linux/drivers/kvm/kvm_main.c

/*
 * Kernel-based Virtual Machine driver for Linux
 *
 * This module enables machines with Intel VT-x extensions to run virtual
 * machines without emulation or binary translation.
 *
 * Copyright (C) 2006 Qumranet, Inc.
 *
 * Authors:
 *   Avi Kivity   <avi@qumranet.com>
 *   Yaniv Kamay  <yaniv@qumranet.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 */

#include "kvm.h"
#include "x86.h"
#include "x86_emulate.h"
#include "irq.h"

#include <linux/kvm.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/percpu.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/vmalloc.h>
#include <linux/reboot.h>
#include <linux/debugfs.h>
#include <linux/highmem.h>
#include <linux/file.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
#include <linux/anon_inodes.h>
#include <linux/profile.h>
#include <linux/kvm_para.h>
#include <linux/pagemap.h>
#include <linux/mman.h>

#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/desc.h>

MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");

static DEFINE_SPINLOCK(kvm_lock);
static LIST_HEAD(vm_list);

static cpumask_t cpus_hardware_enabled;

struct kvm_x86_ops *kvm_x86_ops;
struct kmem_cache *kvm_vcpu_cache;
EXPORT_SYMBOL_GPL(kvm_vcpu_cache);

static __read_mostly struct preempt_ops kvm_preempt_ops;

#define STAT_OFFSET(x) offsetof(struct kvm_vcpu, stat.x)

static struct kvm_stats_debugfs_item {
	const char *name;
	int offset;
	struct dentry *dentry;
} debugfs_entries[] = {
	{ "pf_fixed", STAT_OFFSET(pf_fixed) },
	{ "pf_guest", STAT_OFFSET(pf_guest) },
	{ "tlb_flush", STAT_OFFSET(tlb_flush) },
	{ "invlpg", STAT_OFFSET(invlpg) },
	{ "exits", STAT_OFFSET(exits) },
	{ "io_exits", STAT_OFFSET(io_exits) },
	{ "mmio_exits", STAT_OFFSET(mmio_exits) },
	{ "signal_exits", STAT_OFFSET(signal_exits) },
	{ "irq_window", STAT_OFFSET(irq_window_exits) },
	{ "halt_exits", STAT_OFFSET(halt_exits) },
	{ "halt_wakeup", STAT_OFFSET(halt_wakeup) },
	{ "request_irq", STAT_OFFSET(request_irq_exits) },
	{ "irq_exits", STAT_OFFSET(irq_exits) },
	{ "light_exits", STAT_OFFSET(light_exits) },
	{ "efer_reload", STAT_OFFSET(efer_reload) },
	{ NULL }
};

static struct dentry *debugfs_dir;

#define EFER_RESERVED_BITS 0xfffffffffffff2fe

static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
			   unsigned long arg);

static inline int valid_vcpu(int n)
{
	return likely(n >= 0 && n < KVM_MAX_VCPUS);
}

void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
{
	if (!vcpu->fpu_active || vcpu->guest_fpu_loaded)
		return;

	vcpu->guest_fpu_loaded = 1;
	fx_save(&vcpu->host_fx_image);
	fx_restore(&vcpu->guest_fx_image);
}
EXPORT_SYMBOL_GPL(kvm_load_guest_fpu);

void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
{
	if (!vcpu->guest_fpu_loaded)
		return;

	vcpu->guest_fpu_loaded = 0;
	fx_save(&vcpu->guest_fx_image);
	fx_restore(&vcpu->host_fx_image);
}
EXPORT_SYMBOL_GPL(kvm_put_guest_fpu);

/*
 * Switches to specified vcpu, until a matching vcpu_put()
 */
void vcpu_load(struct kvm_vcpu *vcpu)
{
	int cpu;

	mutex_lock(&vcpu->mutex);
	cpu = get_cpu();
	preempt_notifier_register(&vcpu->preempt_notifier);
	kvm_arch_vcpu_load(vcpu, cpu);
	put_cpu();
}

void vcpu_put(struct kvm_vcpu *vcpu)
{
	preempt_disable();
	kvm_arch_vcpu_put(vcpu);
	preempt_notifier_unregister(&vcpu->preempt_notifier);
	preempt_enable();
	mutex_unlock(&vcpu->mutex);
}

static void ack_flush(void *_completed)
{
}

void kvm_flush_remote_tlbs(struct kvm *kvm)
{
	int i, cpu;
	cpumask_t cpus;
	struct kvm_vcpu *vcpu;

	cpus_clear(cpus);
	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
		vcpu = kvm->vcpus[i];
		if (!vcpu)
			continue;
		if (test_and_set_bit(KVM_REQ_TLB_FLUSH, &vcpu->requests))
			continue;
		cpu = vcpu->cpu;
		if (cpu != -1 && cpu != raw_smp_processor_id())
			cpu_set(cpu, cpus);
	}
	smp_call_function_mask(cpus, ack_flush, NULL, 1);
}

int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
{
	struct page *page;
	int r;

	mutex_init(&vcpu->mutex);
	vcpu->cpu = -1;
	vcpu->mmu.root_hpa = INVALID_PAGE;
	vcpu->kvm = kvm;
	vcpu->vcpu_id = id;
	if (!irqchip_in_kernel(kvm) || id == 0)
		vcpu->mp_state = VCPU_MP_STATE_RUNNABLE;
	else
		vcpu->mp_state = VCPU_MP_STATE_UNINITIALIZED;
	init_waitqueue_head(&vcpu->wq);

	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
	if (!page) {
		r = -ENOMEM;
		goto fail;
	}
	vcpu->run = page_address(page);

	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
	if (!page) {
		r = -ENOMEM;
		goto fail_free_run;
	}
	vcpu->pio_data = page_address(page);

	r = kvm_mmu_create(vcpu);
	if (r < 0)
		goto fail_free_pio_data;

	if (irqchip_in_kernel(kvm)) {
		r = kvm_create_lapic(vcpu);
		if (r < 0)
			goto fail_mmu_destroy;
	}

	return 0;

fail_mmu_destroy:
	kvm_mmu_destroy(vcpu);
fail_free_pio_data:
	free_page((unsigned long)vcpu->pio_data);
fail_free_run:
	free_page((unsigned long)vcpu->run);
fail:
	return r;
}
EXPORT_SYMBOL_GPL(kvm_vcpu_init);

void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
{
	kvm_free_lapic(vcpu);
	kvm_mmu_destroy(vcpu);
	free_page((unsigned long)vcpu->pio_data);
	free_page((unsigned long)vcpu->run);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);

static struct kvm *kvm_create_vm(void)
{
	struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);

	if (!kvm)
		return ERR_PTR(-ENOMEM);

	kvm_io_bus_init(&kvm->pio_bus);
	mutex_init(&kvm->lock);
	INIT_LIST_HEAD(&kvm->active_mmu_pages);
	kvm_io_bus_init(&kvm->mmio_bus);
	spin_lock(&kvm_lock);
	list_add(&kvm->vm_list, &vm_list);
	spin_unlock(&kvm_lock);
	return kvm;
}

/*
 * Free any memory in @free but not in @dont.
 */
static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
				  struct kvm_memory_slot *dont)
{
	if (!dont || free->rmap != dont->rmap)
		vfree(free->rmap);

	if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
		vfree(free->dirty_bitmap);

	free->npages = 0;
	free->dirty_bitmap = NULL;
	free->rmap = NULL;
}

static void kvm_free_physmem(struct kvm *kvm)
{
	int i;

	for (i = 0; i < kvm->nmemslots; ++i)
		kvm_free_physmem_slot(&kvm->memslots[i], NULL);
}

static void free_pio_guest_pages(struct kvm_vcpu *vcpu)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(vcpu->pio.guest_pages); ++i)
		if (vcpu->pio.guest_pages[i]) {
			kvm_release_page(vcpu->pio.guest_pages[i]);
			vcpu->pio.guest_pages[i] = NULL;
		}
}

static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
{
	vcpu_load(vcpu);
	kvm_mmu_unload(vcpu);
	vcpu_put(vcpu);
}

static void kvm_free_vcpus(struct kvm *kvm)
{
	unsigned int i;

	/*
	 * Unpin any mmu pages first.
	 */
	for (i = 0; i < KVM_MAX_VCPUS; ++i)
		if (kvm->vcpus[i])
			kvm_unload_vcpu_mmu(kvm->vcpus[i]);
	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
		if (kvm->vcpus[i]) {
			kvm_x86_ops->vcpu_free(kvm->vcpus[i]);
			kvm->vcpus[i] = NULL;
		}
	}

}

static void kvm_destroy_vm(struct kvm *kvm)
{
	spin_lock(&kvm_lock);
	list_del(&kvm->vm_list);
	spin_unlock(&kvm_lock);
	kvm_io_bus_destroy(&kvm->pio_bus);
	kvm_io_bus_destroy(&kvm->mmio_bus);
	kfree(kvm->vpic);
	kfree(kvm->vioapic);
	kvm_free_vcpus(kvm);
	kvm_free_physmem(kvm);
	kfree(kvm);
}

static int kvm_vm_release(struct inode *inode, struct file *filp)
{
	struct kvm *kvm = filp->private_data;

	kvm_destroy_vm(kvm);
	return 0;
}

static void inject_gp(struct kvm_vcpu *vcpu)
{
	kvm_x86_ops->inject_gp(vcpu, 0);
}

void fx_init(struct kvm_vcpu *vcpu)
{
	unsigned after_mxcsr_mask;

	/* Initialize guest FPU by resetting ours and saving into guest's */
	preempt_disable();
	fx_save(&vcpu->host_fx_image);
	fpu_init();
	fx_save(&vcpu->guest_fx_image);
	fx_restore(&vcpu->host_fx_image);
	preempt_enable();

	vcpu->cr0 |= X86_CR0_ET;
	after_mxcsr_mask = offsetof(struct i387_fxsave_struct, st_space);
	vcpu->guest_fx_image.mxcsr = 0x1f80;
	memset((void *)&vcpu->guest_fx_image + after_mxcsr_mask,
	       0, sizeof(struct i387_fxsave_struct) - after_mxcsr_mask);
}
EXPORT_SYMBOL_GPL(fx_init);

/*
 * Allocate some memory and give it an address in the guest physical address
 * space.
 *
 * Discontiguous memory is allowed, mostly for framebuffers.
 *
 * Must be called holding kvm->lock.
 */
int __kvm_set_memory_region(struct kvm *kvm,
			    struct kvm_userspace_memory_region *mem,
			    int user_alloc)
{
	int r;
	gfn_t base_gfn;
	unsigned long npages;
	unsigned long i;
	struct kvm_memory_slot *memslot;
	struct kvm_memory_slot old, new;

	r = -EINVAL;
	/* General sanity checks */
	if (mem->memory_size & (PAGE_SIZE - 1))
		goto out;
	if (mem->guest_phys_addr & (PAGE_SIZE - 1))
		goto out;
	if (mem->slot >= KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS)
		goto out;
	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
		goto out;

	memslot = &kvm->memslots[mem->slot];
	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
	npages = mem->memory_size >> PAGE_SHIFT;

	if (!npages)
		mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;

	new = old = *memslot;

	new.base_gfn = base_gfn;
	new.npages = npages;
	new.flags = mem->flags;

	/* Disallow changing a memory slot's size. */
	r = -EINVAL;
	if (npages && old.npages && npages != old.npages)
		goto out_free;

	/* Check for overlaps */
	r = -EEXIST;
	for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
		struct kvm_memory_slot *s = &kvm->memslots[i];

		if (s == memslot)
			continue;
		if (!((base_gfn + npages <= s->base_gfn) ||
		      (base_gfn >= s->base_gfn + s->npages)))
			goto out_free;
	}

