Merge remote-tracking branch 'devicetree/devicetree/next'

[linux-2.6/next.git] / virt / 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.
 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
 *
 * 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 "iodev.h"

#include <linux/kvm_host.h>
#include <linux/kvm.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/percpu.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/syscore_ops.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 <linux/swap.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/compat.h>
#include <linux/srcu.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>

#include <asm/processor.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>

#include "coalesced_mmio.h"
#include "async_pf.h"

#define CREATE_TRACE_POINTS
#include <trace/events/kvm.h>

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

/*
 * Ordering of locks:
 *
 *              kvm->lock --> kvm->slots_lock --> kvm->irq_lock
 */

DEFINE_RAW_SPINLOCK(kvm_lock);
LIST_HEAD(vm_list);

static cpumask_var_t cpus_hardware_enabled;
static int kvm_usage_count = 0;
static atomic_t hardware_enable_failed;

struct kmem_cache *kvm_vcpu_cache;
EXPORT_SYMBOL_GPL(kvm_vcpu_cache);

static __read_mostly struct preempt_ops kvm_preempt_ops;

struct dentry *kvm_debugfs_dir;

static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
                           unsigned long arg);
#ifdef CONFIG_COMPAT
static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
                                  unsigned long arg);
#endif
static int hardware_enable_all(void);
static void hardware_disable_all(void);

static void kvm_io_bus_destroy(struct kvm_io_bus *bus);

bool kvm_rebooting;
EXPORT_SYMBOL_GPL(kvm_rebooting);

static bool largepages_enabled = true;

static struct page *hwpoison_page;
static pfn_t hwpoison_pfn;

struct page *fault_page;
pfn_t fault_pfn;

inline int kvm_is_mmio_pfn(pfn_t pfn)
{
        if (pfn_valid(pfn)) {
                int reserved;
                struct page *tail = pfn_to_page(pfn);
                struct page *head = compound_trans_head(tail);
                reserved = PageReserved(head);
                if (head != tail) {
                        /*
                         * "head" is not a dangling pointer
                         * (compound_trans_head takes care of that)
                         * but the hugepage may have been splitted
                         * from under us (and we may not hold a
                         * reference count on the head page so it can
                         * be reused before we run PageReferenced), so
                         * we've to check PageTail before returning
                         * what we just read.
                         */
                        smp_rmb();
                        if (PageTail(tail))
                                return reserved;
                }
                return PageReserved(tail);
        }

        return true;
}

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

        mutex_lock(&vcpu->mutex);
        if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) {
                /* The thread running this VCPU changed. */
                struct pid *oldpid = vcpu->pid;
                struct pid *newpid = get_task_pid(current, PIDTYPE_PID);
                rcu_assign_pointer(vcpu->pid, newpid);
                synchronize_rcu();
                put_pid(oldpid);
        }
        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)
{
}

static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
{
        int i, cpu, me;
        cpumask_var_t cpus;
        bool called = true;
        struct kvm_vcpu *vcpu;

        zalloc_cpumask_var(&cpus, GFP_ATOMIC);

        me = get_cpu();
        kvm_for_each_vcpu(i, vcpu, kvm) {
                kvm_make_request(req, vcpu);
                cpu = vcpu->cpu;

                /* Set ->requests bit before we read ->mode */
                smp_mb();

                if (cpus != NULL && cpu != -1 && cpu != me &&
                      kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE)
                        cpumask_set_cpu(cpu, cpus);
        }
        if (unlikely(cpus == NULL))
                smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1);
        else if (!cpumask_empty(cpus))
                smp_call_function_many(cpus, ack_flush, NULL, 1);
        else
                called = false;
        put_cpu();
        free_cpumask_var(cpus);
        return called;
}

void kvm_flush_remote_tlbs(struct kvm *kvm)
{
        int dirty_count = kvm->tlbs_dirty;

        smp_mb();
        if (make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
                ++kvm->stat.remote_tlb_flush;
        cmpxchg(&kvm->tlbs_dirty, dirty_count, 0);
}

void kvm_reload_remote_mmus(struct kvm *kvm)
{
        make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
}

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->kvm = kvm;
        vcpu->vcpu_id = id;
        vcpu->pid = NULL;
        init_waitqueue_head(&vcpu->wq);
        kvm_async_pf_vcpu_init(vcpu);

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

        r = kvm_arch_vcpu_init(vcpu);
        if (r < 0)
                goto fail_free_run;
        return 0;

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)
{
        put_pid(vcpu->pid);
        kvm_arch_vcpu_uninit(vcpu);
        free_page((unsigned long)vcpu->run);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);

#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn)
{
        return container_of(mn, struct kvm, mmu_notifier);
}

static void kvm_mmu_notifier_invalidate_page(struct mmu_notifier *mn,
                                             struct mm_struct *mm,
                                             unsigned long address)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);
        int need_tlb_flush, idx;

        /*
         * When ->invalidate_page runs, the linux pte has been zapped
         * already but the page is still allocated until
         * ->invalidate_page returns. So if we increase the sequence
         * here the kvm page fault will notice if the spte can't be
         * established because the page is going to be freed. If
         * instead the kvm page fault establishes the spte before
         * ->invalidate_page runs, kvm_unmap_hva will release it
         * before returning.
         *
         * The sequence increase only need to be seen at spin_unlock
         * time, and not at spin_lock time.
         *
         * Increasing the sequence after the spin_unlock would be
         * unsafe because the kvm page fault could then establish the
         * pte after kvm_unmap_hva returned, without noticing the page
         * is going to be freed.
         */
        idx = srcu_read_lock(&kvm->srcu);
        spin_lock(&kvm->mmu_lock);
        kvm->mmu_notifier_seq++;
        need_tlb_flush = kvm_unmap_hva(kvm, address) | kvm->tlbs_dirty;
        spin_unlock(&kvm->mmu_lock);
        srcu_read_unlock(&kvm->srcu, idx);

        /* we've to flush the tlb before the pages can be freed */
        if (need_tlb_flush)
                kvm_flush_remote_tlbs(kvm);

}

static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
                                        struct mm_struct *mm,
                                        unsigned long address,
                                        pte_t pte)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);
        int idx;

        idx = srcu_read_lock(&kvm->srcu);
        spin_lock(&kvm->mmu_lock);
        kvm->mmu_notifier_seq++;
        kvm_set_spte_hva(kvm, address, pte);
        spin_unlock(&kvm->mmu_lock);
        srcu_read_unlock(&kvm->srcu, idx);
}

static void kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
                                                    struct mm_struct *mm,
                                                    unsigned long start,
                                                    unsigned long end)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);
        int need_tlb_flush = 0, idx;

        idx = srcu_read_lock(&kvm->srcu);
        spin_lock(&kvm->mmu_lock);
        /*
         * The count increase must become visible at unlock time as no
         * spte can be established without taking the mmu_lock and
         * count is also read inside the mmu_lock critical section.
         */
        kvm->mmu_notifier_count++;
        for (; start < end; start += PAGE_SIZE)
                need_tlb_flush |= kvm_unmap_hva(kvm, start);
        need_tlb_flush |= kvm->tlbs_dirty;
        spin_unlock(&kvm->mmu_lock);
        srcu_read_unlock(&kvm->srcu, idx);

