Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6

[deliverable/linux.git] / drivers / kvm / vmx.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 "vmx.h"
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/profile.h>
#include <linux/sched.h>
#include <asm/io.h>
#include <asm/desc.h>

#include "segment_descriptor.h"

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

static DEFINE_PER_CPU(struct vmcs *, vmxarea);
static DEFINE_PER_CPU(struct vmcs *, current_vmcs);

#ifdef CONFIG_X86_64
#define HOST_IS_64 1
#else
#define HOST_IS_64 0
#endif

static struct vmcs_descriptor {
        int size;
        int order;
        u32 revision_id;
} vmcs_descriptor;

#define VMX_SEGMENT_FIELD(seg)                                  \
        [VCPU_SREG_##seg] = {                                   \
                .selector = GUEST_##seg##_SELECTOR,             \
                .base = GUEST_##seg##_BASE,                     \
                .limit = GUEST_##seg##_LIMIT,                   \
                .ar_bytes = GUEST_##seg##_AR_BYTES,             \
        }

static struct kvm_vmx_segment_field {
        unsigned selector;
        unsigned base;
        unsigned limit;
        unsigned ar_bytes;
} kvm_vmx_segment_fields[] = {
        VMX_SEGMENT_FIELD(CS),
        VMX_SEGMENT_FIELD(DS),
        VMX_SEGMENT_FIELD(ES),
        VMX_SEGMENT_FIELD(FS),
        VMX_SEGMENT_FIELD(GS),
        VMX_SEGMENT_FIELD(SS),
        VMX_SEGMENT_FIELD(TR),
        VMX_SEGMENT_FIELD(LDTR),
};

/*
 * Keep MSR_K6_STAR at the end, as setup_msrs() will try to optimize it
 * away by decrementing the array size.
 */
static const u32 vmx_msr_index[] = {
#ifdef CONFIG_X86_64
        MSR_SYSCALL_MASK, MSR_LSTAR, MSR_CSTAR, MSR_KERNEL_GS_BASE,
#endif
        MSR_EFER, MSR_K6_STAR,
};
#define NR_VMX_MSR ARRAY_SIZE(vmx_msr_index)

#ifdef CONFIG_X86_64
static unsigned msr_offset_kernel_gs_base;
#define NR_64BIT_MSRS 4
/*
 * avoid save/load MSR_SYSCALL_MASK and MSR_LSTAR by std vt
 * mechanism (cpu bug AA24)
 */
#define NR_BAD_MSRS 2
#else
#define NR_64BIT_MSRS 0
#define NR_BAD_MSRS 0
#endif

static inline int is_page_fault(u32 intr_info)
{
        return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
                             INTR_INFO_VALID_MASK)) ==
                (INTR_TYPE_EXCEPTION | PF_VECTOR | INTR_INFO_VALID_MASK);
}

static inline int is_no_device(u32 intr_info)
{
        return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
                             INTR_INFO_VALID_MASK)) ==
                (INTR_TYPE_EXCEPTION | NM_VECTOR | INTR_INFO_VALID_MASK);
}

static inline int is_external_interrupt(u32 intr_info)
{
        return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
                == (INTR_TYPE_EXT_INTR | INTR_INFO_VALID_MASK);
}

static struct vmx_msr_entry *find_msr_entry(struct kvm_vcpu *vcpu, u32 msr)
{
        int i;

        for (i = 0; i < vcpu->nmsrs; ++i)
                if (vcpu->guest_msrs[i].index == msr)
                        return &vcpu->guest_msrs[i];
        return NULL;
}

static void vmcs_clear(struct vmcs *vmcs)
{
        u64 phys_addr = __pa(vmcs);
        u8 error;

        asm volatile (ASM_VMX_VMCLEAR_RAX "; setna %0"
                      : "=g"(error) : "a"(&phys_addr), "m"(phys_addr)
                      : "cc", "memory");
        if (error)
                printk(KERN_ERR "kvm: vmclear fail: %p/%llx\n",
                       vmcs, phys_addr);
}

static void __vcpu_clear(void *arg)
{
        struct kvm_vcpu *vcpu = arg;
        int cpu = raw_smp_processor_id();

        if (vcpu->cpu == cpu)
                vmcs_clear(vcpu->vmcs);
        if (per_cpu(current_vmcs, cpu) == vcpu->vmcs)
                per_cpu(current_vmcs, cpu) = NULL;
}

static void vcpu_clear(struct kvm_vcpu *vcpu)
{
        if (vcpu->cpu != raw_smp_processor_id() && vcpu->cpu != -1)
                smp_call_function_single(vcpu->cpu, __vcpu_clear, vcpu, 0, 1);
        else
                __vcpu_clear(vcpu);
        vcpu->launched = 0;
}

static unsigned long vmcs_readl(unsigned long field)
{
        unsigned long value;

        asm volatile (ASM_VMX_VMREAD_RDX_RAX
                      : "=a"(value) : "d"(field) : "cc");
        return value;
}

static u16 vmcs_read16(unsigned long field)
{
        return vmcs_readl(field);
}

static u32 vmcs_read32(unsigned long field)
{
        return vmcs_readl(field);
}

static u64 vmcs_read64(unsigned long field)
{
#ifdef CONFIG_X86_64
        return vmcs_readl(field);
#else
        return vmcs_readl(field) | ((u64)vmcs_readl(field+1) << 32);
#endif
}

static noinline void vmwrite_error(unsigned long field, unsigned long value)
{
        printk(KERN_ERR "vmwrite error: reg %lx value %lx (err %d)\n",
               field, value, vmcs_read32(VM_INSTRUCTION_ERROR));
        dump_stack();
}

static void vmcs_writel(unsigned long field, unsigned long value)
{
        u8 error;

        asm volatile (ASM_VMX_VMWRITE_RAX_RDX "; setna %0"
                       : "=q"(error) : "a"(value), "d"(field) : "cc" );
        if (unlikely(error))
                vmwrite_error(field, value);
}

static void vmcs_write16(unsigned long field, u16 value)
{
        vmcs_writel(field, value);
}

static void vmcs_write32(unsigned long field, u32 value)
{
        vmcs_writel(field, value);
}

static void vmcs_write64(unsigned long field, u64 value)
{
#ifdef CONFIG_X86_64
        vmcs_writel(field, value);
#else
        vmcs_writel(field, value);
        asm volatile ("");
        vmcs_writel(field+1, value >> 32);
#endif
}

static void vmcs_clear_bits(unsigned long field, u32 mask)
{
        vmcs_writel(field, vmcs_readl(field) & ~mask);
}

static void vmcs_set_bits(unsigned long field, u32 mask)
{
        vmcs_writel(field, vmcs_readl(field) | mask);
}

/*
 * Switches to specified vcpu, until a matching vcpu_put(), but assumes
 * vcpu mutex is already taken.
 */
static void vmx_vcpu_load(struct kvm_vcpu *vcpu)
{
        u64 phys_addr = __pa(vcpu->vmcs);
        int cpu;

        cpu = get_cpu();

        if (vcpu->cpu != cpu)
                vcpu_clear(vcpu);

        if (per_cpu(current_vmcs, cpu) != vcpu->vmcs) {
                u8 error;

                per_cpu(current_vmcs, cpu) = vcpu->vmcs;
                asm volatile (ASM_VMX_VMPTRLD_RAX "; setna %0"
                              : "=g"(error) : "a"(&phys_addr), "m"(phys_addr)
                              : "cc");
                if (error)
                        printk(KERN_ERR "kvm: vmptrld %p/%llx fail\n",
                               vcpu->vmcs, phys_addr);
        }

        if (vcpu->cpu != cpu) {
                struct descriptor_table dt;
                unsigned long sysenter_esp;

                vcpu->cpu = cpu;
                /*
                 * Linux uses per-cpu TSS and GDT, so set these when switching
                 * processors.
                 */
                vmcs_writel(HOST_TR_BASE, read_tr_base()); /* 22.2.4 */
                get_gdt(&dt);
                vmcs_writel(HOST_GDTR_BASE, dt.base);   /* 22.2.4 */

                rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
                vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
        }
}

static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
{
        kvm_put_guest_fpu(vcpu);
        put_cpu();
}

static void vmx_vcpu_decache(struct kvm_vcpu *vcpu)
{
        vcpu_clear(vcpu);
}

static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
{
        return vmcs_readl(GUEST_RFLAGS);
}

static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
{
        vmcs_writel(GUEST_RFLAGS, rflags);
}

static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
{
        unsigned long rip;
        u32 interruptibility;

        rip = vmcs_readl(GUEST_RIP);
        rip += vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
        vmcs_writel(GUEST_RIP, rip);

        /*
         * We emulated an instruction, so temporary interrupt blocking
         * should be removed, if set.
         */
        interruptibility = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
        if (interruptibility & 3)
                vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
                             interruptibility & ~3);
        vcpu->interrupt_window_open = 1;
}

static void vmx_inject_gp(struct kvm_vcpu *vcpu, unsigned error_code)
{
        printk(KERN_DEBUG "inject_general_protection: rip 0x%lx\n",
               vmcs_readl(GUEST_RIP));
        vmcs_write32(VM_ENTRY_EXCEPTION_ERROR_CODE, error_code);
        vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
                     GP_VECTOR |
                     INTR_TYPE_EXCEPTION |
                     INTR_INFO_DELIEVER_CODE_MASK |
                     INTR_INFO_VALID_MASK);
}

/*
 * Set up the vmcs to automatically save and restore system
 * msrs.  Don't touch the 64-bit msrs if the guest is in legacy
 * mode, as fiddling with msrs is very expensive.
 */
static void setup_msrs(struct kvm_vcpu *vcpu)
{
        int nr_skip, nr_good_msrs;

        if (is_long_mode(vcpu))
                nr_skip = NR_BAD_MSRS;
        else
                nr_skip = NR_64BIT_MSRS;
        nr_good_msrs = vcpu->nmsrs - nr_skip;

