/*
 * vmx.c: handling VMX architecture-related VM exits
 * Copyright (c) 2004, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; If not, see <http://www.gnu.org/licenses/>.
 */

#include <xen/guest_access.h>
#include <xen/init.h>
#include <xen/lib.h>
#include <xen/param.h>
#include <xen/trace.h>
#include <xen/sched.h>
#include <xen/irq.h>
#include <xen/softirq.h>
#include <xen/domain_page.h>
#include <xen/hypercall.h>
#include <xen/perfc.h>
#include <asm/current.h>
#include <asm/io.h>
#include <asm/iocap.h>
#include <asm/regs.h>
#include <asm/cpufeature.h>
#include <asm/processor.h>
#include <asm/debugreg.h>
#include <asm/msr.h>
#include <asm/p2m.h>
#include <asm/mem_sharing.h>
#include <asm/hvm/emulate.h>
#include <asm/hvm/hvm.h>
#include <asm/hvm/support.h>
#include <asm/hvm/vmx/vmx.h>
#include <asm/hvm/vmx/vmcs.h>
#include <public/sched.h>
#include <public/hvm/ioreq.h>
#include <asm/hvm/vpic.h>
#include <asm/hvm/vlapic.h>
#include <asm/x86_emulate.h>
#include <asm/hvm/vpt.h>
#include <public/hvm/save.h>
#include <asm/hvm/trace.h>
#include <asm/hvm/monitor.h>
#include <asm/xenoprof.h>
#include <asm/debugger.h>
#include <asm/apic.h>
#include <asm/hvm/nestedhvm.h>
#include <asm/altp2m.h>
#include <asm/event.h>
#include <asm/mce.h>
#include <asm/monitor.h>
#include <public/arch-x86/cpuid.h>

static bool_t __initdata opt_force_ept;
boolean_param("force-ept", opt_force_ept);

static void vmx_ctxt_switch_from(struct vcpu *v);
static void vmx_ctxt_switch_to(struct vcpu *v);

static int  vmx_alloc_vlapic_mapping(struct domain *d);
static void vmx_free_vlapic_mapping(struct domain *d);
static void vmx_install_vlapic_mapping(struct vcpu *v);
static void vmx_update_guest_cr(struct vcpu *v, unsigned int cr,
                                unsigned int flags);
static void vmx_update_guest_efer(struct vcpu *v);
static void vmx_wbinvd_intercept(void);
static void vmx_fpu_dirty_intercept(void);
static int vmx_msr_read_intercept(unsigned int msr, uint64_t *msr_content);
static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content);
static void vmx_invlpg(struct vcpu *v, unsigned long linear);

/* Values for domain's ->arch.hvm_domain.pi_ops.flags. */
#define PI_CSW_FROM (1u << 0)
#define PI_CSW_TO   (1u << 1)

struct vmx_pi_blocking_vcpu {
    struct list_head     list;
    spinlock_t           lock;
};

/*
 * We maintain a per-CPU linked-list of vCPUs, so in PI wakeup
 * handler we can find which vCPU should be woken up.
 */
static DEFINE_PER_CPU(struct vmx_pi_blocking_vcpu, vmx_pi_blocking);

uint8_t __read_mostly posted_intr_vector;
static uint8_t __read_mostly pi_wakeup_vector;

void vmx_pi_per_cpu_init(unsigned int cpu)
{
    INIT_LIST_HEAD(&per_cpu(vmx_pi_blocking, cpu).list);
    spin_lock_init(&per_cpu(vmx_pi_blocking, cpu).lock);
}

static void vmx_vcpu_block(struct vcpu *v)
{
    unsigned long flags;
    unsigned int dest;
    spinlock_t *old_lock;
    spinlock_t *pi_blocking_list_lock =
		&per_cpu(vmx_pi_blocking, v->processor).lock;
    struct pi_desc *pi_desc = &v->arch.hvm.vmx.pi_desc;

    spin_lock_irqsave(pi_blocking_list_lock, flags);
    old_lock = cmpxchg(&v->arch.hvm.vmx.pi_blocking.lock, NULL,
                       pi_blocking_list_lock);

    /*
     * 'v->arch.hvm.vmx.pi_blocking.lock' should be NULL before
     * being assigned to a new value, since the vCPU is currently
     * running and it cannot be on any blocking list.
     */
    ASSERT(old_lock == NULL);

    list_add_tail(&v->arch.hvm.vmx.pi_blocking.list,
                  &per_cpu(vmx_pi_blocking, v->processor).list);
    spin_unlock_irqrestore(pi_blocking_list_lock, flags);

    ASSERT(!pi_test_sn(pi_desc));

    dest = cpu_physical_id(v->processor);

    ASSERT(pi_desc->ndst ==
           (x2apic_enabled ? dest : MASK_INSR(dest, PI_xAPIC_NDST_MASK)));

    write_atomic(&pi_desc->nv, pi_wakeup_vector);
}

static void vmx_pi_switch_from(struct vcpu *v)
{
    struct pi_desc *pi_desc = &v->arch.hvm.vmx.pi_desc;

    if ( test_bit(_VPF_blocked, &v->pause_flags) )
        return;

    pi_set_sn(pi_desc);
}

static void vmx_pi_switch_to(struct vcpu *v)
{
    struct pi_desc *pi_desc = &v->arch.hvm.vmx.pi_desc;
    unsigned int dest = cpu_physical_id(v->processor);

    write_atomic(&pi_desc->ndst,
                 x2apic_enabled ? dest : MASK_INSR(dest, PI_xAPIC_NDST_MASK));

    pi_clear_sn(pi_desc);
}

static void vmx_pi_unblock_vcpu(struct vcpu *v)
{
    unsigned long flags;
    spinlock_t *pi_blocking_list_lock;
    struct pi_desc *pi_desc = &v->arch.hvm.vmx.pi_desc;

    /*
     * Set 'NV' field back to posted_intr_vector, so the
     * Posted-Interrupts can be delivered to the vCPU when
     * it is running in non-root mode.
     */
    write_atomic(&pi_desc->nv, posted_intr_vector);

    pi_blocking_list_lock = v->arch.hvm.vmx.pi_blocking.lock;

    /* Prevent the compiler from eliminating the local variable.*/
    smp_rmb();

    /* The vCPU is not on any blocking list. */
    if ( pi_blocking_list_lock == NULL )
        return;

    spin_lock_irqsave(pi_blocking_list_lock, flags);

    /*
     * v->arch.hvm.vmx.pi_blocking.lock == NULL here means the vCPU
     * was removed from the blocking list while we are acquiring the lock.
     */
    if ( v->arch.hvm.vmx.pi_blocking.lock != NULL )
    {
        ASSERT(v->arch.hvm.vmx.pi_blocking.lock == pi_blocking_list_lock);
        list_del(&v->arch.hvm.vmx.pi_blocking.list);
        v->arch.hvm.vmx.pi_blocking.lock = NULL;
    }

    spin_unlock_irqrestore(pi_blocking_list_lock, flags);
}

static void vmx_pi_do_resume(struct vcpu *v)
{
    ASSERT(!test_bit(_VPF_blocked, &v->pause_flags));

    vmx_pi_unblock_vcpu(v);
}

void vmx_pi_desc_fixup(unsigned int cpu)
{
    unsigned int new_cpu, dest;
    unsigned long flags;
    struct vmx_vcpu *vmx, *tmp;
    spinlock_t *new_lock, *old_lock = &per_cpu(vmx_pi_blocking, cpu).lock;
    struct list_head *blocked_vcpus = &per_cpu(vmx_pi_blocking, cpu).list;

    if ( !iommu_intpost )
        return;

    /*
     * We are in the context of CPU_DEAD or CPU_UP_CANCELED notification,
     * and it is impossible for a second CPU go down in parallel. So we
     * can safely acquire the old cpu's lock and then acquire the new_cpu's
     * lock after that.
     */
    spin_lock_irqsave(old_lock, flags);

    list_for_each_entry_safe(vmx, tmp, blocked_vcpus, pi_blocking.list)
    {
        /*
         * Suppress notification or we may miss an interrupt when the
         * target cpu is dying.
         */
        pi_set_sn(&vmx->pi_desc);

        /*
         * Check whether a notification is pending before doing the
         * movement, if that is the case we need to wake up it directly
         * other than moving it to the new cpu's list.
         */
        if ( pi_test_on(&vmx->pi_desc) )
        {
            list_del(&vmx->pi_blocking.list);
            vmx->pi_blocking.lock = NULL;
            vcpu_unblock(container_of(vmx, struct vcpu, arch.hvm.vmx));
        }
        else
        {
            /*
             * We need to find an online cpu as the NDST of the PI descriptor, it
             * doesn't matter whether it is within the cpupool of the domain or
             * not. As long as it is online, the vCPU will be woken up once the
             * notification event arrives.
             */
            new_cpu = cpumask_any(&cpu_online_map);
            new_lock = &per_cpu(vmx_pi_blocking, new_cpu).lock;

            spin_lock(new_lock);

            ASSERT(vmx->pi_blocking.lock == old_lock);

            dest = cpu_physical_id(new_cpu);
            write_atomic(&vmx->pi_desc.ndst,
                         x2apic_enabled ? dest : MASK_INSR(dest, PI_xAPIC_NDST_MASK));

            list_move(&vmx->pi_blocking.list,
                      &per_cpu(vmx_pi_blocking, new_cpu).list);
            vmx->pi_blocking.lock = new_lock;

            spin_unlock(new_lock);
        }

        pi_clear_sn(&vmx->pi_desc);
    }

    spin_unlock_irqrestore(old_lock, flags);
}

/*
 * To handle posted interrupts correctly, we need to set the following
 * state:
 *
 * * The PI notification vector (NV)
 * * The PI notification destination processor (NDST)
 * * The PI "suppress notification" bit (SN)
 * * The vcpu pi "blocked" list
 *
 * VMX implements the runstate transitions as the following:
 *
 * A: ... -> running
 *  - SN = 0
 *  - NDST = v->processor
 *  If a VM is currently running, we want the PI delivered to the guest vcpu
 *  on the proper pcpu.
 *
 * B: running -> ...
 *  - SN = 1
 *
 * C: ... -> blocked
 *  - SN = 0
 *  - NV = pi_wakeup_vector
 *  - Add vcpu to blocked list
 *  If the vm is blocked, we want the PI delivered to Xen so that it can
 *  wake it up.
 *
 * D: ... -> vmentry
 *  - SN = 0
 *  - NV = posted_intr_vector
 *  - Take vcpu off blocked list
 *
 *  If the VM is currently either preempted or offline (i.e., not running
 *  because of some reason other than blocking waiting for an interrupt),
 *  there's nothing Xen can do -- we want the interrupt pending bit set in
 *  the guest, but we don't want to bother Xen with an interrupt (SN clear).
 *
 * There's a brief window of time between vmx_intr_assist() and checking
 * softirqs where if an interrupt comes in it may be lost; so we need Xen
 * to get an interrupt and raise a softirq so that it will go through the
 * vmx_intr_assist() path again (SN clear, NV = posted_interrupt).
 */

/* This function is called when pcidevs_lock is held */
void vmx_pi_hooks_assign(struct domain *d)
{
    struct vcpu *v;

    if ( !iommu_intpost || !is_hvm_domain(d) )
        return;

    ASSERT(!d->arch.hvm.pi_ops.vcpu_block);

    /*
     * We carefully handle the timing here:
     * - Install the context switch first
     * - Then set the NDST field
     * - Install the block and resume hooks in the end
     *
     * This can make sure the PI (especially the NDST feild) is
     * in proper state when we call vmx_vcpu_block().
     */
    d->arch.hvm.pi_ops.flags = PI_CSW_FROM | PI_CSW_TO;

    for_each_vcpu ( d, v )
    {
        unsigned int dest = cpu_physical_id(v->processor);
        struct pi_desc *pi_desc = &v->arch.hvm.vmx.pi_desc;

        /*
         * We don't need to update NDST if vmx_pi_switch_to()
         * has already got called.
         */
        (void)cmpxchg(&pi_desc->ndst, APIC_INVALID_DEST,
                x2apic_enabled ? dest : MASK_INSR(dest, PI_xAPIC_NDST_MASK));
    }

    d->arch.hvm.pi_ops.vcpu_block = vmx_vcpu_block;
}

/* This function is called when pcidevs_lock is held */
void vmx_pi_hooks_deassign(struct domain *d)
{
    struct vcpu *v;

    if ( !iommu_intpost || !is_hvm_domain(d) )
        return;

    ASSERT(d->arch.hvm.pi_ops.vcpu_block);

    /*
     * Pausing the domain can make sure the vCPUs are not
     * running and hence not calling the hooks simultaneously
     * when deassigning the PI hooks and removing the vCPU
     * from the blocking list.
     */
    ASSERT(current->domain != d);
    domain_pause(d);

    /*
     * Note that we don't set 'd->arch.hvm.pi_ops.switch_to' to NULL
     * here. If we deassign the hooks while the vCPU is runnable in the
     * runqueue with 'SN' set, all the future notification event will be
     * suppressed since vmx_deliver_posted_intr() also use 'SN' bit
     * as the suppression flag. Preserving the 'switch_to' hook function can
     * clear the 'SN' bit when the vCPU becomes running next time. After
     * that, No matter which status(runnable, running or block) the vCPU is in,
     * the 'SN' bit will keep clear for the 'switch_from' hook function that set
     * the 'SN' bit has been removed. At that time, the 'switch_to' hook function
     * is also useless. Considering the function doesn't do harm to the whole
     * system, leave it here until we find a clean solution to deassign the
     * 'switch_to' hook function.
     */
    d->arch.hvm.pi_ops.vcpu_block = NULL;
    d->arch.hvm.pi_ops.flags = PI_CSW_TO;

    for_each_vcpu ( d, v )
        vmx_pi_unblock_vcpu(v);

    domain_unpause(d);
}

static int vmx_domain_initialise(struct domain *d)
{
    static const struct arch_csw csw = {
        .from = vmx_ctxt_switch_from,
        .to   = vmx_ctxt_switch_to,
        .tail = vmx_do_resume,
    };
    int rc;

    d->arch.ctxt_switch = &csw;

    /*
     * Work around CVE-2018-12207?  The hardware domain is already permitted
     * to reboot the system, so doesn't need mitigating against DoS's.
     */
    d->arch.hvm.vmx.exec_sp = is_hardware_domain(d) || opt_ept_exec_sp;

    if ( !has_vlapic(d) )
        return 0;

    if ( (rc = vmx_alloc_vlapic_mapping(d)) != 0 )
        return rc;

    return 0;
}

static void vmx_domain_relinquish_resources(struct domain *d)
{
    if ( !has_vlapic(d) )
        return;

    vmx_free_vlapic_mapping(d);
}

static int vmx_vcpu_initialise(struct vcpu *v)
{
    int rc;

    spin_lock_init(&v->arch.hvm.vmx.vmcs_lock);

    INIT_LIST_HEAD(&v->arch.hvm.vmx.pi_blocking.list);

    vcpu_2_nvmx(v).vmxon_region_pa = INVALID_PADDR;

    if ( (rc = vmx_create_vmcs(v)) != 0 )
    {
        dprintk(XENLOG_WARNING,
                "Failed to create VMCS for vcpu %d: err=%d.\n",
                v->vcpu_id, rc);
        return rc;
    }

    /*
     * It's rare but still possible that domain has already been in log-dirty
     * mode when vcpu is being created (commented by Tim), in which case we
     * should enable PML for this vcpu if PML has been enabled for the domain,
     * and failure to enable results in failure of creating this vcpu.
     *
     * Note even there's no vcpu created for the domain, vmx_domain_enable_pml
     * will return successful in which case vmx_domain_pml_enabled will also
     * return true. And even this is the first vcpu to be created with
     * vmx_domain_pml_enabled being true, failure of enabling PML still results
     * in failure of creating vcpu, to avoid complicated logic to revert PML
     * style EPT table to non-PML style EPT table.
     */
    if ( vmx_domain_pml_enabled(v->domain) )
    {
        if ( (rc = vmx_vcpu_enable_pml(v)) != 0 )
        {
            dprintk(XENLOG_ERR, "%pv: Failed to enable PML.\n", v);
            vmx_destroy_vmcs(v);
            return rc;
        }
    }

    vmx_install_vlapic_mapping(v);

    return 0;
}

static void vmx_vcpu_destroy(struct vcpu *v)
{
    /*
     * There are cases that domain still remains in log-dirty mode when it is
     * about to be destroyed (ex, user types 'xl destroy <dom>'), in which case
     * we should disable PML manually here. Note that vmx_vcpu_destroy is called
     * prior to vmx_domain_destroy so we need to disable PML for each vcpu
     * separately here.
     */
    vmx_vcpu_disable_pml(v);
    vmx_destroy_vmcs(v);
    passive_domain_destroy(v);
}

/*
 * To avoid MSR save/restore at every VM exit/entry time, we restore
 * the x86_64 specific MSRs at domain switch time. Since these MSRs
 * are not modified once set for para domains, we don't save them,
 * but simply reset them to values set in percpu_traps_init().
 */
static void vmx_restore_host_msrs(void)
{
    /* No PV guests?  No need to restore host SYSCALL infrastructure. */
    if ( !IS_ENABLED(CONFIG_PV) )
        return;

    /* Relies on the SYSCALL trampoline being at the start of the stubs. */
    wrmsrl(MSR_STAR,         XEN_MSR_STAR);
    wrmsrl(MSR_LSTAR,        this_cpu(stubs.addr));
    wrmsrl(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK);
}

static void vmx_save_guest_msrs(struct vcpu *v)
{
    /*
     * We cannot cache SHADOW_GS_BASE while the VCPU runs, as it can
     * be updated at any time via SWAPGS, which we cannot trap.
     */
    v->arch.hvm.vmx.shadow_gs = rdgsshadow();
}

static void vmx_restore_guest_msrs(struct vcpu *v)
{
    wrgsshadow(v->arch.hvm.vmx.shadow_gs);
    wrmsrl(MSR_STAR,           v->arch.hvm.vmx.star);
    wrmsrl(MSR_LSTAR,          v->arch.hvm.vmx.lstar);
    wrmsrl(MSR_SYSCALL_MASK,   v->arch.hvm.vmx.sfmask);

    if ( cpu_has_msr_tsc_aux )
        wrmsr_tsc_aux(v->arch.msrs->tsc_aux);
}

void vmx_update_cpu_exec_control(struct vcpu *v)
{
    if ( nestedhvm_vcpu_in_guestmode(v) )
        nvmx_update_exec_control(v, v->arch.hvm.vmx.exec_control);
    else
        __vmwrite(CPU_BASED_VM_EXEC_CONTROL, v->arch.hvm.vmx.exec_control);
}

void vmx_update_secondary_exec_control(struct vcpu *v)
{
    if ( nestedhvm_vcpu_in_guestmode(v) )
        nvmx_update_secondary_exec_control(v,
            v->arch.hvm.vmx.secondary_exec_control);
    else
        __vmwrite(SECONDARY_VM_EXEC_CONTROL,
                  v->arch.hvm.vmx.secondary_exec_control);
}

void vmx_update_exception_bitmap(struct vcpu *v)
{
    u32 bitmap = unlikely(v->arch.hvm.vmx.vmx_realmode)
        ? 0xffffffffu : v->arch.hvm.vmx.exception_bitmap;

    if ( nestedhvm_vcpu_in_guestmode(v) )
        nvmx_update_exception_bitmap(v, bitmap);
    else
        __vmwrite(EXCEPTION_BITMAP, bitmap);
}

static void vmx_cpuid_policy_changed(struct vcpu *v)
{
    const struct cpuid_policy *cp = v->domain->arch.cpuid;

    if ( opt_hvm_fep ||
         (v->domain->arch.cpuid->x86_vendor != boot_cpu_data.x86_vendor) )
        v->arch.hvm.vmx.exception_bitmap |= (1U << TRAP_invalid_op);
    else
        v->arch.hvm.vmx.exception_bitmap &= ~(1U << TRAP_invalid_op);

    vmx_vmcs_enter(v);
    vmx_update_exception_bitmap(v);
    vmx_vmcs_exit(v);

    /*
     * We can safely pass MSR_SPEC_CTRL through to the guest, even if STIBP
     * isn't enumerated in hardware, as SPEC_CTRL_STIBP is ignored.
     */
    if ( cp->feat.ibrsb )
        vmx_clear_msr_intercept(v, MSR_SPEC_CTRL, VMX_MSR_RW);
    else
        vmx_set_msr_intercept(v, MSR_SPEC_CTRL, VMX_MSR_RW);

    /* MSR_PRED_CMD is safe to pass through if the guest knows about it. */
    if ( cp->feat.ibrsb || cp->extd.ibpb )
        vmx_clear_msr_intercept(v, MSR_PRED_CMD,  VMX_MSR_RW);
    else
        vmx_set_msr_intercept(v, MSR_PRED_CMD,  VMX_MSR_RW);