        /* we've to flush the tlb before the pages can be freed */
        if (need_tlb_flush)
                kvm_flush_remote_tlbs(kvm);
}

static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
                                                  struct mm_struct *mm,
                                                  unsigned long start,
                                                  unsigned long end)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);

        spin_lock(&kvm->mmu_lock);
        /*
         * This sequence increase will notify the kvm page fault that
         * the page that is going to be mapped in the spte could have
         * been freed.
         */
        kvm->mmu_notifier_seq++;
        /*
         * The above sequence increase must be visible before the
         * below count decrease but both values are read by the kvm
         * page fault under mmu_lock spinlock so we don't need to add
         * a smb_wmb() here in between the two.
         */
        kvm->mmu_notifier_count--;
        spin_unlock(&kvm->mmu_lock);

        BUG_ON(kvm->mmu_notifier_count < 0);
}

static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
                                              struct mm_struct *mm,
                                              unsigned long address)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);
        int young, idx;

        idx = srcu_read_lock(&kvm->srcu);
        spin_lock(&kvm->mmu_lock);
        young = kvm_age_hva(kvm, address);
        spin_unlock(&kvm->mmu_lock);
        srcu_read_unlock(&kvm->srcu, idx);

        if (young)
                kvm_flush_remote_tlbs(kvm);

        return young;
}

static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
                                       struct mm_struct *mm,
                                       unsigned long address)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);
        int young, idx;

        idx = srcu_read_lock(&kvm->srcu);
        spin_lock(&kvm->mmu_lock);
        young = kvm_test_age_hva(kvm, address);
        spin_unlock(&kvm->mmu_lock);
        srcu_read_unlock(&kvm->srcu, idx);

        return young;
}

static void kvm_mmu_notifier_release(struct mmu_notifier *mn,
                                     struct mm_struct *mm)
{
        struct kvm *kvm = mmu_notifier_to_kvm(mn);
        int idx;

        idx = srcu_read_lock(&kvm->srcu);
        kvm_arch_flush_shadow(kvm);
        srcu_read_unlock(&kvm->srcu, idx);
}

static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
        .invalidate_page        = kvm_mmu_notifier_invalidate_page,
        .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start,
        .invalidate_range_end   = kvm_mmu_notifier_invalidate_range_end,
        .clear_flush_young      = kvm_mmu_notifier_clear_flush_young,
        .test_young             = kvm_mmu_notifier_test_young,
        .change_pte             = kvm_mmu_notifier_change_pte,
        .release                = kvm_mmu_notifier_release,
};

static int kvm_init_mmu_notifier(struct kvm *kvm)
{
        kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops;
        return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
}

#else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */

static int kvm_init_mmu_notifier(struct kvm *kvm)
{
        return 0;
}

#endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */

static struct kvm *kvm_create_vm(void)
{
        int r, i;
        struct kvm *kvm = kvm_arch_alloc_vm();

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

        r = kvm_arch_init_vm(kvm);
        if (r)
                goto out_err_nodisable;

        r = hardware_enable_all();
        if (r)
                goto out_err_nodisable;

#ifdef CONFIG_HAVE_KVM_IRQCHIP
        INIT_HLIST_HEAD(&kvm->mask_notifier_list);
        INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
#endif

        r = -ENOMEM;
        kvm->memslots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
        if (!kvm->memslots)
                goto out_err_nosrcu;
        if (init_srcu_struct(&kvm->srcu))
                goto out_err_nosrcu;
        for (i = 0; i < KVM_NR_BUSES; i++) {
                kvm->buses[i] = kzalloc(sizeof(struct kvm_io_bus),
                                        GFP_KERNEL);
                if (!kvm->buses[i])
                        goto out_err;
        }

        spin_lock_init(&kvm->mmu_lock);
        kvm->mm = current->mm;
        atomic_inc(&kvm->mm->mm_count);
        kvm_eventfd_init(kvm);
        mutex_init(&kvm->lock);
        mutex_init(&kvm->irq_lock);
        mutex_init(&kvm->slots_lock);
        atomic_set(&kvm->users_count, 1);

        r = kvm_init_mmu_notifier(kvm);
        if (r)
                goto out_err;

        raw_spin_lock(&kvm_lock);
        list_add(&kvm->vm_list, &vm_list);
        raw_spin_unlock(&kvm_lock);

        return kvm;

out_err:
        cleanup_srcu_struct(&kvm->srcu);
out_err_nosrcu:
        hardware_disable_all();
out_err_nodisable:
        for (i = 0; i < KVM_NR_BUSES; i++)
                kfree(kvm->buses[i]);
        kfree(kvm->memslots);
        kvm_arch_free_vm(kvm);
        return ERR_PTR(r);
}

static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
{
        if (!memslot->dirty_bitmap)
                return;

        if (2 * kvm_dirty_bitmap_bytes(memslot) > PAGE_SIZE)
                vfree(memslot->dirty_bitmap_head);
        else
                kfree(memslot->dirty_bitmap_head);

        memslot->dirty_bitmap = NULL;
        memslot->dirty_bitmap_head = NULL;
}

/*
 * 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)
{
        int i;

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

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


        for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i) {
                if (!dont || free->lpage_info[i] != dont->lpage_info[i]) {
                        vfree(free->lpage_info[i]);
                        free->lpage_info[i] = NULL;
                }
        }

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

void kvm_free_physmem(struct kvm *kvm)
{
        int i;
        struct kvm_memslots *slots = kvm->memslots;

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

        kfree(kvm->memslots);
}

static void kvm_destroy_vm(struct kvm *kvm)
{
        int i;
        struct mm_struct *mm = kvm->mm;

        kvm_arch_sync_events(kvm);
        raw_spin_lock(&kvm_lock);
        list_del(&kvm->vm_list);
        raw_spin_unlock(&kvm_lock);
        kvm_free_irq_routing(kvm);
        for (i = 0; i < KVM_NR_BUSES; i++)
                kvm_io_bus_destroy(kvm->buses[i]);
        kvm_coalesced_mmio_free(kvm);
#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
        mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
#else
        kvm_arch_flush_shadow(kvm);
#endif
        kvm_arch_destroy_vm(kvm);
        kvm_free_physmem(kvm);
        cleanup_srcu_struct(&kvm->srcu);
        kvm_arch_free_vm(kvm);
        hardware_disable_all();
        mmdrop(mm);
}

void kvm_get_kvm(struct kvm *kvm)
{
        atomic_inc(&kvm->users_count);
}
EXPORT_SYMBOL_GPL(kvm_get_kvm);

void kvm_put_kvm(struct kvm *kvm)
{
        if (atomic_dec_and_test(&kvm->users_count))
                kvm_destroy_vm(kvm);
}
EXPORT_SYMBOL_GPL(kvm_put_kvm);


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

        kvm_irqfd_release(kvm);

        kvm_put_kvm(kvm);
        return 0;
}

#ifndef CONFIG_S390
/*
 * Allocation size is twice as large as the actual dirty bitmap size.
 * This makes it possible to do double buffering: see x86's
 * kvm_vm_ioctl_get_dirty_log().
 */
static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
{
        unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot);

        if (dirty_bytes > PAGE_SIZE)
                memslot->dirty_bitmap = vzalloc(dirty_bytes);
        else
                memslot->dirty_bitmap = kzalloc(dirty_bytes, GFP_KERNEL);

        if (!memslot->dirty_bitmap)
                return -ENOMEM;

        memslot->dirty_bitmap_head = memslot->dirty_bitmap;
        return 0;
}
#endif /* !CONFIG_S390 */