        /*
         * MSR_K6_STAR is only needed on long mode guests, and only
         * if efer.sce is enabled.
         */
        if (find_msr_entry(vcpu, MSR_K6_STAR)) {
                --nr_good_msrs;
#ifdef CONFIG_X86_64
                if (is_long_mode(vcpu) && (vcpu->shadow_efer & EFER_SCE))
                        ++nr_good_msrs;
#endif
        }

        vmcs_writel(VM_ENTRY_MSR_LOAD_ADDR,
                    virt_to_phys(vcpu->guest_msrs + nr_skip));
        vmcs_writel(VM_EXIT_MSR_STORE_ADDR,
                    virt_to_phys(vcpu->guest_msrs + nr_skip));
        vmcs_writel(VM_EXIT_MSR_LOAD_ADDR,
                    virt_to_phys(vcpu->host_msrs + nr_skip));
        vmcs_write32(VM_EXIT_MSR_STORE_COUNT, nr_good_msrs); /* 22.2.2 */
        vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, nr_good_msrs);  /* 22.2.2 */
        vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, nr_good_msrs); /* 22.2.2 */
}

/*
 * reads and returns guest's timestamp counter "register"
 * guest_tsc = host_tsc + tsc_offset    -- 21.3
 */
static u64 guest_read_tsc(void)
{
        u64 host_tsc, tsc_offset;

        rdtscll(host_tsc);
        tsc_offset = vmcs_read64(TSC_OFFSET);
        return host_tsc + tsc_offset;
}

/*
 * writes 'guest_tsc' into guest's timestamp counter "register"
 * guest_tsc = host_tsc + tsc_offset ==> tsc_offset = guest_tsc - host_tsc
 */
static void guest_write_tsc(u64 guest_tsc)
{
        u64 host_tsc;

        rdtscll(host_tsc);
        vmcs_write64(TSC_OFFSET, guest_tsc - host_tsc);
}

static void reload_tss(void)
{
#ifndef CONFIG_X86_64

        /*
         * VT restores TR but not its size.  Useless.
         */
        struct descriptor_table gdt;
        struct segment_descriptor *descs;

        get_gdt(&gdt);
        descs = (void *)gdt.base;
        descs[GDT_ENTRY_TSS].type = 9; /* available TSS */
        load_TR_desc();
#endif
}

/*
 * Reads an msr value (of 'msr_index') into 'pdata'.
 * Returns 0 on success, non-0 otherwise.
 * Assumes vcpu_load() was already called.
 */
static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
{
        u64 data;
        struct vmx_msr_entry *msr;

        if (!pdata) {
                printk(KERN_ERR "BUG: get_msr called with NULL pdata\n");
                return -EINVAL;
        }

        switch (msr_index) {
#ifdef CONFIG_X86_64
        case MSR_FS_BASE:
                data = vmcs_readl(GUEST_FS_BASE);
                break;
        case MSR_GS_BASE:
                data = vmcs_readl(GUEST_GS_BASE);
                break;
        case MSR_EFER:
                return kvm_get_msr_common(vcpu, msr_index, pdata);
#endif
        case MSR_IA32_TIME_STAMP_COUNTER:
                data = guest_read_tsc();
                break;
        case MSR_IA32_SYSENTER_CS:
                data = vmcs_read32(GUEST_SYSENTER_CS);
                break;
        case MSR_IA32_SYSENTER_EIP:
                data = vmcs_readl(GUEST_SYSENTER_EIP);
                break;
        case MSR_IA32_SYSENTER_ESP:
                data = vmcs_readl(GUEST_SYSENTER_ESP);
                break;
        default:
                msr = find_msr_entry(vcpu, msr_index);
                if (msr) {
                        data = msr->data;
                        break;
                }
                return kvm_get_msr_common(vcpu, msr_index, pdata);
        }

        *pdata = data;
        return 0;
}

/*
 * Writes msr value into into the appropriate "register".
 * Returns 0 on success, non-0 otherwise.
 * Assumes vcpu_load() was already called.
 */
static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
{
        struct vmx_msr_entry *msr;
        switch (msr_index) {
#ifdef CONFIG_X86_64
        case MSR_EFER:
                return kvm_set_msr_common(vcpu, msr_index, data);
        case MSR_FS_BASE:
                vmcs_writel(GUEST_FS_BASE, data);
                break;
        case MSR_GS_BASE:
                vmcs_writel(GUEST_GS_BASE, data);
                break;
#endif
        case MSR_IA32_SYSENTER_CS:
                vmcs_write32(GUEST_SYSENTER_CS, data);
                break;
        case MSR_IA32_SYSENTER_EIP:
                vmcs_writel(GUEST_SYSENTER_EIP, data);
                break;
        case MSR_IA32_SYSENTER_ESP:
                vmcs_writel(GUEST_SYSENTER_ESP, data);
                break;
        case MSR_IA32_TIME_STAMP_COUNTER:
                guest_write_tsc(data);
                break;
        default:
                msr = find_msr_entry(vcpu, msr_index);
                if (msr) {
                        msr->data = data;
                        break;
                }
                return kvm_set_msr_common(vcpu, msr_index, data);
                msr->data = data;
                break;
        }

        return 0;
}

/*
 * Sync the rsp and rip registers into the vcpu structure.  This allows
 * registers to be accessed by indexing vcpu->regs.
 */
static void vcpu_load_rsp_rip(struct kvm_vcpu *vcpu)
{
        vcpu->regs[VCPU_REGS_RSP] = vmcs_readl(GUEST_RSP);
        vcpu->rip = vmcs_readl(GUEST_RIP);
}

/*
 * Syncs rsp and rip back into the vmcs.  Should be called after possible
 * modification.
 */
static void vcpu_put_rsp_rip(struct kvm_vcpu *vcpu)
{
        vmcs_writel(GUEST_RSP, vcpu->regs[VCPU_REGS_RSP]);
        vmcs_writel(GUEST_RIP, vcpu->rip);
}

static int set_guest_debug(struct kvm_vcpu *vcpu, struct kvm_debug_guest *dbg)
{
        unsigned long dr7 = 0x400;
        u32 exception_bitmap;
        int old_singlestep;

        exception_bitmap = vmcs_read32(EXCEPTION_BITMAP);
        old_singlestep = vcpu->guest_debug.singlestep;

        vcpu->guest_debug.enabled = dbg->enabled;
        if (vcpu->guest_debug.enabled) {
                int i;

                dr7 |= 0x200;  /* exact */
                for (i = 0; i < 4; ++i) {
                        if (!dbg->breakpoints[i].enabled)
                                continue;
                        vcpu->guest_debug.bp[i] = dbg->breakpoints[i].address;
                        dr7 |= 2 << (i*2);    /* global enable */
                        dr7 |= 0 << (i*4+16); /* execution breakpoint */
                }

                exception_bitmap |= (1u << 1);  /* Trap debug exceptions */

                vcpu->guest_debug.singlestep = dbg->singlestep;
        } else {
                exception_bitmap &= ~(1u << 1); /* Ignore debug exceptions */
                vcpu->guest_debug.singlestep = 0;
        }

        if (old_singlestep && !vcpu->guest_debug.singlestep) {
                unsigned long flags;

                flags = vmcs_readl(GUEST_RFLAGS);
                flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
                vmcs_writel(GUEST_RFLAGS, flags);
        }

        vmcs_write32(EXCEPTION_BITMAP, exception_bitmap);
        vmcs_writel(GUEST_DR7, dr7);

        return 0;
}

static __init int cpu_has_kvm_support(void)
{
        unsigned long ecx = cpuid_ecx(1);
        return test_bit(5, &ecx); /* CPUID.1:ECX.VMX[bit 5] -> VT */
}

static __init int vmx_disabled_by_bios(void)
{
        u64 msr;

        rdmsrl(MSR_IA32_FEATURE_CONTROL, msr);
        return (msr & 5) == 1; /* locked but not enabled */
}

static void hardware_enable(void *garbage)
{
        int cpu = raw_smp_processor_id();
        u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
        u64 old;

        rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
        if ((old & 5) != 5)
                /* enable and lock */
                wrmsrl(MSR_IA32_FEATURE_CONTROL, old | 5);
        write_cr4(read_cr4() | CR4_VMXE); /* FIXME: not cpu hotplug safe */
        asm volatile (ASM_VMX_VMXON_RAX : : "a"(&phys_addr), "m"(phys_addr)
                      : "memory", "cc");
}

static void hardware_disable(void *garbage)
{
        asm volatile (ASM_VMX_VMXOFF : : : "cc");
}

static __init void setup_vmcs_descriptor(void)
{
        u32 vmx_msr_low, vmx_msr_high;

        rdmsr(MSR_IA32_VMX_BASIC, vmx_msr_low, vmx_msr_high);
        vmcs_descriptor.size = vmx_msr_high & 0x1fff;
        vmcs_descriptor.order = get_order(vmcs_descriptor.size);
        vmcs_descriptor.revision_id = vmx_msr_low;
}

static struct vmcs *alloc_vmcs_cpu(int cpu)
{
        int node = cpu_to_node(cpu);
        struct page *pages;
        struct vmcs *vmcs;

        pages = alloc_pages_node(node, GFP_KERNEL, vmcs_descriptor.order);
        if (!pages)
                return NULL;
        vmcs = page_address(pages);
        memset(vmcs, 0, vmcs_descriptor.size);
        vmcs->revision_id = vmcs_descriptor.revision_id; /* vmcs revision id */
        return vmcs;
}