	/* Free page dirty bitmap if unneeded */
	if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
		new.dirty_bitmap = NULL;

	r = -ENOMEM;

	/* Allocate if a slot is being created */
	if (npages && !new.rmap) {
		new.rmap = vmalloc(npages * sizeof(struct page *));

		if (!new.rmap)
			goto out_free;

		memset(new.rmap, 0, npages * sizeof(*new.rmap));

		new.user_alloc = user_alloc;
		if (user_alloc)
			new.userspace_addr = mem->userspace_addr;
		else {
			down_write(&current->mm->mmap_sem);
			new.userspace_addr = do_mmap(NULL, 0,
						     npages * PAGE_SIZE,
						     PROT_READ | PROT_WRITE,
						     MAP_SHARED | MAP_ANONYMOUS,
						     0);
			up_write(&current->mm->mmap_sem);

			if (IS_ERR((void *)new.userspace_addr))
				goto out_free;
		}
	} else {
		if (!old.user_alloc && old.rmap) {
			int ret;

			down_write(&current->mm->mmap_sem);
			ret = do_munmap(current->mm, old.userspace_addr,
					old.npages * PAGE_SIZE);
			up_write(&current->mm->mmap_sem);
			if (ret < 0)
				printk(KERN_WARNING
				       "kvm_vm_ioctl_set_memory_region: "
				       "failed to munmap memory\n");
		}
	}

	/* Allocate page dirty bitmap if needed */
	if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
		unsigned dirty_bytes = ALIGN(npages, BITS_PER_LONG) / 8;

		new.dirty_bitmap = vmalloc(dirty_bytes);
		if (!new.dirty_bitmap)
			goto out_free;
		memset(new.dirty_bitmap, 0, dirty_bytes);
	}

	if (mem->slot >= kvm->nmemslots)
		kvm->nmemslots = mem->slot + 1;

	if (!kvm->n_requested_mmu_pages) {
		unsigned int n_pages;

		if (npages) {
			n_pages = npages * KVM_PERMILLE_MMU_PAGES / 1000;
			kvm_mmu_change_mmu_pages(kvm, kvm->n_alloc_mmu_pages +
						 n_pages);
		} else {
			unsigned int nr_mmu_pages;

			n_pages = old.npages * KVM_PERMILLE_MMU_PAGES / 1000;
			nr_mmu_pages = kvm->n_alloc_mmu_pages - n_pages;
			nr_mmu_pages = max(nr_mmu_pages,
				        (unsigned int) KVM_MIN_ALLOC_MMU_PAGES);
			kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
		}
	}

	*memslot = new;

	kvm_mmu_slot_remove_write_access(kvm, mem->slot);
	kvm_flush_remote_tlbs(kvm);

	kvm_free_physmem_slot(&old, &new);
	return 0;

out_free:
	kvm_free_physmem_slot(&new, &old);
out:
	return r;

}
EXPORT_SYMBOL_GPL(__kvm_set_memory_region);

int kvm_set_memory_region(struct kvm *kvm,
			  struct kvm_userspace_memory_region *mem,
			  int user_alloc)
{
	int r;

	mutex_lock(&kvm->lock);
	r = __kvm_set_memory_region(kvm, mem, user_alloc);
	mutex_unlock(&kvm->lock);
	return r;
}
EXPORT_SYMBOL_GPL(kvm_set_memory_region);

int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
				   struct
				   kvm_userspace_memory_region *mem,
				   int user_alloc)
{
	if (mem->slot >= KVM_MEMORY_SLOTS)
		return -EINVAL;
	return kvm_set_memory_region(kvm, mem, user_alloc);
}

/*
 * Get (and clear) the dirty memory log for a memory slot.
 */
static int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
				      struct kvm_dirty_log *log)
{
	struct kvm_memory_slot *memslot;
	int r, i;
	int n;
	unsigned long any = 0;

	mutex_lock(&kvm->lock);

	r = -EINVAL;
	if (log->slot >= KVM_MEMORY_SLOTS)
		goto out;

	memslot = &kvm->memslots[log->slot];
	r = -ENOENT;
	if (!memslot->dirty_bitmap)
		goto out;

	n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;

	for (i = 0; !any && i < n/sizeof(long); ++i)
		any = memslot->dirty_bitmap[i];

	r = -EFAULT;
	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
		goto out;

	/* If nothing is dirty, don't bother messing with page tables. */
	if (any) {
		kvm_mmu_slot_remove_write_access(kvm, log->slot);
		kvm_flush_remote_tlbs(kvm);
		memset(memslot->dirty_bitmap, 0, n);
	}

	r = 0;

out:
	mutex_unlock(&kvm->lock);
	return r;
}

int is_error_page(struct page *page)
{
	return page == bad_page;
}
EXPORT_SYMBOL_GPL(is_error_page);

gfn_t unalias_gfn(struct kvm *kvm, gfn_t gfn)
{
	int i;
	struct kvm_mem_alias *alias;

	for (i = 0; i < kvm->naliases; ++i) {
		alias = &kvm->aliases[i];
		if (gfn >= alias->base_gfn
		    && gfn < alias->base_gfn + alias->npages)
			return alias->target_gfn + gfn - alias->base_gfn;
	}
	return gfn;
}

static struct kvm_memory_slot *__gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
{
	int i;

	for (i = 0; i < kvm->nmemslots; ++i) {
		struct kvm_memory_slot *memslot = &kvm->memslots[i];

		if (gfn >= memslot->base_gfn
		    && gfn < memslot->base_gfn + memslot->npages)
			return memslot;
	}
	return NULL;
}

struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
{
	gfn = unalias_gfn(kvm, gfn);
	return __gfn_to_memslot(kvm, gfn);
}

int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
{
	int i;

	gfn = unalias_gfn(kvm, gfn);
	for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
		struct kvm_memory_slot *memslot = &kvm->memslots[i];

		if (gfn >= memslot->base_gfn
		    && gfn < memslot->base_gfn + memslot->npages)
			return 1;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);

/*
 * Requires current->mm->mmap_sem to be held
 */
static struct page *__gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
	struct kvm_memory_slot *slot;
	struct page *page[1];
	int npages;

	might_sleep();

	gfn = unalias_gfn(kvm, gfn);
	slot = __gfn_to_memslot(kvm, gfn);
	if (!slot) {
		get_page(bad_page);
		return bad_page;
	}

	npages = get_user_pages(current, current->mm,
				slot->userspace_addr
				+ (gfn - slot->base_gfn) * PAGE_SIZE, 1,
				1, 1, page, NULL);
	if (npages != 1) {
		get_page(bad_page);
		return bad_page;
	}

	return page[0];
}

struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
	struct page *page;

	down_read(&current->mm->mmap_sem);
	page = __gfn_to_page(kvm, gfn);
	up_read(&current->mm->mmap_sem);

	return page;
}

EXPORT_SYMBOL_GPL(gfn_to_page);

void kvm_release_page(struct page *page)
{
	if (!PageReserved(page))
		SetPageDirty(page);
	put_page(page);
}
EXPORT_SYMBOL_GPL(kvm_release_page);

static int next_segment(unsigned long len, int offset)
{
	if (len > PAGE_SIZE - offset)
		return PAGE_SIZE - offset;
	else
		return len;
}

int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
			int len)
{
	void *page_virt;
	struct page *page;

	page = gfn_to_page(kvm, gfn);
	if (is_error_page(page)) {
		kvm_release_page(page);
		return -EFAULT;
	}
	page_virt = kmap_atomic(page, KM_USER0);

	memcpy(data, page_virt + offset, len);

	kunmap_atomic(page_virt, KM_USER0);
	kvm_release_page(page);
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_read_guest_page);

int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len)
{
	gfn_t gfn = gpa >> PAGE_SHIFT;
	int seg;
	int offset = offset_in_page(gpa);
	int ret;

	while ((seg = next_segment(len, offset)) != 0) {
		ret = kvm_read_guest_page(kvm, gfn, data, offset, seg);
		if (ret < 0)
			return ret;
		offset = 0;
		len -= seg;
		data += seg;
		++gfn;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_read_guest);

int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
			 int offset, int len)
{
	void *page_virt;
	struct page *page;

	page = gfn_to_page(kvm, gfn);
	if (is_error_page(page)) {
		kvm_release_page(page);
		return -EFAULT;
	}
	page_virt = kmap_atomic(page, KM_USER0);

	memcpy(page_virt + offset, data, len);

	kunmap_atomic(page_virt, KM_USER0);
	mark_page_dirty(kvm, gfn);
	kvm_release_page(page);
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_write_guest_page);

int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
		    unsigned long len)
{
	gfn_t gfn = gpa >> PAGE_SHIFT;
	int seg;
	int offset = offset_in_page(gpa);
	int ret;

	while ((seg = next_segment(len, offset)) != 0) {
		ret = kvm_write_guest_page(kvm, gfn, data, offset, seg);
		if (ret < 0)
			return ret;
		offset = 0;
		len -= seg;
		data += seg;
		++gfn;
	}
	return 0;
}

int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
{
	void *page_virt;
	struct page *page;

	page = gfn_to_page(kvm, gfn);
	if (is_error_page(page)) {
		kvm_release_page(page);
		return -EFAULT;
	}
	page_virt = kmap_atomic(page, KM_USER0);

	memset(page_virt + offset, 0, len);

	kunmap_atomic(page_virt, KM_USER0);
	kvm_release_page(page);
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_clear_guest_page);

int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
{
	gfn_t gfn = gpa >> PAGE_SHIFT;
	int seg;
	int offset = offset_in_page(gpa);
	int ret;

        while ((seg = next_segment(len, offset)) != 0) {
		ret = kvm_clear_guest_page(kvm, gfn, offset, seg);
		if (ret < 0)
			return ret;
		offset = 0;
		len -= seg;
		++gfn;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_clear_guest);

/* WARNING: Does not work on aliased pages. */
void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
{
	struct kvm_memory_slot *memslot;

	memslot = __gfn_to_memslot(kvm, gfn);
	if (memslot && memslot->dirty_bitmap) {
		unsigned long rel_gfn = gfn - memslot->base_gfn;

		/* avoid RMW */
		if (!test_bit(rel_gfn, memslot->dirty_bitmap))
			set_bit(rel_gfn, memslot->dirty_bitmap);
	}
}

int emulator_read_std(unsigned long addr,
			     void *val,
			     unsigned int bytes,
			     struct kvm_vcpu *vcpu)
{
	void *data = val;

	while (bytes) {
		gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);
		unsigned offset = addr & (PAGE_SIZE-1);
		unsigned tocopy = min(bytes, (unsigned)PAGE_SIZE - offset);
		int ret;

		if (gpa == UNMAPPED_GVA)
			return X86EMUL_PROPAGATE_FAULT;
		ret = kvm_read_guest(vcpu->kvm, gpa, data, tocopy);
		if (ret < 0)
			return X86EMUL_UNHANDLEABLE;

		bytes -= tocopy;
		data += tocopy;
		addr += tocopy;
	}

	return X86EMUL_CONTINUE;
}
EXPORT_SYMBOL_GPL(emulator_read_std);

static int emulator_write_std(unsigned long addr,
			      const void *val,
			      unsigned int bytes,
			      struct kvm_vcpu *vcpu)
{
	pr_unimpl(vcpu, "emulator_write_std: addr %lx n %d\n", addr, bytes);
	return X86EMUL_UNHANDLEABLE;
}

