017	477	#endif
0cf1bfd2	478	}
d910f5c1	479
fc73373b PB	480	static bool __init kvm_detect(void)
	481	{
	482	if (!kvm_para_available())
	483	return false;
	484	return true;
	485	}
	486
	487	const struct hypervisor_x86 x86_hyper_kvm __refconst = {
	488	.name = "KVM",
	489	.detect = kvm_detect,
	490	};
	491	EXPORT_SYMBOL_GPL(x86_hyper_kvm);
	492
d910f5c1 GC	493	static __init int activate_jump_labels(void)
	494	{
	495	if (has_steal_clock) {
c5905afb	496	static_key_slow_inc(&paravirt_steal_enabled);
d910f5c1	497	if (steal_acc)
c5905afb	498	static_key_slow_inc(&paravirt_steal_rq_enabled);
d910f5c1 GC	499	}
	500
	501	return 0;
	502	}
	503	arch_initcall(activate_jump_labels);