// SPDX-License-Identifier: GPL-2.0-only
/*
 * KVM Microsoft Hyper-V emulation
 *
 * derived from arch/x86/kvm/x86.c
 *
 * Copyright (C) 2006 Qumranet, Inc.
 * Copyright (C) 2008 Qumranet, Inc.
 * Copyright IBM Corporation, 2008
 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
 * Copyright (C) 2015 Andrey Smetanin <asmetanin@virtuozzo.com>
 *
 * Authors:
 *   Avi Kivity   <avi@qumranet.com>
 *   Yaniv Kamay  <yaniv@qumranet.com>
 *   Amit Shah    <amit.shah@qumranet.com>
 *   Ben-Ami Yassour <benami@il.ibm.com>
 *   Andrey Smetanin <asmetanin@virtuozzo.com>
 */

#include "x86.h"
#include "lapic.h"
#include "ioapic.h"
#include "cpuid.h"
#include "hyperv.h"
#include "xen.h"

#include <linux/cpu.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>
#include <linux/sched/cputime.h>
#include <linux/eventfd.h>

#include <asm/apicdef.h>
#include <trace/events/kvm.h>

#include "trace.h"
#include "irq.h"
#include "fpu.h"

/* "Hv#1" signature */
#define HYPERV_CPUID_SIGNATURE_EAX 0x31237648

#define KVM_HV_MAX_SPARSE_VCPU_SET_BITS DIV_ROUND_UP(KVM_MAX_VCPUS, 64)

static void stimer_mark_pending(struct kvm_vcpu_hv_stimer *stimer,
				bool vcpu_kick);

static inline u64 synic_read_sint(struct kvm_vcpu_hv_synic *synic, int sint)
{
	return atomic64_read(&synic->sint[sint]);
}

static inline int synic_get_sint_vector(u64 sint_value)
{
	if (sint_value & HV_SYNIC_SINT_MASKED)
		return -1;
	return sint_value & HV_SYNIC_SINT_VECTOR_MASK;
}

static bool synic_has_vector_connected(struct kvm_vcpu_hv_synic *synic,
				      int vector)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(synic->sint); i++) {
		if (synic_get_sint_vector(synic_read_sint(synic, i)) == vector)
			return true;
	}
	return false;
}

static bool synic_has_vector_auto_eoi(struct kvm_vcpu_hv_synic *synic,
				     int vector)
{
	int i;
	u64 sint_value;

	for (i = 0; i < ARRAY_SIZE(synic->sint); i++) {
		sint_value = synic_read_sint(synic, i);
		if (synic_get_sint_vector(sint_value) == vector &&
		    sint_value & HV_SYNIC_SINT_AUTO_EOI)
			return true;
	}
	return false;
}

static void synic_update_vector(struct kvm_vcpu_hv_synic *synic,
				int vector)
{
	struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
	int auto_eoi_old, auto_eoi_new;

	if (vector < HV_SYNIC_FIRST_VALID_VECTOR)
		return;

	if (synic_has_vector_connected(synic, vector))
		__set_bit(vector, synic->vec_bitmap);
	else
		__clear_bit(vector, synic->vec_bitmap);

	auto_eoi_old = bitmap_weight(synic->auto_eoi_bitmap, 256);

	if (synic_has_vector_auto_eoi(synic, vector))
		__set_bit(vector, synic->auto_eoi_bitmap);
	else
		__clear_bit(vector, synic->auto_eoi_bitmap);

	auto_eoi_new = bitmap_weight(synic->auto_eoi_bitmap, 256);

	if (!!auto_eoi_old == !!auto_eoi_new)
		return;

	mutex_lock(&vcpu->kvm->arch.apicv_update_lock);

	if (auto_eoi_new)
		hv->synic_auto_eoi_used++;
	else
		hv->synic_auto_eoi_used--;

	__kvm_request_apicv_update(vcpu->kvm,
				   !hv->synic_auto_eoi_used,
				   APICV_INHIBIT_REASON_HYPERV);

	mutex_unlock(&vcpu->kvm->arch.apicv_update_lock);
}

static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint,
			  u64 data, bool host)
{
	int vector, old_vector;
	bool masked;

	vector = data & HV_SYNIC_SINT_VECTOR_MASK;
	masked = data & HV_SYNIC_SINT_MASKED;

	/*
	 * Valid vectors are 16-255, however, nested Hyper-V attempts to write
	 * default '0x10000' value on boot and this should not #GP. We need to
	 * allow zero-initing the register from host as well.
	 */
	if (vector < HV_SYNIC_FIRST_VALID_VECTOR && !host && !masked)
		return 1;
	/*
	 * Guest may configure multiple SINTs to use the same vector, so
	 * we maintain a bitmap of vectors handled by synic, and a
	 * bitmap of vectors with auto-eoi behavior.  The bitmaps are
	 * updated here, and atomically queried on fast paths.
	 */
	old_vector = synic_read_sint(synic, sint) & HV_SYNIC_SINT_VECTOR_MASK;

	atomic64_set(&synic->sint[sint], data);

	synic_update_vector(synic, old_vector);

	synic_update_vector(synic, vector);

	/* Load SynIC vectors into EOI exit bitmap */
	kvm_make_request(KVM_REQ_SCAN_IOAPIC, hv_synic_to_vcpu(synic));
	return 0;
}

static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx)
{
	struct kvm_vcpu *vcpu = NULL;
	int i;

	if (vpidx >= KVM_MAX_VCPUS)
		return NULL;

	vcpu = kvm_get_vcpu(kvm, vpidx);
	if (vcpu && kvm_hv_get_vpindex(vcpu) == vpidx)
		return vcpu;
	kvm_for_each_vcpu(i, vcpu, kvm)
		if (kvm_hv_get_vpindex(vcpu) == vpidx)
			return vcpu;
	return NULL;
}

static struct kvm_vcpu_hv_synic *synic_get(struct kvm *kvm, u32 vpidx)
{
	struct kvm_vcpu *vcpu;
	struct kvm_vcpu_hv_synic *synic;

	vcpu = get_vcpu_by_vpidx(kvm, vpidx);
	if (!vcpu || !to_hv_vcpu(vcpu))
		return NULL;
	synic = to_hv_synic(vcpu);
	return (synic->active) ? synic : NULL;
}

static void kvm_hv_notify_acked_sint(struct kvm_vcpu *vcpu, u32 sint)
{
	struct kvm *kvm = vcpu->kvm;
	struct kvm_vcpu_hv_synic *synic = to_hv_synic(vcpu);
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
	struct kvm_vcpu_hv_stimer *stimer;
	int gsi, idx;

	trace_kvm_hv_notify_acked_sint(vcpu->vcpu_id, sint);