    /* MSR_FLUSH_CMD is safe to pass through if the guest knows about it. */
    if ( cp->feat.l1d_flush )
        vmx_clear_msr_intercept(v, MSR_FLUSH_CMD, VMX_MSR_RW);
    else
        vmx_set_msr_intercept(v, MSR_FLUSH_CMD, VMX_MSR_RW);
}

int vmx_guest_x86_mode(struct vcpu *v)
{
    unsigned long cs_ar_bytes;

    if ( unlikely(!(v->arch.hvm.guest_cr[0] & X86_CR0_PE)) )
        return 0;
    if ( unlikely(guest_cpu_user_regs()->eflags & X86_EFLAGS_VM) )
        return 1;
    __vmread(GUEST_CS_AR_BYTES, &cs_ar_bytes);
    if ( hvm_long_mode_active(v) &&
         likely(cs_ar_bytes & X86_SEG_AR_CS_LM_ACTIVE) )
        return 8;
    return (likely(cs_ar_bytes & X86_SEG_AR_DEF_OP_SIZE) ? 4 : 2);
}

static void vmx_save_dr(struct vcpu *v)
{
    if ( !v->arch.hvm.flag_dr_dirty )
        return;

    /* Clear the DR dirty flag and re-enable intercepts for DR accesses. */
    v->arch.hvm.flag_dr_dirty = 0;
    v->arch.hvm.vmx.exec_control |= CPU_BASED_MOV_DR_EXITING;
    vmx_update_cpu_exec_control(v);

    v->arch.dr[0] = read_debugreg(0);
    v->arch.dr[1] = read_debugreg(1);
    v->arch.dr[2] = read_debugreg(2);
    v->arch.dr[3] = read_debugreg(3);
    v->arch.dr6   = read_debugreg(6);
    /* DR7 must be saved as it is used by vmx_restore_dr(). */
    __vmread(GUEST_DR7, &v->arch.dr7);
}

static void __restore_debug_registers(struct vcpu *v)
{
    if ( v->arch.hvm.flag_dr_dirty )
        return;

    v->arch.hvm.flag_dr_dirty = 1;

    write_debugreg(0, v->arch.dr[0]);
    write_debugreg(1, v->arch.dr[1]);
    write_debugreg(2, v->arch.dr[2]);
    write_debugreg(3, v->arch.dr[3]);
    write_debugreg(6, v->arch.dr6);
    /* DR7 is loaded from the VMCS. */
}

/*
 * DR7 is saved and restored on every vmexit.  Other debug registers only
 * need to be restored if their value is going to affect execution -- i.e.,
 * if one of the breakpoints is enabled.  So mask out all bits that don't
 * enable some breakpoint functionality.
 */
static void vmx_restore_dr(struct vcpu *v)
{
    /* NB. __vmread() is not usable here, so we cannot read from the VMCS. */
    if ( unlikely(v->arch.dr7 & DR7_ACTIVE_MASK) )
        __restore_debug_registers(v);
}

static void vmx_vmcs_save(struct vcpu *v, struct hvm_hw_cpu *c)
{
    unsigned long ev;

    vmx_vmcs_enter(v);

    __vmread(GUEST_SYSENTER_CS, &c->sysenter_cs);
    __vmread(GUEST_SYSENTER_ESP, &c->sysenter_esp);
    __vmread(GUEST_SYSENTER_EIP, &c->sysenter_eip);

    __vmread(VM_ENTRY_INTR_INFO, &ev);
    if ( (ev & INTR_INFO_VALID_MASK) &&
         hvm_event_needs_reinjection(MASK_EXTR(ev, INTR_INFO_INTR_TYPE_MASK),
                                     ev & INTR_INFO_VECTOR_MASK) )
    {
        c->pending_event = ev;
        __vmread(VM_ENTRY_EXCEPTION_ERROR_CODE, &ev);
        c->error_code = ev;
    }

    vmx_vmcs_exit(v);
}

static int vmx_restore_cr0_cr3(
    struct vcpu *v, unsigned long cr0, unsigned long cr3)
{
    struct page_info *page = NULL;

    if ( paging_mode_shadow(v->domain) )
    {
        if ( cr0 & X86_CR0_PG )
        {
            page = get_page_from_gfn(v->domain, cr3 >> PAGE_SHIFT,
                                     NULL, P2M_ALLOC);
            if ( !page )
            {
                gdprintk(XENLOG_ERR, "Invalid CR3 value=%#lx\n", cr3);
                return -EINVAL;
            }
        }

        if ( hvm_paging_enabled(v) )
            put_page(pagetable_get_page(v->arch.guest_table));

        v->arch.guest_table =
            page ? pagetable_from_page(page) : pagetable_null();
    }

    v->arch.hvm.guest_cr[0] = cr0 | X86_CR0_ET;
    v->arch.hvm.guest_cr[3] = cr3;

    return 0;
}

static int vmx_vmcs_restore(struct vcpu *v, struct hvm_hw_cpu *c)
{
    int rc;

    if ( c->pending_valid )
    {
        if ( (c->pending_type == 1) || (c->pending_type > 6) ||
             (c->pending_reserved != 0) )
        {
            dprintk(XENLOG_ERR, "%pv: Invalid pending event %#"PRIx32"\n",
                    v, c->pending_event);
            return -EINVAL;
        }

        if ( c->pending_error_valid &&
             c->error_code != (uint16_t)c->error_code )
        {
            dprintk(XENLOG_ERR, "%pv: Invalid error code %#"PRIx32"\n",
                    v, c->error_code);
            return -EINVAL;
        }
    }

    rc = vmx_restore_cr0_cr3(v, c->cr0, c->cr3);
    if ( rc )
        return rc;

    vmx_vmcs_enter(v);

    v->arch.hvm.guest_cr[4] = c->cr4;
    vmx_update_guest_cr(v, 0, 0);
    vmx_update_guest_cr(v, 4, 0);

    v->arch.hvm.guest_efer = c->msr_efer;
    vmx_update_guest_efer(v);

    __vmwrite(GUEST_SYSENTER_CS, c->sysenter_cs);
    __vmwrite(GUEST_SYSENTER_ESP, c->sysenter_esp);
    __vmwrite(GUEST_SYSENTER_EIP, c->sysenter_eip);

    __vmwrite(GUEST_DR7, c->dr7);

    if ( c->pending_valid &&
         hvm_event_needs_reinjection(c->pending_type, c->pending_vector) )
    {
        gdprintk(XENLOG_INFO, "Re-injecting %#"PRIx32", %#"PRIx32"\n",
                 c->pending_event, c->error_code);
        __vmwrite(VM_ENTRY_INTR_INFO, c->pending_event);
        __vmwrite(VM_ENTRY_EXCEPTION_ERROR_CODE, c->error_code);
    }
    else
    {
        __vmwrite(VM_ENTRY_INTR_INFO, 0);
        __vmwrite(VM_ENTRY_EXCEPTION_ERROR_CODE, 0);
    }
    vmx_vmcs_exit(v);

    paging_update_paging_modes(v);

    return 0;
}

static void vmx_save_cpu_state(struct vcpu *v, struct hvm_hw_cpu *data)
{
    data->shadow_gs        = v->arch.hvm.vmx.shadow_gs;
    data->msr_lstar        = v->arch.hvm.vmx.lstar;
    data->msr_star         = v->arch.hvm.vmx.star;
    data->msr_cstar        = v->arch.hvm.vmx.cstar;
    data->msr_syscall_mask = v->arch.hvm.vmx.sfmask;
}

static void vmx_load_cpu_state(struct vcpu *v, struct hvm_hw_cpu *data)
{
    v->arch.hvm.vmx.shadow_gs = data->shadow_gs;
    v->arch.hvm.vmx.star      = data->msr_star;
    v->arch.hvm.vmx.lstar     = data->msr_lstar;
    v->arch.hvm.vmx.cstar     = data->msr_cstar;
    v->arch.hvm.vmx.sfmask    = data->msr_syscall_mask;
}


static void vmx_save_vmcs_ctxt(struct vcpu *v, struct hvm_hw_cpu *ctxt)
{
    if ( v == current )
        vmx_save_guest_msrs(v);

    vmx_save_cpu_state(v, ctxt);
    vmx_vmcs_save(v, ctxt);
}

static int vmx_load_vmcs_ctxt(struct vcpu *v, struct hvm_hw_cpu *ctxt)
{
    /* Not currently safe to use in current context. */
    ASSERT(v != current);

    vmx_load_cpu_state(v, ctxt);

    if ( vmx_vmcs_restore(v, ctxt) )
    {
        gdprintk(XENLOG_ERR, "vmx_vmcs restore failed!\n");
        domain_crash(v->domain);
        return -EINVAL;
    }

    return 0;
}

static void vmx_fpu_enter(struct vcpu *v)
{
    vcpu_restore_fpu_lazy(v);
    v->arch.hvm.vmx.exception_bitmap &= ~(1u << TRAP_no_device);
    vmx_update_exception_bitmap(v);
    v->arch.hvm.vmx.host_cr0 &= ~X86_CR0_TS;
    __vmwrite(HOST_CR0, v->arch.hvm.vmx.host_cr0);
}

static void vmx_fpu_leave(struct vcpu *v)
{
    ASSERT(!v->fpu_dirtied);
    ASSERT(read_cr0() & X86_CR0_TS);

    if ( !(v->arch.hvm.vmx.host_cr0 & X86_CR0_TS) )
    {
        v->arch.hvm.vmx.host_cr0 |= X86_CR0_TS;
        __vmwrite(HOST_CR0, v->arch.hvm.vmx.host_cr0);
    }

    /*
     * If the guest does not have TS enabled then we must cause and handle an
     * exception on first use of the FPU. If the guest *does* have TS enabled
     * then this is not necessary: no FPU activity can occur until the guest
     * clears CR0.TS, and we will initialise the FPU when that happens.
     */
    if ( !(v->arch.hvm.guest_cr[0] & X86_CR0_TS) )
    {
        v->arch.hvm.hw_cr[0] |= X86_CR0_TS;
        __vmwrite(GUEST_CR0, v->arch.hvm.hw_cr[0]);
        v->arch.hvm.vmx.exception_bitmap |= (1u << TRAP_no_device);
        vmx_update_exception_bitmap(v);
    }
}

static void vmx_ctxt_switch_from(struct vcpu *v)
{
    /*
     * Return early if trying to do a context switch without VMX enabled,
     * this can happen when the hypervisor shuts down with HVM guests
     * still running.
     */
    if ( unlikely(!this_cpu(vmxon)) )
        return;

    if ( !v->is_running )
    {
        /*
         * When this vCPU isn't marked as running anymore, a remote pCPU's
         * attempt to pause us (from vmx_vmcs_enter()) won't have a reason
         * to spin in vcpu_sleep_sync(), and hence that pCPU might have taken
         * away the VMCS from us. As we're running with interrupts disabled,
         * we also can't call vmx_vmcs_enter().
         */
        vmx_vmcs_reload(v);
    }

    if ( !v->arch.fully_eager_fpu )
        vmx_fpu_leave(v);
    vmx_save_guest_msrs(v);
    vmx_restore_host_msrs();
    vmx_save_dr(v);

    if ( v->domain->arch.hvm.pi_ops.flags & PI_CSW_FROM )
        vmx_pi_switch_from(v);
}

static void vmx_ctxt_switch_to(struct vcpu *v)
{
    vmx_restore_guest_msrs(v);
    vmx_restore_dr(v);

    if ( v->domain->arch.hvm.pi_ops.flags & PI_CSW_TO )
        vmx_pi_switch_to(v);
}


unsigned int vmx_get_cpl(void)
{
    unsigned long attr;

    __vmread(GUEST_SS_AR_BYTES, &attr);

    return (attr >> 5) & 3;
}

static unsigned int _vmx_get_cpl(struct vcpu *v)
{
    unsigned int cpl;

    vmx_vmcs_enter(v);
    cpl = vmx_get_cpl();
    vmx_vmcs_exit(v);

    return cpl;
}

/*
 * SDM Vol 3: VM Entries > Checks on Guest Segment Registers:
 *
 * We can only enter virtual 8086 mode if all of CS, SS, DS, ES, FS and GS are
 * 16bit ring-3 data segments.  On hardware lacking the unrestricted_guest
 * feature, Xen fakes up real mode using vm86 mode.  The guest thinks it's got
 * ring-0 segments, so we need to fudge things.  We store the ring-3 version
 * in the VMCS to avoid lots of shuffling on vmenter and vmexit, and translate
 * in these accessors.
 */
#define rm_cs_attr   0x9b
#define rm_ds_attr   0x93
#define vm86_ds_attr 0xf3
#define vm86_tr_attr 0x8b

static void vmx_get_segment_register(struct vcpu *v, enum x86_segment seg,
                                     struct segment_register *reg)
{
    unsigned long attr = 0, sel = 0, limit;

    /*
     * We may get here in the context of dump_execstate(), which may have
     * interrupted context switching between setting "current" and
     * vmx_do_resume() reaching the end of vmx_load_vmcs(). That would make
     * all the VMREADs below fail if we don't bail right away.
     */
    if ( unlikely(!vmx_vmcs_try_enter(v)) )
    {
        static bool_t warned;

        if ( !warned )
        {
            warned = 1;
            printk(XENLOG_WARNING "Segment register inaccessible for %pv\n"
                   "(If you see this outside of debugging activity,"
                   " please report to xen-devel@lists.xenproject.org)\n",
                   v);
        }
        memset(reg, 0, sizeof(*reg));
        return;
    }

    switch ( seg )
    {
    case x86_seg_es ... x86_seg_gs:
        __vmread(GUEST_SEG_SELECTOR(seg), &sel);
        __vmread(GUEST_SEG_LIMIT(seg),    &limit);
        __vmread(GUEST_SEG_BASE(seg),     &reg->base);
        __vmread(GUEST_SEG_AR_BYTES(seg), &attr);
        break;
    case x86_seg_tr:
        __vmread(GUEST_TR_SELECTOR, &sel);
        __vmread(GUEST_TR_LIMIT,    &limit);
        __vmread(GUEST_TR_BASE,     &reg->base);
        __vmread(GUEST_TR_AR_BYTES, &attr);
        break;
    case x86_seg_gdtr:
        __vmread(GUEST_GDTR_LIMIT, &limit);
        __vmread(GUEST_GDTR_BASE,  &reg->base);
        break;
    case x86_seg_idtr:
        __vmread(GUEST_IDTR_LIMIT, &limit);
        __vmread(GUEST_IDTR_BASE,  &reg->base);
        break;
    case x86_seg_ldtr:
        __vmread(GUEST_LDTR_SELECTOR, &sel);
        __vmread(GUEST_LDTR_LIMIT,    &limit);
        __vmread(GUEST_LDTR_BASE,     &reg->base);
        __vmread(GUEST_LDTR_AR_BYTES, &attr);
        break;
    default:
        BUG();
        return;
    }

    vmx_vmcs_exit(v);

    reg->sel = sel;
    reg->limit = limit;

    /*
     * Fold VT-x representation into Xen's representation.  The Present bit is
     * unconditionally set to the inverse of unusable.
     */
    reg->attr =
        (!(attr & (1u << 16)) << 7) | (attr & 0x7f) | ((attr >> 4) & 0xf00);

    /* Adjust for virtual 8086 mode */
    if ( v->arch.hvm.vmx.vmx_realmode && seg <= x86_seg_tr
         && !(v->arch.hvm.vmx.vm86_segment_mask & (1u << seg)) )
    {
        struct segment_register *sreg = &v->arch.hvm.vmx.vm86_saved_seg[seg];
        if ( seg == x86_seg_tr ) 
            *reg = *sreg;
        else if ( reg->base != sreg->base || seg == x86_seg_ss )
        {
            /* If the guest's reloaded the segment, remember the new version.
             * We can't tell if the guest reloaded the segment with another 
             * one that has the same base.  By default we assume it hasn't,
             * since we don't want to lose big-real-mode segment attributes,
             * but for SS we assume it has: the Ubuntu graphical bootloader
             * does this and gets badly confused if we leave the old SS in 
             * place. */
            reg->attr = (seg == x86_seg_cs ? rm_cs_attr : rm_ds_attr);
            *sreg = *reg;
        }
        else 
        {
            /* Always give realmode guests a selector that matches the base
             * but keep the attr and limit from before */
            *reg = *sreg;
            reg->sel = reg->base >> 4;
        }
    }
}

static void vmx_set_segment_register(struct vcpu *v, enum x86_segment seg,
                                     struct segment_register *reg)
{
    uint32_t attr, sel, limit;
    uint64_t base;

    sel = reg->sel;
    attr = reg->attr;
    limit = reg->limit;
    base = reg->base;

    /* Adjust CS/SS/DS/ES/FS/GS/TR for virtual 8086 mode */
    if ( v->arch.hvm.vmx.vmx_realmode && seg <= x86_seg_tr )
    {
        /* Remember the proper contents */
        v->arch.hvm.vmx.vm86_saved_seg[seg] = *reg;
        
        if ( seg == x86_seg_tr ) 
        {
            const struct domain *d = v->domain;
            uint64_t val = d->arch.hvm.params[HVM_PARAM_VM86_TSS_SIZED];

            if ( val )
            {
                sel = 0;
                attr = vm86_tr_attr;
                limit = ((val & ~VM86_TSS_UPDATED) >> 32) - 1;
                base = (uint32_t)val;
                if ( val & VM86_TSS_UPDATED )
                {
                    hvm_prepare_vm86_tss(v, base, limit);
                    cmpxchg(&d->arch.hvm.params[HVM_PARAM_VM86_TSS_SIZED],
                            val, val & ~VM86_TSS_UPDATED);
                }
                v->arch.hvm.vmx.vm86_segment_mask &= ~(1u << seg);
            }
            else
                v->arch.hvm.vmx.vm86_segment_mask |= (1u << seg);
        }
        else
        {
            /* Try to fake it out as a 16bit data segment.  This could
             * cause confusion for the guest if it reads the selector,
             * but otherwise we have to emulate if *any* segment hasn't
             * been reloaded. */
            if ( base < 0x100000 && !(base & 0xf) && limit >= 0xffff && reg->p )
            {
                sel = base >> 4;
                attr = vm86_ds_attr;
                limit = 0xffff;
                v->arch.hvm.vmx.vm86_segment_mask &= ~(1u << seg);
            }
            else 
                v->arch.hvm.vmx.vm86_segment_mask |= (1u << seg);
        }
    }