static struct vmcs *alloc_vmcs(void)
{
        return alloc_vmcs_cpu(raw_smp_processor_id());
}

static void free_vmcs(struct vmcs *vmcs)
{
        free_pages((unsigned long)vmcs, vmcs_descriptor.order);
}

static void free_kvm_area(void)
{
        int cpu;

        for_each_online_cpu(cpu)
                free_vmcs(per_cpu(vmxarea, cpu));
}

extern struct vmcs *alloc_vmcs_cpu(int cpu);

static __init int alloc_kvm_area(void)
{
        int cpu;

        for_each_online_cpu(cpu) {
                struct vmcs *vmcs;

                vmcs = alloc_vmcs_cpu(cpu);
                if (!vmcs) {
                        free_kvm_area();
                        return -ENOMEM;
                }

                per_cpu(vmxarea, cpu) = vmcs;
        }
        return 0;
}

static __init int hardware_setup(void)
{
        setup_vmcs_descriptor();
        return alloc_kvm_area();
}

static __exit void hardware_unsetup(void)
{
        free_kvm_area();
}

static void update_exception_bitmap(struct kvm_vcpu *vcpu)
{
        if (vcpu->rmode.active)
                vmcs_write32(EXCEPTION_BITMAP, ~0);
        else
                vmcs_write32(EXCEPTION_BITMAP, 1 << PF_VECTOR);
}

static void fix_pmode_dataseg(int seg, struct kvm_save_segment *save)
{
        struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];

        if (vmcs_readl(sf->base) == save->base && (save->base & AR_S_MASK)) {
                vmcs_write16(sf->selector, save->selector);
                vmcs_writel(sf->base, save->base);
                vmcs_write32(sf->limit, save->limit);
                vmcs_write32(sf->ar_bytes, save->ar);
        } else {
                u32 dpl = (vmcs_read16(sf->selector) & SELECTOR_RPL_MASK)
                        << AR_DPL_SHIFT;
                vmcs_write32(sf->ar_bytes, 0x93 | dpl);
        }
}

static void enter_pmode(struct kvm_vcpu *vcpu)
{
        unsigned long flags;

        vcpu->rmode.active = 0;

        vmcs_writel(GUEST_TR_BASE, vcpu->rmode.tr.base);
        vmcs_write32(GUEST_TR_LIMIT, vcpu->rmode.tr.limit);
        vmcs_write32(GUEST_TR_AR_BYTES, vcpu->rmode.tr.ar);

        flags = vmcs_readl(GUEST_RFLAGS);
        flags &= ~(IOPL_MASK | X86_EFLAGS_VM);
        flags |= (vcpu->rmode.save_iopl << IOPL_SHIFT);
        vmcs_writel(GUEST_RFLAGS, flags);

        vmcs_writel(GUEST_CR4, (vmcs_readl(GUEST_CR4) & ~CR4_VME_MASK) |
                        (vmcs_readl(CR4_READ_SHADOW) & CR4_VME_MASK));

        update_exception_bitmap(vcpu);

        fix_pmode_dataseg(VCPU_SREG_ES, &vcpu->rmode.es);
        fix_pmode_dataseg(VCPU_SREG_DS, &vcpu->rmode.ds);
        fix_pmode_dataseg(VCPU_SREG_GS, &vcpu->rmode.gs);
        fix_pmode_dataseg(VCPU_SREG_FS, &vcpu->rmode.fs);

        vmcs_write16(GUEST_SS_SELECTOR, 0);
        vmcs_write32(GUEST_SS_AR_BYTES, 0x93);

        vmcs_write16(GUEST_CS_SELECTOR,
                     vmcs_read16(GUEST_CS_SELECTOR) & ~SELECTOR_RPL_MASK);
        vmcs_write32(GUEST_CS_AR_BYTES, 0x9b);
}

static int rmode_tss_base(struct kvm* kvm)
{
        gfn_t base_gfn = kvm->memslots[0].base_gfn + kvm->memslots[0].npages - 3;
        return base_gfn << PAGE_SHIFT;
}

static void fix_rmode_seg(int seg, struct kvm_save_segment *save)
{
        struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];

        save->selector = vmcs_read16(sf->selector);
        save->base = vmcs_readl(sf->base);
        save->limit = vmcs_read32(sf->limit);
        save->ar = vmcs_read32(sf->ar_bytes);
        vmcs_write16(sf->selector, vmcs_readl(sf->base) >> 4);
        vmcs_write32(sf->limit, 0xffff);
        vmcs_write32(sf->ar_bytes, 0xf3);
}

static void enter_rmode(struct kvm_vcpu *vcpu)
{
        unsigned long flags;

        vcpu->rmode.active = 1;

        vcpu->rmode.tr.base = vmcs_readl(GUEST_TR_BASE);
        vmcs_writel(GUEST_TR_BASE, rmode_tss_base(vcpu->kvm));

        vcpu->rmode.tr.limit = vmcs_read32(GUEST_TR_LIMIT);
        vmcs_write32(GUEST_TR_LIMIT, RMODE_TSS_SIZE - 1);

        vcpu->rmode.tr.ar = vmcs_read32(GUEST_TR_AR_BYTES);
        vmcs_write32(GUEST_TR_AR_BYTES, 0x008b);

        flags = vmcs_readl(GUEST_RFLAGS);
        vcpu->rmode.save_iopl = (flags & IOPL_MASK) >> IOPL_SHIFT;

        flags |= IOPL_MASK | X86_EFLAGS_VM;

        vmcs_writel(GUEST_RFLAGS, flags);
        vmcs_writel(GUEST_CR4, vmcs_readl(GUEST_CR4) | CR4_VME_MASK);
        update_exception_bitmap(vcpu);

        vmcs_write16(GUEST_SS_SELECTOR, vmcs_readl(GUEST_SS_BASE) >> 4);
        vmcs_write32(GUEST_SS_LIMIT, 0xffff);
        vmcs_write32(GUEST_SS_AR_BYTES, 0xf3);

        vmcs_write32(GUEST_CS_AR_BYTES, 0xf3);
        vmcs_write32(GUEST_CS_LIMIT, 0xffff);
        if (vmcs_readl(GUEST_CS_BASE) == 0xffff0000)
                vmcs_writel(GUEST_CS_BASE, 0xf0000);
        vmcs_write16(GUEST_CS_SELECTOR, vmcs_readl(GUEST_CS_BASE) >> 4);

        fix_rmode_seg(VCPU_SREG_ES, &vcpu->rmode.es);
        fix_rmode_seg(VCPU_SREG_DS, &vcpu->rmode.ds);
        fix_rmode_seg(VCPU_SREG_GS, &vcpu->rmode.gs);
        fix_rmode_seg(VCPU_SREG_FS, &vcpu->rmode.fs);
}

#ifdef CONFIG_X86_64

static void enter_lmode(struct kvm_vcpu *vcpu)
{
        u32 guest_tr_ar;

        guest_tr_ar = vmcs_read32(GUEST_TR_AR_BYTES);
        if ((guest_tr_ar & AR_TYPE_MASK) != AR_TYPE_BUSY_64_TSS) {
                printk(KERN_DEBUG "%s: tss fixup for long mode. \n",
                       __FUNCTION__);
                vmcs_write32(GUEST_TR_AR_BYTES,
                             (guest_tr_ar & ~AR_TYPE_MASK)
                             | AR_TYPE_BUSY_64_TSS);
        }

        vcpu->shadow_efer |= EFER_LMA;

        find_msr_entry(vcpu, MSR_EFER)->data |= EFER_LMA | EFER_LME;
        vmcs_write32(VM_ENTRY_CONTROLS,
                     vmcs_read32(VM_ENTRY_CONTROLS)
                     | VM_ENTRY_CONTROLS_IA32E_MASK);
}

static void exit_lmode(struct kvm_vcpu *vcpu)
{
        vcpu->shadow_efer &= ~EFER_LMA;

        vmcs_write32(VM_ENTRY_CONTROLS,
                     vmcs_read32(VM_ENTRY_CONTROLS)
                     & ~VM_ENTRY_CONTROLS_IA32E_MASK);
}

#endif

static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)
{
        vcpu->cr4 &= KVM_GUEST_CR4_MASK;
        vcpu->cr4 |= vmcs_readl(GUEST_CR4) & ~KVM_GUEST_CR4_MASK;
}

static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
{
        if (vcpu->rmode.active && (cr0 & CR0_PE_MASK))
                enter_pmode(vcpu);

        if (!vcpu->rmode.active && !(cr0 & CR0_PE_MASK))
                enter_rmode(vcpu);

#ifdef CONFIG_X86_64
        if (vcpu->shadow_efer & EFER_LME) {
                if (!is_paging(vcpu) && (cr0 & CR0_PG_MASK))
                        enter_lmode(vcpu);
                if (is_paging(vcpu) && !(cr0 & CR0_PG_MASK))
                        exit_lmode(vcpu);
        }
#endif

        if (!(cr0 & CR0_TS_MASK)) {
                vcpu->fpu_active = 1;
                vmcs_clear_bits(EXCEPTION_BITMAP, CR0_TS_MASK);
        }

        vmcs_writel(CR0_READ_SHADOW, cr0);
        vmcs_writel(GUEST_CR0,
                    (cr0 & ~KVM_GUEST_CR0_MASK) | KVM_VM_CR0_ALWAYS_ON);
        vcpu->cr0 = cr0;
}

static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
{
        vmcs_writel(GUEST_CR3, cr3);

        if (!(vcpu->cr0 & CR0_TS_MASK)) {
                vcpu->fpu_active = 0;
                vmcs_set_bits(GUEST_CR0, CR0_TS_MASK);
                vmcs_set_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
        }
}

static void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
{
        vmcs_writel(CR4_READ_SHADOW, cr4);
        vmcs_writel(GUEST_CR4, cr4 | (vcpu->rmode.active ?
                    KVM_RMODE_VM_CR4_ALWAYS_ON : KVM_PMODE_VM_CR4_ALWAYS_ON));
        vcpu->cr4 = cr4;
}