	/* Try to deliver pending Hyper-V SynIC timers messages */
	for (idx = 0; idx < ARRAY_SIZE(hv_vcpu->stimer); idx++) {
		stimer = &hv_vcpu->stimer[idx];
		if (stimer->msg_pending && stimer->config.enable &&
		    !stimer->config.direct_mode &&
		    stimer->config.sintx == sint)
			stimer_mark_pending(stimer, false);
	}

	idx = srcu_read_lock(&kvm->irq_srcu);
	gsi = atomic_read(&synic->sint_to_gsi[sint]);
	if (gsi != -1)
		kvm_notify_acked_gsi(kvm, gsi);
	srcu_read_unlock(&kvm->irq_srcu, idx);
}

static void synic_exit(struct kvm_vcpu_hv_synic *synic, u32 msr)
{
	struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);

	hv_vcpu->exit.type = KVM_EXIT_HYPERV_SYNIC;
	hv_vcpu->exit.u.synic.msr = msr;
	hv_vcpu->exit.u.synic.control = synic->control;
	hv_vcpu->exit.u.synic.evt_page = synic->evt_page;
	hv_vcpu->exit.u.synic.msg_page = synic->msg_page;

	kvm_make_request(KVM_REQ_HV_EXIT, vcpu);
}

static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
			 u32 msr, u64 data, bool host)
{
	struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
	int ret;

	if (!synic->active && (!host || data))
		return 1;

	trace_kvm_hv_synic_set_msr(vcpu->vcpu_id, msr, data, host);

	ret = 0;
	switch (msr) {
	case HV_X64_MSR_SCONTROL:
		synic->control = data;
		if (!host)
			synic_exit(synic, msr);
		break;
	case HV_X64_MSR_SVERSION:
		if (!host) {
			ret = 1;
			break;
		}
		synic->version = data;
		break;
	case HV_X64_MSR_SIEFP:
		if ((data & HV_SYNIC_SIEFP_ENABLE) && !host &&
		    !synic->dont_zero_synic_pages)
			if (kvm_clear_guest(vcpu->kvm,
					    data & PAGE_MASK, PAGE_SIZE)) {
				ret = 1;
				break;
			}
		synic->evt_page = data;
		if (!host)
			synic_exit(synic, msr);
		break;
	case HV_X64_MSR_SIMP:
		if ((data & HV_SYNIC_SIMP_ENABLE) && !host &&
		    !synic->dont_zero_synic_pages)
			if (kvm_clear_guest(vcpu->kvm,
					    data & PAGE_MASK, PAGE_SIZE)) {
				ret = 1;
				break;
			}
		synic->msg_page = data;
		if (!host)
			synic_exit(synic, msr);
		break;
	case HV_X64_MSR_EOM: {
		int i;

		if (!synic->active)
			break;

		for (i = 0; i < ARRAY_SIZE(synic->sint); i++)
			kvm_hv_notify_acked_sint(vcpu, i);
		break;
	}
	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
		ret = synic_set_sint(synic, msr - HV_X64_MSR_SINT0, data, host);
		break;
	default:
		ret = 1;
		break;
	}
	return ret;
}

static bool kvm_hv_is_syndbg_enabled(struct kvm_vcpu *vcpu)
{
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);

	return hv_vcpu->cpuid_cache.syndbg_cap_eax &
		HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING;
}

static int kvm_hv_syndbg_complete_userspace(struct kvm_vcpu *vcpu)
{
	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);

	if (vcpu->run->hyperv.u.syndbg.msr == HV_X64_MSR_SYNDBG_CONTROL)
		hv->hv_syndbg.control.status =
			vcpu->run->hyperv.u.syndbg.status;
	return 1;
}

static void syndbg_exit(struct kvm_vcpu *vcpu, u32 msr)
{
	struct kvm_hv_syndbg *syndbg = to_hv_syndbg(vcpu);
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);

	hv_vcpu->exit.type = KVM_EXIT_HYPERV_SYNDBG;
	hv_vcpu->exit.u.syndbg.msr = msr;
	hv_vcpu->exit.u.syndbg.control = syndbg->control.control;
	hv_vcpu->exit.u.syndbg.send_page = syndbg->control.send_page;
	hv_vcpu->exit.u.syndbg.recv_page = syndbg->control.recv_page;
	hv_vcpu->exit.u.syndbg.pending_page = syndbg->control.pending_page;
	vcpu->arch.complete_userspace_io =
			kvm_hv_syndbg_complete_userspace;

	kvm_make_request(KVM_REQ_HV_EXIT, vcpu);
}

static int syndbg_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
{
	struct kvm_hv_syndbg *syndbg = to_hv_syndbg(vcpu);

	if (!kvm_hv_is_syndbg_enabled(vcpu) && !host)
		return 1;

	trace_kvm_hv_syndbg_set_msr(vcpu->vcpu_id,
				    to_hv_vcpu(vcpu)->vp_index, msr, data);
	switch (msr) {
	case HV_X64_MSR_SYNDBG_CONTROL:
		syndbg->control.control = data;
		if (!host)
			syndbg_exit(vcpu, msr);
		break;
	case HV_X64_MSR_SYNDBG_STATUS:
		syndbg->control.status = data;
		break;
	case HV_X64_MSR_SYNDBG_SEND_BUFFER:
		syndbg->control.send_page = data;
		break;
	case HV_X64_MSR_SYNDBG_RECV_BUFFER:
		syndbg->control.recv_page = data;
		break;
	case HV_X64_MSR_SYNDBG_PENDING_BUFFER:
		syndbg->control.pending_page = data;
		if (!host)
			syndbg_exit(vcpu, msr);
		break;
	case HV_X64_MSR_SYNDBG_OPTIONS:
		syndbg->options = data;
		break;
	default:
		break;
	}