    /*
     * Unfold Xen representation into VT-x representation.  The unusable bit
     * is unconditionally set to the inverse of present.
     */
    attr = (!(attr & (1u << 7)) << 16) | ((attr & 0xf00) << 4) | (attr & 0xff);

    vmx_vmcs_enter(v);

    switch ( seg )
    {
    case x86_seg_es ... x86_seg_gs:
        __vmwrite(GUEST_SEG_SELECTOR(seg), sel);
        __vmwrite(GUEST_SEG_LIMIT(seg),    limit);
        __vmwrite(GUEST_SEG_BASE(seg),     base);
        __vmwrite(GUEST_SEG_AR_BYTES(seg), attr);
        break;
    case x86_seg_tr:
        __vmwrite(GUEST_TR_SELECTOR, sel);
        __vmwrite(GUEST_TR_LIMIT, limit);
        __vmwrite(GUEST_TR_BASE, base);
        __vmwrite(GUEST_TR_AR_BYTES, attr);
        break;
    case x86_seg_gdtr:
        __vmwrite(GUEST_GDTR_LIMIT, limit);
        __vmwrite(GUEST_GDTR_BASE, base);
        break;
    case x86_seg_idtr:
        __vmwrite(GUEST_IDTR_LIMIT, limit);
        __vmwrite(GUEST_IDTR_BASE, base);
        break;
    case x86_seg_ldtr:
        __vmwrite(GUEST_LDTR_SELECTOR, sel);
        __vmwrite(GUEST_LDTR_LIMIT, limit);
        __vmwrite(GUEST_LDTR_BASE, base);
        __vmwrite(GUEST_LDTR_AR_BYTES, attr);
        break;
    default:
        BUG();
    }

    vmx_vmcs_exit(v);
}

static unsigned long vmx_get_shadow_gs_base(struct vcpu *v)
{
    return v->arch.hvm.vmx.shadow_gs;
}

static int vmx_set_guest_pat(struct vcpu *v, u64 gpat)
{
    if ( !paging_mode_hap(v->domain) ||
         unlikely(v->arch.hvm.cache_mode == NO_FILL_CACHE_MODE) )
        return 0;

    vmx_vmcs_enter(v);
    __vmwrite(GUEST_PAT, gpat);
    vmx_vmcs_exit(v);
    return 1;
}

static int vmx_get_guest_pat(struct vcpu *v, u64 *gpat)
{
    if ( !paging_mode_hap(v->domain) ||
         unlikely(v->arch.hvm.cache_mode == NO_FILL_CACHE_MODE) )
        return 0;

    vmx_vmcs_enter(v);
    __vmread(GUEST_PAT, gpat);
    vmx_vmcs_exit(v);
    return 1;
}

static bool vmx_set_guest_bndcfgs(struct vcpu *v, u64 val)
{
    ASSERT(cpu_has_mpx && cpu_has_vmx_mpx);

    vmx_vmcs_enter(v);
    __vmwrite(GUEST_BNDCFGS, val);
    vmx_vmcs_exit(v);

    return true;
}

static bool vmx_get_guest_bndcfgs(struct vcpu *v, u64 *val)
{
    ASSERT(cpu_has_mpx && cpu_has_vmx_mpx);

    vmx_vmcs_enter(v);
    __vmread(GUEST_BNDCFGS, val);
    vmx_vmcs_exit(v);

    return true;
}

static void vmx_handle_cd(struct vcpu *v, unsigned long value)
{
    if ( !paging_mode_hap(v->domain) )
    {
        /*
         * For shadow, 'load IA32_PAT' VM-entry control is 0, so it cannot
         * set guest memory type as UC via IA32_PAT. Xen drop all shadows
         * so that any new ones would be created on demand.
         */
        hvm_shadow_handle_cd(v, value);
    }
    else
    {
        u64 *pat = &v->arch.hvm.pat_cr;

        if ( value & X86_CR0_CD )
        {
            /*
             * For EPT, set guest IA32_PAT fields as UC so that guest
             * memory type are all UC.
             */
            u64 uc_pat =
                ((uint64_t)PAT_TYPE_UNCACHABLE)       |       /* PAT0 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 8)  |       /* PAT1 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 16) |       /* PAT2 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 24) |       /* PAT3 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 32) |       /* PAT4 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 40) |       /* PAT5 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 48) |       /* PAT6 */
                ((uint64_t)PAT_TYPE_UNCACHABLE << 56);        /* PAT7 */

            vmx_get_guest_pat(v, pat);
            vmx_set_guest_pat(v, uc_pat);
            vmx_set_msr_intercept(v, MSR_IA32_CR_PAT, VMX_MSR_RW);

            wbinvd();               /* flush possibly polluted cache */
            hvm_asid_flush_vcpu(v); /* invalidate memory type cached in TLB */
            v->arch.hvm.cache_mode = NO_FILL_CACHE_MODE;
        }
        else
        {
            v->arch.hvm.cache_mode = NORMAL_CACHE_MODE;
            vmx_set_guest_pat(v, *pat);
            if ( !is_iommu_enabled(v->domain) || iommu_snoop )
                vmx_clear_msr_intercept(v, MSR_IA32_CR_PAT, VMX_MSR_RW);
            hvm_asid_flush_vcpu(v); /* no need to flush cache */
        }
    }
}

static void vmx_setup_tsc_scaling(struct vcpu *v)
{
    if ( v->domain->arch.vtsc )
        return;

    vmx_vmcs_enter(v);
    __vmwrite(TSC_MULTIPLIER, hvm_tsc_scaling_ratio(v->domain));
    vmx_vmcs_exit(v);
}

static void vmx_set_tsc_offset(struct vcpu *v, u64 offset, u64 at_tsc)
{
    vmx_vmcs_enter(v);

    if ( nestedhvm_vcpu_in_guestmode(v) )
        offset += nvmx_get_tsc_offset(v);

    __vmwrite(TSC_OFFSET, offset);
    vmx_vmcs_exit(v);
}

static void vmx_set_rdtsc_exiting(struct vcpu *v, bool_t enable)
{
    vmx_vmcs_enter(v);
    v->arch.hvm.vmx.exec_control &= ~CPU_BASED_RDTSC_EXITING;
    if ( enable )
        v->arch.hvm.vmx.exec_control |= CPU_BASED_RDTSC_EXITING;
    vmx_update_cpu_exec_control(v);
    vmx_vmcs_exit(v);
}

static void vmx_set_descriptor_access_exiting(struct vcpu *v, bool enable)
{
    if ( enable )
        v->arch.hvm.vmx.secondary_exec_control |=
            SECONDARY_EXEC_DESCRIPTOR_TABLE_EXITING;
    else
        v->arch.hvm.vmx.secondary_exec_control &=
            ~SECONDARY_EXEC_DESCRIPTOR_TABLE_EXITING;

    vmx_vmcs_enter(v);
    vmx_update_secondary_exec_control(v);
    vmx_vmcs_exit(v);
}

static void vmx_init_hypercall_page(void *p)
{
    unsigned int i;

    for ( i = 0; i < (PAGE_SIZE / 32); i++, p += 32 )
    {
        if ( unlikely(i == __HYPERVISOR_iret) )
        {
            /* HYPERVISOR_iret isn't supported */
            *(u16 *)p = 0x0b0f; /* ud2 */

            continue;
        }

        *(u8  *)(p + 0) = 0xb8; /* mov imm32, %eax */
        *(u32 *)(p + 1) = i;
        *(u8  *)(p + 5) = 0x0f; /* vmcall */
        *(u8  *)(p + 6) = 0x01;
        *(u8  *)(p + 7) = 0xc1;
        *(u8  *)(p + 8) = 0xc3; /* ret */
    }
}

static unsigned int vmx_get_interrupt_shadow(struct vcpu *v)
{
    unsigned long intr_shadow;

    __vmread(GUEST_INTERRUPTIBILITY_INFO, &intr_shadow);

    return intr_shadow;
}

static void vmx_set_interrupt_shadow(struct vcpu *v, unsigned int intr_shadow)
{
    __vmwrite(GUEST_INTERRUPTIBILITY_INFO, intr_shadow);
}

static void vmx_load_pdptrs(struct vcpu *v)
{
    uint32_t cr3 = v->arch.hvm.guest_cr[3];
    const uint64_t *guest_pdptes;
    struct page_info *page;
    p2m_type_t p2mt;

    /* EPT needs to load PDPTRS into VMCS for PAE. */
    if ( !hvm_pae_enabled(v) || hvm_long_mode_active(v) )
        return;

    page = get_page_from_gfn(v->domain, cr3 >> PAGE_SHIFT, &p2mt, P2M_ALLOC);
    if ( !page )
    {
        /* Ideally you don't want to crash but rather go into a wait 
         * queue, but this is the wrong place. We're holding at least
         * the paging lock */
        gdprintk(XENLOG_ERR,
                 "Bad cr3 on load pdptrs gfn %"PRIx32" type %d\n",
                 cr3 >> PAGE_SHIFT, (int) p2mt);
        domain_crash(v->domain);
        return;
    }

    guest_pdptes = __map_domain_page(page) + (cr3 & ~(PAGE_MASK | 0x1f));

    /*
     * We do not check the PDPTRs for validity. The CPU will do this during
     * vm entry, and we can handle the failure there and crash the guest.
     * The only thing we could do better here is #GP instead.
     */

    vmx_vmcs_enter(v);

    __vmwrite(GUEST_PDPTE(0), guest_pdptes[0]);
    __vmwrite(GUEST_PDPTE(1), guest_pdptes[1]);
    __vmwrite(GUEST_PDPTE(2), guest_pdptes[2]);
    __vmwrite(GUEST_PDPTE(3), guest_pdptes[3]);

    vmx_vmcs_exit(v);

    unmap_domain_page(guest_pdptes);
    put_page(page);
    return;
}

static void vmx_update_host_cr3(struct vcpu *v)
{
    vmx_vmcs_enter(v);
    __vmwrite(HOST_CR3, v->arch.cr3);
    vmx_vmcs_exit(v);
}

void vmx_update_debug_state(struct vcpu *v)
{
    if ( v->arch.hvm.debug_state_latch )
        v->arch.hvm.vmx.exception_bitmap |= 1U << TRAP_int3;
    else
        v->arch.hvm.vmx.exception_bitmap &= ~(1U << TRAP_int3);

    vmx_vmcs_enter(v);
    vmx_update_exception_bitmap(v);
    vmx_vmcs_exit(v);
}

static void vmx_update_guest_cr(struct vcpu *v, unsigned int cr,
                                unsigned int flags)
{
    vmx_vmcs_enter(v);

    switch ( cr )
    {
    case 0:
    {
        bool realmode;
        unsigned long hw_cr0_mask = X86_CR0_NE;

        if ( !vmx_unrestricted_guest(v) )
            hw_cr0_mask |= X86_CR0_PG | X86_CR0_PE;

        if ( paging_mode_shadow(v->domain) )
            hw_cr0_mask |= X86_CR0_WP;

        if ( paging_mode_hap(v->domain) )
        {
            /* Manage GUEST_CR3 when CR0.PE=0. */
            uint32_t old_ctls = v->arch.hvm.vmx.exec_control;
            uint32_t cr3_ctls = (CPU_BASED_CR3_LOAD_EXITING |
                                 CPU_BASED_CR3_STORE_EXITING);

            v->arch.hvm.vmx.exec_control &= ~cr3_ctls;
            if ( !hvm_paging_enabled(v) && !vmx_unrestricted_guest(v) )
                v->arch.hvm.vmx.exec_control |= cr3_ctls;

            /* Trap CR3 updates if CR3 memory events are enabled. */
            if ( v->domain->arch.monitor.write_ctrlreg_enabled &
                 monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3) )
                v->arch.hvm.vmx.exec_control |= CPU_BASED_CR3_LOAD_EXITING;

            if ( old_ctls != v->arch.hvm.vmx.exec_control )
                vmx_update_cpu_exec_control(v);
        }

        if ( !nestedhvm_vcpu_in_guestmode(v) )
            __vmwrite(CR0_READ_SHADOW, v->arch.hvm.guest_cr[0]);
        else
            nvmx_set_cr_read_shadow(v, 0);

        if ( !(v->arch.hvm.guest_cr[0] & X86_CR0_TS) )
        {
            if ( v != current )
            {
                if ( !v->arch.fully_eager_fpu )
                    hw_cr0_mask |= X86_CR0_TS;
            }
            else if ( v->arch.hvm.hw_cr[0] & X86_CR0_TS )
                vmx_fpu_enter(v);
        }

        realmode = !(v->arch.hvm.guest_cr[0] & X86_CR0_PE);

        if ( !vmx_unrestricted_guest(v) &&
             (realmode != v->arch.hvm.vmx.vmx_realmode) )
        {
            enum x86_segment s;
            struct segment_register reg[x86_seg_tr + 1];

            BUILD_BUG_ON(x86_seg_tr != x86_seg_gs + 1);

            /* Entering or leaving real mode: adjust the segment registers.
             * Need to read them all either way, as realmode reads can update
             * the saved values we'll use when returning to prot mode. */
            for ( s = 0; s < ARRAY_SIZE(reg); s++ )
                hvm_get_segment_register(v, s, &reg[s]);
            v->arch.hvm.vmx.vmx_realmode = realmode;

            if ( realmode )
            {
                for ( s = 0; s < ARRAY_SIZE(reg); s++ )
                    hvm_set_segment_register(v, s, &reg[s]);
            }
            else
            {
                for ( s = 0; s < ARRAY_SIZE(reg); s++ )
                    if ( !(v->arch.hvm.vmx.vm86_segment_mask & (1<<s)) )
                        hvm_set_segment_register(
                            v, s, &v->arch.hvm.vmx.vm86_saved_seg[s]);
            }

            vmx_update_exception_bitmap(v);
        }

        v->arch.hvm.hw_cr[0] =
            v->arch.hvm.guest_cr[0] | hw_cr0_mask;
        __vmwrite(GUEST_CR0, v->arch.hvm.hw_cr[0]);
    }
        /* Fallthrough: Changing CR0 can change some bits in real CR4. */
    case 4:
        v->arch.hvm.hw_cr[4] = HVM_CR4_HOST_MASK;
        if ( paging_mode_hap(v->domain) )
            v->arch.hvm.hw_cr[4] &= ~X86_CR4_PAE;

        if ( !nestedhvm_vcpu_in_guestmode(v) )
            __vmwrite(CR4_READ_SHADOW, v->arch.hvm.guest_cr[4]);
        else
            nvmx_set_cr_read_shadow(v, 4);

        v->arch.hvm.hw_cr[4] |= v->arch.hvm.guest_cr[4];
        if ( v->arch.hvm.vmx.vmx_realmode )
            v->arch.hvm.hw_cr[4] |= X86_CR4_VME;

        if ( !hvm_paging_enabled(v) )
        {
            /*
             * When the guest thinks paging is disabled, Xen may need to hide
             * the effects of running with CR0.PG actually enabled.  There are
             * two subtly complicated cases.
             */

            if ( paging_mode_hap(v->domain) )
            {
                /*
                 * On hardware lacking the Unrestricted Guest feature (or with
                 * it disabled in the VMCS), we may not enter the guest with
                 * CR0.PG actually disabled.  When EPT is enabled, we run with
                 * guest paging settings, but with CR3 pointing at
                 * HVM_PARAM_IDENT_PT which is a 32bit pagetable using 4M
                 * superpages.  Override the guests paging settings to match.
                 */
                v->arch.hvm.hw_cr[4] |= X86_CR4_PSE;
                v->arch.hvm.hw_cr[4] &= ~X86_CR4_PAE;
            }

            /*
             * Without CR0.PG, all memory accesses are user mode, so
             * _PAGE_USER must be set in the pagetables for guest userspace to
             * function.  This in turn trips up guest supervisor mode if
             * SMEP/SMAP are left active in context.  They wouldn't have any
             * effect if paging was actually disabled, so hide them behind the
             * back of the guest.
             */
            v->arch.hvm.hw_cr[4] &= ~(X86_CR4_SMEP | X86_CR4_SMAP);
        }

        __vmwrite(GUEST_CR4, v->arch.hvm.hw_cr[4]);

        /*
         * Shadow path has not been optimized because it requires
         * unconditionally trapping more CR4 bits, at which point the
         * performance benefit of doing this is quite dubious.
         */
        if ( paging_mode_hap(v->domain) )
        {
            /*
             * Update CR4 host mask to only trap when the guest tries to set
             * bits that are controlled by the hypervisor.
             */
            v->arch.hvm.vmx.cr4_host_mask =
                (HVM_CR4_HOST_MASK | X86_CR4_PKE |
                 ~hvm_cr4_guest_valid_bits(v->domain, false));

            v->arch.hvm.vmx.cr4_host_mask |= v->arch.hvm.vmx.vmx_realmode ?
                                             X86_CR4_VME : 0;
            v->arch.hvm.vmx.cr4_host_mask |= !hvm_paging_enabled(v) ?
                                             (X86_CR4_PSE | X86_CR4_SMEP |
                                              X86_CR4_SMAP)
                                             : 0;
            if ( v->domain->arch.monitor.write_ctrlreg_enabled &
                 monitor_ctrlreg_bitmask(VM_EVENT_X86_CR4) )
                v->arch.hvm.vmx.cr4_host_mask |=
                ~v->domain->arch.monitor.write_ctrlreg_mask[VM_EVENT_X86_CR4];

            if ( nestedhvm_vcpu_in_guestmode(v) )
                /* Add the nested host mask to get the more restrictive one. */
                v->arch.hvm.vmx.cr4_host_mask |= get_vvmcs(v,
                                                           CR4_GUEST_HOST_MASK);

            __vmwrite(CR4_GUEST_HOST_MASK, v->arch.hvm.vmx.cr4_host_mask);
        }

        break;

    case 2:
        /* CR2 is updated in exit stub. */
        break;

    case 3:
        if ( paging_mode_hap(v->domain) )
        {
            if ( !hvm_paging_enabled(v) && !vmx_unrestricted_guest(v) )
                v->arch.hvm.hw_cr[3] =
                    v->domain->arch.hvm.params[HVM_PARAM_IDENT_PT];
            vmx_load_pdptrs(v);
        }

        __vmwrite(GUEST_CR3, v->arch.hvm.hw_cr[3]);

        if ( !(flags & HVM_UPDATE_GUEST_CR3_NOFLUSH) )
            hvm_asid_flush_vcpu(v);
        break;

    default:
        BUG();
    }

    vmx_vmcs_exit(v);
}

static void vmx_update_guest_efer(struct vcpu *v)
{
    unsigned long entry_ctls, guest_efer = v->arch.hvm.guest_efer,
        xen_efer = read_efer();

    if ( paging_mode_shadow(v->domain) )
    {
        /*
         * When using shadow pagetables, EFER.NX is a Xen-owned bit and is not
         * under guest control.
         */
        guest_efer &= ~EFER_NX;
        guest_efer |= xen_efer & EFER_NX;
    }

    if ( !vmx_unrestricted_guest(v) )
    {
        /*
         * When Unrestricted Guest is not enabled in the VMCS, hardware does
         * not tolerate the LME and LMA settings being different.  As writes
         * to CR0 are intercepted, it is safe to leave LME clear at this
         * point, and fix up both LME and LMA when CR0.PG is set.
         *
         * Furthermore, when using shadow pagetables (subsumed by the
         * Unrestricted Guest check), CR0.PG is a Xen-owned bit, and remains
         * set even when the guest has logically disabled paging.  LMA was
         * calculated using the guest CR0.PG setting, but LME needs clearing
         * to avoid interacting with Xen's CR0.PG setting.
         */
        if ( !(guest_efer & EFER_LMA) )
            guest_efer &= ~EFER_LME;
    }

    vmx_vmcs_enter(v);

    /*
     * The intended guest running mode is derived from VM_ENTRY_IA32E_MODE,
     * which (architecturally) is the guest's LMA setting.
     */
    __vmread(VM_ENTRY_CONTROLS, &entry_ctls);

    entry_ctls &= ~VM_ENTRY_IA32E_MODE;
    if ( guest_efer & EFER_LMA )
        entry_ctls |= VM_ENTRY_IA32E_MODE;

    __vmwrite(VM_ENTRY_CONTROLS, entry_ctls);

    /* We expect to use EFER loading in the common case, but... */
    if ( likely(cpu_has_vmx_efer) )
        __vmwrite(GUEST_EFER, guest_efer);

    /* ... on Gen1 VT-x hardware, we have to use MSR load/save lists instead. */
    else
    {
        /*
         * When the guests choice of EFER matches Xen's, remove the load/save
         * list entries.  It is unnecessary overhead, especially as this is
         * expected to be the common case for 64bit guests.
         */
        if ( guest_efer == xen_efer )
        {
            vmx_del_msr(v, MSR_EFER, VMX_MSR_HOST);
            vmx_del_msr(v, MSR_EFER, VMX_MSR_GUEST_LOADONLY);
        }
        else
        {
            vmx_add_msr(v, MSR_EFER, xen_efer, VMX_MSR_HOST);
            vmx_add_msr(v, MSR_EFER, guest_efer, VMX_MSR_GUEST_LOADONLY);
        }
    }

    vmx_vmcs_exit(v);

    /*
     * If the guests virtualised view of MSR_EFER matches the value loaded
     * into hardware, clear the read intercept to avoid unnecessary VMExits.
     */
    if ( guest_efer == v->arch.hvm.guest_efer )
        vmx_clear_msr_intercept(v, MSR_EFER, VMX_MSR_R);
    else
        vmx_set_msr_intercept(v, MSR_EFER, VMX_MSR_R);
}

void nvmx_enqueue_n2_exceptions(struct vcpu *v, 
            unsigned long intr_fields, int error_code, uint8_t source)
{
    struct nestedvmx *nvmx = &vcpu_2_nvmx(v);

    if ( !(nvmx->intr.intr_info & INTR_INFO_VALID_MASK) ) {
        /* enqueue the exception till the VMCS switch back to L1 */
        nvmx->intr.intr_info = intr_fields;
        nvmx->intr.error_code = error_code;
        nvmx->intr.source = source;
        vcpu_nestedhvm(v).nv_vmexit_pending = 1;
        return;
    }
    else
        gdprintk(XENLOG_ERR, "Double Fault on Nested Guest: exception %lx %x"
                 "on %lx %x\n", intr_fields, error_code,
                 nvmx->intr.intr_info, nvmx->intr.error_code);
}

static int nvmx_vmexit_event(struct vcpu *v, const struct x86_event *event)
{
    nvmx_enqueue_n2_exceptions(v, event->vector, event->error_code,
                               hvm_intsrc_none);
    return NESTEDHVM_VMEXIT_DONE;
}

static void __vmx_inject_exception(int trap, int type, int error_code)
{
    unsigned long intr_fields;
    struct vcpu *curr = current;