/*
 * 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 mmap_sem for write.
 */
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;
        struct kvm_memslots *slots, *old_memslots;

        r = -EINVAL;
        /* General sanity checks */
        if (mem->memory_size & (PAGE_SIZE - 1))
                goto out;
        if (mem->guest_phys_addr & (PAGE_SIZE - 1))
                goto out;
        /* We can read the guest memory with __xxx_user() later on. */
        if (user_alloc &&
            ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
             !access_ok(VERIFY_WRITE,
                        (void __user *)(unsigned long)mem->userspace_addr,
                        mem->memory_size)))
                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->memslots[mem->slot];
        base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
        npages = mem->memory_size >> PAGE_SHIFT;

        r = -EINVAL;
        if (npages > KVM_MEM_MAX_NR_PAGES)
                goto out;

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

        new = old = *memslot;

        new.id = mem->slot;
        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->memslots[i];

                if (s == memslot || !s->npages)
                        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 */
#ifndef CONFIG_S390
        if (npages && !new.rmap) {
                new.rmap = vzalloc(npages * sizeof(*new.rmap));

                if (!new.rmap)
                        goto out_free;

                new.user_alloc = user_alloc;
                new.userspace_addr = mem->userspace_addr;
        }
        if (!npages)
                goto skip_lpage;

        for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i) {
                unsigned long ugfn;
                unsigned long j;
                int lpages;
                int level = i + 2;

                /* Avoid unused variable warning if no large pages */
                (void)level;

                if (new.lpage_info[i])
                        continue;

                lpages = 1 + ((base_gfn + npages - 1)
                             >> KVM_HPAGE_GFN_SHIFT(level));
                lpages -= base_gfn >> KVM_HPAGE_GFN_SHIFT(level);

                new.lpage_info[i] = vzalloc(lpages * sizeof(*new.lpage_info[i]));

                if (!new.lpage_info[i])
                        goto out_free;

                if (base_gfn & (KVM_PAGES_PER_HPAGE(level) - 1))
                        new.lpage_info[i][0].write_count = 1;
                if ((base_gfn+npages) & (KVM_PAGES_PER_HPAGE(level) - 1))
                        new.lpage_info[i][lpages - 1].write_count = 1;
                ugfn = new.userspace_addr >> PAGE_SHIFT;
                /*
                 * If the gfn and userspace address are not aligned wrt each
                 * other, or if explicitly asked to, disable large page
                 * support for this slot
                 */
                if ((base_gfn ^ ugfn) & (KVM_PAGES_PER_HPAGE(level) - 1) ||
                    !largepages_enabled)
                        for (j = 0; j < lpages; ++j)
                                new.lpage_info[i][j].write_count = 1;
        }

skip_lpage:

        /* Allocate page dirty bitmap if needed */
        if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
                if (kvm_create_dirty_bitmap(&new) < 0)
                        goto out_free;
                /* destroy any largepage mappings for dirty tracking */
        }
#else  /* not defined CONFIG_S390 */
        new.user_alloc = user_alloc;
        if (user_alloc)
                new.userspace_addr = mem->userspace_addr;
#endif /* not defined CONFIG_S390 */

        if (!npages) {
                r = -ENOMEM;
                slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
                if (!slots)
                        goto out_free;
                memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
                if (mem->slot >= slots->nmemslots)
                        slots->nmemslots = mem->slot + 1;
                slots->generation++;
                slots->memslots[mem->slot].flags |= KVM_MEMSLOT_INVALID;

                old_memslots = kvm->memslots;
                rcu_assign_pointer(kvm->memslots, slots);
                synchronize_srcu_expedited(&kvm->srcu);
                /* From this point no new shadow pages pointing to a deleted
                 * memslot will be created.
                 *
                 * validation of sp->gfn happens in:
                 *      - gfn_to_hva (kvm_read_guest, gfn_to_pfn)
                 *      - kvm_is_visible_gfn (mmu_check_roots)
                 */
                kvm_arch_flush_shadow(kvm);
                kfree(old_memslots);
        }

        r = kvm_arch_prepare_memory_region(kvm, &new, old, mem, user_alloc);
        if (r)
                goto out_free;

        /* map the pages in iommu page table */
        if (npages) {
                r = kvm_iommu_map_pages(kvm, &new);
                if (r)
                        goto out_free;
        }

        r = -ENOMEM;
        slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
        if (!slots)
                goto out_free;
        memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
        if (mem->slot >= slots->nmemslots)
                slots->nmemslots = mem->slot + 1;
        slots->generation++;

        /* actual memory is freed via old in kvm_free_physmem_slot below */
        if (!npages) {
                new.rmap = NULL;
                new.dirty_bitmap = NULL;
                for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i)
                        new.lpage_info[i] = NULL;
        }

        slots->memslots[mem->slot] = new;
        old_memslots = kvm->memslots;
        rcu_assign_pointer(kvm->memslots, slots);
        synchronize_srcu_expedited(&kvm->srcu);

        kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);

        /*
         * If the new memory slot is created, we need to clear all
         * mmio sptes.
         */
        if (npages && old.base_gfn != mem->guest_phys_addr >> PAGE_SHIFT)
                kvm_arch_flush_shadow(kvm);

        kvm_free_physmem_slot(&old, &new);
        kfree(old_memslots);

        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->slots_lock);
        r = __kvm_set_memory_region(kvm, mem, user_alloc);
        mutex_unlock(&kvm->slots_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);
}

int kvm_get_dirty_log(struct kvm *kvm,
                        struct kvm_dirty_log *log, int *is_dirty)
{
        struct kvm_memory_slot *memslot;
        int r, i;
        unsigned long n;
        unsigned long any = 0;

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

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

        n = kvm_dirty_bitmap_bytes(memslot);

        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 (any)
                *is_dirty = 1;

        r = 0;
out:
        return r;
}

void kvm_disable_largepages(void)
{
        largepages_enabled = false;
}
EXPORT_SYMBOL_GPL(kvm_disable_largepages);

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

int is_error_pfn(pfn_t pfn)
{
        return pfn == bad_pfn || pfn == hwpoison_pfn || pfn == fault_pfn;
}
EXPORT_SYMBOL_GPL(is_error_pfn);

int is_hwpoison_pfn(pfn_t pfn)
{
        return pfn == hwpoison_pfn;
}
EXPORT_SYMBOL_GPL(is_hwpoison_pfn);

int is_fault_pfn(pfn_t pfn)
{
        return pfn == fault_pfn;
}
EXPORT_SYMBOL_GPL(is_fault_pfn);

int is_noslot_pfn(pfn_t pfn)
{
        return pfn == bad_pfn;
}
EXPORT_SYMBOL_GPL(is_noslot_pfn);

int is_invalid_pfn(pfn_t pfn)
{
        return pfn == hwpoison_pfn || pfn == fault_pfn;
}
EXPORT_SYMBOL_GPL(is_invalid_pfn);

static inline unsigned long bad_hva(void)
{
        return PAGE_OFFSET;
}

int kvm_is_error_hva(unsigned long addr)
{
        return addr == bad_hva();
}
EXPORT_SYMBOL_GPL(kvm_is_error_hva);

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

        for (i = 0; i < slots->nmemslots; ++i) {
                struct kvm_memory_slot *memslot = &slots->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)
{
        return __gfn_to_memslot(kvm_memslots(kvm), gfn);
}
EXPORT_SYMBOL_GPL(gfn_to_memslot);

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

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

                if (memslot->flags & KVM_MEMSLOT_INVALID)
                        continue;