/*
 * Only apic need an MMIO device hook, so shortcut now..
 */
static struct kvm_io_device *vcpu_find_pervcpu_dev(struct kvm_vcpu *vcpu,
						gpa_t addr)
{
	struct kvm_io_device *dev;

	if (vcpu->apic) {
		dev = &vcpu->apic->dev;
		if (dev->in_range(dev, addr))
			return dev;
	}
	return NULL;
}

static struct kvm_io_device *vcpu_find_mmio_dev(struct kvm_vcpu *vcpu,
						gpa_t addr)
{
	struct kvm_io_device *dev;

	dev = vcpu_find_pervcpu_dev(vcpu, addr);
	if (dev == NULL)
		dev = kvm_io_bus_find_dev(&vcpu->kvm->mmio_bus, addr);
	return dev;
}

static struct kvm_io_device *vcpu_find_pio_dev(struct kvm_vcpu *vcpu,
					       gpa_t addr)
{
	return kvm_io_bus_find_dev(&vcpu->kvm->pio_bus, addr);
}

static int emulator_read_emulated(unsigned long addr,
				  void *val,
				  unsigned int bytes,
				  struct kvm_vcpu *vcpu)
{
	struct kvm_io_device *mmio_dev;
	gpa_t                 gpa;

	if (vcpu->mmio_read_completed) {
		memcpy(val, vcpu->mmio_data, bytes);
		vcpu->mmio_read_completed = 0;
		return X86EMUL_CONTINUE;
	}

	gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);

	/* For APIC access vmexit */
	if ((gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
		goto mmio;

	if (emulator_read_std(addr, val, bytes, vcpu)
			== X86EMUL_CONTINUE)
		return X86EMUL_CONTINUE;
	if (gpa == UNMAPPED_GVA)
		return X86EMUL_PROPAGATE_FAULT;

mmio:
	/*
	 * Is this MMIO handled locally?
	 */
	mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
	if (mmio_dev) {
		kvm_iodevice_read(mmio_dev, gpa, bytes, val);
		return X86EMUL_CONTINUE;
	}

	vcpu->mmio_needed = 1;
	vcpu->mmio_phys_addr = gpa;
	vcpu->mmio_size = bytes;
	vcpu->mmio_is_write = 0;

	return X86EMUL_UNHANDLEABLE;
}

static int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
			       const void *val, int bytes)
{
	int ret;

	ret = kvm_write_guest(vcpu->kvm, gpa, val, bytes);
	if (ret < 0)
		return 0;
	kvm_mmu_pte_write(vcpu, gpa, val, bytes);
	return 1;
}

static int emulator_write_emulated_onepage(unsigned long addr,
					   const void *val,
					   unsigned int bytes,
					   struct kvm_vcpu *vcpu)
{
	struct kvm_io_device *mmio_dev;
	gpa_t                 gpa = vcpu->mmu.gva_to_gpa(vcpu, addr);

	if (gpa == UNMAPPED_GVA) {
		kvm_x86_ops->inject_page_fault(vcpu, addr, 2);
		return X86EMUL_PROPAGATE_FAULT;
	}

	/* For APIC access vmexit */
	if ((gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
		goto mmio;

	if (emulator_write_phys(vcpu, gpa, val, bytes))
		return X86EMUL_CONTINUE;

mmio:
	/*
	 * Is this MMIO handled locally?
	 */
	mmio_dev = vcpu_find_mmio_dev(vcpu, gpa);
	if (mmio_dev) {
		kvm_iodevice_write(mmio_dev, gpa, bytes, val);
		return X86EMUL_CONTINUE;
	}

	vcpu->mmio_needed = 1;
	vcpu->mmio_phys_addr = gpa;
	vcpu->mmio_size = bytes;
	vcpu->mmio_is_write = 1;
	memcpy(vcpu->mmio_data, val, bytes);

	return X86EMUL_CONTINUE;
}

int emulator_write_emulated(unsigned long addr,
				   const void *val,
				   unsigned int bytes,
				   struct kvm_vcpu *vcpu)
{
	/* Crossing a page boundary? */
	if (((addr + bytes - 1) ^ addr) & PAGE_MASK) {
		int rc, now;

		now = -addr & ~PAGE_MASK;
		rc = emulator_write_emulated_onepage(addr, val, now, vcpu);
		if (rc != X86EMUL_CONTINUE)
			return rc;
		addr += now;
		val += now;
		bytes -= now;
	}
	return emulator_write_emulated_onepage(addr, val, bytes, vcpu);
}
EXPORT_SYMBOL_GPL(emulator_write_emulated);

static int emulator_cmpxchg_emulated(unsigned long addr,
				     const void *old,
				     const void *new,
				     unsigned int bytes,
				     struct kvm_vcpu *vcpu)
{
	static int reported;

	if (!reported) {
		reported = 1;
		printk(KERN_WARNING "kvm: emulating exchange as write\n");
	}
	return emulator_write_emulated(addr, new, bytes, vcpu);
}

static unsigned long get_segment_base(struct kvm_vcpu *vcpu, int seg)
{
	return kvm_x86_ops->get_segment_base(vcpu, seg);
}

int emulate_invlpg(struct kvm_vcpu *vcpu, gva_t address)
{
	return X86EMUL_CONTINUE;
}

int emulate_clts(struct kvm_vcpu *vcpu)
{
	kvm_x86_ops->set_cr0(vcpu, vcpu->cr0 & ~X86_CR0_TS);
	return X86EMUL_CONTINUE;
}

int emulator_get_dr(struct x86_emulate_ctxt *ctxt, int dr, unsigned long *dest)
{
	struct kvm_vcpu *vcpu = ctxt->vcpu;

	switch (dr) {
	case 0 ... 3:
		*dest = kvm_x86_ops->get_dr(vcpu, dr);
		return X86EMUL_CONTINUE;
	default:
		pr_unimpl(vcpu, "%s: unexpected dr %u\n", __FUNCTION__, dr);
		return X86EMUL_UNHANDLEABLE;
	}
}

int emulator_set_dr(struct x86_emulate_ctxt *ctxt, int dr, unsigned long value)
{
	unsigned long mask = (ctxt->mode == X86EMUL_MODE_PROT64) ? ~0ULL : ~0U;
	int exception;

	kvm_x86_ops->set_dr(ctxt->vcpu, dr, value & mask, &exception);
	if (exception) {
		/* FIXME: better handling */
		return X86EMUL_UNHANDLEABLE;
	}
	return X86EMUL_CONTINUE;
}

void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context)
{
	static int reported;
	u8 opcodes[4];
	unsigned long rip = vcpu->rip;
	unsigned long rip_linear;

	rip_linear = rip + get_segment_base(vcpu, VCPU_SREG_CS);

	if (reported)
		return;

	emulator_read_std(rip_linear, (void *)opcodes, 4, vcpu);

	printk(KERN_ERR "emulation failed (%s) rip %lx %02x %02x %02x %02x\n",
	       context, rip, opcodes[0], opcodes[1], opcodes[2], opcodes[3]);
	reported = 1;
}
EXPORT_SYMBOL_GPL(kvm_report_emulation_failure);

struct x86_emulate_ops emulate_ops = {
	.read_std            = emulator_read_std,
	.write_std           = emulator_write_std,
	.read_emulated       = emulator_read_emulated,
	.write_emulated      = emulator_write_emulated,
	.cmpxchg_emulated    = emulator_cmpxchg_emulated,
};

int emulate_instruction(struct kvm_vcpu *vcpu,
			struct kvm_run *run,
			unsigned long cr2,
			u16 error_code,
			int no_decode)
{
	int r;

	vcpu->mmio_fault_cr2 = cr2;
	kvm_x86_ops->cache_regs(vcpu);

	vcpu->mmio_is_write = 0;
	vcpu->pio.string = 0;

	if (!no_decode) {
		int cs_db, cs_l;
		kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);

		vcpu->emulate_ctxt.vcpu = vcpu;
		vcpu->emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);
		vcpu->emulate_ctxt.cr2 = cr2;
		vcpu->emulate_ctxt.mode =
			(vcpu->emulate_ctxt.eflags & X86_EFLAGS_VM)
			? X86EMUL_MODE_REAL : cs_l
			? X86EMUL_MODE_PROT64 :	cs_db
			? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;

		if (vcpu->emulate_ctxt.mode == X86EMUL_MODE_PROT64) {
			vcpu->emulate_ctxt.cs_base = 0;
			vcpu->emulate_ctxt.ds_base = 0;
			vcpu->emulate_ctxt.es_base = 0;
			vcpu->emulate_ctxt.ss_base = 0;
		} else {
			vcpu->emulate_ctxt.cs_base =
					get_segment_base(vcpu, VCPU_SREG_CS);
			vcpu->emulate_ctxt.ds_base =
					get_segment_base(vcpu, VCPU_SREG_DS);
			vcpu->emulate_ctxt.es_base =
					get_segment_base(vcpu, VCPU_SREG_ES);
			vcpu->emulate_ctxt.ss_base =
					get_segment_base(vcpu, VCPU_SREG_SS);
		}

		vcpu->emulate_ctxt.gs_base =
					get_segment_base(vcpu, VCPU_SREG_GS);
		vcpu->emulate_ctxt.fs_base =
					get_segment_base(vcpu, VCPU_SREG_FS);

		r = x86_decode_insn(&vcpu->emulate_ctxt, &emulate_ops);
		if (r)  {
			if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
				return EMULATE_DONE;
			return EMULATE_FAIL;
		}
	}

	r = x86_emulate_insn(&vcpu->emulate_ctxt, &emulate_ops);

	if (vcpu->pio.string)
		return EMULATE_DO_MMIO;

	if ((r || vcpu->mmio_is_write) && run) {
		run->exit_reason = KVM_EXIT_MMIO;
		run->mmio.phys_addr = vcpu->mmio_phys_addr;
		memcpy(run->mmio.data, vcpu->mmio_data, 8);
		run->mmio.len = vcpu->mmio_size;
		run->mmio.is_write = vcpu->mmio_is_write;
	}

	if (r) {
		if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
			return EMULATE_DONE;
		if (!vcpu->mmio_needed) {
			kvm_report_emulation_failure(vcpu, "mmio");
			return EMULATE_FAIL;
		}
		return EMULATE_DO_MMIO;
	}

	kvm_x86_ops->decache_regs(vcpu);
	kvm_x86_ops->set_rflags(vcpu, vcpu->emulate_ctxt.eflags);

	if (vcpu->mmio_is_write) {
		vcpu->mmio_needed = 0;
		return EMULATE_DO_MMIO;
	}

	return EMULATE_DONE;
}
EXPORT_SYMBOL_GPL(emulate_instruction);

/*
 * The vCPU has executed a HLT instruction with in-kernel mode enabled.
 */
static void kvm_vcpu_block(struct kvm_vcpu *vcpu)
{
	DECLARE_WAITQUEUE(wait, current);

	add_wait_queue(&vcpu->wq, &wait);

	/*
	 * We will block until either an interrupt or a signal wakes us up
	 */
	while (!kvm_cpu_has_interrupt(vcpu)
	       && !signal_pending(current)
	       && vcpu->mp_state != VCPU_MP_STATE_RUNNABLE
	       && vcpu->mp_state != VCPU_MP_STATE_SIPI_RECEIVED) {
		set_current_state(TASK_INTERRUPTIBLE);
		vcpu_put(vcpu);
		schedule();
		vcpu_load(vcpu);
	}