    /*
     * NB. Callers do not need to worry about clearing STI/MOV-SS blocking:
     *  "If the VM entry is injecting, there is no blocking by STI or by
     *   MOV SS following the VM entry, regardless of the contents of the
     *   interruptibility-state field [in the guest-state area before the
     *   VM entry]", PRM Vol. 3, 22.6.1 (Interruptibility State).
     */

    intr_fields = INTR_INFO_VALID_MASK |
                  MASK_INSR(type, INTR_INFO_INTR_TYPE_MASK) |
                  MASK_INSR(trap, INTR_INFO_VECTOR_MASK);
    if ( error_code != X86_EVENT_NO_EC )
    {
        ASSERT(error_code == (uint16_t)error_code);
        __vmwrite(VM_ENTRY_EXCEPTION_ERROR_CODE, error_code);
        intr_fields |= INTR_INFO_DELIVER_CODE_MASK;
    }

    __vmwrite(VM_ENTRY_INTR_INFO, intr_fields);

    /* Can't inject exceptions in virtual 8086 mode because they would 
     * use the protected-mode IDT.  Emulate at the next vmenter instead. */
    if ( curr->arch.hvm.vmx.vmx_realmode )
        curr->arch.hvm.vmx.vmx_emulate = 1;
}

void vmx_inject_extint(int trap, uint8_t source)
{
    struct vcpu *v = current;
    u32    pin_based_cntrl;

    if ( nestedhvm_vcpu_in_guestmode(v) ) {
        pin_based_cntrl = get_vvmcs(v, PIN_BASED_VM_EXEC_CONTROL);
        if ( pin_based_cntrl & PIN_BASED_EXT_INTR_MASK ) {
            nvmx_enqueue_n2_exceptions (v, 
               INTR_INFO_VALID_MASK |
               MASK_INSR(X86_EVENTTYPE_EXT_INTR, INTR_INFO_INTR_TYPE_MASK) |
               MASK_INSR(trap, INTR_INFO_VECTOR_MASK),
               X86_EVENT_NO_EC, source);
            return;
        }
    }
    __vmx_inject_exception(trap, X86_EVENTTYPE_EXT_INTR,
                           X86_EVENT_NO_EC);
}

void vmx_inject_nmi(void)
{
    struct vcpu *v = current;
    u32    pin_based_cntrl;

    if ( nestedhvm_vcpu_in_guestmode(v) ) {
        pin_based_cntrl = get_vvmcs(v, PIN_BASED_VM_EXEC_CONTROL);
        if ( pin_based_cntrl & PIN_BASED_NMI_EXITING ) {
            nvmx_enqueue_n2_exceptions (v, 
               INTR_INFO_VALID_MASK |
               MASK_INSR(X86_EVENTTYPE_NMI, INTR_INFO_INTR_TYPE_MASK) |
               MASK_INSR(TRAP_nmi, INTR_INFO_VECTOR_MASK),
               X86_EVENT_NO_EC, hvm_intsrc_nmi);
            return;
        }
    }
    __vmx_inject_exception(2, X86_EVENTTYPE_NMI,
                           X86_EVENT_NO_EC);
}

/*
 * Generate a virtual event in the guest.
 * NOTES:
 *  - INT 3 (CC) and INTO (CE) are X86_EVENTTYPE_SW_EXCEPTION;
 *  - INT nn (CD nn) is X86_EVENTTYPE_SW_INTERRUPT;
 *  - #DB is X86_EVENTTYPE_HW_EXCEPTION, except when generated by
 *    opcode 0xf1 (which is X86_EVENTTYPE_PRI_SW_EXCEPTION)
 */
static void vmx_inject_event(const struct x86_event *event)
{
    unsigned long intr_info;
    struct vcpu *curr = current;
    struct x86_event _event = *event;

    switch ( _event.vector | -(_event.type == X86_EVENTTYPE_SW_INTERRUPT) )
    {
    case TRAP_debug:
        if ( guest_cpu_user_regs()->eflags & X86_EFLAGS_TF )
        {
            __restore_debug_registers(curr);
            write_debugreg(6, read_debugreg(6) | DR_STEP);
        }
        if ( !nestedhvm_vcpu_in_guestmode(curr) ||
             !nvmx_intercepts_exception(curr, TRAP_debug, _event.error_code) )
        {
            unsigned long val;

            __vmread(GUEST_DR7, &val);
            __vmwrite(GUEST_DR7, val & ~DR_GENERAL_DETECT);
            __vmread(GUEST_IA32_DEBUGCTL, &val);
            __vmwrite(GUEST_IA32_DEBUGCTL, val & ~IA32_DEBUGCTLMSR_LBR);
        }
        if ( cpu_has_monitor_trap_flag )
            break;
        /* fall through */
    case TRAP_int3:
        if ( curr->domain->debugger_attached )
        {
            /* Debug/Int3: Trap to debugger. */
            domain_pause_for_debugger();
            return;
        }
        break;

    case TRAP_page_fault:
        ASSERT(_event.type == X86_EVENTTYPE_HW_EXCEPTION);
        curr->arch.hvm.guest_cr[2] = _event.cr2;
        break;
    }

    if ( nestedhvm_vcpu_in_guestmode(curr) )
        intr_info = vcpu_2_nvmx(curr).intr.intr_info;
    else
        __vmread(VM_ENTRY_INTR_INFO, &intr_info);

    if ( unlikely(intr_info & INTR_INFO_VALID_MASK) &&
         (MASK_EXTR(intr_info, INTR_INFO_INTR_TYPE_MASK) ==
          X86_EVENTTYPE_HW_EXCEPTION) )
    {
        _event.vector = hvm_combine_hw_exceptions(
            (uint8_t)intr_info, _event.vector);
        if ( _event.vector == TRAP_double_fault )
            _event.error_code = 0;
    }

    if ( _event.type >= X86_EVENTTYPE_SW_INTERRUPT )
        __vmwrite(VM_ENTRY_INSTRUCTION_LEN, _event.insn_len);

    if ( nestedhvm_vcpu_in_guestmode(curr) &&
         nvmx_intercepts_exception(curr, _event.vector, _event.error_code) )
    {
        nvmx_enqueue_n2_exceptions (curr, 
            INTR_INFO_VALID_MASK |
            MASK_INSR(_event.type, INTR_INFO_INTR_TYPE_MASK) |
            MASK_INSR(_event.vector, INTR_INFO_VECTOR_MASK),
            _event.error_code, hvm_intsrc_none);
        return;
    }
    else
        __vmx_inject_exception(_event.vector, _event.type, _event.error_code);

    if ( (_event.vector == TRAP_page_fault) &&
         (_event.type == X86_EVENTTYPE_HW_EXCEPTION) )
        HVMTRACE_LONG_2D(PF_INJECT, _event.error_code,
                         TRC_PAR_LONG(curr->arch.hvm.guest_cr[2]));
    else
        HVMTRACE_2D(INJ_EXC, _event.vector, _event.error_code);
}

static bool vmx_event_pending(const struct vcpu *v)
{
    unsigned long intr_info;

    ASSERT(v == current);
    __vmread(VM_ENTRY_INTR_INFO, &intr_info);

    return intr_info & INTR_INFO_VALID_MASK;
}

static void vmx_set_info_guest(struct vcpu *v)
{
    unsigned long intr_shadow;

    vmx_vmcs_enter(v);

    __vmwrite(GUEST_DR7, v->arch.dr7);

    /* 
     * If the interruptibility-state field indicates blocking by STI,
     * setting the TF flag in the EFLAGS may cause VM entry to fail
     * and crash the guest. See SDM 3B 22.3.1.5.
     * Resetting the VMX_INTR_SHADOW_STI flag looks hackish but
     * to set the GUEST_PENDING_DBG_EXCEPTIONS.BS here incurs
     * immediately vmexit and hence make no progress.
     */
    __vmread(GUEST_INTERRUPTIBILITY_INFO, &intr_shadow);
    if ( v->domain->debugger_attached &&
         (v->arch.user_regs.eflags & X86_EFLAGS_TF) &&
         (intr_shadow & VMX_INTR_SHADOW_STI) )
    {
        intr_shadow &= ~VMX_INTR_SHADOW_STI;
        __vmwrite(GUEST_INTERRUPTIBILITY_INFO, intr_shadow);
    }

    vmx_vmcs_exit(v);
}

static void vmx_update_eoi_exit_bitmap(struct vcpu *v, uint8_t vector, bool set)
{
    if ( set )
        vmx_set_eoi_exit_bitmap(v, vector);
    else
        vmx_clear_eoi_exit_bitmap(v, vector);
}

static u8 set_svi(int isr)
{
    unsigned long status;
    u8 old;

    if ( isr < 0 )
        isr = 0;

    __vmread(GUEST_INTR_STATUS, &status);
    old = status >> VMX_GUEST_INTR_STATUS_SVI_OFFSET;
    if ( isr != old )
    {
        status &= VMX_GUEST_INTR_STATUS_SUBFIELD_BITMASK;
        status |= isr << VMX_GUEST_INTR_STATUS_SVI_OFFSET;
        __vmwrite(GUEST_INTR_STATUS, status);
    }

    return old;
}

static void vmx_process_isr(int isr, struct vcpu *v)
{
    unsigned int i;
    const struct vlapic *vlapic = vcpu_vlapic(v);

    vmx_vmcs_enter(v);

    set_svi(isr);

    /*
     * Theoretically, only level triggered interrupts can have their
     * corresponding bits set in the eoi exit bitmap. That is, the bits
     * set in the eoi exit bitmap should also be set in TMR. But a periodic
     * timer interrupt does not follow the rule: it is edge triggered, but
     * requires its corresponding bit be set in the eoi exit bitmap. So we
     * should not construct the eoi exit bitmap based on TMR.
     * Here we will construct the eoi exit bitmap via (IRR | ISR). This
     * means that EOIs to the interrupts that are set in the IRR or ISR will
     * cause VM exits after restoring, regardless of the trigger modes. It
     * is acceptable because the subsequent interrupts will set up the eoi
     * bitmap correctly.
     */
    for ( i = 0x10; i < X86_NR_VECTORS; ++i )
        if ( vlapic_test_vector(i, &vlapic->regs->data[APIC_IRR]) ||
             vlapic_test_vector(i, &vlapic->regs->data[APIC_ISR]) )
            set_bit(i, v->arch.hvm.vmx.eoi_exit_bitmap);

    for ( i = 0; i < ARRAY_SIZE(v->arch.hvm.vmx.eoi_exit_bitmap); ++i )
        __vmwrite(EOI_EXIT_BITMAP(i), v->arch.hvm.vmx.eoi_exit_bitmap[i]);

    vmx_vmcs_exit(v);
}

static void __vmx_deliver_posted_interrupt(struct vcpu *v)
{
    bool_t running = v->is_running;

    vcpu_unblock(v);
    /*
     * Just like vcpu_kick(), nothing is needed for the following two cases:
     * 1. The target vCPU is not running, meaning it is blocked or runnable.
     * 2. The target vCPU is the current vCPU and we're in non-interrupt
     * context.
     */
    if ( running && (in_irq() || (v != current)) )
    {
        /*
         * Note: Only two cases will reach here:
         * 1. The target vCPU is running on other pCPU.
         * 2. The target vCPU is the current vCPU.
         *
         * Note2: Don't worry the v->processor may change. The vCPU being
         * moved to another processor is guaranteed to sync PIR to vIRR,
         * due to the involved scheduling cycle.
         */
        unsigned int cpu = v->processor;

        /*
         * For case 1, we send an IPI to the pCPU. When an IPI arrives, the
         * target vCPU maybe is running in non-root mode, running in root
         * mode, runnable or blocked. If the target vCPU is running in
         * non-root mode, the hardware will sync PIR to vIRR for
         * 'posted_intr_vector' is special to the pCPU. If the target vCPU is
         * running in root-mode, the interrupt handler starts to run.
         * Considering an IPI may arrive in the window between the call to
         * vmx_intr_assist() and interrupts getting disabled, the interrupt
         * handler should raise a softirq to ensure events will be delivered
         * in time. If the target vCPU is runnable, it will sync PIR to
         * vIRR next time it is chose to run. In this case, a IPI and a
         * softirq is sent to a wrong vCPU which will not have any adverse
         * effect. If the target vCPU is blocked, since vcpu_block() checks
         * whether there is an event to be delivered through
         * local_events_need_delivery() just after blocking, the vCPU must
         * have synced PIR to vIRR. Similarly, there is a IPI and a softirq
         * sent to a wrong vCPU.
         */
        if ( cpu != smp_processor_id() )
            send_IPI_mask(cpumask_of(cpu), posted_intr_vector);
        /*
         * For case 2, raising a softirq ensures PIR will be synced to vIRR.
         * As any softirq will do, as an optimization we only raise one if
         * none is pending already.
         */
        else if ( !softirq_pending(cpu) )
            raise_softirq(VCPU_KICK_SOFTIRQ);
    }
}

static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
{
    struct pi_desc old, new, prev;

    if ( pi_test_and_set_pir(vector, &v->arch.hvm.vmx.pi_desc) )
        return;

    if ( unlikely(v->arch.hvm.vmx.eoi_exitmap_changed) )
    {
        /*
         * If EOI exitbitmap needs to changed or notification vector
         * can't be allocated, interrupt will not be injected till
         * VMEntry as it used to be.
         */
        pi_set_on(&v->arch.hvm.vmx.pi_desc);
        vcpu_kick(v);
        return;
    }

    prev.control = v->arch.hvm.vmx.pi_desc.control;

    do {
        /*
         * Currently, we don't support urgent interrupt, all
         * interrupts are recognized as non-urgent interrupt,
         * Besides that, if 'ON' is already set, no need to
         * send posted-interrupts notification event as well,
         * according to hardware behavior.
         */
        if ( pi_test_sn(&prev) || pi_test_on(&prev) )
        {
            vcpu_kick(v);
            return;
        }

        old.control = v->arch.hvm.vmx.pi_desc.control &
                      ~((1 << POSTED_INTR_ON) | (1 << POSTED_INTR_SN));
        new.control = v->arch.hvm.vmx.pi_desc.control |
                      (1 << POSTED_INTR_ON);

        prev.control = cmpxchg(&v->arch.hvm.vmx.pi_desc.control,
                               old.control, new.control);
    } while ( prev.control != old.control );

    __vmx_deliver_posted_interrupt(v);
}

static void vmx_sync_pir_to_irr(struct vcpu *v)
{
    struct vlapic *vlapic = vcpu_vlapic(v);
    unsigned int group, i;
    DECLARE_BITMAP(pending_intr, X86_NR_VECTORS);

    if ( !pi_test_and_clear_on(&v->arch.hvm.vmx.pi_desc) )
        return;

    for ( group = 0; group < ARRAY_SIZE(pending_intr); group++ )
        pending_intr[group] = pi_get_pir(&v->arch.hvm.vmx.pi_desc, group);

    for_each_set_bit(i, pending_intr, X86_NR_VECTORS)
        vlapic_set_vector(i, &vlapic->regs->data[APIC_IRR]);
}

static bool vmx_test_pir(const struct vcpu *v, uint8_t vec)
{
    return pi_test_pir(vec, &v->arch.hvm.vmx.pi_desc);
}

static void vmx_handle_eoi(uint8_t vector, int isr)
{
    uint8_t old_svi = set_svi(isr);
    static bool warned;

    if ( vector != old_svi && !test_and_set_bool(warned) )
        printk(XENLOG_WARNING "EOI for %02x but SVI=%02x\n", vector, old_svi);
}

static void vmx_enable_msr_interception(struct domain *d, uint32_t msr)
{
    struct vcpu *v;

    for_each_vcpu ( d, v )
        vmx_set_msr_intercept(v, msr, VMX_MSR_W);
}

static bool_t vmx_is_singlestep_supported(void)
{
    return !!cpu_has_monitor_trap_flag;
}

static void vmx_vcpu_update_eptp(struct vcpu *v)
{
    struct domain *d = v->domain;
    struct p2m_domain *p2m = NULL;
    struct ept_data *ept;

    if ( altp2m_active(d) )
        p2m = p2m_get_altp2m(v);
    if ( !p2m )
        p2m = p2m_get_hostp2m(d);

    ept = &p2m->ept;
    ept->mfn = pagetable_get_pfn(p2m_get_pagetable(p2m));

    vmx_vmcs_enter(v);

    __vmwrite(EPT_POINTER, ept->eptp);

    if ( v->arch.hvm.vmx.secondary_exec_control &
         SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS )
        __vmwrite(EPTP_INDEX, vcpu_altp2m(v).p2midx);

    vmx_vmcs_exit(v);
}

static void vmx_vcpu_update_vmfunc_ve(struct vcpu *v)
{
    struct domain *d = v->domain;
    u32 mask = SECONDARY_EXEC_ENABLE_VM_FUNCTIONS;

    if ( !cpu_has_vmx_vmfunc )
        return;

    if ( cpu_has_vmx_virt_exceptions )
        mask |= SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS;

    vmx_vmcs_enter(v);

    if ( !d->is_dying && altp2m_active(d) )
    {
        v->arch.hvm.vmx.secondary_exec_control |= mask;
        __vmwrite(VM_FUNCTION_CONTROL, VMX_VMFUNC_EPTP_SWITCHING);
        __vmwrite(EPTP_LIST_ADDR, virt_to_maddr(d->arch.altp2m_visible_eptp));

        if ( cpu_has_vmx_virt_exceptions )
        {
            const struct page_info *pg = vcpu_altp2m(v).veinfo_pg;

            if ( pg )
            {
                __vmwrite(VIRT_EXCEPTION_INFO, page_to_maddr(pg));
                /*
                 * Make sure we have an up-to-date EPTP_INDEX when
                 * setting SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS.
                 */
                __vmwrite(EPTP_INDEX, vcpu_altp2m(v).p2midx);
            }
            else
                v->arch.hvm.vmx.secondary_exec_control &=
                    ~SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS;
        }
    }
    else
        v->arch.hvm.vmx.secondary_exec_control &= ~mask;

    vmx_update_secondary_exec_control(v);
    vmx_vmcs_exit(v);
}

static int vmx_vcpu_emulate_vmfunc(const struct cpu_user_regs *regs)
{
    int rc = X86EMUL_EXCEPTION;
    struct vcpu *curr = current;

    if ( !cpu_has_vmx_vmfunc && altp2m_active(curr->domain) &&
         regs->eax == 0 &&
         p2m_switch_vcpu_altp2m_by_id(curr, regs->ecx) )
        rc = X86EMUL_OKAY;

    return rc;
}

static bool_t vmx_vcpu_emulate_ve(struct vcpu *v)
{
    const struct page_info *pg = vcpu_altp2m(v).veinfo_pg;
    ve_info_t *veinfo;
    bool rc = false;

    if ( !pg )
        return rc;

    veinfo = __map_domain_page(pg);

    if ( veinfo->semaphore != 0 )
        goto out;

    rc = true;
    veinfo->exit_reason = EXIT_REASON_EPT_VIOLATION;
    veinfo->semaphore = ~0;
    veinfo->eptp_index = vcpu_altp2m(v).p2midx;

    vmx_vmcs_enter(v);
    __vmread(EXIT_QUALIFICATION, &veinfo->exit_qualification);
    __vmread(GUEST_LINEAR_ADDRESS, &veinfo->gla);
    __vmread(GUEST_PHYSICAL_ADDRESS, &veinfo->gpa);
    vmx_vmcs_exit(v);

    hvm_inject_hw_exception(TRAP_virtualisation,
                            X86_EVENT_NO_EC);

 out:
    unmap_domain_page(veinfo);

    if ( rc )
        paging_mark_dirty(v->domain, page_to_mfn(pg));

    return rc;
}

static bool vmx_get_pending_event(struct vcpu *v, struct x86_event *info)
{
    unsigned long intr_info, error_code;

    vmx_vmcs_enter(v);
    __vmread(VM_ENTRY_INTR_INFO, &intr_info);
    __vmread(VM_ENTRY_EXCEPTION_ERROR_CODE, &error_code);
    vmx_vmcs_exit(v);

    if ( !(intr_info & INTR_INFO_VALID_MASK) )
        return false;

    info->vector = MASK_EXTR(intr_info, INTR_INFO_VECTOR_MASK);
    info->type = MASK_EXTR(intr_info, INTR_INFO_INTR_TYPE_MASK);
    info->error_code = error_code;

    return true;
}

static struct hvm_function_table __initdata vmx_function_table = {
    .name                 = "VMX",
    .cpu_up_prepare       = vmx_cpu_up_prepare,
    .cpu_dead             = vmx_cpu_dead,
    .domain_initialise    = vmx_domain_initialise,
    .domain_relinquish_resources = vmx_domain_relinquish_resources,
    .vcpu_initialise      = vmx_vcpu_initialise,
    .vcpu_destroy         = vmx_vcpu_destroy,
    .save_cpu_ctxt        = vmx_save_vmcs_ctxt,
    .load_cpu_ctxt        = vmx_load_vmcs_ctxt,
    .get_interrupt_shadow = vmx_get_interrupt_shadow,
    .set_interrupt_shadow = vmx_set_interrupt_shadow,
    .guest_x86_mode       = vmx_guest_x86_mode,
    .get_cpl              = _vmx_get_cpl,
    .get_segment_register = vmx_get_segment_register,
    .set_segment_register = vmx_set_segment_register,
    .get_shadow_gs_base   = vmx_get_shadow_gs_base,
    .update_host_cr3      = vmx_update_host_cr3,
    .update_guest_cr      = vmx_update_guest_cr,
    .update_guest_efer    = vmx_update_guest_efer,
    .cpuid_policy_changed = vmx_cpuid_policy_changed,
    .fpu_leave            = vmx_fpu_leave,
    .set_guest_pat        = vmx_set_guest_pat,
    .get_guest_pat        = vmx_get_guest_pat,
    .set_tsc_offset       = vmx_set_tsc_offset,
    .inject_event         = vmx_inject_event,
    .init_hypercall_page  = vmx_init_hypercall_page,
    .event_pending        = vmx_event_pending,
    .get_pending_event    = vmx_get_pending_event,
    .invlpg               = vmx_invlpg,
    .cpu_up               = vmx_cpu_up,
    .cpu_down             = vmx_cpu_down,
    .wbinvd_intercept     = vmx_wbinvd_intercept,
    .fpu_dirty_intercept  = vmx_fpu_dirty_intercept,
    .msr_read_intercept   = vmx_msr_read_intercept,
    .msr_write_intercept  = vmx_msr_write_intercept,
    .handle_cd            = vmx_handle_cd,
    .set_info_guest       = vmx_set_info_guest,
    .set_rdtsc_exiting    = vmx_set_rdtsc_exiting,
    .nhvm_vcpu_initialise = nvmx_vcpu_initialise,
    .nhvm_vcpu_destroy    = nvmx_vcpu_destroy,
    .nhvm_vcpu_reset      = nvmx_vcpu_reset,
    .nhvm_vcpu_p2m_base   = nvmx_vcpu_eptp_base,
    .nhvm_vmcx_hap_enabled = nvmx_ept_enabled,
    .nhvm_vmcx_guest_intercepts_event = nvmx_intercepts_exception,
    .nhvm_vcpu_vmexit_event = nvmx_vmexit_event,
    .nhvm_intr_blocked    = nvmx_intr_blocked,
    .nhvm_domain_relinquish_resources = nvmx_domain_relinquish_resources,
    .nhvm_hap_walk_L1_p2m = nvmx_hap_walk_L1_p2m,
    .enable_msr_interception = vmx_enable_msr_interception,
    .is_singlestep_supported = vmx_is_singlestep_supported,
    .altp2m_vcpu_update_p2m = vmx_vcpu_update_eptp,
    .altp2m_vcpu_update_vmfunc_ve = vmx_vcpu_update_vmfunc_ve,
    .altp2m_vcpu_emulate_ve = vmx_vcpu_emulate_ve,
    .altp2m_vcpu_emulate_vmfunc = vmx_vcpu_emulate_vmfunc,
    .tsc_scaling = {
        .max_ratio = VMX_TSC_MULTIPLIER_MAX,
    },
};