#ifdef CONFIG_X86_64

static void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
{
        struct vmx_msr_entry *msr = find_msr_entry(vcpu, MSR_EFER);

        vcpu->shadow_efer = efer;
        if (efer & EFER_LMA) {
                vmcs_write32(VM_ENTRY_CONTROLS,
                                     vmcs_read32(VM_ENTRY_CONTROLS) |
                                     VM_ENTRY_CONTROLS_IA32E_MASK);
                msr->data = efer;

        } else {
                vmcs_write32(VM_ENTRY_CONTROLS,
                                     vmcs_read32(VM_ENTRY_CONTROLS) &
                                     ~VM_ENTRY_CONTROLS_IA32E_MASK);

                msr->data = efer & ~EFER_LME;
        }
        setup_msrs(vcpu);
}

#endif

static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)
{
        struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];

        return vmcs_readl(sf->base);
}

static void vmx_get_segment(struct kvm_vcpu *vcpu,
                            struct kvm_segment *var, int seg)
{
        struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
        u32 ar;

        var->base = vmcs_readl(sf->base);
        var->limit = vmcs_read32(sf->limit);
        var->selector = vmcs_read16(sf->selector);
        ar = vmcs_read32(sf->ar_bytes);
        if (ar & AR_UNUSABLE_MASK)
                ar = 0;
        var->type = ar & 15;
        var->s = (ar >> 4) & 1;
        var->dpl = (ar >> 5) & 3;
        var->present = (ar >> 7) & 1;
        var->avl = (ar >> 12) & 1;
        var->l = (ar >> 13) & 1;
        var->db = (ar >> 14) & 1;
        var->g = (ar >> 15) & 1;
        var->unusable = (ar >> 16) & 1;
}

static void vmx_set_segment(struct kvm_vcpu *vcpu,
                            struct kvm_segment *var, int seg)
{
        struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];
        u32 ar;

        vmcs_writel(sf->base, var->base);
        vmcs_write32(sf->limit, var->limit);
        vmcs_write16(sf->selector, var->selector);
        if (vcpu->rmode.active && var->s) {
                /*
                 * Hack real-mode segments into vm86 compatibility.
                 */
                if (var->base == 0xffff0000 && var->selector == 0xf000)
                        vmcs_writel(sf->base, 0xf0000);
                ar = 0xf3;
        } else if (var->unusable)
                ar = 1 << 16;
        else {
                ar = var->type & 15;
                ar |= (var->s & 1) << 4;
                ar |= (var->dpl & 3) << 5;
                ar |= (var->present & 1) << 7;
                ar |= (var->avl & 1) << 12;
                ar |= (var->l & 1) << 13;
                ar |= (var->db & 1) << 14;
                ar |= (var->g & 1) << 15;
        }
        if (ar == 0) /* a 0 value means unusable */
                ar = AR_UNUSABLE_MASK;
        vmcs_write32(sf->ar_bytes, ar);
}

static void vmx_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
{
        u32 ar = vmcs_read32(GUEST_CS_AR_BYTES);

        *db = (ar >> 14) & 1;
        *l = (ar >> 13) & 1;
}

static void vmx_get_idt(struct kvm_vcpu *vcpu, struct descriptor_table *dt)
{
        dt->limit = vmcs_read32(GUEST_IDTR_LIMIT);
        dt->base = vmcs_readl(GUEST_IDTR_BASE);
}

static void vmx_set_idt(struct kvm_vcpu *vcpu, struct descriptor_table *dt)
{
        vmcs_write32(GUEST_IDTR_LIMIT, dt->limit);
        vmcs_writel(GUEST_IDTR_BASE, dt->base);
}

static void vmx_get_gdt(struct kvm_vcpu *vcpu, struct descriptor_table *dt)
{
        dt->limit = vmcs_read32(GUEST_GDTR_LIMIT);
        dt->base = vmcs_readl(GUEST_GDTR_BASE);
}

static void vmx_set_gdt(struct kvm_vcpu *vcpu, struct descriptor_table *dt)
{
        vmcs_write32(GUEST_GDTR_LIMIT, dt->limit);
        vmcs_writel(GUEST_GDTR_BASE, dt->base);
}

static int init_rmode_tss(struct kvm* kvm)
{
        struct page *p1, *p2, *p3;
        gfn_t fn = rmode_tss_base(kvm) >> PAGE_SHIFT;
        char *page;

        p1 = gfn_to_page(kvm, fn++);
        p2 = gfn_to_page(kvm, fn++);
        p3 = gfn_to_page(kvm, fn);

        if (!p1 || !p2 || !p3) {
                kvm_printf(kvm,"%s: gfn_to_page failed\n", __FUNCTION__);
                return 0;
        }

        page = kmap_atomic(p1, KM_USER0);
        memset(page, 0, PAGE_SIZE);
        *(u16*)(page + 0x66) = TSS_BASE_SIZE + TSS_REDIRECTION_SIZE;
        kunmap_atomic(page, KM_USER0);

        page = kmap_atomic(p2, KM_USER0);
        memset(page, 0, PAGE_SIZE);
        kunmap_atomic(page, KM_USER0);

        page = kmap_atomic(p3, KM_USER0);
        memset(page, 0, PAGE_SIZE);
        *(page + RMODE_TSS_SIZE - 2 * PAGE_SIZE - 1) = ~0;
        kunmap_atomic(page, KM_USER0);

        return 1;
}

static void vmcs_write32_fixedbits(u32 msr, u32 vmcs_field, u32 val)
{
        u32 msr_high, msr_low;

        rdmsr(msr, msr_low, msr_high);

        val &= msr_high;
        val |= msr_low;
        vmcs_write32(vmcs_field, val);
}

static void seg_setup(int seg)
{
        struct kvm_vmx_segment_field *sf = &kvm_vmx_segment_fields[seg];

        vmcs_write16(sf->selector, 0);
        vmcs_writel(sf->base, 0);
        vmcs_write32(sf->limit, 0xffff);
        vmcs_write32(sf->ar_bytes, 0x93);
}

/*
 * Sets up the vmcs for emulated real mode.
 */
static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
{
        u32 host_sysenter_cs;
        u32 junk;
        unsigned long a;
        struct descriptor_table dt;
        int i;
        int ret = 0;
        extern asmlinkage void kvm_vmx_return(void);

        if (!init_rmode_tss(vcpu->kvm)) {
                ret = -ENOMEM;
                goto out;
        }

        memset(vcpu->regs, 0, sizeof(vcpu->regs));
        vcpu->regs[VCPU_REGS_RDX] = get_rdx_init_val();
        vcpu->cr8 = 0;
        vcpu->apic_base = 0xfee00000 |
                        /*for vcpu 0*/ MSR_IA32_APICBASE_BSP |
                        MSR_IA32_APICBASE_ENABLE;

        fx_init(vcpu);

        /*
         * GUEST_CS_BASE should really be 0xffff0000, but VT vm86 mode
         * insists on having GUEST_CS_BASE == GUEST_CS_SELECTOR << 4.  Sigh.
         */
        vmcs_write16(GUEST_CS_SELECTOR, 0xf000);
        vmcs_writel(GUEST_CS_BASE, 0x000f0000);
        vmcs_write32(GUEST_CS_LIMIT, 0xffff);
        vmcs_write32(GUEST_CS_AR_BYTES, 0x9b);

        seg_setup(VCPU_SREG_DS);
        seg_setup(VCPU_SREG_ES);
        seg_setup(VCPU_SREG_FS);
        seg_setup(VCPU_SREG_GS);
        seg_setup(VCPU_SREG_SS);

        vmcs_write16(GUEST_TR_SELECTOR, 0);
        vmcs_writel(GUEST_TR_BASE, 0);
        vmcs_write32(GUEST_TR_LIMIT, 0xffff);
        vmcs_write32(GUEST_TR_AR_BYTES, 0x008b);

        vmcs_write16(GUEST_LDTR_SELECTOR, 0);
        vmcs_writel(GUEST_LDTR_BASE, 0);
        vmcs_write32(GUEST_LDTR_LIMIT, 0xffff);
        vmcs_write32(GUEST_LDTR_AR_BYTES, 0x00082);

        vmcs_write32(GUEST_SYSENTER_CS, 0);
        vmcs_writel(GUEST_SYSENTER_ESP, 0);
        vmcs_writel(GUEST_SYSENTER_EIP, 0);

        vmcs_writel(GUEST_RFLAGS, 0x02);
        vmcs_writel(GUEST_RIP, 0xfff0);
        vmcs_writel(GUEST_RSP, 0);

        //todo: dr0 = dr1 = dr2 = dr3 = 0; dr6 = 0xffff0ff0
        vmcs_writel(GUEST_DR7, 0x400);

        vmcs_writel(GUEST_GDTR_BASE, 0);
        vmcs_write32(GUEST_GDTR_LIMIT, 0xffff);

        vmcs_writel(GUEST_IDTR_BASE, 0);
        vmcs_write32(GUEST_IDTR_LIMIT, 0xffff);

        vmcs_write32(GUEST_ACTIVITY_STATE, 0);
        vmcs_write32(GUEST_INTERRUPTIBILITY_INFO, 0);
        vmcs_write32(GUEST_PENDING_DBG_EXCEPTIONS, 0);