	__set_current_state(TASK_RUNNING);
	remove_wait_queue(&vcpu->wq, &wait);
}

int kvm_emulate_halt(struct kvm_vcpu *vcpu)
{
	++vcpu->stat.halt_exits;
	if (irqchip_in_kernel(vcpu->kvm)) {
		vcpu->mp_state = VCPU_MP_STATE_HALTED;
		kvm_vcpu_block(vcpu);
		if (vcpu->mp_state != VCPU_MP_STATE_RUNNABLE)
			return -EINTR;
		return 1;
	} else {
		vcpu->run->exit_reason = KVM_EXIT_HLT;
		return 0;
	}
}
EXPORT_SYMBOL_GPL(kvm_emulate_halt);

int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
{
	unsigned long nr, a0, a1, a2, a3, ret;

	kvm_x86_ops->cache_regs(vcpu);

	nr = vcpu->regs[VCPU_REGS_RAX];
	a0 = vcpu->regs[VCPU_REGS_RBX];
	a1 = vcpu->regs[VCPU_REGS_RCX];
	a2 = vcpu->regs[VCPU_REGS_RDX];
	a3 = vcpu->regs[VCPU_REGS_RSI];

	if (!is_long_mode(vcpu)) {
		nr &= 0xFFFFFFFF;
		a0 &= 0xFFFFFFFF;
		a1 &= 0xFFFFFFFF;
		a2 &= 0xFFFFFFFF;
		a3 &= 0xFFFFFFFF;
	}

	switch (nr) {
	default:
		ret = -KVM_ENOSYS;
		break;
	}
	vcpu->regs[VCPU_REGS_RAX] = ret;
	kvm_x86_ops->decache_regs(vcpu);
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);

int kvm_fix_hypercall(struct kvm_vcpu *vcpu)
{
	char instruction[3];
	int ret = 0;

	mutex_lock(&vcpu->kvm->lock);

	/*
	 * Blow out the MMU to ensure that no other VCPU has an active mapping
	 * to ensure that the updated hypercall appears atomically across all
	 * VCPUs.
	 */
	kvm_mmu_zap_all(vcpu->kvm);

	kvm_x86_ops->cache_regs(vcpu);
	kvm_x86_ops->patch_hypercall(vcpu, instruction);
	if (emulator_write_emulated(vcpu->rip, instruction, 3, vcpu)
	    != X86EMUL_CONTINUE)
		ret = -EFAULT;

	mutex_unlock(&vcpu->kvm->lock);

	return ret;
}

static u64 mk_cr_64(u64 curr_cr, u32 new_val)
{
	return (curr_cr & ~((1ULL << 32) - 1)) | new_val;
}

void realmode_lgdt(struct kvm_vcpu *vcpu, u16 limit, unsigned long base)
{
	struct descriptor_table dt = { limit, base };

	kvm_x86_ops->set_gdt(vcpu, &dt);
}

void realmode_lidt(struct kvm_vcpu *vcpu, u16 limit, unsigned long base)
{
	struct descriptor_table dt = { limit, base };

	kvm_x86_ops->set_idt(vcpu, &dt);
}

void realmode_lmsw(struct kvm_vcpu *vcpu, unsigned long msw,
		   unsigned long *rflags)
{
	lmsw(vcpu, msw);
	*rflags = kvm_x86_ops->get_rflags(vcpu);
}

unsigned long realmode_get_cr(struct kvm_vcpu *vcpu, int cr)
{
	kvm_x86_ops->decache_cr4_guest_bits(vcpu);
	switch (cr) {
	case 0:
		return vcpu->cr0;
	case 2:
		return vcpu->cr2;
	case 3:
		return vcpu->cr3;
	case 4:
		return vcpu->cr4;
	default:
		vcpu_printf(vcpu, "%s: unexpected cr %u\n", __FUNCTION__, cr);
		return 0;
	}
}

void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long val,
		     unsigned long *rflags)
{
	switch (cr) {
	case 0:
		set_cr0(vcpu, mk_cr_64(vcpu->cr0, val));
		*rflags = kvm_x86_ops->get_rflags(vcpu);
		break;
	case 2:
		vcpu->cr2 = val;
		break;
	case 3:
		set_cr3(vcpu, val);
		break;
	case 4:
		set_cr4(vcpu, mk_cr_64(vcpu->cr4, val));
		break;
	default:
		vcpu_printf(vcpu, "%s: unexpected cr %u\n", __FUNCTION__, cr);
	}
}

int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
{
	u64 data;

	switch (msr) {
	case 0xc0010010: /* SYSCFG */
	case 0xc0010015: /* HWCR */
	case MSR_IA32_PLATFORM_ID:
	case MSR_IA32_P5_MC_ADDR:
	case MSR_IA32_P5_MC_TYPE:
	case MSR_IA32_MC0_CTL:
	case MSR_IA32_MCG_STATUS:
	case MSR_IA32_MCG_CAP:
	case MSR_IA32_MC0_MISC:
	case MSR_IA32_MC0_MISC+4:
	case MSR_IA32_MC0_MISC+8:
	case MSR_IA32_MC0_MISC+12:
	case MSR_IA32_MC0_MISC+16:
	case MSR_IA32_UCODE_REV:
	case MSR_IA32_PERF_STATUS:
	case MSR_IA32_EBL_CR_POWERON:
		/* MTRR registers */
	case 0xfe:
	case 0x200 ... 0x2ff:
		data = 0;
		break;
	case 0xcd: /* fsb frequency */
		data = 3;
		break;
	case MSR_IA32_APICBASE:
		data = kvm_get_apic_base(vcpu);
		break;
	case MSR_IA32_MISC_ENABLE:
		data = vcpu->ia32_misc_enable_msr;
		break;
#ifdef CONFIG_X86_64
	case MSR_EFER:
		data = vcpu->shadow_efer;
		break;
#endif
	default:
		pr_unimpl(vcpu, "unhandled rdmsr: 0x%x\n", msr);
		return 1;
	}
	*pdata = data;
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_get_msr_common);

/*
 * Reads an msr value (of 'msr_index') into 'pdata'.
 * Returns 0 on success, non-0 otherwise.
 * Assumes vcpu_load() was already called.
 */
int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
{
	return kvm_x86_ops->get_msr(vcpu, msr_index, pdata);
}

#ifdef CONFIG_X86_64

static void set_efer(struct kvm_vcpu *vcpu, u64 efer)
{
	if (efer & EFER_RESERVED_BITS) {
		printk(KERN_DEBUG "set_efer: 0x%llx #GP, reserved bits\n",
		       efer);
		inject_gp(vcpu);
		return;
	}

	if (is_paging(vcpu)
	    && (vcpu->shadow_efer & EFER_LME) != (efer & EFER_LME)) {
		printk(KERN_DEBUG "set_efer: #GP, change LME while paging\n");
		inject_gp(vcpu);
		return;
	}

	kvm_x86_ops->set_efer(vcpu, efer);

	efer &= ~EFER_LMA;
	efer |= vcpu->shadow_efer & EFER_LMA;

	vcpu->shadow_efer = efer;
}

#endif

int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
	switch (msr) {
#ifdef CONFIG_X86_64
	case MSR_EFER:
		set_efer(vcpu, data);
		break;
#endif
	case MSR_IA32_MC0_STATUS:
		pr_unimpl(vcpu, "%s: MSR_IA32_MC0_STATUS 0x%llx, nop\n",
		       __FUNCTION__, data);
		break;
	case MSR_IA32_MCG_STATUS:
		pr_unimpl(vcpu, "%s: MSR_IA32_MCG_STATUS 0x%llx, nop\n",
			__FUNCTION__, data);
		break;
	case MSR_IA32_UCODE_REV:
	case MSR_IA32_UCODE_WRITE:
	case 0x200 ... 0x2ff: /* MTRRs */
		break;
	case MSR_IA32_APICBASE:
		kvm_set_apic_base(vcpu, data);
		break;
	case MSR_IA32_MISC_ENABLE:
		vcpu->ia32_misc_enable_msr = data;
		break;
	default:
		pr_unimpl(vcpu, "unhandled wrmsr: 0x%x\n", msr);
		return 1;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_set_msr_common);

/*
 * Writes msr value into into the appropriate "register".
 * Returns 0 on success, non-0 otherwise.
 * Assumes vcpu_load() was already called.
 */
int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
{
	return kvm_x86_ops->set_msr(vcpu, msr_index, data);
}

void kvm_resched(struct kvm_vcpu *vcpu)
{
	if (!need_resched())
		return;
	cond_resched();
}
EXPORT_SYMBOL_GPL(kvm_resched);

void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
{
	int i;
	u32 function;
	struct kvm_cpuid_entry *e, *best;

	kvm_x86_ops->cache_regs(vcpu);
	function = vcpu->regs[VCPU_REGS_RAX];
	vcpu->regs[VCPU_REGS_RAX] = 0;
	vcpu->regs[VCPU_REGS_RBX] = 0;
	vcpu->regs[VCPU_REGS_RCX] = 0;
	vcpu->regs[VCPU_REGS_RDX] = 0;
	best = NULL;
	for (i = 0; i < vcpu->cpuid_nent; ++i) {
		e = &vcpu->cpuid_entries[i];
		if (e->function == function) {
			best = e;
			break;
		}
		/*
		 * Both basic or both extended?
		 */
		if (((e->function ^ function) & 0x80000000) == 0)
			if (!best || e->function > best->function)
				best = e;
	}
	if (best) {
		vcpu->regs[VCPU_REGS_RAX] = best->eax;
		vcpu->regs[VCPU_REGS_RBX] = best->ebx;
		vcpu->regs[VCPU_REGS_RCX] = best->ecx;
		vcpu->regs[VCPU_REGS_RDX] = best->edx;
	}
	kvm_x86_ops->decache_regs(vcpu);
	kvm_x86_ops->skip_emulated_instruction(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);

static int pio_copy_data(struct kvm_vcpu *vcpu)
{
	void *p = vcpu->pio_data;
	void *q;
	unsigned bytes;
	int nr_pages = vcpu->pio.guest_pages[1] ? 2 : 1;

	q = vmap(vcpu->pio.guest_pages, nr_pages, VM_READ|VM_WRITE,
		 PAGE_KERNEL);
	if (!q) {
		free_pio_guest_pages(vcpu);
		return -ENOMEM;
	}
	q += vcpu->pio.guest_page_offset;
	bytes = vcpu->pio.size * vcpu->pio.cur_count;
	if (vcpu->pio.in)
		memcpy(q, p, bytes);
	else
		memcpy(p, q, bytes);
	q -= vcpu->pio.guest_page_offset;
	vunmap(q);
	free_pio_guest_pages(vcpu);
	return 0;
}

static int complete_pio(struct kvm_vcpu *vcpu)
{
	struct kvm_pio_request *io = &vcpu->pio;
	long delta;
	int r;

	kvm_x86_ops->cache_regs(vcpu);

	if (!io->string) {
		if (io->in)
			memcpy(&vcpu->regs[VCPU_REGS_RAX], vcpu->pio_data,
			       io->size);
	} else {
		if (io->in) {
			r = pio_copy_data(vcpu);
			if (r) {
				kvm_x86_ops->cache_regs(vcpu);
				return r;
			}
		}

		delta = 1;
		if (io->rep) {
			delta *= io->cur_count;
			/*
			 * The size of the register should really depend on
			 * current address size.
			 */
			vcpu->regs[VCPU_REGS_RCX] -= delta;
		}
		if (io->down)
			delta = -delta;
		delta *= io->size;
		if (io->in)
			vcpu->regs[VCPU_REGS_RDI] += delta;
		else
			vcpu->regs[VCPU_REGS_RSI] += delta;
	}

	kvm_x86_ops->decache_regs(vcpu);

	io->count -= io->cur_count;
	io->cur_count = 0;