/* Handle VT-d posted-interrupt when VCPU is blocked. */
static void pi_wakeup_interrupt(struct cpu_user_regs *regs)
{
    struct vmx_vcpu *vmx, *tmp;
    spinlock_t *lock = &per_cpu(vmx_pi_blocking, smp_processor_id()).lock;
    struct list_head *blocked_vcpus =
		&per_cpu(vmx_pi_blocking, smp_processor_id()).list;

    ack_APIC_irq();
    this_cpu(irq_count)++;

    spin_lock(lock);

    /*
     * XXX: The length of the list depends on how many vCPU is current
     * blocked on this specific pCPU. This may hurt the interrupt latency
     * if the list grows to too many entries.
     */
    list_for_each_entry_safe(vmx, tmp, blocked_vcpus, pi_blocking.list)
    {
        if ( pi_test_on(&vmx->pi_desc) )
        {
            list_del(&vmx->pi_blocking.list);
            ASSERT(vmx->pi_blocking.lock == lock);
            vmx->pi_blocking.lock = NULL;
            vcpu_unblock(container_of(vmx, struct vcpu, arch.hvm.vmx));
        }
    }

    spin_unlock(lock);
}

/* Handle VT-d posted-interrupt when VCPU is running. */
static void pi_notification_interrupt(struct cpu_user_regs *regs)
{
    ack_APIC_irq();
    this_cpu(irq_count)++;

    /*
     * We get here when a vCPU is running in root-mode (such as via hypercall,
     * or any other reasons which can result in VM-Exit), and before vCPU is
     * back to non-root, external interrupts from an assigned device happen
     * and a notification event is delivered to this logical CPU.
     *
     * we need to set VCPU_KICK_SOFTIRQ for the current cpu, just like
     * __vmx_deliver_posted_interrupt(). So the pending interrupt in PIRR will
     * be synced to vIRR before VM-Exit in time.
     *
     * Please refer to the following code fragments from
     * xen/arch/x86/hvm/vmx/entry.S:
     *
     *     .Lvmx_do_vmentry
     *
     *      ......
     *
     *      point 1
     *
     *      cli
     *      cmp  %ecx,(%rdx,%rax,1)
     *      jnz  .Lvmx_process_softirqs
     *
     *      ......
     *
     *      je   .Lvmx_launch
     *
     *      ......
     *
     *     .Lvmx_process_softirqs:
     *      sti
     *      call do_softirq
     *      jmp  .Lvmx_do_vmentry
     *
     * If VT-d engine issues a notification event at point 1 above, it cannot
     * be delivered to the guest during this VM-entry without raising the
     * softirq in this notification handler.
     */
    raise_softirq(VCPU_KICK_SOFTIRQ);
}

static void __init lbr_tsx_fixup_check(void);
static void __init ler_to_fixup_check(void);

/*
 * Calculate whether the CPU is vulnerable to Instruction Fetch page
 * size-change MCEs.
 */
static bool __init has_if_pschange_mc(void)
{
    uint64_t caps = 0;

    /*
     * If we are virtualised, there is nothing we can do.  Our EPT tables are
     * shadowed by our hypervisor, and not walked by hardware.
     */
    if ( cpu_has_hypervisor )
        return false;

    if ( boot_cpu_has(X86_FEATURE_ARCH_CAPS) )
        rdmsrl(MSR_ARCH_CAPABILITIES, caps);

    if ( caps & ARCH_CAPS_IF_PSCHANGE_MC_NO )
        return false;

    /*
     * IF_PSCHANGE_MC is only known to affect Intel Family 6 processors at
     * this time.
     */
    if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
         boot_cpu_data.x86 != 6 )
        return false;

    switch ( boot_cpu_data.x86_model )
    {
        /*
         * Core processors since at least Nehalem are vulnerable.
         */
    case 0x1f: /* Auburndale / Havendale */
    case 0x1e: /* Nehalem */
    case 0x1a: /* Nehalem EP */
    case 0x2e: /* Nehalem EX */
    case 0x25: /* Westmere */
    case 0x2c: /* Westmere EP */
    case 0x2f: /* Westmere EX */
    case 0x2a: /* SandyBridge */
    case 0x2d: /* SandyBridge EP/EX */
    case 0x3a: /* IvyBridge */
    case 0x3e: /* IvyBridge EP/EX */
    case 0x3c: /* Haswell */
    case 0x3f: /* Haswell EX/EP */
    case 0x45: /* Haswell D */
    case 0x46: /* Haswell H */
    case 0x3d: /* Broadwell */
    case 0x47: /* Broadwell H */
    case 0x4f: /* Broadwell EP/EX */
    case 0x56: /* Broadwell D */
    case 0x4e: /* Skylake M */
    case 0x5e: /* Skylake D */
    case 0x55: /* Skylake-X / Cascade Lake */
    case 0x7d: /* Ice Lake */
    case 0x7e: /* Ice Lake */
    case 0x8e: /* Kaby / Coffee / Whiskey Lake M */
    case 0x9e: /* Kaby / Coffee / Whiskey Lake D */
    case 0xa5: /* Comet Lake H/S */
    case 0xa6: /* Comet Lake U */
        return true;

        /*
         * Atom processors are not vulnerable.
         */
    case 0x1c: /* Pineview */
    case 0x26: /* Lincroft */
    case 0x27: /* Penwell */
    case 0x35: /* Cloverview */
    case 0x36: /* Cedarview */
    case 0x37: /* Baytrail / Valleyview (Silvermont) */
    case 0x4d: /* Avaton / Rangely (Silvermont) */
    case 0x4c: /* Cherrytrail / Brasswell */
    case 0x4a: /* Merrifield */
    case 0x5a: /* Moorefield */
    case 0x5c: /* Goldmont */
    case 0x5d: /* SoFIA 3G Granite/ES2.1 */
    case 0x65: /* SoFIA LTE AOSP */
    case 0x5f: /* Denverton */
    case 0x6e: /* Cougar Mountain */
    case 0x75: /* Lightning Mountain */
    case 0x7a: /* Gemini Lake */
    case 0x86: /* Jacobsville */

        /*
         * Knights processors are not vulnerable.
         */
    case 0x57: /* Knights Landing */
    case 0x85: /* Knights Mill */
        return false;

    default:
        printk("Unrecognised CPU model %#x - assuming vulnerable to IF_PSCHANGE_MC\n",
               boot_cpu_data.x86_model);
        return true;
    }
}

const struct hvm_function_table * __init start_vmx(void)
{
    set_in_cr4(X86_CR4_VMXE);

    if ( vmx_vmcs_init() )
    {
        printk("VMX: failed to initialise.\n");
        return NULL;
    }

    if ( cpu_has_vmx_dt_exiting )
        vmx_function_table.set_descriptor_access_exiting =
            vmx_set_descriptor_access_exiting;

    /*
     * Do not enable EPT when (!cpu_has_vmx_pat), to prevent security hole
     * (refer to https://xenbits.xen.org/xsa/advisory-60.html).
     */
    if ( cpu_has_vmx_ept && (cpu_has_vmx_pat || opt_force_ept) )
    {
        bool cpu_has_bug_pschange_mc = has_if_pschange_mc();

        if ( opt_ept_exec_sp == -1 )
        {
            /* Default to non-executable superpages on vulnerable hardware. */
            opt_ept_exec_sp = !cpu_has_bug_pschange_mc;

            if ( cpu_has_bug_pschange_mc )
                printk("VMX: Disabling executable EPT superpages due to CVE-2018-12207\n");
        }

        vmx_function_table.hap_supported = 1;
        vmx_function_table.altp2m_supported = 1;

        vmx_function_table.hap_capabilities = 0;

        if ( cpu_has_vmx_ept_2mb )
            vmx_function_table.hap_capabilities |= HVM_HAP_SUPERPAGE_2MB;
        if ( cpu_has_vmx_ept_1gb )
            vmx_function_table.hap_capabilities |= HVM_HAP_SUPERPAGE_1GB;

        setup_ept_dump();
    }

    if ( cpu_has_vmx_virtual_intr_delivery )
    {
        vmx_function_table.update_eoi_exit_bitmap = vmx_update_eoi_exit_bitmap;
        vmx_function_table.process_isr = vmx_process_isr;
        vmx_function_table.handle_eoi = vmx_handle_eoi;
        vmx_function_table.virtual_intr_delivery_enabled = true;
    }

    if ( cpu_has_vmx_posted_intr_processing )
    {
        alloc_direct_apic_vector(&posted_intr_vector, pi_notification_interrupt);
        if ( iommu_intpost )
            alloc_direct_apic_vector(&pi_wakeup_vector, pi_wakeup_interrupt);

        vmx_function_table.deliver_posted_intr = vmx_deliver_posted_intr;
        vmx_function_table.sync_pir_to_irr     = vmx_sync_pir_to_irr;
        vmx_function_table.test_pir            = vmx_test_pir;
    }

    if ( cpu_has_vmx_tsc_scaling )
    {
        vmx_function_table.tsc_scaling.ratio_frac_bits = 48;
        vmx_function_table.tsc_scaling.setup = vmx_setup_tsc_scaling;
    }

    if ( cpu_has_mpx && cpu_has_vmx_mpx )
    {
        vmx_function_table.set_guest_bndcfgs = vmx_set_guest_bndcfgs;
        vmx_function_table.get_guest_bndcfgs = vmx_get_guest_bndcfgs;
    }

    lbr_tsx_fixup_check();
    ler_to_fixup_check();

    return &vmx_function_table;
}

/*
 * Not all cases receive valid value in the VM-exit instruction length field.
 * Callers must know what they're doing!
 */
static int get_instruction_length(void)
{
    unsigned long len;

    __vmread(VM_EXIT_INSTRUCTION_LEN, &len); /* Safe: callers audited */
    BUG_ON((len < 1) || (len > MAX_INST_LEN));
    return len;
}

void update_guest_eip(void)
{
    struct cpu_user_regs *regs = guest_cpu_user_regs();
    unsigned long x;

    regs->rip += get_instruction_length(); /* Safe: callers audited */
    regs->eflags &= ~X86_EFLAGS_RF;

    __vmread(GUEST_INTERRUPTIBILITY_INFO, &x);
    if ( x & (VMX_INTR_SHADOW_STI | VMX_INTR_SHADOW_MOV_SS) )
    {
        x &= ~(VMX_INTR_SHADOW_STI | VMX_INTR_SHADOW_MOV_SS);
        __vmwrite(GUEST_INTERRUPTIBILITY_INFO, x);
    }

    if ( regs->eflags & X86_EFLAGS_TF )
        hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC);
}

static void vmx_fpu_dirty_intercept(void)
{
    struct vcpu *curr = current;

    vmx_fpu_enter(curr);

    /* Disable TS in guest CR0 unless the guest wants the exception too. */
    if ( !(curr->arch.hvm.guest_cr[0] & X86_CR0_TS) )
    {
        curr->arch.hvm.hw_cr[0] &= ~X86_CR0_TS;
        __vmwrite(GUEST_CR0, curr->arch.hvm.hw_cr[0]);
    }
}

static void vmx_dr_access(unsigned long exit_qualification,
                          struct cpu_user_regs *regs)
{
    struct vcpu *v = current;

    HVMTRACE_0D(DR_WRITE);

    if ( !v->arch.hvm.flag_dr_dirty )
        __restore_debug_registers(v);

    /* Allow guest direct access to DR registers */
    v->arch.hvm.vmx.exec_control &= ~CPU_BASED_MOV_DR_EXITING;
    vmx_update_cpu_exec_control(v);
}

static void vmx_invlpg_intercept(unsigned long linear)
{
    HVMTRACE_LONG_2D(INVLPG, /*invlpga=*/ 0, TRC_PAR_LONG(linear));
    paging_invlpg(current, linear);
}

static void vmx_invlpg(struct vcpu *v, unsigned long linear)
{
    if ( cpu_has_vmx_vpid )
        vpid_sync_vcpu_gva(v, linear);
}

static int vmx_vmfunc_intercept(struct cpu_user_regs *regs)
{
    /*
     * This handler is a placeholder for future where Xen may
     * want to handle VMFUNC exits and resume a domain normally without
     * injecting a #UD to the guest - for example, in a VT-nested
     * scenario where Xen may want to lazily shadow the alternate
     * EPTP list.
     */
    gdprintk(XENLOG_ERR, "Failed guest VMFUNC execution\n");
    return X86EMUL_EXCEPTION;
}

static int vmx_cr_access(cr_access_qual_t qual)
{
    struct vcpu *curr = current;

    switch ( qual.access_type )
    {
    case VMX_CR_ACCESS_TYPE_MOV_TO_CR:
        return hvm_mov_to_cr(qual.cr, qual.gpr);

    case VMX_CR_ACCESS_TYPE_MOV_FROM_CR:
        return hvm_mov_from_cr(qual.cr, qual.gpr);

    case VMX_CR_ACCESS_TYPE_CLTS:
    {
        unsigned long old = curr->arch.hvm.guest_cr[0];
        unsigned long value = old & ~X86_CR0_TS;

        /*
         * Special case unlikely to be interesting to a
         * VM_EVENT_FLAG_DENY-capable application, so the hvm_monitor_crX()
         * return value is ignored for now.
         */
        hvm_monitor_crX(CR0, value, old);
        curr->arch.hvm.guest_cr[0] = value;
        vmx_update_guest_cr(curr, 0, 0);
        HVMTRACE_0D(CLTS);
        break;
    }

    case VMX_CR_ACCESS_TYPE_LMSW:
    {
        unsigned long value = curr->arch.hvm.guest_cr[0];
        int rc;

        /* LMSW can (1) set PE; (2) set or clear MP, EM, and TS. */
        value = (value & ~(X86_CR0_MP|X86_CR0_EM|X86_CR0_TS)) |
                (qual.lmsw_data &
                 (X86_CR0_PE|X86_CR0_MP|X86_CR0_EM|X86_CR0_TS));
        HVMTRACE_LONG_1D(LMSW, value);

        if ( (rc = hvm_set_cr0(value, true)) == X86EMUL_EXCEPTION )
            hvm_inject_hw_exception(TRAP_gp_fault, 0);

        return rc;
    }

    default:
        ASSERT_UNREACHABLE();
        return X86EMUL_UNHANDLEABLE;
    }

    return X86EMUL_OKAY;
}

static const struct lbr_info {
    u32 base, count;
} p4_lbr[] = {
    { MSR_P4_LER_FROM_LIP,          1 },
    { MSR_P4_LER_TO_LIP,            1 },
    { MSR_P4_LASTBRANCH_TOS,        1 },
    { MSR_P4_LASTBRANCH_0_FROM_LIP, NUM_MSR_P4_LASTBRANCH_FROM_TO },
    { MSR_P4_LASTBRANCH_0_TO_LIP,   NUM_MSR_P4_LASTBRANCH_FROM_TO },
    { 0, 0 }
}, c2_lbr[] = {
    { MSR_IA32_LASTINTFROMIP,       1 },
    { MSR_IA32_LASTINTTOIP,         1 },
    { MSR_C2_LASTBRANCH_TOS,        1 },
    { MSR_C2_LASTBRANCH_0_FROM_IP,  NUM_MSR_C2_LASTBRANCH_FROM_TO },
    { MSR_C2_LASTBRANCH_0_TO_IP,    NUM_MSR_C2_LASTBRANCH_FROM_TO },
    { 0, 0 }
}, nh_lbr[] = {
    { MSR_IA32_LASTINTFROMIP,       1 },
    { MSR_IA32_LASTINTTOIP,         1 },
    { MSR_C2_LASTBRANCH_TOS,        1 },
    { MSR_P4_LASTBRANCH_0_FROM_LIP, NUM_MSR_P4_LASTBRANCH_FROM_TO },
    { MSR_P4_LASTBRANCH_0_TO_LIP,   NUM_MSR_P4_LASTBRANCH_FROM_TO },
    { 0, 0 }
}, sk_lbr[] = {
    { MSR_IA32_LASTINTFROMIP,       1 },
    { MSR_IA32_LASTINTTOIP,         1 },
    { MSR_SKL_LASTBRANCH_TOS,       1 },
    { MSR_SKL_LASTBRANCH_0_FROM_IP, NUM_MSR_SKL_LASTBRANCH },
    { MSR_SKL_LASTBRANCH_0_TO_IP,   NUM_MSR_SKL_LASTBRANCH },
    { MSR_SKL_LASTBRANCH_0_INFO,    NUM_MSR_SKL_LASTBRANCH },
    { 0, 0 }
}, at_lbr[] = {
    { MSR_IA32_LASTINTFROMIP,       1 },
    { MSR_IA32_LASTINTTOIP,         1 },
    { MSR_C2_LASTBRANCH_TOS,        1 },
    { MSR_C2_LASTBRANCH_0_FROM_IP,  NUM_MSR_ATOM_LASTBRANCH_FROM_TO },
    { MSR_C2_LASTBRANCH_0_TO_IP,    NUM_MSR_ATOM_LASTBRANCH_FROM_TO },
    { 0, 0 }
}, gm_lbr[] = {
    { MSR_IA32_LASTINTFROMIP,       1 },
    { MSR_IA32_LASTINTTOIP,         1 },
    { MSR_GM_LASTBRANCH_TOS,        1 },
    { MSR_GM_LASTBRANCH_0_FROM_IP,  NUM_MSR_GM_LASTBRANCH_FROM_TO },
    { MSR_GM_LASTBRANCH_0_TO_IP,    NUM_MSR_GM_LASTBRANCH_FROM_TO },
    { 0, 0 }
};

static const struct lbr_info *last_branch_msr_get(void)
{
    switch ( boot_cpu_data.x86 )
    {
    case 6:
        switch ( boot_cpu_data.x86_model )
        {
        /* Core2 Duo */
        case 0x0f:
        /* Enhanced Core */
        case 0x17:
        /* Xeon 7400 */
        case 0x1d:
            return c2_lbr;
        /* Nehalem */
        case 0x1a: case 0x1e: case 0x1f: case 0x2e:
        /* Westmere */
        case 0x25: case 0x2c: case 0x2f:
        /* Sandy Bridge */
        case 0x2a: case 0x2d:
        /* Ivy Bridge */
        case 0x3a: case 0x3e:
        /* Haswell */
        case 0x3c: case 0x3f: case 0x45: case 0x46:
        /* Broadwell */
        case 0x3d: case 0x47: case 0x4f: case 0x56:
            return nh_lbr;
        /* Skylake */
        case 0x4e: case 0x5e:
        /* Xeon Scalable */
        case 0x55:
        /* Cannon Lake */
        case 0x66:
        /* Goldmont Plus */
        case 0x7a:
        /* Ice Lake */
        case 0x7d: case 0x7e:
        /* Tremont */
        case 0x86:
        /* Kaby Lake */
        case 0x8e: case 0x9e:
        /* Comet Lake */
        case 0xa5: case 0xa6:
            return sk_lbr;
        /* Atom */
        case 0x1c: case 0x26: case 0x27: case 0x35: case 0x36:
        /* Silvermont */
        case 0x37: case 0x4a: case 0x4d: case 0x5a: case 0x5d:
        /* Xeon Phi Knights Landing */
        case 0x57:
        /* Xeon Phi Knights Mill */
        case 0x85:
        /* Airmont */
        case 0x4c:
            return at_lbr;
        /* Goldmont */
        case 0x5c: case 0x5f:
            return gm_lbr;
        }
        break;

    case 15:
        switch ( boot_cpu_data.x86_model )
        {
        /* Pentium4/Xeon with em64t */
        case 3: case 4: case 6:
            return p4_lbr;
        }
        break;
    }

    return NULL;
}

enum
{
    LBR_FORMAT_32                 = 0x0, /* 32-bit record format */
    LBR_FORMAT_LIP                = 0x1, /* 64-bit LIP record format */
    LBR_FORMAT_EIP                = 0x2, /* 64-bit EIP record format */
    LBR_FORMAT_EIP_FLAGS          = 0x3, /* 64-bit EIP, Flags */
    LBR_FORMAT_EIP_FLAGS_TSX      = 0x4, /* 64-bit EIP, Flags, TSX */
    LBR_FORMAT_EIP_FLAGS_TSX_INFO = 0x5, /* 64-bit EIP, Flags, TSX, LBR_INFO */
    LBR_FORMAT_EIP_FLAGS_CYCLES   = 0x6, /* 64-bit EIP, Flags, Cycles */
    LBR_FORMAT_LIP_FLAGS_TSX_INFO = 0x7, /* 64-bit LIP, Flags, TSX, LBR_INFO */
};