	return 0;
}

static int syndbg_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
{
	struct kvm_hv_syndbg *syndbg = to_hv_syndbg(vcpu);

	if (!kvm_hv_is_syndbg_enabled(vcpu) && !host)
		return 1;

	switch (msr) {
	case HV_X64_MSR_SYNDBG_CONTROL:
		*pdata = syndbg->control.control;
		break;
	case HV_X64_MSR_SYNDBG_STATUS:
		*pdata = syndbg->control.status;
		break;
	case HV_X64_MSR_SYNDBG_SEND_BUFFER:
		*pdata = syndbg->control.send_page;
		break;
	case HV_X64_MSR_SYNDBG_RECV_BUFFER:
		*pdata = syndbg->control.recv_page;
		break;
	case HV_X64_MSR_SYNDBG_PENDING_BUFFER:
		*pdata = syndbg->control.pending_page;
		break;
	case HV_X64_MSR_SYNDBG_OPTIONS:
		*pdata = syndbg->options;
		break;
	default:
		break;
	}

	trace_kvm_hv_syndbg_get_msr(vcpu->vcpu_id, kvm_hv_get_vpindex(vcpu), msr, *pdata);

	return 0;
}

static int synic_get_msr(struct kvm_vcpu_hv_synic *synic, u32 msr, u64 *pdata,
			 bool host)
{
	int ret;

	if (!synic->active && !host)
		return 1;

	ret = 0;
	switch (msr) {
	case HV_X64_MSR_SCONTROL:
		*pdata = synic->control;
		break;
	case HV_X64_MSR_SVERSION:
		*pdata = synic->version;
		break;
	case HV_X64_MSR_SIEFP:
		*pdata = synic->evt_page;
		break;
	case HV_X64_MSR_SIMP:
		*pdata = synic->msg_page;
		break;
	case HV_X64_MSR_EOM:
		*pdata = 0;
		break;
	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
		*pdata = atomic64_read(&synic->sint[msr - HV_X64_MSR_SINT0]);
		break;
	default:
		ret = 1;
		break;
	}
	return ret;
}

static int synic_set_irq(struct kvm_vcpu_hv_synic *synic, u32 sint)
{
	struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
	struct kvm_lapic_irq irq;
	int ret, vector;

	if (KVM_BUG_ON(!lapic_in_kernel(vcpu), vcpu->kvm))
		return -EINVAL;

	if (sint >= ARRAY_SIZE(synic->sint))
		return -EINVAL;

	vector = synic_get_sint_vector(synic_read_sint(synic, sint));
	if (vector < 0)
		return -ENOENT;

	memset(&irq, 0, sizeof(irq));
	irq.shorthand = APIC_DEST_SELF;
	irq.dest_mode = APIC_DEST_PHYSICAL;
	irq.delivery_mode = APIC_DM_FIXED;
	irq.vector = vector;
	irq.level = 1;

	ret = kvm_irq_delivery_to_apic(vcpu->kvm, vcpu->arch.apic, &irq, NULL);
	trace_kvm_hv_synic_set_irq(vcpu->vcpu_id, sint, irq.vector, ret);
	return ret;
}

int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vpidx, u32 sint)
{
	struct kvm_vcpu_hv_synic *synic;

	synic = synic_get(kvm, vpidx);
	if (!synic)
		return -EINVAL;

	return synic_set_irq(synic, sint);
}

void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector)
{
	struct kvm_vcpu_hv_synic *synic = to_hv_synic(vcpu);
	int i;

	trace_kvm_hv_synic_send_eoi(vcpu->vcpu_id, vector);

	for (i = 0; i < ARRAY_SIZE(synic->sint); i++)
		if (synic_get_sint_vector(synic_read_sint(synic, i)) == vector)
			kvm_hv_notify_acked_sint(vcpu, i);
}

static int kvm_hv_set_sint_gsi(struct kvm *kvm, u32 vpidx, u32 sint, int gsi)
{
	struct kvm_vcpu_hv_synic *synic;

	synic = synic_get(kvm, vpidx);
	if (!synic)
		return -EINVAL;

	if (sint >= ARRAY_SIZE(synic->sint_to_gsi))
		return -EINVAL;

	atomic_set(&synic->sint_to_gsi[sint], gsi);
	return 0;
}

void kvm_hv_irq_routing_update(struct kvm *kvm)
{
	struct kvm_irq_routing_table *irq_rt;
	struct kvm_kernel_irq_routing_entry *e;
	u32 gsi;

	irq_rt = srcu_dereference_check(kvm->irq_routing, &kvm->irq_srcu,
					lockdep_is_held(&kvm->irq_lock));

	for (gsi = 0; gsi < irq_rt->nr_rt_entries; gsi++) {
		hlist_for_each_entry(e, &irq_rt->map[gsi], link) {
			if (e->type == KVM_IRQ_ROUTING_HV_SINT)
				kvm_hv_set_sint_gsi(kvm, e->hv_sint.vcpu,
						    e->hv_sint.sint, gsi);
		}
	}
}

static void synic_init(struct kvm_vcpu_hv_synic *synic)
{
	int i;

	memset(synic, 0, sizeof(*synic));
	synic->version = HV_SYNIC_VERSION_1;
	for (i = 0; i < ARRAY_SIZE(synic->sint); i++) {
		atomic64_set(&synic->sint[i], HV_SYNIC_SINT_MASKED);
		atomic_set(&synic->sint_to_gsi[i], -1);
	}
}

static u64 get_time_ref_counter(struct kvm *kvm)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	struct kvm_vcpu *vcpu;
	u64 tsc;