	return 0;
}

static void kernel_pio(struct kvm_io_device *pio_dev,
		       struct kvm_vcpu *vcpu,
		       void *pd)
{
	/* TODO: String I/O for in kernel device */

	mutex_lock(&vcpu->kvm->lock);
	if (vcpu->pio.in)
		kvm_iodevice_read(pio_dev, vcpu->pio.port,
				  vcpu->pio.size,
				  pd);
	else
		kvm_iodevice_write(pio_dev, vcpu->pio.port,
				   vcpu->pio.size,
				   pd);
	mutex_unlock(&vcpu->kvm->lock);
}

static void pio_string_write(struct kvm_io_device *pio_dev,
			     struct kvm_vcpu *vcpu)
{
	struct kvm_pio_request *io = &vcpu->pio;
	void *pd = vcpu->pio_data;
	int i;

	mutex_lock(&vcpu->kvm->lock);
	for (i = 0; i < io->cur_count; i++) {
		kvm_iodevice_write(pio_dev, io->port,
				   io->size,
				   pd);
		pd += io->size;
	}
	mutex_unlock(&vcpu->kvm->lock);
}

int kvm_emulate_pio(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
		  int size, unsigned port)
{
	struct kvm_io_device *pio_dev;

	vcpu->run->exit_reason = KVM_EXIT_IO;
	vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT;
	vcpu->run->io.size = vcpu->pio.size = size;
	vcpu->run->io.data_offset = KVM_PIO_PAGE_OFFSET * PAGE_SIZE;
	vcpu->run->io.count = vcpu->pio.count = vcpu->pio.cur_count = 1;
	vcpu->run->io.port = vcpu->pio.port = port;
	vcpu->pio.in = in;
	vcpu->pio.string = 0;
	vcpu->pio.down = 0;
	vcpu->pio.guest_page_offset = 0;
	vcpu->pio.rep = 0;

	kvm_x86_ops->cache_regs(vcpu);
	memcpy(vcpu->pio_data, &vcpu->regs[VCPU_REGS_RAX], 4);
	kvm_x86_ops->decache_regs(vcpu);

	kvm_x86_ops->skip_emulated_instruction(vcpu);

	pio_dev = vcpu_find_pio_dev(vcpu, port);
	if (pio_dev) {
		kernel_pio(pio_dev, vcpu, vcpu->pio_data);
		complete_pio(vcpu);
		return 1;
	}
	return 0;
}
EXPORT_SYMBOL_GPL(kvm_emulate_pio);

int kvm_emulate_pio_string(struct kvm_vcpu *vcpu, struct kvm_run *run, int in,
		  int size, unsigned long count, int down,
		  gva_t address, int rep, unsigned port)
{
	unsigned now, in_page;
	int i, ret = 0;
	int nr_pages = 1;
	struct page *page;
	struct kvm_io_device *pio_dev;

	vcpu->run->exit_reason = KVM_EXIT_IO;
	vcpu->run->io.direction = in ? KVM_EXIT_IO_IN : KVM_EXIT_IO_OUT;
	vcpu->run->io.size = vcpu->pio.size = size;
	vcpu->run->io.data_offset = KVM_PIO_PAGE_OFFSET * PAGE_SIZE;
	vcpu->run->io.count = vcpu->pio.count = vcpu->pio.cur_count = count;
	vcpu->run->io.port = vcpu->pio.port = port;
	vcpu->pio.in = in;
	vcpu->pio.string = 1;
	vcpu->pio.down = down;
	vcpu->pio.guest_page_offset = offset_in_page(address);
	vcpu->pio.rep = rep;

	if (!count) {
		kvm_x86_ops->skip_emulated_instruction(vcpu);
		return 1;
	}

	if (!down)
		in_page = PAGE_SIZE - offset_in_page(address);
	else
		in_page = offset_in_page(address) + size;
	now = min(count, (unsigned long)in_page / size);
	if (!now) {
		/*
		 * String I/O straddles page boundary.  Pin two guest pages
		 * so that we satisfy atomicity constraints.  Do just one
		 * transaction to avoid complexity.
		 */
		nr_pages = 2;
		now = 1;
	}
	if (down) {
		/*
		 * String I/O in reverse.  Yuck.  Kill the guest, fix later.
		 */
		pr_unimpl(vcpu, "guest string pio down\n");
		inject_gp(vcpu);
		return 1;
	}
	vcpu->run->io.count = now;
	vcpu->pio.cur_count = now;

	if (vcpu->pio.cur_count == vcpu->pio.count)
		kvm_x86_ops->skip_emulated_instruction(vcpu);

	for (i = 0; i < nr_pages; ++i) {
		mutex_lock(&vcpu->kvm->lock);
		page = gva_to_page(vcpu, address + i * PAGE_SIZE);
		vcpu->pio.guest_pages[i] = page;
		mutex_unlock(&vcpu->kvm->lock);
		if (!page) {
			inject_gp(vcpu);
			free_pio_guest_pages(vcpu);
			return 1;
		}
	}

	pio_dev = vcpu_find_pio_dev(vcpu, port);
	if (!vcpu->pio.in) {
		/* string PIO write */
		ret = pio_copy_data(vcpu);
		if (ret >= 0 && pio_dev) {
			pio_string_write(pio_dev, vcpu);
			complete_pio(vcpu);
			if (vcpu->pio.count == 0)
				ret = 1;
		}
	} else if (pio_dev)
		pr_unimpl(vcpu, "no string pio read support yet, "
		       "port %x size %d count %ld\n",
			port, size, count);

	return ret;
}
EXPORT_SYMBOL_GPL(kvm_emulate_pio_string);

/*
 * Check if userspace requested an interrupt window, and that the
 * interrupt window is open.
 *
 * No need to exit to userspace if we already have an interrupt queued.
 */
static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu,
					  struct kvm_run *kvm_run)
{
	return (!vcpu->irq_summary &&
		kvm_run->request_interrupt_window &&
		vcpu->interrupt_window_open &&
		(kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_IF));
}

static void post_kvm_run_save(struct kvm_vcpu *vcpu,
			      struct kvm_run *kvm_run)
{
	kvm_run->if_flag = (kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_IF) != 0;
	kvm_run->cr8 = get_cr8(vcpu);
	kvm_run->apic_base = kvm_get_apic_base(vcpu);
	if (irqchip_in_kernel(vcpu->kvm))
		kvm_run->ready_for_interrupt_injection = 1;
	else
		kvm_run->ready_for_interrupt_injection =
					(vcpu->interrupt_window_open &&
					 vcpu->irq_summary == 0);
}

static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
	int r;

	if (unlikely(vcpu->mp_state == VCPU_MP_STATE_SIPI_RECEIVED)) {
		pr_debug("vcpu %d received sipi with vector # %x\n",
		       vcpu->vcpu_id, vcpu->sipi_vector);
		kvm_lapic_reset(vcpu);
		r = kvm_x86_ops->vcpu_reset(vcpu);
		if (r)
			return r;
		vcpu->mp_state = VCPU_MP_STATE_RUNNABLE;
	}

preempted:
	if (vcpu->guest_debug.enabled)
		kvm_x86_ops->guest_debug_pre(vcpu);

again:
	r = kvm_mmu_reload(vcpu);
	if (unlikely(r))
		goto out;

	kvm_inject_pending_timer_irqs(vcpu);

	preempt_disable();

	kvm_x86_ops->prepare_guest_switch(vcpu);
	kvm_load_guest_fpu(vcpu);

	local_irq_disable();

	if (signal_pending(current)) {
		local_irq_enable();
		preempt_enable();
		r = -EINTR;
		kvm_run->exit_reason = KVM_EXIT_INTR;
		++vcpu->stat.signal_exits;
		goto out;
	}

	if (irqchip_in_kernel(vcpu->kvm))
		kvm_x86_ops->inject_pending_irq(vcpu);
	else if (!vcpu->mmio_read_completed)
		kvm_x86_ops->inject_pending_vectors(vcpu, kvm_run);

	vcpu->guest_mode = 1;
	kvm_guest_enter();

	if (vcpu->requests)
		if (test_and_clear_bit(KVM_REQ_TLB_FLUSH, &vcpu->requests))
			kvm_x86_ops->tlb_flush(vcpu);

	kvm_x86_ops->run(vcpu, kvm_run);

	vcpu->guest_mode = 0;
	local_irq_enable();

	++vcpu->stat.exits;

	/*
	 * We must have an instruction between local_irq_enable() and
	 * kvm_guest_exit(), so the timer interrupt isn't delayed by
	 * the interrupt shadow.  The stat.exits increment will do nicely.
	 * But we need to prevent reordering, hence this barrier():
	 */
	barrier();

	kvm_guest_exit();

	preempt_enable();

	/*
	 * Profile KVM exit RIPs:
	 */
	if (unlikely(prof_on == KVM_PROFILING)) {
		kvm_x86_ops->cache_regs(vcpu);
		profile_hit(KVM_PROFILING, (void *)vcpu->rip);
	}

	r = kvm_x86_ops->handle_exit(kvm_run, vcpu);

	if (r > 0) {
		if (dm_request_for_irq_injection(vcpu, kvm_run)) {
			r = -EINTR;
			kvm_run->exit_reason = KVM_EXIT_INTR;
			++vcpu->stat.request_irq_exits;
			goto out;
		}
		if (!need_resched()) {
			++vcpu->stat.light_exits;
			goto again;
		}
	}

out:
	if (r > 0) {
		kvm_resched(vcpu);
		goto preempted;
	}

	post_kvm_run_save(vcpu, kvm_run);

	return r;
}


static int kvm_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
	int r;
	sigset_t sigsaved;

	vcpu_load(vcpu);

	if (unlikely(vcpu->mp_state == VCPU_MP_STATE_UNINITIALIZED)) {
		kvm_vcpu_block(vcpu);
		vcpu_put(vcpu);
		return -EAGAIN;
	}

	if (vcpu->sigset_active)
		sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);

	/* re-sync apic's tpr */
	if (!irqchip_in_kernel(vcpu->kvm))
		set_cr8(vcpu, kvm_run->cr8);

	if (vcpu->pio.cur_count) {
		r = complete_pio(vcpu);
		if (r)
			goto out;
	}
#if CONFIG_HAS_IOMEM
	if (vcpu->mmio_needed) {
		memcpy(vcpu->mmio_data, kvm_run->mmio.data, 8);
		vcpu->mmio_read_completed = 1;
		vcpu->mmio_needed = 0;
		r = emulate_instruction(vcpu, kvm_run,
					vcpu->mmio_fault_cr2, 0, 1);
		if (r == EMULATE_DO_MMIO) {
			/*
			 * Read-modify-write.  Back to userspace.
			 */
			r = 0;
			goto out;
		}
	}
#endif
	if (kvm_run->exit_reason == KVM_EXIT_HYPERCALL) {
		kvm_x86_ops->cache_regs(vcpu);
		vcpu->regs[VCPU_REGS_RAX] = kvm_run->hypercall.ret;
		kvm_x86_ops->decache_regs(vcpu);
	}

	r = __vcpu_run(vcpu, kvm_run);

out:
	if (vcpu->sigset_active)
		sigprocmask(SIG_SETMASK, &sigsaved, NULL);

	vcpu_put(vcpu);
	return r;
}

static int kvm_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu,
				   struct kvm_regs *regs)
{
	vcpu_load(vcpu);

	kvm_x86_ops->cache_regs(vcpu);

	regs->rax = vcpu->regs[VCPU_REGS_RAX];
	regs->rbx = vcpu->regs[VCPU_REGS_RBX];
	regs->rcx = vcpu->regs[VCPU_REGS_RCX];
	regs->rdx = vcpu->regs[VCPU_REGS_RDX];
	regs->rsi = vcpu->regs[VCPU_REGS_RSI];
	regs->rdi = vcpu->regs[VCPU_REGS_RDI];
	regs->rsp = vcpu->regs[VCPU_REGS_RSP];
	regs->rbp = vcpu->regs[VCPU_REGS_RBP];
#ifdef CONFIG_X86_64
	regs->r8 = vcpu->regs[VCPU_REGS_R8];
	regs->r9 = vcpu->regs[VCPU_REGS_R9];
	regs->r10 = vcpu->regs[VCPU_REGS_R10];
	regs->r11 = vcpu->regs[VCPU_REGS_R11];
	regs->r12 = vcpu->regs[VCPU_REGS_R12];
	regs->r13 = vcpu->regs[VCPU_REGS_R13];
	regs->r14 = vcpu->regs[VCPU_REGS_R14];
	regs->r15 = vcpu->regs[VCPU_REGS_R15];
#endif

	regs->rip = vcpu->rip;
	regs->rflags = kvm_x86_ops->get_rflags(vcpu);