#define LBR_FROM_SIGNEXT_2MSB  ((1ULL << 59) | (1ULL << 60))

#define LBR_MSRS_INSERTED      (1u << 0)
#define LBR_FIXUP_TSX          (1u << 1)
#define LBR_FIXUP_LER_TO       (1u << 2)
#define LBR_FIXUP_MASK         (LBR_FIXUP_TSX | LBR_FIXUP_LER_TO)

static bool __read_mostly lbr_tsx_fixup_needed;
static bool __read_mostly ler_to_fixup_needed;

static void __init lbr_tsx_fixup_check(void)
{
    uint64_t caps;
    uint32_t lbr_format;

    /*
     * Haswell erratum HSM182 et al, Broadwell erratum BDM127 et al:
     *
     * On processors that do not support Intel Transactional Synchronization
     * Extensions (Intel TSX) (CPUID.07H.EBX bits 4 and 11 are both zero),
     * writes to MSR_LASTBRANCH_x_FROM_IP (MSR 680H to 68FH) may #GP unless
     * bits[62:61] are equal to bit[47].
     *
     * Software should sign extend the MSRs.
     *
     * Experimentally, MSR_LER_FROM_LIP (1DDH) is similarly impacted, so is
     * fixed up as well.
     */
    if ( cpu_has_hle || cpu_has_rtm ||
         boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
         boot_cpu_data.x86 != 6 )
        return;

    switch ( boot_cpu_data.x86_model )
    {
    case 0x3c: /* HSM182, HSD172 - 4th gen Core */
    case 0x3f: /* HSE117 - Xeon E5 v3 */
    case 0x45: /* HSM182 - 4th gen Core */
    case 0x46: /* HSM182, HSD172 - 4th gen Core (GT3) */
    case 0x3d: /* BDM127 - 5th gen Core */
    case 0x47: /* BDD117 - 5th gen Core (GT3)
                  BDW117 - Xeon E3-1200 v4 */
    case 0x4f: /* BDF85  - Xeon E5-2600 v4
                  BDH75  - Core-i7 for LGA2011-v3 Socket
                  BDX88  - Xeon E7-x800 v4 */
    case 0x56: /* BDE105 - Xeon D-1500 */
        break;
    default:
        return;
    }

    /*
     * Fixup is needed only when TSX support is disabled and the address
     * format of LBR includes TSX bits 61:62
     */
    if ( !cpu_has_pdcm )
        return;

    rdmsrl(MSR_IA32_PERF_CAPABILITIES, caps);
    lbr_format = caps & MSR_IA32_PERF_CAP_LBR_FORMAT;

    if ( lbr_format == LBR_FORMAT_EIP_FLAGS_TSX )
        lbr_tsx_fixup_needed = true;
}

static void __init ler_to_fixup_check(void)
{
    /*
     * Broadwell erratum BDF93 et al:
     *
     * Reads from MSR_LER_TO_LIP (MSR 1DEH) may return values for bits[63:61]
     * that are not equal to bit[47].  Attempting to context switch this value
     * may cause a #GP.  Software should sign extend the MSR.
     */
    if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL ||
         boot_cpu_data.x86 != 6 )
        return;

    switch ( boot_cpu_data.x86_model )
    {
    case 0x3d: /* BDM131 - 5th gen Core */
    case 0x47: /* BDD??? - 5th gen Core (H-Processor line)
                  BDW120 - Xeon E3-1200 v4 */
    case 0x4f: /* BDF93  - Xeon E5-2600 v4
                  BDH80  - Core-i7 for LGA2011-v3 Socket
                  BDX93  - Xeon E7-x800 v4 */
    case 0x56: /* BDE??? - Xeon D-1500 */
        ler_to_fixup_needed = true;
        break;
    }
}

static int is_last_branch_msr(u32 ecx)
{
    const struct lbr_info *lbr = last_branch_msr_get();

    if ( lbr == NULL )
        return 0;

    for ( ; lbr->count; lbr++ )
        if ( (ecx >= lbr->base) && (ecx < (lbr->base + lbr->count)) )
            return 1;

    return 0;
}

static int vmx_msr_read_intercept(unsigned int msr, uint64_t *msr_content)
{
    struct vcpu *curr = current;

    HVM_DBG_LOG(DBG_LEVEL_MSR, "ecx=%#x", msr);

    switch ( msr )
    {
    case MSR_IA32_SYSENTER_CS:
        __vmread(GUEST_SYSENTER_CS, msr_content);
        break;
    case MSR_IA32_SYSENTER_ESP:
        __vmread(GUEST_SYSENTER_ESP, msr_content);
        break;
    case MSR_IA32_SYSENTER_EIP:
        __vmread(GUEST_SYSENTER_EIP, msr_content);
        break;

    case MSR_FS_BASE:
        __vmread(GUEST_FS_BASE, msr_content);
        break;

    case MSR_GS_BASE:
        __vmread(GUEST_GS_BASE, msr_content);
        break;

    case MSR_SHADOW_GS_BASE:
        *msr_content = rdgsshadow();
        break;

    case MSR_STAR:
        *msr_content = curr->arch.hvm.vmx.star;
        break;

    case MSR_LSTAR:
        *msr_content = curr->arch.hvm.vmx.lstar;
        break;

    case MSR_CSTAR:
        *msr_content = curr->arch.hvm.vmx.cstar;
        break;

    case MSR_SYSCALL_MASK:
        *msr_content = curr->arch.hvm.vmx.sfmask;
        break;

    case MSR_IA32_DEBUGCTLMSR:
        __vmread(GUEST_IA32_DEBUGCTL, msr_content);
        break;

    case MSR_IA32_VMX_BASIC...MSR_IA32_VMX_VMFUNC:
        if ( !nvmx_msr_read_intercept(msr, msr_content) )
            goto gp_fault;
        break;
    case MSR_IA32_MISC_ENABLE:
        rdmsrl(MSR_IA32_MISC_ENABLE, *msr_content);
        /* Debug Trace Store is not supported. */
        *msr_content |= MSR_IA32_MISC_ENABLE_BTS_UNAVAIL |
                       MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL;
        /* Perhaps vpmu will change some bits. */
        /* FALLTHROUGH */
    case MSR_P6_PERFCTR(0)...MSR_P6_PERFCTR(7):
    case MSR_P6_EVNTSEL(0)...MSR_P6_EVNTSEL(3):
    case MSR_CORE_PERF_FIXED_CTR0...MSR_CORE_PERF_FIXED_CTR2:
    case MSR_CORE_PERF_FIXED_CTR_CTRL...MSR_CORE_PERF_GLOBAL_OVF_CTRL:
    case MSR_IA32_PEBS_ENABLE:
    case MSR_IA32_DS_AREA:
        if ( vpmu_do_rdmsr(msr, msr_content) )
            goto gp_fault;
        break;

    default:
        if ( passive_domain_do_rdmsr(msr, msr_content) )
            goto done;

        if ( vmx_read_guest_msr(curr, msr, msr_content) == 0 )
            break;

        if ( is_last_branch_msr(msr) )
        {
            *msr_content = 0;
            break;
        }

        gdprintk(XENLOG_WARNING, "RDMSR 0x%08x unimplemented\n", msr);
        goto gp_fault;
    }

done:
    HVM_DBG_LOG(DBG_LEVEL_MSR, "returns: ecx=%#x, msr_value=%#"PRIx64,
                msr, *msr_content);
    return X86EMUL_OKAY;

gp_fault:
    return X86EMUL_EXCEPTION;
}

static int vmx_alloc_vlapic_mapping(struct domain *d)
{
    struct page_info *pg;
    mfn_t mfn;

    if ( !cpu_has_vmx_virtualize_apic_accesses )
        return 0;

    pg = alloc_domheap_page(d, MEMF_no_refcount);
    if ( !pg )
        return -ENOMEM;

    if ( !get_page_and_type(pg, d, PGT_writable_page) )
    {
        /*
         * The domain can't possibly know about this page yet, so failure
         * here is a clear indication of something fishy going on.
         */
        domain_crash(d);
        return -ENODATA;
    }

    mfn = page_to_mfn(pg);
    clear_domain_page(mfn);
    d->arch.hvm.vmx.apic_access_mfn = mfn;

    return set_mmio_p2m_entry(d, gaddr_to_gfn(APIC_DEFAULT_PHYS_BASE), mfn,
                              PAGE_ORDER_4K);
}

static void vmx_free_vlapic_mapping(struct domain *d)
{
    mfn_t mfn = d->arch.hvm.vmx.apic_access_mfn;

    d->arch.hvm.vmx.apic_access_mfn = _mfn(0);
    if ( !mfn_eq(mfn, _mfn(0)) )
    {
        struct page_info *pg = mfn_to_page(mfn);

        put_page_alloc_ref(pg);
        put_page_and_type(pg);
    }
}

static void vmx_install_vlapic_mapping(struct vcpu *v)
{
    paddr_t virt_page_ma, apic_page_ma;

    if ( mfn_eq(v->domain->arch.hvm.vmx.apic_access_mfn, _mfn(0)) )
        return;

    ASSERT(cpu_has_vmx_virtualize_apic_accesses);

    virt_page_ma = page_to_maddr(vcpu_vlapic(v)->regs_page);
    apic_page_ma = mfn_to_maddr(v->domain->arch.hvm.vmx.apic_access_mfn);

    vmx_vmcs_enter(v);
    __vmwrite(VIRTUAL_APIC_PAGE_ADDR, virt_page_ma);
    __vmwrite(APIC_ACCESS_ADDR, apic_page_ma);
    vmx_vmcs_exit(v);
}

void vmx_vlapic_msr_changed(struct vcpu *v)
{
    int virtualize_x2apic_mode;
    struct vlapic *vlapic = vcpu_vlapic(v);
    unsigned int msr;

    virtualize_x2apic_mode = ( (cpu_has_vmx_apic_reg_virt ||
                                cpu_has_vmx_virtual_intr_delivery) &&
                               cpu_has_vmx_virtualize_x2apic_mode );

    if ( !cpu_has_vmx_virtualize_apic_accesses &&
         !virtualize_x2apic_mode )
        return;

    vmx_vmcs_enter(v);
    v->arch.hvm.vmx.secondary_exec_control &=
        ~(SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
          SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE);
    if ( !vlapic_hw_disabled(vlapic) &&
         (vlapic_base_address(vlapic) == APIC_DEFAULT_PHYS_BASE) )
    {
        if ( virtualize_x2apic_mode && vlapic_x2apic_mode(vlapic) )
        {
            v->arch.hvm.vmx.secondary_exec_control |=
                SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
            if ( cpu_has_vmx_apic_reg_virt )
            {
                for ( msr = MSR_X2APIC_FIRST;
                      msr <= MSR_X2APIC_FIRST + 0xff; msr++ )
                    vmx_clear_msr_intercept(v, msr, VMX_MSR_R);

                vmx_set_msr_intercept(v, MSR_X2APIC_PPR, VMX_MSR_R);
                vmx_set_msr_intercept(v, MSR_X2APIC_TMICT, VMX_MSR_R);
                vmx_set_msr_intercept(v, MSR_X2APIC_TMCCT, VMX_MSR_R);
            }
            if ( cpu_has_vmx_virtual_intr_delivery )
            {
                vmx_clear_msr_intercept(v, MSR_X2APIC_TPR, VMX_MSR_W);
                vmx_clear_msr_intercept(v, MSR_X2APIC_EOI, VMX_MSR_W);
                vmx_clear_msr_intercept(v, MSR_X2APIC_SELF, VMX_MSR_W);
            }
        }
        else
            v->arch.hvm.vmx.secondary_exec_control |=
                SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
    }
    if ( !(v->arch.hvm.vmx.secondary_exec_control &
           SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE) )
        for ( msr = MSR_X2APIC_FIRST;
              msr <= MSR_X2APIC_FIRST + 0xff; msr++ )
            vmx_set_msr_intercept(v, msr, VMX_MSR_RW);

    vmx_update_secondary_exec_control(v);
    vmx_vmcs_exit(v);
}

static int vmx_msr_write_intercept(unsigned int msr, uint64_t msr_content)
{
    struct vcpu *v = current;
    const struct cpuid_policy *cp = v->domain->arch.cpuid;

    HVM_DBG_LOG(DBG_LEVEL_MSR, "ecx=%#x, msr_value=%#"PRIx64, msr, msr_content);

    switch ( msr )
    {
        uint64_t rsvd, tmp;

    case MSR_IA32_SYSENTER_CS:
        __vmwrite(GUEST_SYSENTER_CS, msr_content);
        break;
    case MSR_IA32_SYSENTER_ESP:
        if ( !is_canonical_address(msr_content) )
            goto gp_fault;
        __vmwrite(GUEST_SYSENTER_ESP, msr_content);
        break;
    case MSR_IA32_SYSENTER_EIP:
        if ( !is_canonical_address(msr_content) )
            goto gp_fault;
        __vmwrite(GUEST_SYSENTER_EIP, msr_content);
        break;

    case MSR_FS_BASE:
    case MSR_GS_BASE:
    case MSR_SHADOW_GS_BASE:
        if ( !is_canonical_address(msr_content) )
            goto gp_fault;

        if ( msr == MSR_FS_BASE )
            __vmwrite(GUEST_FS_BASE, msr_content);
        else if ( msr == MSR_GS_BASE )
            __vmwrite(GUEST_GS_BASE, msr_content);
        else
            wrgsshadow(msr_content);

        break;

    case MSR_STAR:
        v->arch.hvm.vmx.star = msr_content;
        wrmsrl(MSR_STAR, msr_content);
        break;

    case MSR_LSTAR:
        if ( !is_canonical_address(msr_content) )
            goto gp_fault;
        v->arch.hvm.vmx.lstar = msr_content;
        wrmsrl(MSR_LSTAR, msr_content);
        break;

    case MSR_CSTAR:
        if ( !is_canonical_address(msr_content) )
            goto gp_fault;
        v->arch.hvm.vmx.cstar = msr_content;
        break;

    case MSR_SYSCALL_MASK:
        v->arch.hvm.vmx.sfmask = msr_content;
        wrmsrl(MSR_SYSCALL_MASK, msr_content);
        break;

    case MSR_IA32_DEBUGCTLMSR:
        rsvd = ~(IA32_DEBUGCTLMSR_LBR | IA32_DEBUGCTLMSR_BTF);

        /* TODO: Wire vPMU settings properly through the CPUID policy */
        if ( vpmu_is_set(vcpu_vpmu(v), VPMU_CPU_HAS_BTS) )
        {
            rsvd &= ~(IA32_DEBUGCTLMSR_TR | IA32_DEBUGCTLMSR_BTS |
                      IA32_DEBUGCTLMSR_BTINT);

            if ( cpu_has(&current_cpu_data, X86_FEATURE_DSCPL) )
                rsvd &= ~(IA32_DEBUGCTLMSR_BTS_OFF_OS |
                          IA32_DEBUGCTLMSR_BTS_OFF_USR);
        }

        if ( cp->feat.rtm )
            rsvd &= ~IA32_DEBUGCTLMSR_RTM;

        if ( msr_content & rsvd )
            goto gp_fault;

        /*
         * When a guest first enables LBR, arrange to save and restore the LBR
         * MSRs and allow the guest direct access.
         *
         * MSR_DEBUGCTL and LBR has existed almost as long as MSRs have
         * existed, and there is no architectural way to hide the feature, or
         * fail the attempt to enable LBR.
         *
         * Unknown host LBR MSRs or hitting -ENOSPC with the guest load/save
         * list are definitely hypervisor bugs, whereas -ENOMEM for allocating
         * the load/save list is simply unlucky (and shouldn't occur with
         * sensible management by the toolstack).
         *
         * Either way, there is nothing we can do right now to recover, and
         * the guest won't execute correctly either.  Simply crash the domain
         * to make the failure obvious.
         */
        if ( !(v->arch.hvm.vmx.lbr_flags & LBR_MSRS_INSERTED) &&
             (msr_content & IA32_DEBUGCTLMSR_LBR) )
        {
            const struct lbr_info *lbr = last_branch_msr_get();

            if ( unlikely(!lbr) )
            {
                gprintk(XENLOG_ERR, "Unknown Host LBR MSRs\n");
                domain_crash(v->domain);
                return X86EMUL_OKAY;
            }

            for ( ; lbr->count; lbr++ )
            {
                unsigned int i;

                for ( i = 0; i < lbr->count; i++ )
                {
                    int rc = vmx_add_guest_msr(v, lbr->base + i, 0);

                    if ( unlikely(rc) )
                    {
                        gprintk(XENLOG_ERR,
                                "Guest load/save list error %d\n", rc);
                        domain_crash(v->domain);
                        return X86EMUL_OKAY;
                    }

                    vmx_clear_msr_intercept(v, lbr->base + i, VMX_MSR_RW);
                }
            }

            v->arch.hvm.vmx.lbr_flags |= LBR_MSRS_INSERTED;
            if ( lbr_tsx_fixup_needed )
                v->arch.hvm.vmx.lbr_flags |= LBR_FIXUP_TSX;
            if ( ler_to_fixup_needed )
                v->arch.hvm.vmx.lbr_flags |= LBR_FIXUP_LER_TO;
        }

        __vmwrite(GUEST_IA32_DEBUGCTL, msr_content);
        break;

    case MSR_IA32_MISC_ENABLE:
        /*
         * Silently drop writes that don't change the reported value: At least
         * some Windows guests will expect to be able to write to MISC_ENABLE
         * with the same value that's been read from it.
         */
        if ( vmx_msr_read_intercept(msr, &tmp) != X86EMUL_OKAY ||
             tmp != msr_content )
            goto gp_fault;
        break;

    case MSR_P6_PERFCTR(0)...MSR_P6_PERFCTR(7):
    case MSR_P6_EVNTSEL(0)...MSR_P6_EVNTSEL(7):
    case MSR_CORE_PERF_FIXED_CTR0...MSR_CORE_PERF_FIXED_CTR2:
    case MSR_CORE_PERF_FIXED_CTR_CTRL...MSR_CORE_PERF_GLOBAL_OVF_CTRL:
    case MSR_IA32_PEBS_ENABLE:
    case MSR_IA32_DS_AREA:
         if ( vpmu_do_wrmsr(msr, msr_content, 0) )
            goto gp_fault;
        break;

    default:
        if ( passive_domain_do_wrmsr(msr, msr_content) )
            return X86EMUL_OKAY;

        if ( vmx_write_guest_msr(v, msr, msr_content) == 0 ||
             is_last_branch_msr(msr) )
            break;

        gdprintk(XENLOG_WARNING,
                 "WRMSR 0x%08x val 0x%016"PRIx64" unimplemented\n",
                 msr, msr_content);
        goto gp_fault;
    }

    return X86EMUL_OKAY;

gp_fault:
    return X86EMUL_EXCEPTION;
}

static void vmx_do_extint(struct cpu_user_regs *regs)
{
    unsigned long vector;