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

unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
{
        struct vm_area_struct *vma;
        unsigned long addr, size;

        size = PAGE_SIZE;

        addr = gfn_to_hva(kvm, gfn);
        if (kvm_is_error_hva(addr))
                return PAGE_SIZE;

        down_read(&current->mm->mmap_sem);
        vma = find_vma(current->mm, addr);
        if (!vma)
                goto out;

        size = vma_kernel_pagesize(vma);

out:
        up_read(&current->mm->mmap_sem);

        return size;
}

static unsigned long gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn,
                                     gfn_t *nr_pages)
{
        if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
                return bad_hva();

        if (nr_pages)
                *nr_pages = slot->npages - (gfn - slot->base_gfn);

        return gfn_to_hva_memslot(slot, gfn);
}

unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
{
        return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_hva);

static pfn_t get_fault_pfn(void)
{
        get_page(fault_page);
        return fault_pfn;
}

int get_user_page_nowait(struct task_struct *tsk, struct mm_struct *mm,
        unsigned long start, int write, struct page **page)
{
        int flags = FOLL_TOUCH | FOLL_NOWAIT | FOLL_HWPOISON | FOLL_GET;

        if (write)
                flags |= FOLL_WRITE;

        return __get_user_pages(tsk, mm, start, 1, flags, page, NULL, NULL);
}

static inline int check_user_page_hwpoison(unsigned long addr)
{
        int rc, flags = FOLL_TOUCH | FOLL_HWPOISON | FOLL_WRITE;

        rc = __get_user_pages(current, current->mm, addr, 1,
                              flags, NULL, NULL, NULL);
        return rc == -EHWPOISON;
}

static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
                        bool *async, bool write_fault, bool *writable)
{
        struct page *page[1];
        int npages = 0;
        pfn_t pfn;

        /* we can do it either atomically or asynchronously, not both */
        BUG_ON(atomic && async);

        BUG_ON(!write_fault && !writable);

        if (writable)
                *writable = true;

        if (atomic || async)
                npages = __get_user_pages_fast(addr, 1, 1, page);

        if (unlikely(npages != 1) && !atomic) {
                might_sleep();

                if (writable)
                        *writable = write_fault;

                if (async) {
                        down_read(&current->mm->mmap_sem);
                        npages = get_user_page_nowait(current, current->mm,
                                                     addr, write_fault, page);
                        up_read(&current->mm->mmap_sem);
                } else
                        npages = get_user_pages_fast(addr, 1, write_fault,
                                                     page);

                /* map read fault as writable if possible */
                if (unlikely(!write_fault) && npages == 1) {
                        struct page *wpage[1];

                        npages = __get_user_pages_fast(addr, 1, 1, wpage);
                        if (npages == 1) {
                                *writable = true;
                                put_page(page[0]);
                                page[0] = wpage[0];
                        }
                        npages = 1;
                }
        }

        if (unlikely(npages != 1)) {
                struct vm_area_struct *vma;

                if (atomic)
                        return get_fault_pfn();

                down_read(&current->mm->mmap_sem);
                if (npages == -EHWPOISON ||
                        (!async && check_user_page_hwpoison(addr))) {
                        up_read(&current->mm->mmap_sem);
                        get_page(hwpoison_page);
                        return page_to_pfn(hwpoison_page);
                }

                vma = find_vma_intersection(current->mm, addr, addr+1);

                if (vma == NULL)
                        pfn = get_fault_pfn();
                else if ((vma->vm_flags & VM_PFNMAP)) {
                        pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) +
                                vma->vm_pgoff;
                        BUG_ON(!kvm_is_mmio_pfn(pfn));
                } else {
                        if (async && (vma->vm_flags & VM_WRITE))
                                *async = true;
                        pfn = get_fault_pfn();
                }
                up_read(&current->mm->mmap_sem);
        } else
                pfn = page_to_pfn(page[0]);

        return pfn;
}

pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr)
{
        return hva_to_pfn(kvm, addr, true, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(hva_to_pfn_atomic);

static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async,
                          bool write_fault, bool *writable)
{
        unsigned long addr;

        if (async)
                *async = false;

        addr = gfn_to_hva(kvm, gfn);
        if (kvm_is_error_hva(addr)) {
                get_page(bad_page);
                return page_to_pfn(bad_page);
        }

        return hva_to_pfn(kvm, addr, atomic, async, write_fault, writable);
}

pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
{
        return __gfn_to_pfn(kvm, gfn, true, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);

pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async,
                       bool write_fault, bool *writable)
{
        return __gfn_to_pfn(kvm, gfn, false, async, write_fault, writable);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_async);

pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
{
        return __gfn_to_pfn(kvm, gfn, false, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn);

pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
                      bool *writable)
{
        return __gfn_to_pfn(kvm, gfn, false, NULL, write_fault, writable);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);

pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
                         struct kvm_memory_slot *slot, gfn_t gfn)
{
        unsigned long addr = gfn_to_hva_memslot(slot, gfn);
        return hva_to_pfn(kvm, addr, false, NULL, true, NULL);
}

int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,
                                                                  int nr_pages)
{
        unsigned long addr;
        gfn_t entry;

        addr = gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, &entry);
        if (kvm_is_error_hva(addr))
                return -1;

        if (entry < nr_pages)
                return 0;

        return __get_user_pages_fast(addr, nr_pages, 1, pages);
}
EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);

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

        pfn = gfn_to_pfn(kvm, gfn);
        if (!kvm_is_mmio_pfn(pfn))
                return pfn_to_page(pfn);

        WARN_ON(kvm_is_mmio_pfn(pfn));

        get_page(bad_page);
        return bad_page;
}

EXPORT_SYMBOL_GPL(gfn_to_page);

void kvm_release_page_clean(struct page *page)
{
        kvm_release_pfn_clean(page_to_pfn(page));
}
EXPORT_SYMBOL_GPL(kvm_release_page_clean);

void kvm_release_pfn_clean(pfn_t pfn)
{
        if (!kvm_is_mmio_pfn(pfn))
                put_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);

void kvm_release_page_dirty(struct page *page)
{
        kvm_release_pfn_dirty(page_to_pfn(page));
}
EXPORT_SYMBOL_GPL(kvm_release_page_dirty);

void kvm_release_pfn_dirty(pfn_t pfn)
{
        kvm_set_pfn_dirty(pfn);
        kvm_release_pfn_clean(pfn);
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_dirty);

void kvm_set_page_dirty(struct page *page)
{
        kvm_set_pfn_dirty(page_to_pfn(page));
}
EXPORT_SYMBOL_GPL(kvm_set_page_dirty);

void kvm_set_pfn_dirty(pfn_t pfn)
{
        if (!kvm_is_mmio_pfn(pfn)) {
                struct page *page = pfn_to_page(pfn);
                if (!PageReserved(page))
                        SetPageDirty(page);
        }
}
EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);

void kvm_set_pfn_accessed(pfn_t pfn)
{
        if (!kvm_is_mmio_pfn(pfn))
                mark_page_accessed(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);

void kvm_get_pfn(pfn_t pfn)
{
        if (!kvm_is_mmio_pfn(pfn))
                get_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_get_pfn);