        /* I/O */
        vmcs_write64(IO_BITMAP_A, 0);
        vmcs_write64(IO_BITMAP_B, 0);

        guest_write_tsc(0);

        vmcs_write64(VMCS_LINK_POINTER, -1ull); /* 22.3.1.5 */

        /* Special registers */
        vmcs_write64(GUEST_IA32_DEBUGCTL, 0);

        /* Control */
        vmcs_write32_fixedbits(MSR_IA32_VMX_PINBASED_CTLS,
                               PIN_BASED_VM_EXEC_CONTROL,
                               PIN_BASED_EXT_INTR_MASK   /* 20.6.1 */
                               | PIN_BASED_NMI_EXITING   /* 20.6.1 */
                        );
        vmcs_write32_fixedbits(MSR_IA32_VMX_PROCBASED_CTLS,
                               CPU_BASED_VM_EXEC_CONTROL,
                               CPU_BASED_HLT_EXITING         /* 20.6.2 */
                               | CPU_BASED_CR8_LOAD_EXITING    /* 20.6.2 */
                               | CPU_BASED_CR8_STORE_EXITING   /* 20.6.2 */
                               | CPU_BASED_UNCOND_IO_EXITING   /* 20.6.2 */
                               | CPU_BASED_MOV_DR_EXITING
                               | CPU_BASED_USE_TSC_OFFSETING   /* 21.3 */
                        );

        vmcs_write32(EXCEPTION_BITMAP, 1 << PF_VECTOR);
        vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, 0);
        vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, 0);
        vmcs_write32(CR3_TARGET_COUNT, 0);           /* 22.2.1 */

        vmcs_writel(HOST_CR0, read_cr0());  /* 22.2.3 */
        vmcs_writel(HOST_CR4, read_cr4());  /* 22.2.3, 22.2.5 */
        vmcs_writel(HOST_CR3, read_cr3());  /* 22.2.3  FIXME: shadow tables */

        vmcs_write16(HOST_CS_SELECTOR, __KERNEL_CS);  /* 22.2.4 */
        vmcs_write16(HOST_DS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
        vmcs_write16(HOST_ES_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
        vmcs_write16(HOST_FS_SELECTOR, read_fs());    /* 22.2.4 */
        vmcs_write16(HOST_GS_SELECTOR, read_gs());    /* 22.2.4 */
        vmcs_write16(HOST_SS_SELECTOR, __KERNEL_DS);  /* 22.2.4 */
#ifdef CONFIG_X86_64
        rdmsrl(MSR_FS_BASE, a);
        vmcs_writel(HOST_FS_BASE, a); /* 22.2.4 */
        rdmsrl(MSR_GS_BASE, a);
        vmcs_writel(HOST_GS_BASE, a); /* 22.2.4 */
#else
        vmcs_writel(HOST_FS_BASE, 0); /* 22.2.4 */
        vmcs_writel(HOST_GS_BASE, 0); /* 22.2.4 */
#endif

        vmcs_write16(HOST_TR_SELECTOR, GDT_ENTRY_TSS*8);  /* 22.2.4 */

        get_idt(&dt);
        vmcs_writel(HOST_IDTR_BASE, dt.base);   /* 22.2.4 */


        vmcs_writel(HOST_RIP, (unsigned long)kvm_vmx_return); /* 22.2.5 */

        rdmsr(MSR_IA32_SYSENTER_CS, host_sysenter_cs, junk);
        vmcs_write32(HOST_IA32_SYSENTER_CS, host_sysenter_cs);
        rdmsrl(MSR_IA32_SYSENTER_ESP, a);
        vmcs_writel(HOST_IA32_SYSENTER_ESP, a);   /* 22.2.3 */
        rdmsrl(MSR_IA32_SYSENTER_EIP, a);
        vmcs_writel(HOST_IA32_SYSENTER_EIP, a);   /* 22.2.3 */

        for (i = 0; i < NR_VMX_MSR; ++i) {
                u32 index = vmx_msr_index[i];
                u32 data_low, data_high;
                u64 data;
                int j = vcpu->nmsrs;

                if (rdmsr_safe(index, &data_low, &data_high) < 0)
                        continue;
                if (wrmsr_safe(index, data_low, data_high) < 0)
                        continue;
                data = data_low | ((u64)data_high << 32);
                vcpu->host_msrs[j].index = index;
                vcpu->host_msrs[j].reserved = 0;
                vcpu->host_msrs[j].data = data;
                vcpu->guest_msrs[j] = vcpu->host_msrs[j];
#ifdef CONFIG_X86_64
                if (index == MSR_KERNEL_GS_BASE)
                        msr_offset_kernel_gs_base = j;
#endif
                ++vcpu->nmsrs;
        }

        setup_msrs(vcpu);

        vmcs_write32_fixedbits(MSR_IA32_VMX_EXIT_CTLS, VM_EXIT_CONTROLS,
                               (HOST_IS_64 << 9));  /* 22.2,1, 20.7.1 */

        /* 22.2.1, 20.8.1 */
        vmcs_write32_fixedbits(MSR_IA32_VMX_ENTRY_CTLS,
                               VM_ENTRY_CONTROLS, 0);
        vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, 0);  /* 22.2.1 */

#ifdef CONFIG_X86_64
        vmcs_writel(VIRTUAL_APIC_PAGE_ADDR, 0);
        vmcs_writel(TPR_THRESHOLD, 0);
#endif

        vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL);
        vmcs_writel(CR4_GUEST_HOST_MASK, KVM_GUEST_CR4_MASK);

        vcpu->cr0 = 0x60000010;
        vmx_set_cr0(vcpu, vcpu->cr0); // enter rmode
        vmx_set_cr4(vcpu, 0);
#ifdef CONFIG_X86_64
        vmx_set_efer(vcpu, 0);
#endif

        return 0;

out:
        return ret;
}

static void inject_rmode_irq(struct kvm_vcpu *vcpu, int irq)
{
        u16 ent[2];
        u16 cs;
        u16 ip;
        unsigned long flags;
        unsigned long ss_base = vmcs_readl(GUEST_SS_BASE);
        u16 sp =  vmcs_readl(GUEST_RSP);
        u32 ss_limit = vmcs_read32(GUEST_SS_LIMIT);

        if (sp > ss_limit || sp < 6 ) {
                vcpu_printf(vcpu, "%s: #SS, rsp 0x%lx ss 0x%lx limit 0x%x\n",
                            __FUNCTION__,
                            vmcs_readl(GUEST_RSP),
                            vmcs_readl(GUEST_SS_BASE),
                            vmcs_read32(GUEST_SS_LIMIT));
                return;
        }

        if (kvm_read_guest(vcpu, irq * sizeof(ent), sizeof(ent), &ent) !=
                                                                sizeof(ent)) {
                vcpu_printf(vcpu, "%s: read guest err\n", __FUNCTION__);
                return;
        }

        flags =  vmcs_readl(GUEST_RFLAGS);
        cs =  vmcs_readl(GUEST_CS_BASE) >> 4;
        ip =  vmcs_readl(GUEST_RIP);


        if (kvm_write_guest(vcpu, ss_base + sp - 2, 2, &flags) != 2 ||
            kvm_write_guest(vcpu, ss_base + sp - 4, 2, &cs) != 2 ||
            kvm_write_guest(vcpu, ss_base + sp - 6, 2, &ip) != 2) {
                vcpu_printf(vcpu, "%s: write guest err\n", __FUNCTION__);
                return;
        }

        vmcs_writel(GUEST_RFLAGS, flags &
                    ~( X86_EFLAGS_IF | X86_EFLAGS_AC | X86_EFLAGS_TF));
        vmcs_write16(GUEST_CS_SELECTOR, ent[1]) ;
        vmcs_writel(GUEST_CS_BASE, ent[1] << 4);
        vmcs_writel(GUEST_RIP, ent[0]);
        vmcs_writel(GUEST_RSP, (vmcs_readl(GUEST_RSP) & ~0xffff) | (sp - 6));
}

static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
{
        int word_index = __ffs(vcpu->irq_summary);
        int bit_index = __ffs(vcpu->irq_pending[word_index]);
        int irq = word_index * BITS_PER_LONG + bit_index;

        clear_bit(bit_index, &vcpu->irq_pending[word_index]);
        if (!vcpu->irq_pending[word_index])
                clear_bit(word_index, &vcpu->irq_summary);

        if (vcpu->rmode.active) {
                inject_rmode_irq(vcpu, irq);
                return;
        }
        vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
                        irq | INTR_TYPE_EXT_INTR | INTR_INFO_VALID_MASK);
}


static void do_interrupt_requests(struct kvm_vcpu *vcpu,
                                       struct kvm_run *kvm_run)
{
        u32 cpu_based_vm_exec_control;

        vcpu->interrupt_window_open =
                ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
                 (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0);

        if (vcpu->interrupt_window_open &&
            vcpu->irq_summary &&
            !(vmcs_read32(VM_ENTRY_INTR_INFO_FIELD) & INTR_INFO_VALID_MASK))
                /*
                 * If interrupts enabled, and not blocked by sti or mov ss. Good.
                 */
                kvm_do_inject_irq(vcpu);

        cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
        if (!vcpu->interrupt_window_open &&
            (vcpu->irq_summary || kvm_run->request_interrupt_window))
                /*
                 * Interrupts blocked.  Wait for unblock.
                 */
                cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
        else
                cpu_based_vm_exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
        vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
}

static void kvm_guest_debug_pre(struct kvm_vcpu *vcpu)
{
        struct kvm_guest_debug *dbg = &vcpu->guest_debug;

        set_debugreg(dbg->bp[0], 0);
        set_debugreg(dbg->bp[1], 1);
        set_debugreg(dbg->bp[2], 2);
        set_debugreg(dbg->bp[3], 3);

        if (dbg->singlestep) {
                unsigned long flags;

                flags = vmcs_readl(GUEST_RFLAGS);
                flags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
                vmcs_writel(GUEST_RFLAGS, flags);
        }
}

static int handle_rmode_exception(struct kvm_vcpu *vcpu,
                                  int vec, u32 err_code)
{
        if (!vcpu->rmode.active)
                return 0;

        if (vec == GP_VECTOR && err_code == 0)
                if (emulate_instruction(vcpu, NULL, 0, 0) == EMULATE_DONE)
                        return 1;
        return 0;
}

static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u32 intr_info, error_code;
        unsigned long cr2, rip;
        u32 vect_info;
        enum emulation_result er;
        int r;

        vect_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
        intr_info = vmcs_read32(VM_EXIT_INTR_INFO);

        if ((vect_info & VECTORING_INFO_VALID_MASK) &&
                                                !is_page_fault(intr_info)) {
                printk(KERN_ERR "%s: unexpected, vectoring info 0x%x "
                       "intr info 0x%x\n", __FUNCTION__, vect_info, intr_info);
        }

        if (is_external_interrupt(vect_info)) {
                int irq = vect_info & VECTORING_INFO_VECTOR_MASK;
                set_bit(irq, vcpu->irq_pending);
                set_bit(irq / BITS_PER_LONG, &vcpu->irq_summary);
        }

        if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == 0x200) { /* nmi */
                asm ("int $2");
                return 1;
        }

        if (is_no_device(intr_info)) {
                vcpu->fpu_active = 1;
                vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
                if (!(vcpu->cr0 & CR0_TS_MASK))
                        vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);
                return 1;
        }

        error_code = 0;
        rip = vmcs_readl(GUEST_RIP);
        if (intr_info & INTR_INFO_DELIEVER_CODE_MASK)
                error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
        if (is_page_fault(intr_info)) {
                cr2 = vmcs_readl(EXIT_QUALIFICATION);

                spin_lock(&vcpu->kvm->lock);
                r = kvm_mmu_page_fault(vcpu, cr2, error_code);
                if (r < 0) {
                        spin_unlock(&vcpu->kvm->lock);
                        return r;
                }
                if (!r) {
                        spin_unlock(&vcpu->kvm->lock);
                        return 1;
                }

                er = emulate_instruction(vcpu, kvm_run, cr2, error_code);
                spin_unlock(&vcpu->kvm->lock);

                switch (er) {
                case EMULATE_DONE:
                        return 1;
                case EMULATE_DO_MMIO:
                        ++vcpu->stat.mmio_exits;
                        kvm_run->exit_reason = KVM_EXIT_MMIO;
                        return 0;
                 case EMULATE_FAIL:
                        vcpu_printf(vcpu, "%s: emulate fail\n", __FUNCTION__);
                        break;
                default:
                        BUG();
                }
        }

        if (vcpu->rmode.active &&
            handle_rmode_exception(vcpu, intr_info & INTR_INFO_VECTOR_MASK,
                                                                error_code))
                return 1;

        if ((intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK)) == (INTR_TYPE_EXCEPTION | 1)) {
                kvm_run->exit_reason = KVM_EXIT_DEBUG;
                return 0;
        }
        kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
        kvm_run->ex.exception = intr_info & INTR_INFO_VECTOR_MASK;
        kvm_run->ex.error_code = error_code;
        return 0;
}

static int handle_external_interrupt(struct kvm_vcpu *vcpu,
                                     struct kvm_run *kvm_run)
{
        ++vcpu->stat.irq_exits;
        return 1;
}

static int handle_triple_fault(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        kvm_run->exit_reason = KVM_EXIT_SHUTDOWN;
        return 0;
}

static int get_io_count(struct kvm_vcpu *vcpu, unsigned long *count)
{
        u64 inst;
        gva_t rip;
        int countr_size;
        int i, n;

        if ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_VM)) {
                countr_size = 2;
        } else {
                u32 cs_ar = vmcs_read32(GUEST_CS_AR_BYTES);

                countr_size = (cs_ar & AR_L_MASK) ? 8:
                              (cs_ar & AR_DB_MASK) ? 4: 2;
        }

        rip =  vmcs_readl(GUEST_RIP);
        if (countr_size != 8)
                rip += vmcs_readl(GUEST_CS_BASE);

        n = kvm_read_guest(vcpu, rip, sizeof(inst), &inst);

        for (i = 0; i < n; i++) {
                switch (((u8*)&inst)[i]) {
                case 0xf0:
                case 0xf2:
                case 0xf3:
                case 0x2e:
                case 0x36:
                case 0x3e:
                case 0x26:
                case 0x64:
                case 0x65:
                case 0x66:
                        break;
                case 0x67:
                        countr_size = (countr_size == 2) ? 4: (countr_size >> 1);
                default:
                        goto done;
                }
        }
        return 0;
done:
        countr_size *= 8;
        *count = vcpu->regs[VCPU_REGS_RCX] & (~0ULL >> (64 - countr_size));
        //printk("cx: %lx\n", vcpu->regs[VCPU_REGS_RCX]);
        return 1;
}

static int handle_io(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u64 exit_qualification;
        int size, down, in, string, rep;
        unsigned port;
        unsigned long count;
        gva_t address;

        ++vcpu->stat.io_exits;
        exit_qualification = vmcs_read64(EXIT_QUALIFICATION);
        in = (exit_qualification & 8) != 0;
        size = (exit_qualification & 7) + 1;
        string = (exit_qualification & 16) != 0;
        down = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_DF) != 0;
        count = 1;
        rep = (exit_qualification & 32) != 0;
        port = exit_qualification >> 16;
        address = 0;
        if (string) {
                if (rep && !get_io_count(vcpu, &count))
                        return 1;
                address = vmcs_readl(GUEST_LINEAR_ADDRESS);
        }
        return kvm_setup_pio(vcpu, kvm_run, in, size, count, string, down,
                             address, rep, port);
}

static void
vmx_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
{
        /*
         * Patch in the VMCALL instruction:
         */
        hypercall[0] = 0x0f;
        hypercall[1] = 0x01;
        hypercall[2] = 0xc1;
        hypercall[3] = 0xc3;
}

static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u64 exit_qualification;
        int cr;
        int reg;

        exit_qualification = vmcs_read64(EXIT_QUALIFICATION);
        cr = exit_qualification & 15;
        reg = (exit_qualification >> 8) & 15;
        switch ((exit_qualification >> 4) & 3) {
        case 0: /* mov to cr */
                switch (cr) {
                case 0:
                        vcpu_load_rsp_rip(vcpu);
                        set_cr0(vcpu, vcpu->regs[reg]);
                        skip_emulated_instruction(vcpu);
                        return 1;
                case 3:
                        vcpu_load_rsp_rip(vcpu);
                        set_cr3(vcpu, vcpu->regs[reg]);
                        skip_emulated_instruction(vcpu);
                        return 1;
                case 4:
                        vcpu_load_rsp_rip(vcpu);
                        set_cr4(vcpu, vcpu->regs[reg]);
                        skip_emulated_instruction(vcpu);
                        return 1;
                case 8:
                        vcpu_load_rsp_rip(vcpu);
                        set_cr8(vcpu, vcpu->regs[reg]);
                        skip_emulated_instruction(vcpu);
                        return 1;
                };
                break;
        case 2: /* clts */
                vcpu_load_rsp_rip(vcpu);
                vcpu->fpu_active = 1;
                vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
                vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);
                vcpu->cr0 &= ~CR0_TS_MASK;
                vmcs_writel(CR0_READ_SHADOW, vcpu->cr0);
                skip_emulated_instruction(vcpu);
                return 1;
        case 1: /*mov from cr*/
                switch (cr) {
                case 3:
                        vcpu_load_rsp_rip(vcpu);
                        vcpu->regs[reg] = vcpu->cr3;
                        vcpu_put_rsp_rip(vcpu);
                        skip_emulated_instruction(vcpu);
                        return 1;
                case 8:
                        vcpu_load_rsp_rip(vcpu);
                        vcpu->regs[reg] = vcpu->cr8;
                        vcpu_put_rsp_rip(vcpu);
                        skip_emulated_instruction(vcpu);
                        return 1;
                }
                break;
        case 3: /* lmsw */
                lmsw(vcpu, (exit_qualification >> LMSW_SOURCE_DATA_SHIFT) & 0x0f);

                skip_emulated_instruction(vcpu);
                return 1;
        default:
                break;
        }
        kvm_run->exit_reason = 0;
        printk(KERN_ERR "kvm: unhandled control register: op %d cr %d\n",
               (int)(exit_qualification >> 4) & 3, cr);
        return 0;
}

static int handle_dr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u64 exit_qualification;
        unsigned long val;
        int dr, reg;

        /*
         * FIXME: this code assumes the host is debugging the guest.
         *        need to deal with guest debugging itself too.
         */
        exit_qualification = vmcs_read64(EXIT_QUALIFICATION);
        dr = exit_qualification & 7;
        reg = (exit_qualification >> 8) & 15;
        vcpu_load_rsp_rip(vcpu);
        if (exit_qualification & 16) {
                /* mov from dr */
                switch (dr) {
                case 6:
                        val = 0xffff0ff0;
                        break;
                case 7:
                        val = 0x400;
                        break;
                default:
                        val = 0;
                }
                vcpu->regs[reg] = val;
        } else {
                /* mov to dr */
        }
        vcpu_put_rsp_rip(vcpu);
        skip_emulated_instruction(vcpu);
        return 1;
}

static int handle_cpuid(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        kvm_emulate_cpuid(vcpu);
        return 1;
}

static int handle_rdmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u32 ecx = vcpu->regs[VCPU_REGS_RCX];
        u64 data;

        if (vmx_get_msr(vcpu, ecx, &data)) {
                vmx_inject_gp(vcpu, 0);
                return 1;
        }