	/*
	 * Don't leak debug flags in case they were set for guest debugging
	 */
	if (vcpu->guest_debug.enabled && vcpu->guest_debug.singlestep)
		regs->rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);

	vcpu_put(vcpu);

	return 0;
}

static int kvm_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu,
				   struct kvm_regs *regs)
{
	vcpu_load(vcpu);

	vcpu->regs[VCPU_REGS_RAX] = regs->rax;
	vcpu->regs[VCPU_REGS_RBX] = regs->rbx;
	vcpu->regs[VCPU_REGS_RCX] = regs->rcx;
	vcpu->regs[VCPU_REGS_RDX] = regs->rdx;
	vcpu->regs[VCPU_REGS_RSI] = regs->rsi;
	vcpu->regs[VCPU_REGS_RDI] = regs->rdi;
	vcpu->regs[VCPU_REGS_RSP] = regs->rsp;
	vcpu->regs[VCPU_REGS_RBP] = regs->rbp;
#ifdef CONFIG_X86_64
	vcpu->regs[VCPU_REGS_R8] = regs->r8;
	vcpu->regs[VCPU_REGS_R9] = regs->r9;
	vcpu->regs[VCPU_REGS_R10] = regs->r10;
	vcpu->regs[VCPU_REGS_R11] = regs->r11;
	vcpu->regs[VCPU_REGS_R12] = regs->r12;
	vcpu->regs[VCPU_REGS_R13] = regs->r13;
	vcpu->regs[VCPU_REGS_R14] = regs->r14;
	vcpu->regs[VCPU_REGS_R15] = regs->r15;
#endif

	vcpu->rip = regs->rip;
	kvm_x86_ops->set_rflags(vcpu, regs->rflags);

	kvm_x86_ops->decache_regs(vcpu);

	vcpu_put(vcpu);

	return 0;
}

static void get_segment(struct kvm_vcpu *vcpu,
			struct kvm_segment *var, int seg)
{
	return kvm_x86_ops->get_segment(vcpu, var, seg);
}

static int kvm_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
				    struct kvm_sregs *sregs)
{
	struct descriptor_table dt;
	int pending_vec;

	vcpu_load(vcpu);

	get_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
	get_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
	get_segment(vcpu, &sregs->es, VCPU_SREG_ES);
	get_segment(vcpu, &sregs->fs, VCPU_SREG_FS);
	get_segment(vcpu, &sregs->gs, VCPU_SREG_GS);
	get_segment(vcpu, &sregs->ss, VCPU_SREG_SS);

	get_segment(vcpu, &sregs->tr, VCPU_SREG_TR);
	get_segment(vcpu, &sregs->ldt, VCPU_SREG_LDTR);

	kvm_x86_ops->get_idt(vcpu, &dt);
	sregs->idt.limit = dt.limit;
	sregs->idt.base = dt.base;
	kvm_x86_ops->get_gdt(vcpu, &dt);
	sregs->gdt.limit = dt.limit;
	sregs->gdt.base = dt.base;

	kvm_x86_ops->decache_cr4_guest_bits(vcpu);
	sregs->cr0 = vcpu->cr0;
	sregs->cr2 = vcpu->cr2;
	sregs->cr3 = vcpu->cr3;
	sregs->cr4 = vcpu->cr4;
	sregs->cr8 = get_cr8(vcpu);
	sregs->efer = vcpu->shadow_efer;
	sregs->apic_base = kvm_get_apic_base(vcpu);

	if (irqchip_in_kernel(vcpu->kvm)) {
		memset(sregs->interrupt_bitmap, 0,
		       sizeof sregs->interrupt_bitmap);
		pending_vec = kvm_x86_ops->get_irq(vcpu);
		if (pending_vec >= 0)
			set_bit(pending_vec,
				(unsigned long *)sregs->interrupt_bitmap);
	} else
		memcpy(sregs->interrupt_bitmap, vcpu->irq_pending,
		       sizeof sregs->interrupt_bitmap);

	vcpu_put(vcpu);

	return 0;
}

static void set_segment(struct kvm_vcpu *vcpu,
			struct kvm_segment *var, int seg)
{
	return kvm_x86_ops->set_segment(vcpu, var, seg);
}

static int kvm_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
				    struct kvm_sregs *sregs)
{
	int mmu_reset_needed = 0;
	int i, pending_vec, max_bits;
	struct descriptor_table dt;

	vcpu_load(vcpu);

	dt.limit = sregs->idt.limit;
	dt.base = sregs->idt.base;
	kvm_x86_ops->set_idt(vcpu, &dt);
	dt.limit = sregs->gdt.limit;
	dt.base = sregs->gdt.base;
	kvm_x86_ops->set_gdt(vcpu, &dt);

	vcpu->cr2 = sregs->cr2;
	mmu_reset_needed |= vcpu->cr3 != sregs->cr3;
	vcpu->cr3 = sregs->cr3;

	set_cr8(vcpu, sregs->cr8);

	mmu_reset_needed |= vcpu->shadow_efer != sregs->efer;
#ifdef CONFIG_X86_64
	kvm_x86_ops->set_efer(vcpu, sregs->efer);
#endif
	kvm_set_apic_base(vcpu, sregs->apic_base);

	kvm_x86_ops->decache_cr4_guest_bits(vcpu);

	mmu_reset_needed |= vcpu->cr0 != sregs->cr0;
	vcpu->cr0 = sregs->cr0;
	kvm_x86_ops->set_cr0(vcpu, sregs->cr0);

	mmu_reset_needed |= vcpu->cr4 != sregs->cr4;
	kvm_x86_ops->set_cr4(vcpu, sregs->cr4);
	if (!is_long_mode(vcpu) && is_pae(vcpu))
		load_pdptrs(vcpu, vcpu->cr3);

	if (mmu_reset_needed)
		kvm_mmu_reset_context(vcpu);

	if (!irqchip_in_kernel(vcpu->kvm)) {
		memcpy(vcpu->irq_pending, sregs->interrupt_bitmap,
		       sizeof vcpu->irq_pending);
		vcpu->irq_summary = 0;
		for (i = 0; i < ARRAY_SIZE(vcpu->irq_pending); ++i)
			if (vcpu->irq_pending[i])
				__set_bit(i, &vcpu->irq_summary);
	} else {
		max_bits = (sizeof sregs->interrupt_bitmap) << 3;
		pending_vec = find_first_bit(
			(const unsigned long *)sregs->interrupt_bitmap,
			max_bits);
		/* Only pending external irq is handled here */
		if (pending_vec < max_bits) {
			kvm_x86_ops->set_irq(vcpu, pending_vec);
			pr_debug("Set back pending irq %d\n",
				 pending_vec);
		}
	}

	set_segment(vcpu, &sregs->cs, VCPU_SREG_CS);
	set_segment(vcpu, &sregs->ds, VCPU_SREG_DS);
	set_segment(vcpu, &sregs->es, VCPU_SREG_ES);
	set_segment(vcpu, &sregs->fs, VCPU_SREG_FS);
	set_segment(vcpu, &sregs->gs, VCPU_SREG_GS);
	set_segment(vcpu, &sregs->ss, VCPU_SREG_SS);

	set_segment(vcpu, &sregs->tr, VCPU_SREG_TR);
	set_segment(vcpu, &sregs->ldt, VCPU_SREG_LDTR);

	vcpu_put(vcpu);

	return 0;
}

void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
{
	struct kvm_segment cs;

	get_segment(vcpu, &cs, VCPU_SREG_CS);
	*db = cs.db;
	*l = cs.l;
}
EXPORT_SYMBOL_GPL(kvm_get_cs_db_l_bits);

/*
 * Translate a guest virtual address to a guest physical address.
 */
static int kvm_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
				    struct kvm_translation *tr)
{
	unsigned long vaddr = tr->linear_address;
	gpa_t gpa;

	vcpu_load(vcpu);
	mutex_lock(&vcpu->kvm->lock);
	gpa = vcpu->mmu.gva_to_gpa(vcpu, vaddr);
	tr->physical_address = gpa;
	tr->valid = gpa != UNMAPPED_GVA;
	tr->writeable = 1;
	tr->usermode = 0;
	mutex_unlock(&vcpu->kvm->lock);
	vcpu_put(vcpu);

	return 0;
}

static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
				    struct kvm_interrupt *irq)
{
	if (irq->irq < 0 || irq->irq >= 256)
		return -EINVAL;
	if (irqchip_in_kernel(vcpu->kvm))
		return -ENXIO;
	vcpu_load(vcpu);

	set_bit(irq->irq, vcpu->irq_pending);
	set_bit(irq->irq / BITS_PER_LONG, &vcpu->irq_summary);

	vcpu_put(vcpu);

	return 0;
}

static int kvm_vcpu_ioctl_debug_guest(struct kvm_vcpu *vcpu,
				      struct kvm_debug_guest *dbg)
{
	int r;

	vcpu_load(vcpu);

	r = kvm_x86_ops->set_guest_debug(vcpu, dbg);

	vcpu_put(vcpu);

	return r;
}

static struct page *kvm_vcpu_nopage(struct vm_area_struct *vma,
				    unsigned long address,
				    int *type)
{
	struct kvm_vcpu *vcpu = vma->vm_file->private_data;
	unsigned long pgoff;
	struct page *page;

	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	if (pgoff == 0)
		page = virt_to_page(vcpu->run);
	else if (pgoff == KVM_PIO_PAGE_OFFSET)
		page = virt_to_page(vcpu->pio_data);
	else
		return NOPAGE_SIGBUS;
	get_page(page);
	if (type != NULL)
		*type = VM_FAULT_MINOR;

	return page;
}

static struct vm_operations_struct kvm_vcpu_vm_ops = {
	.nopage = kvm_vcpu_nopage,
};

static int kvm_vcpu_mmap(struct file *file, struct vm_area_struct *vma)
{
	vma->vm_ops = &kvm_vcpu_vm_ops;
	return 0;
}

static int kvm_vcpu_release(struct inode *inode, struct file *filp)
{
	struct kvm_vcpu *vcpu = filp->private_data;

	fput(vcpu->kvm->filp);
	return 0;
}

static struct file_operations kvm_vcpu_fops = {
	.release        = kvm_vcpu_release,
	.unlocked_ioctl = kvm_vcpu_ioctl,
	.compat_ioctl   = kvm_vcpu_ioctl,
	.mmap           = kvm_vcpu_mmap,
};