    __vmread(VM_EXIT_INTR_INFO, &vector);
    BUG_ON(!(vector & INTR_INFO_VALID_MASK));

    vector &= INTR_INFO_VECTOR_MASK;
    HVMTRACE_1D(INTR, vector);

    regs->entry_vector = vector;
    do_IRQ(regs);
}

static void vmx_wbinvd_intercept(void)
{
    if ( !cache_flush_permitted(current->domain) || iommu_snoop )
        return;

    if ( cpu_has_wbinvd_exiting )
        flush_all(FLUSH_CACHE);
    else
        wbinvd();
}

static void ept_handle_violation(ept_qual_t q, paddr_t gpa)
{
    unsigned long gla, gfn = gpa >> PAGE_SHIFT;
    mfn_t mfn;
    p2m_type_t p2mt;
    int ret;
    struct domain *d = current->domain;

    /*
     * We treat all write violations also as read violations.
     * The reason why this is required is the following warning:
     * "An EPT violation that occurs during as a result of execution of a
     * read-modify-write operation sets bit 1 (data write). Whether it also
     * sets bit 0 (data read) is implementation-specific and, for a given
     * implementation, may differ for different kinds of read-modify-write
     * operations."
     * - Intel(R) 64 and IA-32 Architectures Software Developer's Manual
     *   Volume 3C: System Programming Guide, Part 3
     */
    struct npfec npfec = {
        .read_access = q.read || q.write,
        .write_access = q.write,
        .insn_fetch = q.fetch,
        .present = q.eff_read || q.eff_write || q.eff_exec,
    };

    if ( tb_init_done )
    {
        struct {
            uint64_t gpa;
            uint64_t mfn;
            u32 qualification;
            u32 p2mt;
        } _d;

        _d.gpa = gpa;
        _d.qualification = q.raw;
        _d.mfn = mfn_x(get_gfn_query_unlocked(d, gfn, &_d.p2mt));

        __trace_var(TRC_HVM_NPF, 0, sizeof(_d), &_d);
    }

    if ( q.gla_valid )
    {
        __vmread(GUEST_LINEAR_ADDRESS, &gla);
        npfec.gla_valid = 1;
        if( q.gla_fault )
            npfec.kind = npfec_kind_with_gla;
        else
            npfec.kind = npfec_kind_in_gpt;
    }
    else
        gla = ~0ull;

    ret = hvm_hap_nested_page_fault(gpa, gla, npfec);
    switch ( ret )
    {
    case 0:         // Unhandled L1 EPT violation
        break;
    case 1:         // This violation is handled completly
        return;
    case -1:        // This vioaltion should be injected to L1 VMM
        vcpu_nestedhvm(current).nv_vmexit_pending = 1;
        return;
    }

    /* Everything else is an error. */
    mfn = get_gfn_query_unlocked(d, gfn, &p2mt);
    gprintk(XENLOG_ERR,
            "EPT violation %#lx (%c%c%c/%c%c%c) gpa %#"PRIpaddr" mfn %#lx type %i\n",
            q.raw,
            q.read  ? 'r' : '-',
            q.write ? 'w' : '-',
            q.fetch ? 'x' : '-',
            q.eff_read  ? 'r' : '-',
            q.eff_write ? 'w' : '-',
            q.eff_exec  ? 'x' : '-',
            gpa, mfn_x(mfn), p2mt);

    ept_walk_table(d, gfn);

    if ( q.gla_valid )
        gprintk(XENLOG_ERR, " --- GLA %#lx\n", gla);

    domain_crash(d);
}

static void vmx_failed_vmentry(unsigned int exit_reason,
                               struct cpu_user_regs *regs)
{
    unsigned int failed_vmentry_reason = (uint16_t)exit_reason;
    unsigned long exit_qualification;
    struct vcpu *curr = current;

    printk("%pv vmentry failure (reason %#x): ", curr, exit_reason);
    __vmread(EXIT_QUALIFICATION, &exit_qualification);
    switch ( failed_vmentry_reason )
    {
    case EXIT_REASON_INVALID_GUEST_STATE:
        printk("Invalid guest state (%lu)\n", exit_qualification);
        break;

    case EXIT_REASON_MSR_LOADING:
    {
        unsigned long idx = exit_qualification - 1;
        const struct vmx_msr_entry *msr;

        printk("MSR loading (entry %lu)\n", idx);

        if ( idx >= (PAGE_SIZE / sizeof(*msr)) )
            printk("  Entry out of range\n");
        else
        {
            msr = &curr->arch.hvm.vmx.msr_area[idx];

            printk("  msr %08x val %016"PRIx64" (mbz %#x)\n",
                   msr->index, msr->data, msr->mbz);
        }
        break;
    }

    case EXIT_REASON_MCE_DURING_VMENTRY:
        printk("MCE\n");
        HVMTRACE_0D(MCE);
        /* Already handled. */
        break;

    default:
        printk("Unknown\n");
        break;
    }

    printk("************* VMCS Area **************\n");
    vmcs_dump_vcpu(curr);
    printk("**************************************\n");

    domain_crash(curr->domain);
}

void vmx_enter_realmode(struct cpu_user_regs *regs)
{
    struct vcpu *v = current;

    /* Adjust RFLAGS to enter virtual 8086 mode with IOPL == 3.  Since
     * we have CR4.VME == 1 and our own TSS with an empty interrupt
     * redirection bitmap, all software INTs will be handled by vm86 */
    v->arch.hvm.vmx.vm86_saved_eflags = regs->eflags;
    regs->eflags |= (X86_EFLAGS_VM | X86_EFLAGS_IOPL);
}

static int vmx_handle_eoi_write(void)
{
    unsigned long exit_qualification;

    /*
     * 1. Must be a linear access data write.
     * 2. Data write must be to the EOI register.
     */
    __vmread(EXIT_QUALIFICATION, &exit_qualification);
    if ( (((exit_qualification >> 12) & 0xf) == 1) &&
         ((exit_qualification & 0xfff) == APIC_EOI) )
    {
        update_guest_eip(); /* Safe: APIC data write */
        vlapic_EOI_set(vcpu_vlapic(current));
        HVMTRACE_0D(VLAPIC);
        return 1;
    }

    return 0;
}

/*
 * Propagate VM_EXIT_INTR_INFO to VM_ENTRY_INTR_INFO.  Used to mirror an
 * intercepted exception back to the guest as if Xen hadn't intercepted it.
 *
 * It is the callers responsibility to ensure that this function is only used
 * in the context of an appropriate vmexit.
 */
static void vmx_propagate_intr(unsigned long intr)
{
    struct x86_event event = {
        .vector = MASK_EXTR(intr, INTR_INFO_VECTOR_MASK),
        .type = MASK_EXTR(intr, INTR_INFO_INTR_TYPE_MASK),
    };
    unsigned long tmp;

    if ( intr & INTR_INFO_DELIVER_CODE_MASK )
    {
        __vmread(VM_EXIT_INTR_ERROR_CODE, &tmp);
        event.error_code = tmp;
    }
    else
        event.error_code = X86_EVENT_NO_EC;

    if ( event.type >= X86_EVENTTYPE_SW_INTERRUPT )
    {
        __vmread(VM_EXIT_INSTRUCTION_LEN, &tmp);
        event.insn_len = tmp;
    }
    else
        event.insn_len = 0;

    hvm_inject_event(&event);
}

static void vmx_idtv_reinject(unsigned long idtv_info)
{

    /* Event delivery caused this intercept? Queue for redelivery. */
    if ( unlikely(idtv_info & INTR_INFO_VALID_MASK) )
    {
        if ( hvm_event_needs_reinjection(MASK_EXTR(idtv_info,
                                                   INTR_INFO_INTR_TYPE_MASK),
                                         idtv_info & INTR_INFO_VECTOR_MASK) )
        {
            /* See SDM 3B 25.7.1.1 and .2 for info about masking resvd bits. */
            __vmwrite(VM_ENTRY_INTR_INFO,
                      idtv_info & ~INTR_INFO_RESVD_BITS_MASK);
            if ( idtv_info & INTR_INFO_DELIVER_CODE_MASK )
            {
                unsigned long ec;

                __vmread(IDT_VECTORING_ERROR_CODE, &ec);
                __vmwrite(VM_ENTRY_EXCEPTION_ERROR_CODE, ec);
            }
        }

        /*
         * Clear NMI-blocking interruptibility info if an NMI delivery faulted.
         * Re-delivery will re-set it (see SDM 3B 25.7.1.2).
         */
        if ( cpu_has_vmx_vnmi &&
             ((idtv_info & INTR_INFO_INTR_TYPE_MASK) ==
              MASK_INSR(X86_EVENTTYPE_NMI, INTR_INFO_INTR_TYPE_MASK)) )
        {
            unsigned long intr_info;

            __vmread(GUEST_INTERRUPTIBILITY_INFO, &intr_info);
            __vmwrite(GUEST_INTERRUPTIBILITY_INFO,
                      intr_info & ~VMX_INTR_SHADOW_NMI);
        }
    }
}

static void vmx_handle_xsaves(void)
{
    gdprintk(XENLOG_ERR, "xsaves should not cause vmexit\n");
    domain_crash(current->domain);
}

static void vmx_handle_xrstors(void)
{
    gdprintk(XENLOG_ERR, "xrstors should not cause vmexit\n");
    domain_crash(current->domain);
}

static void vmx_handle_descriptor_access(uint32_t exit_reason)
{
    uint64_t instr_info;
    uint64_t exit_qualification;
    unsigned int desc;

    __vmread(EXIT_QUALIFICATION, &exit_qualification);
    __vmread(VMX_INSTRUCTION_INFO, &instr_info);

    if ( exit_reason == EXIT_REASON_ACCESS_GDTR_OR_IDTR )
    {
        idt_or_gdt_instr_info_t info;
        info.raw = instr_info;
        desc = info.instr_identity ? VM_EVENT_DESC_IDTR : VM_EVENT_DESC_GDTR;
        hvm_descriptor_access_intercept(info.raw, exit_qualification, desc,
                                        info.instr_write);
    }
    else
    {
        ldt_or_tr_instr_info_t info;
        info.raw = instr_info;
        desc = info.instr_identity ? VM_EVENT_DESC_TR : VM_EVENT_DESC_LDTR;
        hvm_descriptor_access_intercept(info.raw, exit_qualification, desc,
                                        info.instr_write);
    }
}

static int vmx_handle_apic_write(void)
{
    unsigned long exit_qualification;

    ASSERT(cpu_has_vmx_apic_reg_virt);
    __vmread(EXIT_QUALIFICATION, &exit_qualification);

    return vlapic_apicv_write(current, exit_qualification & 0xfff);
}

void vmx_vmexit_handler(struct cpu_user_regs *regs)
{
    unsigned long exit_qualification, exit_reason, idtv_info, intr_info = 0;
    unsigned int vector = 0, mode;
    struct vcpu *v = current;
    struct domain *currd = v->domain;

    __vmread(GUEST_RIP,    &regs->rip);
    __vmread(GUEST_RSP,    &regs->rsp);
    __vmread(GUEST_RFLAGS, &regs->rflags);

    hvm_invalidate_regs_fields(regs);

    if ( paging_mode_hap(v->domain) )
    {
        /*
         * Xen allows the guest to modify some CR4 bits directly, update cached
         * values to match.
         */
        __vmread(GUEST_CR4, &v->arch.hvm.hw_cr[4]);
        v->arch.hvm.guest_cr[4] &= v->arch.hvm.vmx.cr4_host_mask;
        v->arch.hvm.guest_cr[4] |= (v->arch.hvm.hw_cr[4] &
                                    ~v->arch.hvm.vmx.cr4_host_mask);

        __vmread(GUEST_CR3, &v->arch.hvm.hw_cr[3]);
        if ( vmx_unrestricted_guest(v) || hvm_paging_enabled(v) )
            v->arch.hvm.guest_cr[3] = v->arch.hvm.hw_cr[3];
    }

    __vmread(VM_EXIT_REASON, &exit_reason);

    if ( hvm_long_mode_active(v) )
        HVMTRACE_ND(VMEXIT64, 0, 1/*cycles*/, 3, exit_reason,
                    regs->eip, regs->rip >> 32, 0, 0, 0);
    else
        HVMTRACE_ND(VMEXIT, 0, 1/*cycles*/, 2, exit_reason,
                    regs->eip, 0, 0, 0, 0);

    perfc_incra(vmexits, exit_reason);

    /* Handle the interrupt we missed before allowing any more in. */
    switch ( (uint16_t)exit_reason )
    {
    case EXIT_REASON_EXTERNAL_INTERRUPT:
        vmx_do_extint(regs);
        break;
    case EXIT_REASON_EXCEPTION_NMI:
        __vmread(VM_EXIT_INTR_INFO, &intr_info);
        BUG_ON(!(intr_info & INTR_INFO_VALID_MASK));
        vector = intr_info & INTR_INFO_VECTOR_MASK;
        if ( vector == TRAP_machine_check )
            do_machine_check(regs);
        if ( (vector == TRAP_nmi) &&
             ((intr_info & INTR_INFO_INTR_TYPE_MASK) ==
              MASK_INSR(X86_EVENTTYPE_NMI, INTR_INFO_INTR_TYPE_MASK)) )
        {
            exception_table[TRAP_nmi](regs);
            enable_nmis();
        }
        break;
    case EXIT_REASON_MCE_DURING_VMENTRY:
        do_machine_check(regs);
        break;
    }

    /* Now enable interrupts so it's safe to take locks. */
    local_irq_enable();

    /*
     * If the guest has the ability to switch EPTP without an exit,
     * figure out whether it has done so and update the altp2m data.
     */
    if ( altp2m_active(v->domain) &&
        (v->arch.hvm.vmx.secondary_exec_control &
        SECONDARY_EXEC_ENABLE_VM_FUNCTIONS) )
    {
        unsigned long idx;

        if ( v->arch.hvm.vmx.secondary_exec_control &
            SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS )
            __vmread(EPTP_INDEX, &idx);
        else
        {
            unsigned long eptp;

            __vmread(EPT_POINTER, &eptp);

            if ( (idx = p2m_find_altp2m_by_eptp(v->domain, eptp)) ==
                 INVALID_ALTP2M )
            {
                gdprintk(XENLOG_ERR, "EPTP not found in alternate p2m list\n");
                domain_crash(v->domain);

                return;
            }
        }

        if ( idx != vcpu_altp2m(v).p2midx )
        {
            BUG_ON(idx >= MAX_ALTP2M);
            atomic_dec(&p2m_get_altp2m(v)->active_vcpus);
            vcpu_altp2m(v).p2midx = idx;
            atomic_inc(&p2m_get_altp2m(v)->active_vcpus);
        }
    }

    /* XXX: This looks ugly, but we need a mechanism to ensure
     * any pending vmresume has really happened
     */
    vcpu_nestedhvm(v).nv_vmswitch_in_progress = 0;
    if ( nestedhvm_vcpu_in_guestmode(v) )
    {
        paging_update_nestedmode(v);
        if ( nvmx_n2_vmexit_handler(regs, exit_reason) )
            goto out;
    }

    if ( unlikely(exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY) )
        return vmx_failed_vmentry(exit_reason, regs);

    if ( v->arch.hvm.vmx.vmx_realmode )
    {
        /* Put RFLAGS back the way the guest wants it */
        regs->eflags &= ~(X86_EFLAGS_VM | X86_EFLAGS_IOPL);
        regs->eflags |= (v->arch.hvm.vmx.vm86_saved_eflags & X86_EFLAGS_IOPL);

        /* Unless this exit was for an interrupt, we've hit something
         * vm86 can't handle.  Try again, using the emulator. */
        switch ( exit_reason )
        {
        case EXIT_REASON_EXCEPTION_NMI:
            if ( vector != TRAP_page_fault
                 && vector != TRAP_nmi 
                 && vector != TRAP_machine_check ) 
            {
        default:
                perfc_incr(realmode_exits);
                v->arch.hvm.vmx.vmx_emulate = 1;
                HVMTRACE_0D(REALMODE_EMULATE);
                return;
            }
        case EXIT_REASON_EXTERNAL_INTERRUPT:
        case EXIT_REASON_INIT:
        case EXIT_REASON_SIPI:
        case EXIT_REASON_PENDING_VIRT_INTR:
        case EXIT_REASON_PENDING_VIRT_NMI:
        case EXIT_REASON_MCE_DURING_VMENTRY:
        case EXIT_REASON_GETSEC:
        case EXIT_REASON_ACCESS_GDTR_OR_IDTR:
        case EXIT_REASON_ACCESS_LDTR_OR_TR:
        case EXIT_REASON_VMX_PREEMPTION_TIMER_EXPIRED:
        case EXIT_REASON_INVEPT:
        case EXIT_REASON_INVVPID:
            break;
        }
    }

    hvm_maybe_deassert_evtchn_irq();

    __vmread(IDT_VECTORING_INFO, &idtv_info);
    if ( exit_reason != EXIT_REASON_TASK_SWITCH )
        vmx_idtv_reinject(idtv_info);

    switch ( exit_reason )
    {
        unsigned long ecode;

    case EXIT_REASON_EXCEPTION_NMI:
    {
        /*
         * We don't set the software-interrupt exiting (INT n).
         * (1) We can get an exception (e.g. #PG) in the guest, or
         * (2) NMI
         */

        /*
         * Re-set the NMI shadow if vmexit caused by a guest IRET fault (see 3B
         * 25.7.1.2, "Resuming Guest Software after Handling an Exception").
         * (NB. If we emulate this IRET for any reason, we should re-clear!)
         */
        if ( unlikely(intr_info & INTR_INFO_NMI_UNBLOCKED_BY_IRET) &&
             !(idtv_info & INTR_INFO_VALID_MASK) &&
             (vector != TRAP_double_fault) )
        {
            unsigned long guest_info;

            __vmread(GUEST_INTERRUPTIBILITY_INFO, &guest_info);
            __vmwrite(GUEST_INTERRUPTIBILITY_INFO,
                      guest_info | VMX_INTR_SHADOW_NMI);
        }

        perfc_incra(cause_vector, vector);

        switch ( vector )
        {
        case TRAP_debug:
            /*
             * Updates DR6 where debugger can peek (See 3B 23.2.1,
             * Table 23-1, "Exit Qualification for Debug Exceptions").
             */
            __vmread(EXIT_QUALIFICATION, &exit_qualification);
            HVMTRACE_1D(TRAP_DEBUG, exit_qualification);
            __restore_debug_registers(v);
            write_debugreg(6, exit_qualification | DR_STATUS_RESERVED_ONE);

            /*
             * Work around SingleStep + STI/MovSS VMEntry failures.
             *
             * We intercept #DB unconditionally to work around CVE-2015-8104 /
             * XSA-156 (guest-kernel induced host DoS).
             *
             * STI/MovSS shadows block/defer interrupts/exceptions (exact
             * details are complicated and poorly documented).  Debug
             * exceptions delayed for any reason are stored in the
             * PENDING_DBG_EXCEPTIONS field.
             *
             * The falling edge of PENDING_DBG causes #DB to be delivered,
             * resulting in a VMExit, as #DB is intercepted.  The VMCS still
             * reports blocked-by-STI/MovSS.
             *
             * The VMEntry checks when EFLAGS.TF is set don't like a VMCS in
             * this state.  Despite a #DB queued in VMENTRY_INTR_INFO, the
             * state is rejected as DR6.BS isn't pending.  Fix this up.
             */
            if ( unlikely(regs->eflags & X86_EFLAGS_TF) )
            {
                unsigned long int_info;

                __vmread(GUEST_INTERRUPTIBILITY_INFO, &int_info);

                if ( int_info & (VMX_INTR_SHADOW_STI | VMX_INTR_SHADOW_MOV_SS) )
                {
                    unsigned long pending_dbg;