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)
{
        int r;
        unsigned long addr;

        addr = gfn_to_hva(kvm, gfn);
        if (kvm_is_error_hva(addr))
                return -EFAULT;
        r = __copy_from_user(data, (void __user *)addr + offset, len);
        if (r)
                return -EFAULT;
        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_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
                          unsigned long len)
{
        int r;
        unsigned long addr;
        gfn_t gfn = gpa >> PAGE_SHIFT;
        int offset = offset_in_page(gpa);

        addr = gfn_to_hva(kvm, gfn);
        if (kvm_is_error_hva(addr))
                return -EFAULT;
        pagefault_disable();
        r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
        pagefault_enable();
        if (r)
                return -EFAULT;
        return 0;
}
EXPORT_SYMBOL(kvm_read_guest_atomic);

int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
                         int offset, int len)
{
        int r;
        unsigned long addr;

        addr = gfn_to_hva(kvm, gfn);
        if (kvm_is_error_hva(addr))
                return -EFAULT;
        r = __copy_to_user((void __user *)addr + offset, data, len);
        if (r)
                return -EFAULT;
        mark_page_dirty(kvm, gfn);
        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_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                              gpa_t gpa)
{
        struct kvm_memslots *slots = kvm_memslots(kvm);
        int offset = offset_in_page(gpa);
        gfn_t gfn = gpa >> PAGE_SHIFT;

        ghc->gpa = gpa;
        ghc->generation = slots->generation;
        ghc->memslot = __gfn_to_memslot(slots, gfn);
        ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL);
        if (!kvm_is_error_hva(ghc->hva))
                ghc->hva += offset;
        else
                return -EFAULT;

        return 0;
}
EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);

int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                           void *data, unsigned long len)
{
        struct kvm_memslots *slots = kvm_memslots(kvm);
        int r;

        if (slots->generation != ghc->generation)
                kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);

        if (kvm_is_error_hva(ghc->hva))
                return -EFAULT;

        r = __copy_to_user((void __user *)ghc->hva, data, len);
        if (r)
                return -EFAULT;
        mark_page_dirty_in_slot(kvm, ghc->memslot, ghc->gpa >> PAGE_SHIFT);

        return 0;
}
EXPORT_SYMBOL_GPL(kvm_write_guest_cached);

int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
                           void *data, unsigned long len)
{
        struct kvm_memslots *slots = kvm_memslots(kvm);
        int r;

        if (slots->generation != ghc->generation)
                kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);

        if (kvm_is_error_hva(ghc->hva))
                return -EFAULT;

        r = __copy_from_user(data, (void __user *)ghc->hva, len);
        if (r)
                return -EFAULT;

        return 0;
}
EXPORT_SYMBOL_GPL(kvm_read_guest_cached);

int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
{
        return kvm_write_guest_page(kvm, gfn, (const void *) empty_zero_page,
                                    offset, len);
}
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);

void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
                             gfn_t gfn)
{
        if (memslot && memslot->dirty_bitmap) {
                unsigned long rel_gfn = gfn - memslot->base_gfn;

                __set_bit_le(rel_gfn, memslot->dirty_bitmap);
        }
}

void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
{
        struct kvm_memory_slot *memslot;

        memslot = gfn_to_memslot(kvm, gfn);
        mark_page_dirty_in_slot(kvm, memslot, gfn);
}

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

        for (;;) {
                prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);

                if (kvm_arch_vcpu_runnable(vcpu)) {
                        kvm_make_request(KVM_REQ_UNHALT, vcpu);
                        break;
                }
                if (kvm_cpu_has_pending_timer(vcpu))
                        break;
                if (signal_pending(current))
                        break;

                schedule();
        }

        finish_wait(&vcpu->wq, &wait);
}

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

void kvm_vcpu_on_spin(struct kvm_vcpu *me)
{
        struct kvm *kvm = me->kvm;
        struct kvm_vcpu *vcpu;
        int last_boosted_vcpu = me->kvm->last_boosted_vcpu;
        int yielded = 0;
        int pass;
        int i;

        /*
         * We boost the priority of a VCPU that is runnable but not
         * currently running, because it got preempted by something
         * else and called schedule in __vcpu_run.  Hopefully that
         * VCPU is holding the lock that we need and will release it.
         * We approximate round-robin by starting at the last boosted VCPU.
         */
        for (pass = 0; pass < 2 && !yielded; pass++) {
                kvm_for_each_vcpu(i, vcpu, kvm) {
                        struct task_struct *task = NULL;
                        struct pid *pid;
                        if (!pass && i < last_boosted_vcpu) {
                                i = last_boosted_vcpu;
                                continue;
                        } else if (pass && i > last_boosted_vcpu)
                                break;
                        if (vcpu == me)
                                continue;
                        if (waitqueue_active(&vcpu->wq))
                                continue;
                        rcu_read_lock();
                        pid = rcu_dereference(vcpu->pid);
                        if (pid)
                                task = get_pid_task(vcpu->pid, PIDTYPE_PID);
                        rcu_read_unlock();
                        if (!task)
                                continue;
                        if (task->flags & PF_VCPU) {
                                put_task_struct(task);
                                continue;
                        }
                        if (yield_to(task, 1)) {
                                put_task_struct(task);
                                kvm->last_boosted_vcpu = i;
                                yielded = 1;
                                break;
                        }
                        put_task_struct(task);
                }
        }
}
EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);

static int kvm_vcpu_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct kvm_vcpu *vcpu = vma->vm_file->private_data;
        struct page *page;

        if (vmf->pgoff == 0)
                page = virt_to_page(vcpu->run);
#ifdef CONFIG_X86
        else if (vmf->pgoff == KVM_PIO_PAGE_OFFSET)
                page = virt_to_page(vcpu->arch.pio_data);
#endif
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
        else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET)
                page = virt_to_page(vcpu->kvm->coalesced_mmio_ring);
#endif
        else
                return VM_FAULT_SIGBUS;
        get_page(page);
        vmf->page = page;
        return 0;
}

static const struct vm_operations_struct kvm_vcpu_vm_ops = {
        .fault = kvm_vcpu_fault,
};

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;

        kvm_put_kvm(vcpu->kvm);
        return 0;
}

static struct file_operations kvm_vcpu_fops = {
        .release        = kvm_vcpu_release,
        .unlocked_ioctl = kvm_vcpu_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = kvm_vcpu_compat_ioctl,
#endif
        .mmap           = kvm_vcpu_mmap,
        .llseek         = noop_llseek,
};

/*
 * Allocates an inode for the vcpu.
 */
static int create_vcpu_fd(struct kvm_vcpu *vcpu)
{
        return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, O_RDWR);
}

/*
 * Creates some virtual cpus.  Good luck creating more than one.
 */
static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
{
        int r;
        struct kvm_vcpu *vcpu, *v;

        vcpu = kvm_arch_vcpu_create(kvm, id);
        if (IS_ERR(vcpu))
                return PTR_ERR(vcpu);

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

        r = kvm_arch_vcpu_setup(vcpu);
        if (r)
                goto vcpu_destroy;

        mutex_lock(&kvm->lock);
        if (atomic_read(&kvm->online_vcpus) == KVM_MAX_VCPUS) {
                r = -EINVAL;
                goto unlock_vcpu_destroy;
        }

        kvm_for_each_vcpu(r, v, kvm)
                if (v->vcpu_id == id) {
                        r = -EEXIST;
                        goto unlock_vcpu_destroy;
                }

        BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);

        /* Now it's all set up, let userspace reach it */
        kvm_get_kvm(kvm);
        r = create_vcpu_fd(vcpu);
        if (r < 0) {
                kvm_put_kvm(kvm);
                goto unlock_vcpu_destroy;
        }

        kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
        smp_wmb();
        atomic_inc(&kvm->online_vcpus);