/*
 * Allocates an inode for the vcpu.
 */
static int create_vcpu_fd(struct kvm_vcpu *vcpu)
{
	int fd, r;
	struct inode *inode;
	struct file *file;

	r = anon_inode_getfd(&fd, &inode, &file,
			     "kvm-vcpu", &kvm_vcpu_fops, vcpu);
	if (r)
		return r;
	atomic_inc(&vcpu->kvm->filp->f_count);
	return fd;
}

/*
 * Creates some virtual cpus.  Good luck creating more than one.
 */
static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
{
	int r;
	struct kvm_vcpu *vcpu;

	if (!valid_vcpu(n))
		return -EINVAL;

	vcpu = kvm_x86_ops->vcpu_create(kvm, n);
	if (IS_ERR(vcpu))
		return PTR_ERR(vcpu);

	preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);

	/* We do fxsave: this must be aligned. */
	BUG_ON((unsigned long)&vcpu->host_fx_image & 0xF);

	vcpu_load(vcpu);
	r = kvm_x86_ops->vcpu_reset(vcpu);
	if (r == 0)
		r = kvm_mmu_setup(vcpu);
	vcpu_put(vcpu);
	if (r < 0)
		goto free_vcpu;

	mutex_lock(&kvm->lock);
	if (kvm->vcpus[n]) {
		r = -EEXIST;
		mutex_unlock(&kvm->lock);
		goto mmu_unload;
	}
	kvm->vcpus[n] = vcpu;
	mutex_unlock(&kvm->lock);

	/* Now it's all set up, let userspace reach it */
	r = create_vcpu_fd(vcpu);
	if (r < 0)
		goto unlink;
	return r;

unlink:
	mutex_lock(&kvm->lock);
	kvm->vcpus[n] = NULL;
	mutex_unlock(&kvm->lock);

mmu_unload:
	vcpu_load(vcpu);
	kvm_mmu_unload(vcpu);
	vcpu_put(vcpu);

free_vcpu:
	kvm_x86_ops->vcpu_free(vcpu);
	return r;
}

static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
{
	if (sigset) {
		sigdelsetmask(sigset, sigmask(SIGKILL)|sigmask(SIGSTOP));
		vcpu->sigset_active = 1;
		vcpu->sigset = *sigset;
	} else
		vcpu->sigset_active = 0;
	return 0;
}

/*
 * fxsave fpu state.  Taken from x86_64/processor.h.  To be killed when
 * we have asm/x86/processor.h
 */
struct fxsave {
	u16	cwd;
	u16	swd;
	u16	twd;
	u16	fop;
	u64	rip;
	u64	rdp;
	u32	mxcsr;
	u32	mxcsr_mask;
	u32	st_space[32];	/* 8*16 bytes for each FP-reg = 128 bytes */
#ifdef CONFIG_X86_64
	u32	xmm_space[64];	/* 16*16 bytes for each XMM-reg = 256 bytes */
#else
	u32	xmm_space[32];	/* 8*16 bytes for each XMM-reg = 128 bytes */
#endif
};

static int kvm_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
{
	struct fxsave *fxsave = (struct fxsave *)&vcpu->guest_fx_image;

	vcpu_load(vcpu);

	memcpy(fpu->fpr, fxsave->st_space, 128);
	fpu->fcw = fxsave->cwd;
	fpu->fsw = fxsave->swd;
	fpu->ftwx = fxsave->twd;
	fpu->last_opcode = fxsave->fop;
	fpu->last_ip = fxsave->rip;
	fpu->last_dp = fxsave->rdp;
	memcpy(fpu->xmm, fxsave->xmm_space, sizeof fxsave->xmm_space);

	vcpu_put(vcpu);

	return 0;
}

static int kvm_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
{
	struct fxsave *fxsave = (struct fxsave *)&vcpu->guest_fx_image;

	vcpu_load(vcpu);

	memcpy(fxsave->st_space, fpu->fpr, 128);
	fxsave->cwd = fpu->fcw;
	fxsave->swd = fpu->fsw;
	fxsave->twd = fpu->ftwx;
	fxsave->fop = fpu->last_opcode;
	fxsave->rip = fpu->last_ip;
	fxsave->rdp = fpu->last_dp;
	memcpy(fxsave->xmm_space, fpu->xmm, sizeof fxsave->xmm_space);

	vcpu_put(vcpu);

	return 0;
}

static long kvm_vcpu_ioctl(struct file *filp,
			   unsigned int ioctl, unsigned long arg)
{
	struct kvm_vcpu *vcpu = filp->private_data;
	void __user *argp = (void __user *)arg;
	int r;

	switch (ioctl) {
	case KVM_RUN:
		r = -EINVAL;
		if (arg)
			goto out;
		r = kvm_vcpu_ioctl_run(vcpu, vcpu->run);
		break;
	case KVM_GET_REGS: {
		struct kvm_regs kvm_regs;

		memset(&kvm_regs, 0, sizeof kvm_regs);
		r = kvm_vcpu_ioctl_get_regs(vcpu, &kvm_regs);
		if (r)
			goto out;
		r = -EFAULT;
		if (copy_to_user(argp, &kvm_regs, sizeof kvm_regs))
			goto out;
		r = 0;
		break;
	}
	case KVM_SET_REGS: {
		struct kvm_regs kvm_regs;

		r = -EFAULT;
		if (copy_from_user(&kvm_regs, argp, sizeof kvm_regs))
			goto out;
		r = kvm_vcpu_ioctl_set_regs(vcpu, &kvm_regs);
		if (r)
			goto out;
		r = 0;
		break;
	}
	case KVM_GET_SREGS: {
		struct kvm_sregs kvm_sregs;

		memset(&kvm_sregs, 0, sizeof kvm_sregs);
		r = kvm_vcpu_ioctl_get_sregs(vcpu, &kvm_sregs);
		if (r)
			goto out;
		r = -EFAULT;
		if (copy_to_user(argp, &kvm_sregs, sizeof kvm_sregs))
			goto out;
		r = 0;
		break;
	}
	case KVM_SET_SREGS: {
		struct kvm_sregs kvm_sregs;

		r = -EFAULT;
		if (copy_from_user(&kvm_sregs, argp, sizeof kvm_sregs))
			goto out;
		r = kvm_vcpu_ioctl_set_sregs(vcpu, &kvm_sregs);
		if (r)
			goto out;
		r = 0;
		break;
	}
	case KVM_TRANSLATE: {
		struct kvm_translation tr;

		r = -EFAULT;
		if (copy_from_user(&tr, argp, sizeof tr))
			goto out;
		r = kvm_vcpu_ioctl_translate(vcpu, &tr);
		if (r)
			goto out;
		r = -EFAULT;
		if (copy_to_user(argp, &tr, sizeof tr))
			goto out;
		r = 0;
		break;
	}
	case KVM_INTERRUPT: {
		struct kvm_interrupt irq;

		r = -EFAULT;
		if (copy_from_user(&irq, argp, sizeof irq))
			goto out;
		r = kvm_vcpu_ioctl_interrupt(vcpu, &irq);
		if (r)
			goto out;
		r = 0;
		break;
	}
	case KVM_DEBUG_GUEST: {
		struct kvm_debug_guest dbg;

		r = -EFAULT;
		if (copy_from_user(&dbg, argp, sizeof dbg))
			goto out;
		r = kvm_vcpu_ioctl_debug_guest(vcpu, &dbg);
		if (r)
			goto out;
		r = 0;
		break;
	}
	case KVM_SET_SIGNAL_MASK: {
		struct kvm_signal_mask __user *sigmask_arg = argp;
		struct kvm_signal_mask kvm_sigmask;
		sigset_t sigset, *p;

		p = NULL;
		if (argp) {
			r = -EFAULT;
			if (copy_from_user(&kvm_sigmask, argp,
					   sizeof kvm_sigmask))
				goto out;
			r = -EINVAL;
			if (kvm_sigmask.len != sizeof sigset)
				goto out;
			r = -EFAULT;
			if (copy_from_user(&sigset, sigmask_arg->sigset,
					   sizeof sigset))
				goto out;
			p = &sigset;
		}
		r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
		break;
	}
	case KVM_GET_FPU: {
		struct kvm_fpu fpu;

		memset(&fpu, 0, sizeof fpu);
		r = kvm_vcpu_ioctl_get_fpu(vcpu, &fpu);
		if (r)
			goto out;
		r = -EFAULT;
		if (copy_to_user(argp, &fpu, sizeof fpu))
			goto out;
		r = 0;
		break;
	}
	case KVM_SET_FPU: {
		struct kvm_fpu fpu;

		r = -EFAULT;
		if (copy_from_user(&fpu, argp, sizeof fpu))
			goto out;
		r = kvm_vcpu_ioctl_set_fpu(vcpu, &fpu);
		if (r)
			goto out;
		r = 0;
		break;
	}
	default:
		r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
	}
out:
	return r;
}

static long kvm_vm_ioctl(struct file *filp,
			   unsigned int ioctl, unsigned long arg)
{
	struct kvm *kvm = filp->private_data;
	void __user *argp = (void __user *)arg;
	int r;

	switch (ioctl) {
	case KVM_CREATE_VCPU:
		r = kvm_vm_ioctl_create_vcpu(kvm, arg);
		if (r < 0)
			goto out;
		break;
	case KVM_SET_USER_MEMORY_REGION: {
		struct kvm_userspace_memory_region kvm_userspace_mem;

		r = -EFAULT;
		if (copy_from_user(&kvm_userspace_mem, argp,
						sizeof kvm_userspace_mem))
			goto out;

		r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem, 1);
		if (r)
			goto out;
		break;
	}
	case KVM_GET_DIRTY_LOG: {
		struct kvm_dirty_log log;

		r = -EFAULT;
		if (copy_from_user(&log, argp, sizeof log))
			goto out;
		r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
		if (r)
			goto out;
		break;
	}
	default:
		r = kvm_arch_vm_ioctl(filp, ioctl, arg);
	}
out:
	return r;
}

static struct page *kvm_vm_nopage(struct vm_area_struct *vma,
				  unsigned long address,
				  int *type)
{
	struct kvm *kvm = vma->vm_file->private_data;
	unsigned long pgoff;
	struct page *page;

	pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	if (!kvm_is_visible_gfn(kvm, pgoff))
		return NOPAGE_SIGBUS;
	/* current->mm->mmap_sem is already held so call lockless version */
	page = __gfn_to_page(kvm, pgoff);
	if (is_error_page(page)) {
		kvm_release_page(page);
		return NOPAGE_SIGBUS;
	}
	if (type != NULL)
		*type = VM_FAULT_MINOR;

	return page;
}

static struct vm_operations_struct kvm_vm_vm_ops = {
	.nopage = kvm_vm_nopage,
};

static int kvm_vm_mmap(struct file *file, struct vm_area_struct *vma)
{
	vma->vm_ops = &kvm_vm_vm_ops;
	return 0;
}

static struct file_operations kvm_vm_fops = {
	.release        = kvm_vm_release,
	.unlocked_ioctl = kvm_vm_ioctl,
	.compat_ioctl   = kvm_vm_ioctl,
	.mmap           = kvm_vm_mmap,
};

static int kvm_dev_ioctl_create_vm(void)
{
	int fd, r;
	struct inode *inode;
	struct file *file;
	struct kvm *kvm;

	kvm = kvm_create_vm();
	if (IS_ERR(kvm))
		return PTR_ERR(kvm);
	r = anon_inode_getfd(&fd, &inode, &file, "kvm-vm", &kvm_vm_fops, kvm);
	if (r) {
		kvm_destroy_vm(kvm);
		return r;
	}

	kvm->filp = file;

	return fd;
}

static long kvm_dev_ioctl(struct file *filp,
			  unsigned int ioctl, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	long r = -EINVAL;

	switch (ioctl) {
	case KVM_GET_API_VERSION:
		r = -EINVAL;
		if (arg)
			goto out;
		r = KVM_API_VERSION;
		break;
	case KVM_CREATE_VM:
		r = -EINVAL;
		if (arg)
			goto out;
		r = kvm_dev_ioctl_create_vm();
		break;
	case KVM_CHECK_EXTENSION: {
		int ext = (long)argp;

		switch (ext) {
		case KVM_CAP_IRQCHIP:
		case KVM_CAP_HLT:
		case KVM_CAP_MMU_SHADOW_CACHE_CONTROL:
		case KVM_CAP_USER_MEMORY:
		case KVM_CAP_SET_TSS_ADDR:
			r = 1;
			break;
		default:
			r = 0;
			break;
		}
		break;
	}
	case KVM_GET_VCPU_MMAP_SIZE:
		r = -EINVAL;
		if (arg)
			goto out;
		r = 2 * PAGE_SIZE;
		break;
	default:
		return kvm_arch_dev_ioctl(filp, ioctl, arg);
	}
out:
	return r;
}

static struct file_operations kvm_chardev_ops = {
	.unlocked_ioctl = kvm_dev_ioctl,
	.compat_ioctl   = kvm_dev_ioctl,
};

static struct miscdevice kvm_dev = {
	KVM_MINOR,
	"kvm",
	&kvm_chardev_ops,
};