	/*
	 * Fall back to get_kvmclock_ns() when TSC page hasn't been set up,
	 * is broken, disabled or being updated.
	 */
	if (hv->hv_tsc_page_status != HV_TSC_PAGE_SET)
		return div_u64(get_kvmclock_ns(kvm), 100);

	vcpu = kvm_get_vcpu(kvm, 0);
	tsc = kvm_read_l1_tsc(vcpu, rdtsc());
	return mul_u64_u64_shr(tsc, hv->tsc_ref.tsc_scale, 64)
		+ hv->tsc_ref.tsc_offset;
}

static void stimer_mark_pending(struct kvm_vcpu_hv_stimer *stimer,
				bool vcpu_kick)
{
	struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);

	set_bit(stimer->index,
		to_hv_vcpu(vcpu)->stimer_pending_bitmap);
	kvm_make_request(KVM_REQ_HV_STIMER, vcpu);
	if (vcpu_kick)
		kvm_vcpu_kick(vcpu);
}

static void stimer_cleanup(struct kvm_vcpu_hv_stimer *stimer)
{
	struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);

	trace_kvm_hv_stimer_cleanup(hv_stimer_to_vcpu(stimer)->vcpu_id,
				    stimer->index);

	hrtimer_cancel(&stimer->timer);
	clear_bit(stimer->index,
		  to_hv_vcpu(vcpu)->stimer_pending_bitmap);
	stimer->msg_pending = false;
	stimer->exp_time = 0;
}

static enum hrtimer_restart stimer_timer_callback(struct hrtimer *timer)
{
	struct kvm_vcpu_hv_stimer *stimer;

	stimer = container_of(timer, struct kvm_vcpu_hv_stimer, timer);
	trace_kvm_hv_stimer_callback(hv_stimer_to_vcpu(stimer)->vcpu_id,
				     stimer->index);
	stimer_mark_pending(stimer, true);

	return HRTIMER_NORESTART;
}

/*
 * stimer_start() assumptions:
 * a) stimer->count is not equal to 0
 * b) stimer->config has HV_STIMER_ENABLE flag
 */
static int stimer_start(struct kvm_vcpu_hv_stimer *stimer)
{
	u64 time_now;
	ktime_t ktime_now;

	time_now = get_time_ref_counter(hv_stimer_to_vcpu(stimer)->kvm);
	ktime_now = ktime_get();

	if (stimer->config.periodic) {
		if (stimer->exp_time) {
			if (time_now >= stimer->exp_time) {
				u64 remainder;

				div64_u64_rem(time_now - stimer->exp_time,
					      stimer->count, &remainder);
				stimer->exp_time =
					time_now + (stimer->count - remainder);
			}
		} else
			stimer->exp_time = time_now + stimer->count;

		trace_kvm_hv_stimer_start_periodic(
					hv_stimer_to_vcpu(stimer)->vcpu_id,
					stimer->index,
					time_now, stimer->exp_time);

		hrtimer_start(&stimer->timer,
			      ktime_add_ns(ktime_now,
					   100 * (stimer->exp_time - time_now)),
			      HRTIMER_MODE_ABS);
		return 0;
	}
	stimer->exp_time = stimer->count;
	if (time_now >= stimer->count) {
		/*
		 * Expire timer according to Hypervisor Top-Level Functional
		 * specification v4(15.3.1):
		 * "If a one shot is enabled and the specified count is in
		 * the past, it will expire immediately."
		 */
		stimer_mark_pending(stimer, false);
		return 0;
	}

	trace_kvm_hv_stimer_start_one_shot(hv_stimer_to_vcpu(stimer)->vcpu_id,
					   stimer->index,
					   time_now, stimer->count);

	hrtimer_start(&stimer->timer,
		      ktime_add_ns(ktime_now, 100 * (stimer->count - time_now)),
		      HRTIMER_MODE_ABS);
	return 0;
}

static int stimer_set_config(struct kvm_vcpu_hv_stimer *stimer, u64 config,
			     bool host)
{
	union hv_stimer_config new_config = {.as_uint64 = config},
		old_config = {.as_uint64 = stimer->config.as_uint64};
	struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
	struct kvm_vcpu_hv_synic *synic = to_hv_synic(vcpu);

	if (!synic->active && (!host || config))
		return 1;

	if (unlikely(!host && hv_vcpu->enforce_cpuid && new_config.direct_mode &&
		     !(hv_vcpu->cpuid_cache.features_edx &
		       HV_STIMER_DIRECT_MODE_AVAILABLE)))
		return 1;

	trace_kvm_hv_stimer_set_config(hv_stimer_to_vcpu(stimer)->vcpu_id,
				       stimer->index, config, host);

	stimer_cleanup(stimer);
	if (old_config.enable &&
	    !new_config.direct_mode && new_config.sintx == 0)
		new_config.enable = 0;
	stimer->config.as_uint64 = new_config.as_uint64;

	if (stimer->config.enable)
		stimer_mark_pending(stimer, false);

	return 0;
}

static int stimer_set_count(struct kvm_vcpu_hv_stimer *stimer, u64 count,
			    bool host)
{
	struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);
	struct kvm_vcpu_hv_synic *synic = to_hv_synic(vcpu);

	if (!synic->active && (!host || count))
		return 1;

	trace_kvm_hv_stimer_set_count(hv_stimer_to_vcpu(stimer)->vcpu_id,
				      stimer->index, count, host);

	stimer_cleanup(stimer);
	stimer->count = count;
	if (!host) {
		if (stimer->count == 0)
			stimer->config.enable = 0;
		else if (stimer->config.auto_enable)
			stimer->config.enable = 1;
	}

	if (stimer->config.enable)
		stimer_mark_pending(stimer, false);

	return 0;
}

static int stimer_get_config(struct kvm_vcpu_hv_stimer *stimer, u64 *pconfig)
{
	*pconfig = stimer->config.as_uint64;
	return 0;
}

static int stimer_get_count(struct kvm_vcpu_hv_stimer *stimer, u64 *pcount)
{
	*pcount = stimer->count;
	return 0;
}

static int synic_deliver_msg(struct kvm_vcpu_hv_synic *synic, u32 sint,
			     struct hv_message *src_msg, bool no_retry)
{
	struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
	int msg_off = offsetof(struct hv_message_page, sint_message[sint]);
	gfn_t msg_page_gfn;
	struct hv_message_header hv_hdr;
	int r;

	if (!(synic->msg_page & HV_SYNIC_SIMP_ENABLE))
		return -ENOENT;

	msg_page_gfn = synic->msg_page >> PAGE_SHIFT;

	/*
	 * Strictly following the spec-mandated ordering would assume setting
	 * .msg_pending before checking .message_type.  However, this function
	 * is only called in vcpu context so the entire update is atomic from
	 * guest POV and thus the exact order here doesn't matter.
	 */
	r = kvm_vcpu_read_guest_page(vcpu, msg_page_gfn, &hv_hdr.message_type,
				     msg_off + offsetof(struct hv_message,
							header.message_type),
				     sizeof(hv_hdr.message_type));
	if (r < 0)
		return r;

	if (hv_hdr.message_type != HVMSG_NONE) {
		if (no_retry)
			return 0;

		hv_hdr.message_flags.msg_pending = 1;
		r = kvm_vcpu_write_guest_page(vcpu, msg_page_gfn,
					      &hv_hdr.message_flags,
					      msg_off +
					      offsetof(struct hv_message,
						       header.message_flags),
					      sizeof(hv_hdr.message_flags));
		if (r < 0)
			return r;
		return -EAGAIN;
	}

	r = kvm_vcpu_write_guest_page(vcpu, msg_page_gfn, src_msg, msg_off,
				      sizeof(src_msg->header) +
				      src_msg->header.payload_size);
	if (r < 0)
		return r;

	r = synic_set_irq(synic, sint);
	if (r < 0)
		return r;
	if (r == 0)
		return -EFAULT;
	return 0;
}

static int stimer_send_msg(struct kvm_vcpu_hv_stimer *stimer)
{
	struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);
	struct hv_message *msg = &stimer->msg;
	struct hv_timer_message_payload *payload =
			(struct hv_timer_message_payload *)&msg->u.payload;

	/*
	 * To avoid piling up periodic ticks, don't retry message
	 * delivery for them (within "lazy" lost ticks policy).
	 */
	bool no_retry = stimer->config.periodic;

	payload->expiration_time = stimer->exp_time;
	payload->delivery_time = get_time_ref_counter(vcpu->kvm);
	return synic_deliver_msg(to_hv_synic(vcpu),
				 stimer->config.sintx, msg,
				 no_retry);
}

static int stimer_notify_direct(struct kvm_vcpu_hv_stimer *stimer)
{
	struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);
	struct kvm_lapic_irq irq = {
		.delivery_mode = APIC_DM_FIXED,
		.vector = stimer->config.apic_vector
	};

	if (lapic_in_kernel(vcpu))
		return !kvm_apic_set_irq(vcpu, &irq, NULL);
	return 0;
}

static void stimer_expiration(struct kvm_vcpu_hv_stimer *stimer)
{
	int r, direct = stimer->config.direct_mode;

	stimer->msg_pending = true;
	if (!direct)
		r = stimer_send_msg(stimer);
	else
		r = stimer_notify_direct(stimer);
	trace_kvm_hv_stimer_expiration(hv_stimer_to_vcpu(stimer)->vcpu_id,
				       stimer->index, direct, r);
	if (!r) {
		stimer->msg_pending = false;
		if (!(stimer->config.periodic))
			stimer->config.enable = 0;
	}
}

void kvm_hv_process_stimers(struct kvm_vcpu *vcpu)
{
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
	struct kvm_vcpu_hv_stimer *stimer;
	u64 time_now, exp_time;
	int i;

	if (!hv_vcpu)
		return;

	for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++)
		if (test_and_clear_bit(i, hv_vcpu->stimer_pending_bitmap)) {
			stimer = &hv_vcpu->stimer[i];
			if (stimer->config.enable) {
				exp_time = stimer->exp_time;

				if (exp_time) {
					time_now =
						get_time_ref_counter(vcpu->kvm);
					if (time_now >= exp_time)
						stimer_expiration(stimer);
				}

				if ((stimer->config.enable) &&
				    stimer->count) {
					if (!stimer->msg_pending)
						stimer_start(stimer);
				} else
					stimer_cleanup(stimer);
			}
		}
}

void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu)
{
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
	int i;

	if (!hv_vcpu)
		return;

	for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++)
		stimer_cleanup(&hv_vcpu->stimer[i]);

	kfree(hv_vcpu);
	vcpu->arch.hyperv = NULL;
}

bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu)
{
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);

	if (!hv_vcpu)
		return false;

	if (!(hv_vcpu->hv_vapic & HV_X64_MSR_VP_ASSIST_PAGE_ENABLE))
		return false;
	return vcpu->arch.pv_eoi.msr_val & KVM_MSR_ENABLED;
}
EXPORT_SYMBOL_GPL(kvm_hv_assist_page_enabled);

bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu,
			    struct hv_vp_assist_page *assist_page)
{
	if (!kvm_hv_assist_page_enabled(vcpu))
		return false;
	return !kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.pv_eoi.data,
				      assist_page, sizeof(*assist_page));
}
EXPORT_SYMBOL_GPL(kvm_hv_get_assist_page);

static void stimer_prepare_msg(struct kvm_vcpu_hv_stimer *stimer)
{
	struct hv_message *msg = &stimer->msg;
	struct hv_timer_message_payload *payload =
			(struct hv_timer_message_payload *)&msg->u.payload;

	memset(&msg->header, 0, sizeof(msg->header));
	msg->header.message_type = HVMSG_TIMER_EXPIRED;
	msg->header.payload_size = sizeof(*payload);

	payload->timer_index = stimer->index;
	payload->expiration_time = 0;
	payload->delivery_time = 0;
}

static void stimer_init(struct kvm_vcpu_hv_stimer *stimer, int timer_index)
{
	memset(stimer, 0, sizeof(*stimer));
	stimer->index = timer_index;
	hrtimer_init(&stimer->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
	stimer->timer.function = stimer_timer_callback;
	stimer_prepare_msg(stimer);
}

static int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
{
	struct kvm_vcpu_hv *hv_vcpu;
	int i;

	hv_vcpu = kzalloc(sizeof(struct kvm_vcpu_hv), GFP_KERNEL_ACCOUNT);
	if (!hv_vcpu)
		return -ENOMEM;

	vcpu->arch.hyperv = hv_vcpu;
	hv_vcpu->vcpu = vcpu;

	synic_init(&hv_vcpu->synic);

	bitmap_zero(hv_vcpu->stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);
	for (i = 0; i < ARRAY_SIZE(hv_vcpu->stimer); i++)
		stimer_init(&hv_vcpu->stimer[i], i);

	hv_vcpu->vp_index = vcpu->vcpu_idx;

	return 0;
}

int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages)
{
	struct kvm_vcpu_hv_synic *synic;
	int r;

	if (!to_hv_vcpu(vcpu)) {
		r = kvm_hv_vcpu_init(vcpu);
		if (r)
			return r;
	}

	synic = to_hv_synic(vcpu);

	synic->active = true;
	synic->dont_zero_synic_pages = dont_zero_synic_pages;
	synic->control = HV_SYNIC_CONTROL_ENABLE;
	return 0;
}

static bool kvm_hv_msr_partition_wide(u32 msr)
{
	bool r = false;

	switch (msr) {
	case HV_X64_MSR_GUEST_OS_ID:
	case HV_X64_MSR_HYPERCALL:
	case HV_X64_MSR_REFERENCE_TSC:
	case HV_X64_MSR_TIME_REF_COUNT:
	case HV_X64_MSR_CRASH_CTL:
	case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
	case HV_X64_MSR_RESET:
	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
	case HV_X64_MSR_TSC_EMULATION_CONTROL:
	case HV_X64_MSR_TSC_EMULATION_STATUS:
	case HV_X64_MSR_SYNDBG_OPTIONS:
	case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
		r = true;
		break;
	}

	return r;
}

static int kvm_hv_msr_get_crash_data(struct kvm *kvm, u32 index, u64 *pdata)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	size_t size = ARRAY_SIZE(hv->hv_crash_param);

	if (WARN_ON_ONCE(index >= size))
		return -EINVAL;

	*pdata = hv->hv_crash_param[array_index_nospec(index, size)];
	return 0;
}

static int kvm_hv_msr_get_crash_ctl(struct kvm *kvm, u64 *pdata)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);

	*pdata = hv->hv_crash_ctl;
	return 0;
}

static int kvm_hv_msr_set_crash_ctl(struct kvm *kvm, u64 data)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);

	hv->hv_crash_ctl = data & HV_CRASH_CTL_CRASH_NOTIFY;

	return 0;
}

static int kvm_hv_msr_set_crash_data(struct kvm *kvm, u32 index, u64 data)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	size_t size = ARRAY_SIZE(hv->hv_crash_param);

	if (WARN_ON_ONCE(index >= size))
		return -EINVAL;

	hv->hv_crash_param[array_index_nospec(index, size)] = data;
	return 0;
}

/*
 * The kvmclock and Hyper-V TSC page use similar formulas, and converting
 * between them is possible:
 *
 * kvmclock formula:
 *    nsec = (ticks - tsc_timestamp) * tsc_to_system_mul * 2^(tsc_shift-32)
 *           + system_time
 *
 * Hyper-V formula:
 *    nsec/100 = ticks * scale / 2^64 + offset
 *
 * When tsc_timestamp = system_time = 0, offset is zero in the Hyper-V formula.
 * By dividing the kvmclock formula by 100 and equating what's left we get:
 *    ticks * scale / 2^64 = ticks * tsc_to_system_mul * 2^(tsc_shift-32) / 100
 *            scale / 2^64 =         tsc_to_system_mul * 2^(tsc_shift-32) / 100
 *            scale        =         tsc_to_system_mul * 2^(32+tsc_shift) / 100
 *
 * Now expand the kvmclock formula and divide by 100:
 *    nsec = ticks * tsc_to_system_mul * 2^(tsc_shift-32)
 *           - tsc_timestamp * tsc_to_system_mul * 2^(tsc_shift-32)
 *           + system_time
 *    nsec/100 = ticks * tsc_to_system_mul * 2^(tsc_shift-32) / 100
 *               - tsc_timestamp * tsc_to_system_mul * 2^(tsc_shift-32) / 100
 *               + system_time / 100
 *
 * Replace tsc_to_system_mul * 2^(tsc_shift-32) / 100 by scale / 2^64:
 *    nsec/100 = ticks * scale / 2^64
 *               - tsc_timestamp * scale / 2^64
 *               + system_time / 100
 *
 * Equate with the Hyper-V formula so that ticks * scale / 2^64 cancels out:
 *    offset = system_time / 100 - tsc_timestamp * scale / 2^64
 *
 * These two equivalencies are implemented in this function.
 */
static bool compute_tsc_page_parameters(struct pvclock_vcpu_time_info *hv_clock,
					struct ms_hyperv_tsc_page *tsc_ref)
{
	u64 max_mul;

	if (!(hv_clock->flags & PVCLOCK_TSC_STABLE_BIT))
		return false;

	/*
	 * check if scale would overflow, if so we use the time ref counter
	 *    tsc_to_system_mul * 2^(tsc_shift+32) / 100 >= 2^64
	 *    tsc_to_system_mul / 100 >= 2^(32-tsc_shift)
	 *    tsc_to_system_mul >= 100 * 2^(32-tsc_shift)
	 */
	max_mul = 100ull << (32 - hv_clock->tsc_shift);
	if (hv_clock->tsc_to_system_mul >= max_mul)
		return false;

	/*
	 * Otherwise compute the scale and offset according to the formulas
	 * derived above.
	 */
	tsc_ref->tsc_scale =
		mul_u64_u32_div(1ULL << (32 + hv_clock->tsc_shift),
				hv_clock->tsc_to_system_mul,
				100);

	tsc_ref->tsc_offset = hv_clock->system_time;
	do_div(tsc_ref->tsc_offset, 100);
	tsc_ref->tsc_offset -=
		mul_u64_u64_shr(hv_clock->tsc_timestamp, tsc_ref->tsc_scale, 64);
	return true;
}

/*
 * Don't touch TSC page values if the guest has opted for TSC emulation after
 * migration. KVM doesn't fully support reenlightenment notifications and TSC
 * access emulation and Hyper-V is known to expect the values in TSC page to
 * stay constant before TSC access emulation is disabled from guest side
 * (HV_X64_MSR_TSC_EMULATION_STATUS). KVM userspace is expected to preserve TSC
 * frequency and guest visible TSC value across migration (and prevent it when
 * TSC scaling is unsupported).
 */
static inline bool tsc_page_update_unsafe(struct kvm_hv *hv)
{
	return (hv->hv_tsc_page_status != HV_TSC_PAGE_GUEST_CHANGED) &&
		hv->hv_tsc_emulation_control;
}

void kvm_hv_setup_tsc_page(struct kvm *kvm,
			   struct pvclock_vcpu_time_info *hv_clock)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	u32 tsc_seq;
	u64 gfn;

	BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
	BUILD_BUG_ON(offsetof(struct ms_hyperv_tsc_page, tsc_sequence) != 0);

	if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN ||
	    hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET)
		return;

	mutex_lock(&hv->hv_lock);
	if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
		goto out_unlock;

	gfn = hv->hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;
	/*
	 * Because the TSC parameters only vary when there is a
	 * change in the master clock, do not bother with caching.
	 */
	if (unlikely(kvm_read_guest(kvm, gfn_to_gpa(gfn),
				    &tsc_seq, sizeof(tsc_seq))))
		goto out_err;

	if (tsc_seq && tsc_page_update_unsafe(hv)) {
		if (kvm_read_guest(kvm, gfn_to_gpa(gfn), &hv->tsc_ref, sizeof(hv->tsc_ref)))
			goto out_err;

		hv->hv_tsc_page_status = HV_TSC_PAGE_SET;
		goto out_unlock;
	}

	/*
	 * While we're computing and writing the parameters, force the
	 * guest to use the time reference count MSR.
	 */
	hv->tsc_ref.tsc_sequence = 0;
	if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
			    &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
		goto out_err;

	if (!compute_tsc_page_parameters(hv_clock, &hv->tsc_ref))
		goto out_err;

	/* Ensure sequence is zero before writing the rest of the struct.  */
	smp_wmb();
	if (kvm_write_guest(kvm, gfn_to_gpa(gfn), &hv->tsc_ref, sizeof(hv->tsc_ref)))
		goto out_err;

	/*
	 * Now switch to the TSC page mechanism by writing the sequence.
	 */
	tsc_seq++;
	if (tsc_seq == 0xFFFFFFFF || tsc_seq == 0)
		tsc_seq = 1;

	/* Write the struct entirely before the non-zero sequence.  */
	smp_wmb();

	hv->tsc_ref.tsc_sequence = tsc_seq;
	if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
			    &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
		goto out_err;

	hv->hv_tsc_page_status = HV_TSC_PAGE_SET;
	goto out_unlock;

out_err:
	hv->hv_tsc_page_status = HV_TSC_PAGE_BROKEN;
out_unlock:
	mutex_unlock(&hv->hv_lock);
}

void kvm_hv_invalidate_tsc_page(struct kvm *kvm)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	u64 gfn;
	int idx;

	if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN ||
	    hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET ||
	    tsc_page_update_unsafe(hv))
		return;

	mutex_lock(&hv->hv_lock);

	if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
		goto out_unlock;

	/* Preserve HV_TSC_PAGE_GUEST_CHANGED/HV_TSC_PAGE_HOST_CHANGED states */
	if (hv->hv_tsc_page_status == HV_TSC_PAGE_SET)
		hv->hv_tsc_page_status = HV_TSC_PAGE_UPDATING;

	gfn = hv->hv_tsc_page >> HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT;

	hv->tsc_ref.tsc_sequence = 0;

	/*
	 * Take the srcu lock as memslots will be accessed to check the gfn
	 * cache generation against the memslots generation.
	 */
	idx = srcu_read_lock(&kvm->srcu);
	if (kvm_write_guest(kvm, gfn_to_gpa(gfn),
			    &hv->tsc_ref, sizeof(hv->tsc_ref.tsc_sequence)))
		hv->hv_tsc_page_status = HV_TSC_PAGE_BROKEN;
	srcu_read_unlock(&kvm->srcu, idx);

out_unlock:
	mutex_unlock(&hv->hv_lock);
}


static bool hv_check_msr_access(struct kvm_vcpu_hv *hv_vcpu, u32 msr)
{
	if (!hv_vcpu->enforce_cpuid)
		return true;