                    __vmread(GUEST_PENDING_DBG_EXCEPTIONS, &pending_dbg);
                    __vmwrite(GUEST_PENDING_DBG_EXCEPTIONS,
                              pending_dbg | DR_STEP);
                }
            }

            if ( !v->domain->debugger_attached )
            {
                unsigned long insn_len = 0;
                int rc;
                unsigned long trap_type = MASK_EXTR(intr_info,
                                                    INTR_INFO_INTR_TYPE_MASK);

                if ( trap_type >= X86_EVENTTYPE_SW_INTERRUPT )
                    __vmread(VM_EXIT_INSTRUCTION_LEN, &insn_len);

                rc = hvm_monitor_debug(regs->rip,
                                       HVM_MONITOR_DEBUG_EXCEPTION,
                                       trap_type, insn_len, 0);

                if ( rc < 0 )
                    goto exit_and_crash;
                if ( !rc )
                    vmx_propagate_intr(intr_info);
            }
            else
                domain_pause_for_debugger();
            break;
        case TRAP_int3:
            HVMTRACE_1D(TRAP, vector);
            if ( !v->domain->debugger_attached )
            {
                unsigned long insn_len;
                int rc;

                __vmread(VM_EXIT_INSTRUCTION_LEN, &insn_len);
                rc = hvm_monitor_debug(regs->rip,
                                       HVM_MONITOR_SOFTWARE_BREAKPOINT,
                                       X86_EVENTTYPE_SW_EXCEPTION,
                                       insn_len, 0);

                if ( rc < 0 )
                    goto exit_and_crash;
                if ( !rc )
                    vmx_propagate_intr(intr_info);
            }
            else
            {
                update_guest_eip(); /* Safe: INT3 */
                v->arch.gdbsx_vcpu_event = TRAP_int3;
                domain_pause_for_debugger();
            }
            break;
        case TRAP_no_device:
            HVMTRACE_1D(TRAP, vector);
            vmx_fpu_dirty_intercept();
            break;
        case TRAP_page_fault:
            __vmread(EXIT_QUALIFICATION, &exit_qualification);
            __vmread(VM_EXIT_INTR_ERROR_CODE, &ecode);
            regs->error_code = ecode;

            HVM_DBG_LOG(DBG_LEVEL_VMMU,
                        "eax=%lx, ebx=%lx, ecx=%lx, edx=%lx, esi=%lx, edi=%lx",
                        regs->rax, regs->rbx, regs->rcx,
                        regs->rdx, regs->rsi, regs->rdi);

            if ( paging_fault(exit_qualification, regs) )
            {
                if ( trace_will_trace_event(TRC_SHADOW) )
                    break;
                if ( hvm_long_mode_active(v) )
                    HVMTRACE_LONG_2D(PF_XEN, regs->error_code,
                                     TRC_PAR_LONG(exit_qualification) );
                else
                    HVMTRACE_2D(PF_XEN,
                                regs->error_code, exit_qualification );
                break;
            }

            hvm_inject_page_fault(regs->error_code, exit_qualification);
            break;
        case TRAP_alignment_check:
            HVMTRACE_1D(TRAP, vector);
            vmx_propagate_intr(intr_info);
            break;
        case TRAP_nmi:
            if ( MASK_EXTR(intr_info, INTR_INFO_INTR_TYPE_MASK) !=
                 X86_EVENTTYPE_NMI )
                goto exit_and_crash;
            HVMTRACE_0D(NMI);
            /* Already handled above. */
            break;
        case TRAP_machine_check:
            HVMTRACE_0D(MCE);
            /* Already handled above. */
            break;
        case TRAP_invalid_op:
            HVMTRACE_1D(TRAP, vector);
            hvm_ud_intercept(regs);
            break;
        default:
            HVMTRACE_1D(TRAP, vector);
            goto exit_and_crash;
        }
        break;
    }
    case EXIT_REASON_EXTERNAL_INTERRUPT:
        /* Already handled above. */
        break;
    case EXIT_REASON_TRIPLE_FAULT:
        hvm_triple_fault();
        break;
    case EXIT_REASON_PENDING_VIRT_INTR:
        /* Disable the interrupt window. */
        v->arch.hvm.vmx.exec_control &= ~CPU_BASED_VIRTUAL_INTR_PENDING;
        vmx_update_cpu_exec_control(v);
        break;
    case EXIT_REASON_PENDING_VIRT_NMI:
        /* Disable the NMI window. */
        v->arch.hvm.vmx.exec_control &= ~CPU_BASED_VIRTUAL_NMI_PENDING;
        vmx_update_cpu_exec_control(v);
        break;
    case EXIT_REASON_TASK_SWITCH: {
        static const uint8_t reasons[] = {
            TSW_call_or_int, TSW_iret, TSW_jmp, TSW_call_or_int
        };
        unsigned int inst_len, source;

        __vmread(EXIT_QUALIFICATION, &exit_qualification);
        source = (exit_qualification >> 30) & 3;
        /* Vectored event should fill in interrupt information. */
        WARN_ON((source == 3) && !(idtv_info & INTR_INFO_VALID_MASK));
        /*
         * In the following cases there is an instruction to skip over:
         *  - TSW is due to a CALL, IRET or JMP instruction.
         *  - TSW is a vectored event due to a SW exception or SW interrupt.
         */
        inst_len = ((source != 3) ||        /* CALL, IRET, or JMP? */
                    (MASK_EXTR(idtv_info, INTR_INFO_INTR_TYPE_MASK)
                     > 3)) /* IntrType > 3? */
            ? get_instruction_length() /* Safe: SDM 3B 23.2.4 */ : 0;
        if ( (source == 3) && (idtv_info & INTR_INFO_DELIVER_CODE_MASK) )
            __vmread(IDT_VECTORING_ERROR_CODE, &ecode);
        else
             ecode = -1;

        hvm_task_switch(exit_qualification, reasons[source], ecode, inst_len,
                        0 /* EFLAGS.RF already updated. */);
        break;
    }
    case EXIT_REASON_CPUID:
    {
        int rc = hvm_vmexit_cpuid(regs, get_instruction_length());

        /*
         * rc < 0 error in monitor/vm_event, crash
         * !rc    continue normally
         * rc > 0 paused waiting for response, work here is done
         */
        if ( rc < 0 )
            goto exit_and_crash;
        if ( !rc )
            update_guest_eip(); /* Safe: CPUID */
        break;
    }
    case EXIT_REASON_HLT:
        update_guest_eip(); /* Safe: HLT */
        hvm_hlt(regs->eflags);
        break;
    case EXIT_REASON_INVLPG:
        update_guest_eip(); /* Safe: INVLPG */
        __vmread(EXIT_QUALIFICATION, &exit_qualification);
        vmx_invlpg_intercept(exit_qualification);
        break;
    case EXIT_REASON_RDTSCP:
        if ( !currd->arch.cpuid->extd.rdtscp )
        {
            hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
            break;
        }

        regs->rcx = v->arch.msrs->tsc_aux;
        /* fall through */
    case EXIT_REASON_RDTSC:
        update_guest_eip(); /* Safe: RDTSC, RDTSCP */
        hvm_rdtsc_intercept(regs);
        break;

    case EXIT_REASON_VMCALL:
        HVMTRACE_1D(VMMCALL, regs->eax);

        if ( hvm_hypercall(regs) == HVM_HCALL_completed )
            update_guest_eip(); /* Safe: VMCALL */
        break;

    case EXIT_REASON_CR_ACCESS:
    {
        __vmread(EXIT_QUALIFICATION, &exit_qualification);
        if ( vmx_cr_access(exit_qualification) == X86EMUL_OKAY )
            update_guest_eip(); /* Safe: MOV Cn, LMSW, CLTS */
        break;
    }
    case EXIT_REASON_DR_ACCESS:
        __vmread(EXIT_QUALIFICATION, &exit_qualification);
        vmx_dr_access(exit_qualification, regs);
        break;
    case EXIT_REASON_MSR_READ:
    {
        uint64_t msr_content = 0;

        switch ( hvm_msr_read_intercept(regs->ecx, &msr_content) )
        {
        case X86EMUL_OKAY:
            msr_split(regs, msr_content);
            update_guest_eip(); /* Safe: RDMSR */
            break;

        case X86EMUL_EXCEPTION:
            hvm_inject_hw_exception(TRAP_gp_fault, 0);
            break;
        }
        break;
    }

    case EXIT_REASON_MSR_WRITE:
        switch ( hvm_msr_write_intercept(regs->ecx, msr_fold(regs), true) )
        {
        case X86EMUL_OKAY:
            update_guest_eip(); /* Safe: WRMSR */
            break;

        case X86EMUL_EXCEPTION:
            hvm_inject_hw_exception(TRAP_gp_fault, 0);
            break;
        }
        break;

    case EXIT_REASON_VMXOFF:
    case EXIT_REASON_VMXON:
    case EXIT_REASON_VMCLEAR:
    case EXIT_REASON_VMPTRLD:
    case EXIT_REASON_VMPTRST:
    case EXIT_REASON_VMREAD:
    case EXIT_REASON_VMWRITE:
    case EXIT_REASON_VMLAUNCH:
    case EXIT_REASON_VMRESUME:
    case EXIT_REASON_INVEPT:
    case EXIT_REASON_INVVPID:
        if ( nvmx_handle_vmx_insn(regs, exit_reason) == X86EMUL_OKAY )
            update_guest_eip();
        break;

    case EXIT_REASON_VMFUNC:
        if ( vmx_vmfunc_intercept(regs) != X86EMUL_OKAY )
            hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
        else
            update_guest_eip();
        break;

    case EXIT_REASON_MWAIT_INSTRUCTION:
    case EXIT_REASON_MONITOR_INSTRUCTION:
    case EXIT_REASON_GETSEC:
        /*
         * We should never exit on GETSEC because CR4.SMXE is always 0 when
         * running in guest context, and the CPU checks that before getting
         * as far as vmexit.
         */
        WARN_ON(exit_reason == EXIT_REASON_GETSEC);
        hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
        break;

    case EXIT_REASON_TPR_BELOW_THRESHOLD:
        break;

    case EXIT_REASON_APIC_ACCESS:
        if ( !vmx_handle_eoi_write() && !handle_mmio() )
            hvm_inject_hw_exception(TRAP_gp_fault, 0);
        break;

    case EXIT_REASON_EOI_INDUCED:
        __vmread(EXIT_QUALIFICATION, &exit_qualification);

        ASSERT(cpu_has_vmx_virtual_intr_delivery);

        vlapic_handle_EOI(vcpu_vlapic(v), exit_qualification);
        break;

    case EXIT_REASON_IO_INSTRUCTION:
        __vmread(EXIT_QUALIFICATION, &exit_qualification);
        if ( exit_qualification & 0x10 )
        {
            /* INS, OUTS */
            if ( !hvm_emulate_one_insn(x86_insn_is_portio, "port I/O") )
                hvm_inject_hw_exception(TRAP_gp_fault, 0);
        }
        else
        {
            /* IN, OUT */
            uint16_t port = (exit_qualification >> 16) & 0xFFFF;
            int bytes = (exit_qualification & 0x07) + 1;
            int dir = (exit_qualification & 0x08) ? IOREQ_READ : IOREQ_WRITE;
            if ( handle_pio(port, bytes, dir) )
                update_guest_eip(); /* Safe: IN, OUT */
        }
        break;

    case EXIT_REASON_INVD:
    case EXIT_REASON_WBINVD:
    {
        update_guest_eip(); /* Safe: INVD, WBINVD */
        vmx_wbinvd_intercept();
        break;
    }

    case EXIT_REASON_EPT_VIOLATION:
    {
        paddr_t gpa;

        __vmread(GUEST_PHYSICAL_ADDRESS, &gpa);
        __vmread(EXIT_QUALIFICATION, &exit_qualification);
        ept_handle_violation(exit_qualification, gpa);
        break;
    }

    case EXIT_REASON_EPT_MISCONFIG:
    {
        paddr_t gpa;

        __vmread(GUEST_PHYSICAL_ADDRESS, &gpa);
        if ( !ept_handle_misconfig(gpa) )
            goto exit_and_crash;
        break;
    }

    case EXIT_REASON_MONITOR_TRAP_FLAG:
        v->arch.hvm.vmx.exec_control &= ~CPU_BASED_MONITOR_TRAP_FLAG;
        vmx_update_cpu_exec_control(v);
        if ( v->arch.hvm.single_step )
        {
            hvm_monitor_debug(regs->rip,
                              HVM_MONITOR_SINGLESTEP_BREAKPOINT,
                              0, 0, 0);

            if ( v->domain->debugger_attached )
                domain_pause_for_debugger();
        }

        break;

    case EXIT_REASON_PAUSE_INSTRUCTION:
        perfc_incr(pauseloop_exits);
        do_sched_op(SCHEDOP_yield, guest_handle_from_ptr(NULL, void));
        break;

    case EXIT_REASON_XSETBV:
        if ( hvm_handle_xsetbv(regs->ecx, msr_fold(regs)) == X86EMUL_OKAY )
            update_guest_eip(); /* Safe: XSETBV */
        break;

    case EXIT_REASON_APIC_WRITE:
        vmx_handle_apic_write();
        break;

    case EXIT_REASON_PML_FULL:
        vmx_vcpu_flush_pml_buffer(v);
        break;

    case EXIT_REASON_XSAVES:
        vmx_handle_xsaves();
        break;

    case EXIT_REASON_XRSTORS:
        vmx_handle_xrstors();
        break;

    case EXIT_REASON_ACCESS_GDTR_OR_IDTR:
    case EXIT_REASON_ACCESS_LDTR_OR_TR:
        vmx_handle_descriptor_access(exit_reason);
        break;

    case EXIT_REASON_VMX_PREEMPTION_TIMER_EXPIRED:
    case EXIT_REASON_INVPCID:
    /* fall through */
    default:
    exit_and_crash:
        gprintk(XENLOG_ERR, "Unexpected vmexit: reason %lu\n", exit_reason);

        if ( vmx_get_cpl() )
            hvm_inject_hw_exception(TRAP_invalid_op,
                                    X86_EVENT_NO_EC);
        else
            domain_crash(v->domain);
        break;
    }

out:
    if ( nestedhvm_vcpu_in_guestmode(v) )
        nvmx_idtv_handling();

    /*
     * VM entry will fail (causing the guest to get crashed) if rIP (and
     * rFLAGS, but we don't have an issue there) doesn't meet certain
     * criteria. As we must not allow less than fully privileged mode to have
     * such an effect on the domain, we correct rIP in that case (accepting
     * this not being architecturally correct behavior, as the injected #GP
     * fault will then not see the correct [invalid] return address).
     * And since we know the guest will crash, we crash it right away if it
     * already is in most privileged mode.
     */
    mode = vmx_guest_x86_mode(v);
    if ( mode == 8 ? !is_canonical_address(regs->rip)
                   : regs->rip != regs->eip )
    {
        gprintk(XENLOG_WARNING, "Bad rIP %lx for mode %u\n", regs->rip, mode);

        if ( vmx_get_cpl() )
        {
            __vmread(VM_ENTRY_INTR_INFO, &intr_info);
            if ( !(intr_info & INTR_INFO_VALID_MASK) )
                hvm_inject_hw_exception(TRAP_gp_fault, 0);
            /* Need to fix rIP nevertheless. */
            if ( mode == 8 )
                regs->rip = (long)(regs->rip << (64 - VADDR_BITS)) >>
                            (64 - VADDR_BITS);
            else
                regs->rip = regs->eip;
        }
        else
            domain_crash(v->domain);
    }
}

static void lbr_tsx_fixup(void)
{
    struct vcpu *curr = current;
    unsigned int msr_count = curr->arch.hvm.vmx.msr_save_count;
    struct vmx_msr_entry *msr_area = curr->arch.hvm.vmx.msr_area;
    struct vmx_msr_entry *msr;

    if ( (msr = vmx_find_msr(curr, MSR_P4_LASTBRANCH_0_FROM_LIP,
                             VMX_MSR_GUEST)) != NULL )
    {
        const unsigned int lbr_from_end =
            MSR_P4_LASTBRANCH_0_FROM_LIP + NUM_MSR_P4_LASTBRANCH_FROM_TO;

        /*
         * Sign extend into bits 61:62 while preserving bit 63
         * The loop relies on the fact that MSR array is sorted.
         */
        for ( ; msr < msr_area + msr_count && msr->index < lbr_from_end; msr++ )
            msr->data |= ((LBR_FROM_SIGNEXT_2MSB & msr->data) << 2);
    }

    if ( (msr = vmx_find_msr(curr, MSR_IA32_LASTINTFROMIP,
                             VMX_MSR_GUEST)) != NULL )
        msr->data |= ((LBR_FROM_SIGNEXT_2MSB & msr->data) << 2);
}

static void sign_extend_msr(struct vcpu *v, u32 msr, int type)
{
    struct vmx_msr_entry *entry;

    if ( (entry = vmx_find_msr(v, msr, type)) != NULL )
        entry->data = canonicalise_addr(entry->data);
}

static void ler_to_fixup(void)
{
    struct vcpu *curr = current;

    sign_extend_msr(curr, MSR_IA32_LASTINTTOIP, VMX_MSR_GUEST);
}

static void lbr_fixup(void)
{
    struct vcpu *curr = current;

    if ( curr->arch.hvm.vmx.lbr_flags & LBR_FIXUP_TSX )
        lbr_tsx_fixup();
    if ( curr->arch.hvm.vmx.lbr_flags & LBR_FIXUP_LER_TO )
        ler_to_fixup();
}

/* Returns false if the vmentry has to be restarted */
bool vmx_vmenter_helper(const struct cpu_user_regs *regs)
{
    struct vcpu *curr = current;
    struct domain *currd = curr->domain;
    u32 new_asid, old_asid;
    struct hvm_vcpu_asid *p_asid;
    bool_t need_flush;

    ASSERT(hvmemul_cache_disabled(curr));

    /* Shadow EPTP can't be updated here because irqs are disabled */
     if ( nestedhvm_vcpu_in_guestmode(curr) && vcpu_nestedhvm(curr).stale_np2m )
         return false;

    if ( curr->domain->arch.hvm.pi_ops.vcpu_block )
        vmx_pi_do_resume(curr);

    if ( !cpu_has_vmx_vpid )
        goto out;
    if ( nestedhvm_vcpu_in_guestmode(curr) )
        p_asid = &vcpu_nestedhvm(curr).nv_n2asid;
    else
        p_asid = &curr->arch.hvm.n1asid;

    old_asid = p_asid->asid;
    need_flush = hvm_asid_handle_vmenter(p_asid);
    new_asid = p_asid->asid;

    if ( unlikely(new_asid != old_asid) )
    {
        __vmwrite(VIRTUAL_PROCESSOR_ID, new_asid);
        if ( !old_asid && new_asid )
        {
            /* VPID was disabled: now enabled. */
            curr->arch.hvm.vmx.secondary_exec_control |=
                SECONDARY_EXEC_ENABLE_VPID;
            vmx_update_secondary_exec_control(curr);
        }
        else if ( old_asid && !new_asid )
        {
            /* VPID was enabled: now disabled. */
            curr->arch.hvm.vmx.secondary_exec_control &=
                ~SECONDARY_EXEC_ENABLE_VPID;
            vmx_update_secondary_exec_control(curr);
        }
    }

    if ( unlikely(need_flush) )
        vpid_sync_all();

    if ( paging_mode_hap(curr->domain) )
    {
        struct ept_data *ept = &p2m_get_hostp2m(currd)->ept;
        unsigned int cpu = smp_processor_id();
        unsigned int inv = 0; /* None => Single => All */
        struct ept_data *single = NULL; /* Single eptp, iff inv == 1 */

        if ( cpumask_test_cpu(cpu, ept->invalidate) )
        {
            cpumask_clear_cpu(cpu, ept->invalidate);

            /* Automatically invalidate all contexts if nested. */
            inv += 1 + nestedhvm_enabled(currd);
            single = ept;
        }

        if ( altp2m_active(currd) )
        {
            unsigned int i;

            for ( i = 0; i < MAX_ALTP2M; ++i )
            {
                if ( currd->arch.altp2m_eptp[i] == mfn_x(INVALID_MFN) )
                    continue;

                ept = &currd->arch.altp2m_p2m[i]->ept;
                if ( cpumask_test_cpu(cpu, ept->invalidate) )
                {
                    cpumask_clear_cpu(cpu, ept->invalidate);
                    inv++;
                    single = ept;
                }
            }
        }

        if ( inv )
            __invept(inv == 1 ? INVEPT_SINGLE_CONTEXT : INVEPT_ALL_CONTEXT,
                     inv == 1 ? single->eptp          : 0);
    }

 out:
    if ( unlikely(curr->arch.hvm.vmx.lbr_flags & LBR_FIXUP_MASK) )
        lbr_fixup();

    HVMTRACE_ND(VMENTRY, 0, 1/*cycles*/, 0, 0, 0, 0, 0, 0, 0);

    __vmwrite(GUEST_RIP,    regs->rip);
    __vmwrite(GUEST_RSP,    regs->rsp);
    __vmwrite(GUEST_RFLAGS, regs->rflags | X86_EFLAGS_MBS);

    return true;
}

/*
 * Local variables:
 * mode: C
 * c-file-style: "BSD"
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */
