KVM: MMU: Selectively set PageDirty when releasing guest memory

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / 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 "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/io.h>
#include <asm/uaccess.h>
#include <asm/desc.h>
#include <asm/pgtable.h>

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

DEFINE_SPINLOCK(kvm_lock);
LIST_HEAD(vm_list);

static cpumask_t cpus_hardware_enabled;

struct kmem_cache *kvm_vcpu_cache;
EXPORT_SYMBOL_GPL(kvm_vcpu_cache);

static __read_mostly struct preempt_ops kvm_preempt_ops;

static struct dentry *debugfs_dir;

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);
}

/*
 * 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->kvm = kvm;
        vcpu->vcpu_id = id;
        init_waitqueue_head(&vcpu->wq);

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

static struct kvm *kvm_create_vm(void)
{
        struct kvm *kvm = kvm_arch_create_vm();

        if (IS_ERR(kvm))
                goto out;

        kvm_io_bus_init(&kvm->pio_bus);
        mutex_init(&kvm->lock);
        kvm_io_bus_init(&kvm->mmio_bus);
        spin_lock(&kvm_lock);
        list_add(&kvm->vm_list, &vm_list);
        spin_unlock(&kvm_lock);
out:
        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;
}

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 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);
        kvm_arch_destroy_vm(kvm);
}

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

        kvm_destroy_vm(kvm);
        return 0;
}

/*
 * 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);
}

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

        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 (any)
                *is_dirty = 1;

        r = 0;
out:
        return r;
}

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

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);

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);

static unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
{
        struct kvm_memory_slot *slot;

        gfn = unalias_gfn(kvm, gfn);
        slot = __gfn_to_memslot(kvm, gfn);
        if (!slot)
                return bad_hva();
        return (slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE);
}

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

        might_sleep();

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

        npages = get_user_pages(current, current->mm, addr, 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_clean(struct page *page)
{
        put_page(page);
}
EXPORT_SYMBOL_GPL(kvm_release_page_clean);

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

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_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_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
{
        return kvm_write_guest_page(kvm, gfn, 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(struct kvm *kvm, gfn_t gfn)
{
        struct kvm_memory_slot *memslot;

        gfn = unalias_gfn(kvm, gfn);
        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);
        }
}

/*
 * The vCPU has executed a HLT instruction with in-kernel mode enabled.
 */
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);
}

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

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 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_arch_vcpu_create(kvm, n);
        if (IS_ERR(vcpu))
                return PTR_ERR(vcpu);

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

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

        switch (ioctl) {
        case KVM_RUN:
                r = -EINVAL;
                if (arg)
                        goto out;
                r = kvm_arch_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_arch_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_arch_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_arch_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_arch_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_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_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_arch_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_arch_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_arch_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_clean(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:
                r = kvm_dev_ioctl_check_extension((long)argp);
                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,
};

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_arch_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_arch_hardware_disable(NULL);
}

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

        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_UP_CANCELED:
                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:
                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 vm_stat_get(void *_offset)
{
        unsigned offset = (long)_offset;
        u64 total = 0;
        struct kvm *kvm;

        spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
                total += *(u32 *)((void *)kvm + offset);
        spin_unlock(&kvm_lock);
        return total;
}

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

static u64 vcpu_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(vcpu_stat_fops, vcpu_stat_get, NULL, "%llu\n");

static 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;

        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[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(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_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 int vcpu_size,
                  struct module *module)
{
        int r;
        int cpu;

        kvm_init_debug();

        r = kvm_arch_init(opaque);
        if (r)
                goto out4;

        bad_page = alloc_page(GFP_KERNEL | __GFP_ZERO);

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

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

        for_each_online_cpu(cpu) {
                smp_call_function_single(cpu,
                                kvm_arch_check_processor_compat,
                                &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, NULL);
        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;

        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_arch_hardware_unsetup();
out:
        kvm_arch_exit();
        kvm_exit_debug();
out4:
        return r;
}
EXPORT_SYMBOL_GPL(kvm_init);

void kvm_exit(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_arch_hardware_unsetup();
        kvm_arch_exit();
        kvm_exit_debug();
        __free_page(bad_page);
}
EXPORT_SYMBOL_GPL(kvm_exit);