#ifdef CONFIG_KVM_APIC_ARCHITECTURE
        if (kvm->bsp_vcpu_id == id)
                kvm->bsp_vcpu = vcpu;
#endif
        mutex_unlock(&kvm->lock);
        return r;

unlock_vcpu_destroy:
        mutex_unlock(&kvm->lock);
vcpu_destroy:
        kvm_arch_vcpu_destroy(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;
}

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;
        struct kvm_fpu *fpu = NULL;
        struct kvm_sregs *kvm_sregs = NULL;

        if (vcpu->kvm->mm != current->mm)
                return -EIO;

#if defined(CONFIG_S390) || defined(CONFIG_PPC)
        /*
         * Special cases: vcpu ioctls that are asynchronous to vcpu execution,
         * so vcpu_load() would break it.
         */
        if (ioctl == KVM_S390_INTERRUPT || ioctl == KVM_INTERRUPT)
                return kvm_arch_vcpu_ioctl(filp, ioctl, arg);
#endif


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

                r = -ENOMEM;
                kvm_regs = kzalloc(sizeof(struct kvm_regs), GFP_KERNEL);
                if (!kvm_regs)
                        goto out;
                r = kvm_arch_vcpu_ioctl_get_regs(vcpu, kvm_regs);
                if (r)
                        goto out_free1;
                r = -EFAULT;
                if (copy_to_user(argp, kvm_regs, sizeof(struct kvm_regs)))
                        goto out_free1;
                r = 0;
out_free1:
                kfree(kvm_regs);
                break;
        }
        case KVM_SET_REGS: {
                struct kvm_regs *kvm_regs;

                r = -ENOMEM;
                kvm_regs = kzalloc(sizeof(struct kvm_regs), GFP_KERNEL);
                if (!kvm_regs)
                        goto out;
                r = -EFAULT;
                if (copy_from_user(kvm_regs, argp, sizeof(struct kvm_regs)))
                        goto out_free2;
                r = kvm_arch_vcpu_ioctl_set_regs(vcpu, kvm_regs);
                if (r)
                        goto out_free2;
                r = 0;
out_free2:
                kfree(kvm_regs);
                break;
        }
        case KVM_GET_SREGS: {
                kvm_sregs = kzalloc(sizeof(struct kvm_sregs), GFP_KERNEL);
                r = -ENOMEM;
                if (!kvm_sregs)
                        goto out;
                r = kvm_arch_vcpu_ioctl_get_sregs(vcpu, kvm_sregs);
                if (r)
                        goto out;
                r = -EFAULT;
                if (copy_to_user(argp, kvm_sregs, sizeof(struct kvm_sregs)))
                        goto out;
                r = 0;
                break;
        }
        case KVM_SET_SREGS: {
                kvm_sregs = kmalloc(sizeof(struct kvm_sregs), GFP_KERNEL);
                r = -ENOMEM;
                if (!kvm_sregs)
                        goto out;
                r = -EFAULT;
                if (copy_from_user(kvm_sregs, argp, sizeof(struct kvm_sregs)))
                        goto out;
                r = kvm_arch_vcpu_ioctl_set_sregs(vcpu, kvm_sregs);
                if (r)
                        goto out;
                r = 0;
                break;
        }
        case KVM_GET_MP_STATE: {
                struct kvm_mp_state mp_state;

                r = kvm_arch_vcpu_ioctl_get_mpstate(vcpu, &mp_state);
                if (r)
                        goto out;
                r = -EFAULT;
                if (copy_to_user(argp, &mp_state, sizeof mp_state))
                        goto out;
                r = 0;
                break;
        }
        case KVM_SET_MP_STATE: {
                struct kvm_mp_state mp_state;

                r = -EFAULT;
                if (copy_from_user(&mp_state, argp, sizeof mp_state))
                        goto out;
                r = kvm_arch_vcpu_ioctl_set_mpstate(vcpu, &mp_state);
                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_arch_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_SET_GUEST_DEBUG: {
                struct kvm_guest_debug dbg;

                r = -EFAULT;
                if (copy_from_user(&dbg, argp, sizeof dbg))
                        goto out;
                r = kvm_arch_vcpu_ioctl_set_guest_debug(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, p);
                break;
        }
        case KVM_GET_FPU: {
                fpu = kzalloc(sizeof(struct kvm_fpu), GFP_KERNEL);
                r = -ENOMEM;
                if (!fpu)
                        goto out;
                r = kvm_arch_vcpu_ioctl_get_fpu(vcpu, fpu);
                if (r)
                        goto out;
                r = -EFAULT;
                if (copy_to_user(argp, fpu, sizeof(struct kvm_fpu)))
                        goto out;
                r = 0;
                break;
        }
        case KVM_SET_FPU: {
                fpu = kmalloc(sizeof(struct kvm_fpu), GFP_KERNEL);
                r = -ENOMEM;
                if (!fpu)
                        goto out;
                r = -EFAULT;
                if (copy_from_user(fpu, argp, sizeof(struct kvm_fpu)))
                        goto out;
                r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu);
                if (r)
                        goto out;
                r = 0;
                break;
        }
        default:
                r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
        }
out:
        vcpu_put(vcpu);
        kfree(fpu);
        kfree(kvm_sregs);
        return r;
}

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

        if (vcpu->kvm->mm != current->mm)
                return -EIO;

        switch (ioctl) {
        case KVM_SET_SIGNAL_MASK: {
                struct kvm_signal_mask __user *sigmask_arg = argp;
                struct kvm_signal_mask kvm_sigmask;
                compat_sigset_t csigset;
                sigset_t sigset;

                if (argp) {
                        r = -EFAULT;
                        if (copy_from_user(&kvm_sigmask, argp,
                                           sizeof kvm_sigmask))
                                goto out;
                        r = -EINVAL;
                        if (kvm_sigmask.len != sizeof csigset)
                                goto out;
                        r = -EFAULT;
                        if (copy_from_user(&csigset, sigmask_arg->sigset,
                                           sizeof csigset))
                                goto out;
                }
                sigset_from_compat(&sigset, &csigset);
                r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
                break;
        }
        default:
                r = kvm_vcpu_ioctl(filp, ioctl, arg);
        }

out:
        return r;
}
#endif

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;

        if (kvm->mm != current->mm)
                return -EIO;
        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;
        }
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
        case KVM_REGISTER_COALESCED_MMIO: {
                struct kvm_coalesced_mmio_zone zone;
                r = -EFAULT;
                if (copy_from_user(&zone, argp, sizeof zone))
                        goto out;
                r = kvm_vm_ioctl_register_coalesced_mmio(kvm, &zone);
                if (r)
                        goto out;
                r = 0;
                break;
        }
        case KVM_UNREGISTER_COALESCED_MMIO: {
                struct kvm_coalesced_mmio_zone zone;
                r = -EFAULT;
                if (copy_from_user(&zone, argp, sizeof zone))
                        goto out;
                r = kvm_vm_ioctl_unregister_coalesced_mmio(kvm, &zone);
                if (r)
                        goto out;
                r = 0;
                break;
        }
#endif
        case KVM_IRQFD: {
                struct kvm_irqfd data;

                r = -EFAULT;
                if (copy_from_user(&data, argp, sizeof data))
                        goto out;
                r = kvm_irqfd(kvm, data.fd, data.gsi, data.flags);
                break;
        }
        case KVM_IOEVENTFD: {
                struct kvm_ioeventfd data;

                r = -EFAULT;
                if (copy_from_user(&data, argp, sizeof data))
                        goto out;
                r = kvm_ioeventfd(kvm, &data);
                break;
        }
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
        case KVM_SET_BOOT_CPU_ID:
                r = 0;
                mutex_lock(&kvm->lock);
                if (atomic_read(&kvm->online_vcpus) != 0)
                        r = -EBUSY;
                else
                        kvm->bsp_vcpu_id = arg;
                mutex_unlock(&kvm->lock);
                break;
#endif
        default:
                r = kvm_arch_vm_ioctl(filp, ioctl, arg);
                if (r == -ENOTTY)
                        r = kvm_vm_ioctl_assigned_device(kvm, ioctl, arg);
        }
out:
        return r;
}