        /* FIXME: handling of bits 32:63 of rax, rdx */
        vcpu->regs[VCPU_REGS_RAX] = data & -1u;
        vcpu->regs[VCPU_REGS_RDX] = (data >> 32) & -1u;
        skip_emulated_instruction(vcpu);
        return 1;
}

static int handle_wrmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u32 ecx = vcpu->regs[VCPU_REGS_RCX];
        u64 data = (vcpu->regs[VCPU_REGS_RAX] & -1u)
                | ((u64)(vcpu->regs[VCPU_REGS_RDX] & -1u) << 32);

        if (vmx_set_msr(vcpu, ecx, data) != 0) {
                vmx_inject_gp(vcpu, 0);
                return 1;
        }

        skip_emulated_instruction(vcpu);
        return 1;
}

static void post_kvm_run_save(struct kvm_vcpu *vcpu,
                              struct kvm_run *kvm_run)
{
        kvm_run->if_flag = (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) != 0;
        kvm_run->cr8 = vcpu->cr8;
        kvm_run->apic_base = vcpu->apic_base;
        kvm_run->ready_for_interrupt_injection = (vcpu->interrupt_window_open &&
                                                  vcpu->irq_summary == 0);
}

static int handle_interrupt_window(struct kvm_vcpu *vcpu,
                                   struct kvm_run *kvm_run)
{
        /*
         * If the user space waits to inject interrupts, exit as soon as
         * possible
         */
        if (kvm_run->request_interrupt_window &&
            !vcpu->irq_summary) {
                kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
                ++vcpu->stat.irq_window_exits;
                return 0;
        }
        return 1;
}

static int handle_halt(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        skip_emulated_instruction(vcpu);
        if (vcpu->irq_summary)
                return 1;

        kvm_run->exit_reason = KVM_EXIT_HLT;
        ++vcpu->stat.halt_exits;
        return 0;
}

static int handle_vmcall(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        skip_emulated_instruction(vcpu);
        return kvm_hypercall(vcpu, kvm_run);
}

/*
 * The exit handlers return 1 if the exit was handled fully and guest execution
 * may resume.  Otherwise they set the kvm_run parameter to indicate what needs
 * to be done to userspace and return 0.
 */
static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu,
                                      struct kvm_run *kvm_run) = {
        [EXIT_REASON_EXCEPTION_NMI]           = handle_exception,
        [EXIT_REASON_EXTERNAL_INTERRUPT]      = handle_external_interrupt,
        [EXIT_REASON_TRIPLE_FAULT]            = handle_triple_fault,
        [EXIT_REASON_IO_INSTRUCTION]          = handle_io,
        [EXIT_REASON_CR_ACCESS]               = handle_cr,
        [EXIT_REASON_DR_ACCESS]               = handle_dr,
        [EXIT_REASON_CPUID]                   = handle_cpuid,
        [EXIT_REASON_MSR_READ]                = handle_rdmsr,
        [EXIT_REASON_MSR_WRITE]               = handle_wrmsr,
        [EXIT_REASON_PENDING_INTERRUPT]       = handle_interrupt_window,
        [EXIT_REASON_HLT]                     = handle_halt,
        [EXIT_REASON_VMCALL]                  = handle_vmcall,
};

static const int kvm_vmx_max_exit_handlers =
        sizeof(kvm_vmx_exit_handlers) / sizeof(*kvm_vmx_exit_handlers);

/*
 * The guest has exited.  See if we can fix it or if we need userspace
 * assistance.
 */
static int kvm_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
{
        u32 vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);
        u32 exit_reason = vmcs_read32(VM_EXIT_REASON);

        if ( (vectoring_info & VECTORING_INFO_VALID_MASK) &&
                                exit_reason != EXIT_REASON_EXCEPTION_NMI )
                printk(KERN_WARNING "%s: unexpected, valid vectoring info and "
                       "exit reason is 0x%x\n", __FUNCTION__, exit_reason);
        if (exit_reason < kvm_vmx_max_exit_handlers
            && kvm_vmx_exit_handlers[exit_reason])
                return kvm_vmx_exit_handlers[exit_reason](vcpu, kvm_run);
        else {
                kvm_run->exit_reason = KVM_EXIT_UNKNOWN;
                kvm_run->hw.hardware_exit_reason = exit_reason;
        }
        return 0;
}

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

static int vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
        u8 fail;
        u16 fs_sel, gs_sel, ldt_sel;
        int fs_gs_ldt_reload_needed;
        int r;

again:
        /*
         * Set host fs and gs selectors.  Unfortunately, 22.2.3 does not
         * allow segment selectors with cpl > 0 or ti == 1.
         */
        fs_sel = read_fs();
        gs_sel = read_gs();
        ldt_sel = read_ldt();
        fs_gs_ldt_reload_needed = (fs_sel & 7) | (gs_sel & 7) | ldt_sel;
        if (!fs_gs_ldt_reload_needed) {
                vmcs_write16(HOST_FS_SELECTOR, fs_sel);
                vmcs_write16(HOST_GS_SELECTOR, gs_sel);
        } else {
                vmcs_write16(HOST_FS_SELECTOR, 0);
                vmcs_write16(HOST_GS_SELECTOR, 0);
        }

#ifdef CONFIG_X86_64
        vmcs_writel(HOST_FS_BASE, read_msr(MSR_FS_BASE));
        vmcs_writel(HOST_GS_BASE, read_msr(MSR_GS_BASE));
#else
        vmcs_writel(HOST_FS_BASE, segment_base(fs_sel));
        vmcs_writel(HOST_GS_BASE, segment_base(gs_sel));
#endif

        if (!vcpu->mmio_read_completed)
                do_interrupt_requests(vcpu, kvm_run);

        if (vcpu->guest_debug.enabled)
                kvm_guest_debug_pre(vcpu);

        kvm_load_guest_fpu(vcpu);

        /*
         * Loading guest fpu may have cleared host cr0.ts
         */
        vmcs_writel(HOST_CR0, read_cr0());

#ifdef CONFIG_X86_64
        if (is_long_mode(vcpu)) {
                save_msrs(vcpu->host_msrs + msr_offset_kernel_gs_base, 1);
                load_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
        }
#endif

        asm (
                /* Store host registers */
                "pushf \n\t"
#ifdef CONFIG_X86_64
                "push %%rax; push %%rbx; push %%rdx;"
                "push %%rsi; push %%rdi; push %%rbp;"
                "push %%r8;  push %%r9;  push %%r10; push %%r11;"
                "push %%r12; push %%r13; push %%r14; push %%r15;"
                "push %%rcx \n\t"
                ASM_VMX_VMWRITE_RSP_RDX "\n\t"
#else
                "pusha; push %%ecx \n\t"
                ASM_VMX_VMWRITE_RSP_RDX "\n\t"
#endif
                /* Check if vmlaunch of vmresume is needed */
                "cmp $0, %1 \n\t"
                /* Load guest registers.  Don't clobber flags. */
#ifdef CONFIG_X86_64
                "mov %c[cr2](%3), %%rax \n\t"
                "mov %%rax, %%cr2 \n\t"
                "mov %c[rax](%3), %%rax \n\t"
                "mov %c[rbx](%3), %%rbx \n\t"
                "mov %c[rdx](%3), %%rdx \n\t"
                "mov %c[rsi](%3), %%rsi \n\t"
                "mov %c[rdi](%3), %%rdi \n\t"
                "mov %c[rbp](%3), %%rbp \n\t"
                "mov %c[r8](%3),  %%r8  \n\t"
                "mov %c[r9](%3),  %%r9  \n\t"
                "mov %c[r10](%3), %%r10 \n\t"
                "mov %c[r11](%3), %%r11 \n\t"
                "mov %c[r12](%3), %%r12 \n\t"
                "mov %c[r13](%3), %%r13 \n\t"
                "mov %c[r14](%3), %%r14 \n\t"
                "mov %c[r15](%3), %%r15 \n\t"
                "mov %c[rcx](%3), %%rcx \n\t" /* kills %3 (rcx) */
#else
                "mov %c[cr2](%3), %%eax \n\t"
                "mov %%eax,   %%cr2 \n\t"
                "mov %c[rax](%3), %%eax \n\t"
                "mov %c[rbx](%3), %%ebx \n\t"
                "mov %c[rdx](%3), %%edx \n\t"
                "mov %c[rsi](%3), %%esi \n\t"
                "mov %c[rdi](%3), %%edi \n\t"
                "mov %c[rbp](%3), %%ebp \n\t"
                "mov %c[rcx](%3), %%ecx \n\t" /* kills %3 (ecx) */
#endif
                /* Enter guest mode */
                "jne launched \n\t"
                ASM_VMX_VMLAUNCH "\n\t"
                "jmp kvm_vmx_return \n\t"
                "launched: " ASM_VMX_VMRESUME "\n\t"
                ".globl kvm_vmx_return \n\t"
                "kvm_vmx_return: "
                /* Save guest registers, load host registers, keep flags */
#ifdef CONFIG_X86_64
                "xchg %3,     (%%rsp) \n\t"
                "mov %%rax, %c[rax](%3) \n\t"
                "mov %%rbx, %c[rbx](%3) \n\t"
                "pushq (%%rsp); popq %c[rcx](%3) \n\t"
                "mov %%rdx, %c[rdx](%3) \n\t"
                "mov %%rsi, %c[rsi](%3) \n\t"
                "mov %%rdi, %c[rdi](%3) \n\t"
                "mov %%rbp, %c[rbp](%3) \n\t"
                "mov %%r8,  %c[r8](%3) \n\t"
                "mov %%r9,  %c[r9](%3) \n\t"
                "mov %%r10, %c[r10](%3) \n\t"
                "mov %%r11, %c[r11](%3) \n\t"
                "mov %%r12, %c[r12](%3) \n\t"
                "mov %%r13, %c[r13](%3) \n\t"
                "mov %%r14, %c[r14](%3) \n\t"
                "mov %%r15, %c[r15](%3) \n\t"
                "mov %%cr2, %%rax   \n\t"
                "mov %%rax, %c[cr2](%3) \n\t"
                "mov (%%rsp), %3 \n\t"