/*
 * Make sure that a cpu that is being hot-unplugged does not have any vcpus
 * cached on it.
 */
static void decache_vcpus_on_cpu(int cpu)
{
	struct kvm *vm;
	struct kvm_vcpu *vcpu;
	int i;

	spin_lock(&kvm_lock);
	list_for_each_entry(vm, &vm_list, vm_list)
		for (i = 0; i < KVM_MAX_VCPUS; ++i) {
			vcpu = vm->vcpus[i];
			if (!vcpu)
				continue;
			/*
			 * If the vcpu is locked, then it is running on some
			 * other cpu and therefore it is not cached on the
			 * cpu in question.
			 *
			 * If it's not locked, check the last cpu it executed
			 * on.
			 */
			if (mutex_trylock(&vcpu->mutex)) {
				if (vcpu->cpu == cpu) {
					kvm_x86_ops->vcpu_decache(vcpu);
					vcpu->cpu = -1;
				}
				mutex_unlock(&vcpu->mutex);
			}
		}
	spin_unlock(&kvm_lock);
}

static void hardware_enable(void *junk)
{
	int cpu = raw_smp_processor_id();

	if (cpu_isset(cpu, cpus_hardware_enabled))
		return;
	cpu_set(cpu, cpus_hardware_enabled);
	kvm_x86_ops->hardware_enable(NULL);
}

static void hardware_disable(void *junk)
{
	int cpu = raw_smp_processor_id();

	if (!cpu_isset(cpu, cpus_hardware_enabled))
		return;
	cpu_clear(cpu, cpus_hardware_enabled);
	decache_vcpus_on_cpu(cpu);
	kvm_x86_ops->hardware_disable(NULL);
}

static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val,
			   void *v)
{
	int cpu = (long)v;

	switch (val) {
	case CPU_DYING:
	case CPU_DYING_FROZEN:
		printk(KERN_INFO "kvm: disabling virtualization on CPU%d\n",
		       cpu);
		hardware_disable(NULL);
		break;
	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
		printk(KERN_INFO "kvm: disabling virtualization on CPU%d\n",
		       cpu);
		smp_call_function_single(cpu, hardware_disable, NULL, 0, 1);
		break;
	case CPU_ONLINE:
	case CPU_ONLINE_FROZEN:
		printk(KERN_INFO "kvm: enabling virtualization on CPU%d\n",
		       cpu);
		smp_call_function_single(cpu, hardware_enable, NULL, 0, 1);
		break;
	}
	return NOTIFY_OK;
}

static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
		      void *v)
{
	if (val == SYS_RESTART) {
		/*
		 * Some (well, at least mine) BIOSes hang on reboot if
		 * in vmx root mode.
		 */
		printk(KERN_INFO "kvm: exiting hardware virtualization\n");
		on_each_cpu(hardware_disable, NULL, 0, 1);
	}
	return NOTIFY_OK;
}

static struct notifier_block kvm_reboot_notifier = {
	.notifier_call = kvm_reboot,
	.priority = 0,
};

void kvm_io_bus_init(struct kvm_io_bus *bus)
{
	memset(bus, 0, sizeof(*bus));
}

void kvm_io_bus_destroy(struct kvm_io_bus *bus)
{
	int i;

	for (i = 0; i < bus->dev_count; i++) {
		struct kvm_io_device *pos = bus->devs[i];

		kvm_iodevice_destructor(pos);
	}
}

struct kvm_io_device *kvm_io_bus_find_dev(struct kvm_io_bus *bus, gpa_t addr)
{
	int i;

	for (i = 0; i < bus->dev_count; i++) {
		struct kvm_io_device *pos = bus->devs[i];

		if (pos->in_range(pos, addr))
			return pos;
	}

	return NULL;
}

void kvm_io_bus_register_dev(struct kvm_io_bus *bus, struct kvm_io_device *dev)
{
	BUG_ON(bus->dev_count > (NR_IOBUS_DEVS-1));

	bus->devs[bus->dev_count++] = dev;
}

static struct notifier_block kvm_cpu_notifier = {
	.notifier_call = kvm_cpu_hotplug,
	.priority = 20, /* must be > scheduler priority */
};

static u64 stat_get(void *_offset)
{
	unsigned offset = (long)_offset;
	u64 total = 0;
	struct kvm *kvm;
	struct kvm_vcpu *vcpu;
	int i;

	spin_lock(&kvm_lock);
	list_for_each_entry(kvm, &vm_list, vm_list)
		for (i = 0; i < KVM_MAX_VCPUS; ++i) {
			vcpu = kvm->vcpus[i];
			if (vcpu)
				total += *(u32 *)((void *)vcpu + offset);
		}
	spin_unlock(&kvm_lock);
	return total;
}

DEFINE_SIMPLE_ATTRIBUTE(stat_fops, stat_get, NULL, "%llu\n");

static __init void kvm_init_debug(void)
{
	struct kvm_stats_debugfs_item *p;

	debugfs_dir = debugfs_create_dir("kvm", NULL);
	for (p = debugfs_entries; p->name; ++p)
		p->dentry = debugfs_create_file(p->name, 0444, debugfs_dir,
						(void *)(long)p->offset,
						&stat_fops);
}

static void kvm_exit_debug(void)
{
	struct kvm_stats_debugfs_item *p;

	for (p = debugfs_entries; p->name; ++p)
		debugfs_remove(p->dentry);
	debugfs_remove(debugfs_dir);
}

static int kvm_suspend(struct sys_device *dev, pm_message_t state)
{
	hardware_disable(NULL);
	return 0;
}

static int kvm_resume(struct sys_device *dev)
{
	hardware_enable(NULL);
	return 0;
}

static struct sysdev_class kvm_sysdev_class = {
	.name = "kvm",
	.suspend = kvm_suspend,
	.resume = kvm_resume,
};

static struct sys_device kvm_sysdev = {
	.id = 0,
	.cls = &kvm_sysdev_class,
};

struct page *bad_page;

static inline
struct kvm_vcpu *preempt_notifier_to_vcpu(struct preempt_notifier *pn)
{
	return container_of(pn, struct kvm_vcpu, preempt_notifier);
}

static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
{
	struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);

	kvm_x86_ops->vcpu_load(vcpu, cpu);
}

static void kvm_sched_out(struct preempt_notifier *pn,
			  struct task_struct *next)
{
	struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);

	kvm_x86_ops->vcpu_put(vcpu);
}

int kvm_init_x86(struct kvm_x86_ops *ops, unsigned int vcpu_size,
		  struct module *module)
{
	int r;
	int cpu;

	if (kvm_x86_ops) {
		printk(KERN_ERR "kvm: already loaded the other module\n");
		return -EEXIST;
	}

	if (!ops->cpu_has_kvm_support()) {
		printk(KERN_ERR "kvm: no hardware support\n");
		return -EOPNOTSUPP;
	}
	if (ops->disabled_by_bios()) {
		printk(KERN_ERR "kvm: disabled by bios\n");
		return -EOPNOTSUPP;
	}

	kvm_x86_ops = ops;

	r = kvm_x86_ops->hardware_setup();
	if (r < 0)
		goto out;

	for_each_online_cpu(cpu) {
		smp_call_function_single(cpu,
				kvm_x86_ops->check_processor_compatibility,
				&r, 0, 1);
		if (r < 0)
			goto out_free_0;
	}

	on_each_cpu(hardware_enable, NULL, 0, 1);
	r = register_cpu_notifier(&kvm_cpu_notifier);
	if (r)
		goto out_free_1;
	register_reboot_notifier(&kvm_reboot_notifier);

	r = sysdev_class_register(&kvm_sysdev_class);
	if (r)
		goto out_free_2;

	r = sysdev_register(&kvm_sysdev);
	if (r)
		goto out_free_3;

	/* A kmem cache lets us meet the alignment requirements of fx_save. */
	kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size,
					   __alignof__(struct kvm_vcpu), 0, 0);
	if (!kvm_vcpu_cache) {
		r = -ENOMEM;
		goto out_free_4;
	}

	kvm_chardev_ops.owner = module;

	r = misc_register(&kvm_dev);
	if (r) {
		printk(KERN_ERR "kvm: misc device register failed\n");
		goto out_free;
	}

	kvm_preempt_ops.sched_in = kvm_sched_in;
	kvm_preempt_ops.sched_out = kvm_sched_out;

	kvm_mmu_set_nonpresent_ptes(0ull, 0ull);

	return 0;

out_free:
	kmem_cache_destroy(kvm_vcpu_cache);
out_free_4:
	sysdev_unregister(&kvm_sysdev);
out_free_3:
	sysdev_class_unregister(&kvm_sysdev_class);
out_free_2:
	unregister_reboot_notifier(&kvm_reboot_notifier);
	unregister_cpu_notifier(&kvm_cpu_notifier);
out_free_1:
	on_each_cpu(hardware_disable, NULL, 0, 1);
out_free_0:
	kvm_x86_ops->hardware_unsetup();
out:
	kvm_x86_ops = NULL;
	return r;
}
EXPORT_SYMBOL_GPL(kvm_init_x86);

void kvm_exit_x86(void)
{
	misc_deregister(&kvm_dev);
	kmem_cache_destroy(kvm_vcpu_cache);
	sysdev_unregister(&kvm_sysdev);
	sysdev_class_unregister(&kvm_sysdev_class);
	unregister_reboot_notifier(&kvm_reboot_notifier);
	unregister_cpu_notifier(&kvm_cpu_notifier);
	on_each_cpu(hardware_disable, NULL, 0, 1);
	kvm_x86_ops->hardware_unsetup();
	kvm_x86_ops = NULL;
}
EXPORT_SYMBOL_GPL(kvm_exit_x86);

static __init int kvm_init(void)
{
	int r;

	r = kvm_mmu_module_init();
	if (r)
		goto out4;

	kvm_init_debug();

	kvm_arch_init();

	bad_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

	if (bad_page == NULL) {
		r = -ENOMEM;
		goto out;
	}

	return 0;

out:
	kvm_exit_debug();
	kvm_mmu_module_exit();
out4:
	return r;
}

static __exit void kvm_exit(void)
{
	kvm_exit_debug();
	__free_page(bad_page);
	kvm_mmu_module_exit();
}

module_init(kvm_init)
module_exit(kvm_exit)