#ifdef CONFIG_COMPAT
struct compat_kvm_dirty_log {
        __u32 slot;
        __u32 padding1;
        union {
                compat_uptr_t dirty_bitmap; /* one bit per page */
                __u64 padding2;
        };
};

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

        if (kvm->mm != current->mm)
                return -EIO;
        switch (ioctl) {
        case KVM_GET_DIRTY_LOG: {
                struct compat_kvm_dirty_log compat_log;
                struct kvm_dirty_log log;

                r = -EFAULT;
                if (copy_from_user(&compat_log, (void __user *)arg,
                                   sizeof(compat_log)))
                        goto out;
                log.slot         = compat_log.slot;
                log.padding1     = compat_log.padding1;
                log.padding2     = compat_log.padding2;
                log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);

                r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
                if (r)
                        goto out;
                break;
        }
        default:
                r = kvm_vm_ioctl(filp, ioctl, arg);
        }

out:
        return r;
}
#endif

static int kvm_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct page *page[1];
        unsigned long addr;
        int npages;
        gfn_t gfn = vmf->pgoff;
        struct kvm *kvm = vma->vm_file->private_data;

        addr = gfn_to_hva(kvm, gfn);
        if (kvm_is_error_hva(addr))
                return VM_FAULT_SIGBUS;

        npages = get_user_pages(current, current->mm, addr, 1, 1, 0, page,
                                NULL);
        if (unlikely(npages != 1))
                return VM_FAULT_SIGBUS;

        vmf->page = page[0];
        return 0;
}

static const struct vm_operations_struct kvm_vm_vm_ops = {
        .fault = kvm_vm_fault,
};

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,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = kvm_vm_compat_ioctl,
#endif
        .mmap           = kvm_vm_mmap,
        .llseek         = noop_llseek,
};

static int kvm_dev_ioctl_create_vm(void)
{
        int r;
        struct kvm *kvm;

        kvm = kvm_create_vm();
        if (IS_ERR(kvm))
                return PTR_ERR(kvm);
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
        r = kvm_coalesced_mmio_init(kvm);
        if (r < 0) {
                kvm_put_kvm(kvm);
                return r;
        }
#endif
        r = anon_inode_getfd("kvm-vm", &kvm_vm_fops, kvm, O_RDWR);
        if (r < 0)
                kvm_put_kvm(kvm);

        return r;
}

static long kvm_dev_ioctl_check_extension_generic(long arg)
{
        switch (arg) {
        case KVM_CAP_USER_MEMORY:
        case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
        case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS:
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
        case KVM_CAP_SET_BOOT_CPU_ID:
#endif
        case KVM_CAP_INTERNAL_ERROR_DATA:
                return 1;
#ifdef CONFIG_HAVE_KVM_IRQCHIP
        case KVM_CAP_IRQ_ROUTING:
                return KVM_MAX_IRQ_ROUTES;
#endif
        default:
                break;
        }
        return kvm_dev_ioctl_check_extension(arg);
}

static long kvm_dev_ioctl(struct file *filp,
                          unsigned int ioctl, unsigned long 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:
                r = kvm_dev_ioctl_check_extension_generic(arg);
                break;
        case KVM_GET_VCPU_MMAP_SIZE:
                r = -EINVAL;
                if (arg)
                        goto out;
                r = PAGE_SIZE;     /* struct kvm_run */
#ifdef CONFIG_X86
                r += PAGE_SIZE;    /* pio data page */
#endif
#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
                r += PAGE_SIZE;    /* coalesced mmio ring page */
#endif
                break;
        case KVM_TRACE_ENABLE:
        case KVM_TRACE_PAUSE:
        case KVM_TRACE_DISABLE:
                r = -EOPNOTSUPP;
                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,
        .llseek         = noop_llseek,
};

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

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

        if (cpumask_test_cpu(cpu, cpus_hardware_enabled))
                return;

        cpumask_set_cpu(cpu, cpus_hardware_enabled);

        r = kvm_arch_hardware_enable(NULL);

        if (r) {
                cpumask_clear_cpu(cpu, cpus_hardware_enabled);
                atomic_inc(&hardware_enable_failed);
                printk(KERN_INFO "kvm: enabling virtualization on "
                                 "CPU%d failed\n", cpu);
        }
}

static void hardware_enable(void *junk)
{
        raw_spin_lock(&kvm_lock);
        hardware_enable_nolock(junk);
        raw_spin_unlock(&kvm_lock);
}

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

        if (!cpumask_test_cpu(cpu, cpus_hardware_enabled))
                return;
        cpumask_clear_cpu(cpu, cpus_hardware_enabled);
        kvm_arch_hardware_disable(NULL);
}

static void hardware_disable(void *junk)
{
        raw_spin_lock(&kvm_lock);
        hardware_disable_nolock(junk);
        raw_spin_unlock(&kvm_lock);
}

static void hardware_disable_all_nolock(void)
{
        BUG_ON(!kvm_usage_count);

        kvm_usage_count--;
        if (!kvm_usage_count)
                on_each_cpu(hardware_disable_nolock, NULL, 1);
}

static void hardware_disable_all(void)
{
        raw_spin_lock(&kvm_lock);
        hardware_disable_all_nolock();
        raw_spin_unlock(&kvm_lock);
}

static int hardware_enable_all(void)
{
        int r = 0;

        raw_spin_lock(&kvm_lock);

        kvm_usage_count++;
        if (kvm_usage_count == 1) {
                atomic_set(&hardware_enable_failed, 0);
                on_each_cpu(hardware_enable_nolock, NULL, 1);

                if (atomic_read(&hardware_enable_failed)) {
                        hardware_disable_all_nolock();
                        r = -EBUSY;
                }
        }

        raw_spin_unlock(&kvm_lock);

        return r;
}

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

        if (!kvm_usage_count)
                return NOTIFY_OK;

        val &= ~CPU_TASKS_FROZEN;
        switch (val) {
        case CPU_DYING:
                printk(KERN_INFO "kvm: disabling virtualization on CPU%d\n",
                       cpu);
                hardware_disable(NULL);
                break;
        case CPU_STARTING:
                printk(KERN_INFO "kvm: enabling virtualization on CPU%d\n",
                       cpu);
                hardware_enable(NULL);
                break;
        }
        return NOTIFY_OK;
}


asmlinkage void kvm_spurious_fault(void)
{
        /* Fault while not rebooting.  We want the trace. */
        BUG();
}
EXPORT_SYMBOL_GPL(kvm_spurious_fault);

static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
                      void *v)
{
        /*
         * Some (well, at least mine) BIOSes hang on reboot if
         * in vmx root mode.
         *
         * And Intel TXT required VMX off for all cpu when system shutdown.
         */
        printk(KERN_INFO "kvm: exiting hardware virtualization\n");
        kvm_rebooting = true;
        on_each_cpu(hardware_disable_nolock, NULL, 1);
        return NOTIFY_OK;
}