                "pop  %%rcx; pop  %%r15; pop  %%r14; pop  %%r13; pop  %%r12;"
                "pop  %%r11; pop  %%r10; pop  %%r9;  pop  %%r8;"
                "pop  %%rbp; pop  %%rdi; pop  %%rsi;"
                "pop  %%rdx; pop  %%rbx; pop  %%rax \n\t"
#else
                "xchg %3, (%%esp) \n\t"
                "mov %%eax, %c[rax](%3) \n\t"
                "mov %%ebx, %c[rbx](%3) \n\t"
                "pushl (%%esp); popl %c[rcx](%3) \n\t"
                "mov %%edx, %c[rdx](%3) \n\t"
                "mov %%esi, %c[rsi](%3) \n\t"
                "mov %%edi, %c[rdi](%3) \n\t"
                "mov %%ebp, %c[rbp](%3) \n\t"
                "mov %%cr2, %%eax  \n\t"
                "mov %%eax, %c[cr2](%3) \n\t"
                "mov (%%esp), %3 \n\t"

                "pop %%ecx; popa \n\t"
#endif
                "setbe %0 \n\t"
                "popf \n\t"
              : "=q" (fail)
              : "r"(vcpu->launched), "d"((unsigned long)HOST_RSP),
                "c"(vcpu),
                [rax]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RAX])),
                [rbx]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RBX])),
                [rcx]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RCX])),
                [rdx]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RDX])),
                [rsi]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RSI])),
                [rdi]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RDI])),
                [rbp]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_RBP])),
#ifdef CONFIG_X86_64
                [r8 ]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R8 ])),
                [r9 ]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R9 ])),
                [r10]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R10])),
                [r11]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R11])),
                [r12]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R12])),
                [r13]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R13])),
                [r14]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R14])),
                [r15]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R15])),
#endif
                [cr2]"i"(offsetof(struct kvm_vcpu, cr2))
              : "cc", "memory" );

        /*
         * Reload segment selectors ASAP. (it's needed for a functional
         * kernel: x86 relies on having __KERNEL_PDA in %fs and x86_64
         * relies on having 0 in %gs for the CPU PDA to work.)
         */
        if (fs_gs_ldt_reload_needed) {
                load_ldt(ldt_sel);
                load_fs(fs_sel);
                /*
                 * If we have to reload gs, we must take care to
                 * preserve our gs base.
                 */
                local_irq_disable();
                load_gs(gs_sel);
#ifdef CONFIG_X86_64
                wrmsrl(MSR_GS_BASE, vmcs_readl(HOST_GS_BASE));
#endif
                local_irq_enable();

                reload_tss();
        }
        ++vcpu->stat.exits;

#ifdef CONFIG_X86_64
        if (is_long_mode(vcpu)) {
                save_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
                load_msrs(vcpu->host_msrs, NR_BAD_MSRS);
        }
#endif

        vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0;

        asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS));

        if (fail) {
                kvm_run->exit_reason = KVM_EXIT_FAIL_ENTRY;
                kvm_run->fail_entry.hardware_entry_failure_reason
                        = vmcs_read32(VM_INSTRUCTION_ERROR);
                r = 0;
        } else {
                /*
                 * Profile KVM exit RIPs:
                 */
                if (unlikely(prof_on == KVM_PROFILING))
                        profile_hit(KVM_PROFILING, (void *)vmcs_readl(GUEST_RIP));

                vcpu->launched = 1;
                r = kvm_handle_exit(kvm_run, vcpu);
                if (r > 0) {
                        /* Give scheduler a change to reschedule. */
                        if (signal_pending(current)) {
                                ++vcpu->stat.signal_exits;
                                post_kvm_run_save(vcpu, kvm_run);
                                kvm_run->exit_reason = KVM_EXIT_INTR;
                                return -EINTR;
                        }

                        if (dm_request_for_irq_injection(vcpu, kvm_run)) {
                                ++vcpu->stat.request_irq_exits;
                                post_kvm_run_save(vcpu, kvm_run);
                                kvm_run->exit_reason = KVM_EXIT_INTR;
                                return -EINTR;
                        }

                        kvm_resched(vcpu);
                        goto again;
                }
        }

        post_kvm_run_save(vcpu, kvm_run);
        return r;
}

static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
{
        vmcs_writel(GUEST_CR3, vmcs_readl(GUEST_CR3));
}

static void vmx_inject_page_fault(struct kvm_vcpu *vcpu,
                                  unsigned long addr,
                                  u32 err_code)
{
        u32 vect_info = vmcs_read32(IDT_VECTORING_INFO_FIELD);

        ++vcpu->stat.pf_guest;

        if (is_page_fault(vect_info)) {
                printk(KERN_DEBUG "inject_page_fault: "
                       "double fault 0x%lx @ 0x%lx\n",
                       addr, vmcs_readl(GUEST_RIP));
                vmcs_write32(VM_ENTRY_EXCEPTION_ERROR_CODE, 0);
                vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
                             DF_VECTOR |
                             INTR_TYPE_EXCEPTION |
                             INTR_INFO_DELIEVER_CODE_MASK |
                             INTR_INFO_VALID_MASK);
                return;
        }
        vcpu->cr2 = addr;
        vmcs_write32(VM_ENTRY_EXCEPTION_ERROR_CODE, err_code);
        vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
                     PF_VECTOR |
                     INTR_TYPE_EXCEPTION |
                     INTR_INFO_DELIEVER_CODE_MASK |
                     INTR_INFO_VALID_MASK);

}

static void vmx_free_vmcs(struct kvm_vcpu *vcpu)
{
        if (vcpu->vmcs) {
                on_each_cpu(__vcpu_clear, vcpu, 0, 1);
                free_vmcs(vcpu->vmcs);
                vcpu->vmcs = NULL;
        }
}

static void vmx_free_vcpu(struct kvm_vcpu *vcpu)
{
        vmx_free_vmcs(vcpu);
}

static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
{
        struct vmcs *vmcs;

        vcpu->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!vcpu->guest_msrs)
                return -ENOMEM;

        vcpu->host_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!vcpu->host_msrs)
                goto out_free_guest_msrs;

        vmcs = alloc_vmcs();
        if (!vmcs)
                goto out_free_msrs;

        vmcs_clear(vmcs);
        vcpu->vmcs = vmcs;
        vcpu->launched = 0;
        vcpu->fpu_active = 1;

        return 0;

out_free_msrs:
        kfree(vcpu->host_msrs);
        vcpu->host_msrs = NULL;

out_free_guest_msrs:
        kfree(vcpu->guest_msrs);
        vcpu->guest_msrs = NULL;

        return -ENOMEM;
}

static struct kvm_arch_ops vmx_arch_ops = {
        .cpu_has_kvm_support = cpu_has_kvm_support,
        .disabled_by_bios = vmx_disabled_by_bios,
        .hardware_setup = hardware_setup,
        .hardware_unsetup = hardware_unsetup,
        .hardware_enable = hardware_enable,
        .hardware_disable = hardware_disable,

        .vcpu_create = vmx_create_vcpu,
        .vcpu_free = vmx_free_vcpu,

        .vcpu_load = vmx_vcpu_load,
        .vcpu_put = vmx_vcpu_put,
        .vcpu_decache = vmx_vcpu_decache,

        .set_guest_debug = set_guest_debug,
        .get_msr = vmx_get_msr,
        .set_msr = vmx_set_msr,
        .get_segment_base = vmx_get_segment_base,
        .get_segment = vmx_get_segment,
        .set_segment = vmx_set_segment,
        .get_cs_db_l_bits = vmx_get_cs_db_l_bits,
        .decache_cr4_guest_bits = vmx_decache_cr4_guest_bits,
        .set_cr0 = vmx_set_cr0,
        .set_cr3 = vmx_set_cr3,
        .set_cr4 = vmx_set_cr4,
#ifdef CONFIG_X86_64
        .set_efer = vmx_set_efer,
#endif
        .get_idt = vmx_get_idt,
        .set_idt = vmx_set_idt,
        .get_gdt = vmx_get_gdt,
        .set_gdt = vmx_set_gdt,
        .cache_regs = vcpu_load_rsp_rip,
        .decache_regs = vcpu_put_rsp_rip,
        .get_rflags = vmx_get_rflags,
        .set_rflags = vmx_set_rflags,

        .tlb_flush = vmx_flush_tlb,
        .inject_page_fault = vmx_inject_page_fault,

        .inject_gp = vmx_inject_gp,

        .run = vmx_vcpu_run,
        .skip_emulated_instruction = skip_emulated_instruction,
        .vcpu_setup = vmx_vcpu_setup,
        .patch_hypercall = vmx_patch_hypercall,
};

static int __init vmx_init(void)
{
        return kvm_init_arch(&vmx_arch_ops, THIS_MODULE);
}

static void __exit vmx_exit(void)
{
        kvm_exit_arch();
}

module_init(vmx_init)
module_exit(vmx_exit)