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

static 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);
        }
        kfree(bus);
}

/* kvm_io_bus_write - called under kvm->slots_lock */
int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
                     int len, const void *val)
{
        int i;
        struct kvm_io_bus *bus;

        bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
        for (i = 0; i < bus->dev_count; i++)
                if (!kvm_iodevice_write(bus->devs[i], addr, len, val))
                        return 0;
        return -EOPNOTSUPP;
}

/* kvm_io_bus_read - called under kvm->slots_lock */
int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
                    int len, void *val)
{
        int i;
        struct kvm_io_bus *bus;

        bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
        for (i = 0; i < bus->dev_count; i++)
                if (!kvm_iodevice_read(bus->devs[i], addr, len, val))
                        return 0;
        return -EOPNOTSUPP;
}

/* Caller must hold slots_lock. */
int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx,
                            struct kvm_io_device *dev)
{
        struct kvm_io_bus *new_bus, *bus;

        bus = kvm->buses[bus_idx];
        if (bus->dev_count > NR_IOBUS_DEVS-1)
                return -ENOSPC;

        new_bus = kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL);
        if (!new_bus)
                return -ENOMEM;
        memcpy(new_bus, bus, sizeof(struct kvm_io_bus));
        new_bus->devs[new_bus->dev_count++] = dev;
        rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
        synchronize_srcu_expedited(&kvm->srcu);
        kfree(bus);

        return 0;
}

/* Caller must hold slots_lock. */
int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
                              struct kvm_io_device *dev)
{
        int i, r;
        struct kvm_io_bus *new_bus, *bus;

        new_bus = kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL);
        if (!new_bus)
                return -ENOMEM;

        bus = kvm->buses[bus_idx];
        memcpy(new_bus, bus, sizeof(struct kvm_io_bus));

        r = -ENOENT;
        for (i = 0; i < new_bus->dev_count; i++)
                if (new_bus->devs[i] == dev) {
                        r = 0;
                        new_bus->devs[i] = new_bus->devs[--new_bus->dev_count];
                        break;
                }

        if (r) {
                kfree(new_bus);
                return r;
        }

        rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
        synchronize_srcu_expedited(&kvm->srcu);
        kfree(bus);
        return r;
}

static struct notifier_block kvm_cpu_notifier = {
        .notifier_call = kvm_cpu_hotplug,
};

static int vm_stat_get(void *_offset, u64 *val)
{
        unsigned offset = (long)_offset;
        struct kvm *kvm;

        *val = 0;
        raw_spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
                *val += *(u32 *)((void *)kvm + offset);
        raw_spin_unlock(&kvm_lock);
        return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(vm_stat_fops, vm_stat_get, NULL, "%llu\n");

static int vcpu_stat_get(void *_offset, u64 *val)
{
        unsigned offset = (long)_offset;
        struct kvm *kvm;
        struct kvm_vcpu *vcpu;
        int i;

        *val = 0;
        raw_spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
                kvm_for_each_vcpu(i, vcpu, kvm)
                        *val += *(u32 *)((void *)vcpu + offset);

        raw_spin_unlock(&kvm_lock);
        return 0;
}

DEFINE_SIMPLE_ATTRIBUTE(vcpu_stat_fops, vcpu_stat_get, NULL, "%llu\n");

static const struct file_operations *stat_fops[] = {
        [KVM_STAT_VCPU] = &vcpu_stat_fops,
        [KVM_STAT_VM]   = &vm_stat_fops,
};

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

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

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(kvm_debugfs_dir);
}

static int kvm_suspend(void)
{
        if (kvm_usage_count)
                hardware_disable_nolock(NULL);
        return 0;
}

static void kvm_resume(void)
{
        if (kvm_usage_count) {
                WARN_ON(raw_spin_is_locked(&kvm_lock));
                hardware_enable_nolock(NULL);
        }
}

static struct syscore_ops kvm_syscore_ops = {
        .suspend = kvm_suspend,
        .resume = kvm_resume,
};

struct page *bad_page;
pfn_t bad_pfn;

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_arch_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_arch_vcpu_put(vcpu);
}

int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
                  struct module *module)
{
        int r;
        int cpu;

        r = kvm_arch_init(opaque);
        if (r)
                goto out_fail;

        bad_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

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

        bad_pfn = page_to_pfn(bad_page);

        hwpoison_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

        if (hwpoison_page == NULL) {
                r = -ENOMEM;
                goto out_free_0;
        }

        hwpoison_pfn = page_to_pfn(hwpoison_page);

        fault_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

        if (fault_page == NULL) {
                r = -ENOMEM;
                goto out_free_0;
        }

        fault_pfn = page_to_pfn(fault_page);

        if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) {
                r = -ENOMEM;
                goto out_free_0;
        }

        r = kvm_arch_hardware_setup();
        if (r < 0)
                goto out_free_0a;

        for_each_online_cpu(cpu) {
                smp_call_function_single(cpu,
                                kvm_arch_check_processor_compat,
                                &r, 1);
                if (r < 0)
                        goto out_free_1;
        }

        r = register_cpu_notifier(&kvm_cpu_notifier);
        if (r)
                goto out_free_2;
        register_reboot_notifier(&kvm_reboot_notifier);

        /* A kmem cache lets us meet the alignment requirements of fx_save. */
        if (!vcpu_align)
                vcpu_align = __alignof__(struct kvm_vcpu);
        kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
                                           0, NULL);
        if (!kvm_vcpu_cache) {
                r = -ENOMEM;
                goto out_free_3;
        }

        r = kvm_async_pf_init();
        if (r)
                goto out_free;

        kvm_chardev_ops.owner = module;
        kvm_vm_fops.owner = module;
        kvm_vcpu_fops.owner = module;

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

        register_syscore_ops(&kvm_syscore_ops);

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

        kvm_init_debug();

        return 0;

out_unreg:
        kvm_async_pf_deinit();
out_free:
        kmem_cache_destroy(kvm_vcpu_cache);
out_free_3:
        unregister_reboot_notifier(&kvm_reboot_notifier);
        unregister_cpu_notifier(&kvm_cpu_notifier);
out_free_2:
out_free_1:
        kvm_arch_hardware_unsetup();
out_free_0a:
        free_cpumask_var(cpus_hardware_enabled);
out_free_0:
        if (fault_page)
                __free_page(fault_page);
        if (hwpoison_page)
                __free_page(hwpoison_page);
        __free_page(bad_page);
out:
        kvm_arch_exit();
out_fail:
        return r;
}
EXPORT_SYMBOL_GPL(kvm_init);

void kvm_exit(void)
{
        kvm_exit_debug();
        misc_deregister(&kvm_dev);
        kmem_cache_destroy(kvm_vcpu_cache);
        kvm_async_pf_deinit();
        unregister_syscore_ops(&kvm_syscore_ops);
        unregister_reboot_notifier(&kvm_reboot_notifier);
        unregister_cpu_notifier(&kvm_cpu_notifier);
        on_each_cpu(hardware_disable_nolock, NULL, 1);
        kvm_arch_hardware_unsetup();
        kvm_arch_exit();
        free_cpumask_var(cpus_hardware_enabled);
        __free_page(hwpoison_page);
        __free_page(bad_page);
}
EXPORT_SYMBOL_GPL(kvm_exit);