	switch (msr) {
	case HV_X64_MSR_GUEST_OS_ID:
	case HV_X64_MSR_HYPERCALL:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_HYPERCALL_AVAILABLE;
	case HV_X64_MSR_VP_RUNTIME:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_VP_RUNTIME_AVAILABLE;
	case HV_X64_MSR_TIME_REF_COUNT:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_TIME_REF_COUNT_AVAILABLE;
	case HV_X64_MSR_VP_INDEX:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_VP_INDEX_AVAILABLE;
	case HV_X64_MSR_RESET:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_RESET_AVAILABLE;
	case HV_X64_MSR_REFERENCE_TSC:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_REFERENCE_TSC_AVAILABLE;
	case HV_X64_MSR_SCONTROL:
	case HV_X64_MSR_SVERSION:
	case HV_X64_MSR_SIEFP:
	case HV_X64_MSR_SIMP:
	case HV_X64_MSR_EOM:
	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_SYNIC_AVAILABLE;
	case HV_X64_MSR_STIMER0_CONFIG:
	case HV_X64_MSR_STIMER1_CONFIG:
	case HV_X64_MSR_STIMER2_CONFIG:
	case HV_X64_MSR_STIMER3_CONFIG:
	case HV_X64_MSR_STIMER0_COUNT:
	case HV_X64_MSR_STIMER1_COUNT:
	case HV_X64_MSR_STIMER2_COUNT:
	case HV_X64_MSR_STIMER3_COUNT:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_SYNTIMER_AVAILABLE;
	case HV_X64_MSR_EOI:
	case HV_X64_MSR_ICR:
	case HV_X64_MSR_TPR:
	case HV_X64_MSR_VP_ASSIST_PAGE:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_MSR_APIC_ACCESS_AVAILABLE;
		break;
	case HV_X64_MSR_TSC_FREQUENCY:
	case HV_X64_MSR_APIC_FREQUENCY:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_ACCESS_FREQUENCY_MSRS;
	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
	case HV_X64_MSR_TSC_EMULATION_CONTROL:
	case HV_X64_MSR_TSC_EMULATION_STATUS:
		return hv_vcpu->cpuid_cache.features_eax &
			HV_ACCESS_REENLIGHTENMENT;
	case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
	case HV_X64_MSR_CRASH_CTL:
		return hv_vcpu->cpuid_cache.features_edx &
			HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
	case HV_X64_MSR_SYNDBG_OPTIONS:
	case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
		return hv_vcpu->cpuid_cache.features_edx &
			HV_FEATURE_DEBUG_MSRS_AVAILABLE;
	default:
		break;
	}

	return false;
}

static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
			     bool host)
{
	struct kvm *kvm = vcpu->kvm;
	struct kvm_hv *hv = to_kvm_hv(kvm);

	if (unlikely(!host && !hv_check_msr_access(to_hv_vcpu(vcpu), msr)))
		return 1;

	switch (msr) {
	case HV_X64_MSR_GUEST_OS_ID:
		hv->hv_guest_os_id = data;
		/* setting guest os id to zero disables hypercall page */
		if (!hv->hv_guest_os_id)
			hv->hv_hypercall &= ~HV_X64_MSR_HYPERCALL_ENABLE;
		break;
	case HV_X64_MSR_HYPERCALL: {
		u8 instructions[9];
		int i = 0;
		u64 addr;

		/* if guest os id is not set hypercall should remain disabled */
		if (!hv->hv_guest_os_id)
			break;
		if (!(data & HV_X64_MSR_HYPERCALL_ENABLE)) {
			hv->hv_hypercall = data;
			break;
		}

		/*
		 * If Xen and Hyper-V hypercalls are both enabled, disambiguate
		 * the same way Xen itself does, by setting the bit 31 of EAX
		 * which is RsvdZ in the 32-bit Hyper-V hypercall ABI and just
		 * going to be clobbered on 64-bit.
		 */
		if (kvm_xen_hypercall_enabled(kvm)) {
			/* orl $0x80000000, %eax */
			instructions[i++] = 0x0d;
			instructions[i++] = 0x00;
			instructions[i++] = 0x00;
			instructions[i++] = 0x00;
			instructions[i++] = 0x80;
		}

		/* vmcall/vmmcall */
		static_call(kvm_x86_patch_hypercall)(vcpu, instructions + i);
		i += 3;

		/* ret */
		((unsigned char *)instructions)[i++] = 0xc3;

		addr = data & HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK;
		if (kvm_vcpu_write_guest(vcpu, addr, instructions, i))
			return 1;
		hv->hv_hypercall = data;
		break;
	}
	case HV_X64_MSR_REFERENCE_TSC:
		hv->hv_tsc_page = data;
		if (hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) {
			if (!host)
				hv->hv_tsc_page_status = HV_TSC_PAGE_GUEST_CHANGED;
			else
				hv->hv_tsc_page_status = HV_TSC_PAGE_HOST_CHANGED;
			kvm_make_request(KVM_REQ_MASTERCLOCK_UPDATE, vcpu);
		} else {
			hv->hv_tsc_page_status = HV_TSC_PAGE_UNSET;
		}
		break;
	case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
		return kvm_hv_msr_set_crash_data(kvm,
						 msr - HV_X64_MSR_CRASH_P0,
						 data);
	case HV_X64_MSR_CRASH_CTL:
		if (host)
			return kvm_hv_msr_set_crash_ctl(kvm, data);

		if (data & HV_CRASH_CTL_CRASH_NOTIFY) {
			vcpu_debug(vcpu, "hv crash (0x%llx 0x%llx 0x%llx 0x%llx 0x%llx)\n",
				   hv->hv_crash_param[0],
				   hv->hv_crash_param[1],
				   hv->hv_crash_param[2],
				   hv->hv_crash_param[3],
				   hv->hv_crash_param[4]);

			/* Send notification about crash to user space */
			kvm_make_request(KVM_REQ_HV_CRASH, vcpu);
		}
		break;
	case HV_X64_MSR_RESET:
		if (data == 1) {
			vcpu_debug(vcpu, "hyper-v reset requested\n");
			kvm_make_request(KVM_REQ_HV_RESET, vcpu);
		}
		break;
	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
		hv->hv_reenlightenment_control = data;
		break;
	case HV_X64_MSR_TSC_EMULATION_CONTROL:
		hv->hv_tsc_emulation_control = data;
		break;
	case HV_X64_MSR_TSC_EMULATION_STATUS:
		if (data && !host)
			return 1;

		hv->hv_tsc_emulation_status = data;
		break;
	case HV_X64_MSR_TIME_REF_COUNT:
		/* read-only, but still ignore it if host-initiated */
		if (!host)
			return 1;
		break;
	case HV_X64_MSR_SYNDBG_OPTIONS:
	case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
		return syndbg_set_msr(vcpu, msr, data, host);
	default:
		vcpu_unimpl(vcpu, "Hyper-V unhandled wrmsr: 0x%x data 0x%llx\n",
			    msr, data);
		return 1;
	}
	return 0;
}

/* Calculate cpu time spent by current task in 100ns units */
static u64 current_task_runtime_100ns(void)
{
	u64 utime, stime;

	task_cputime_adjusted(current, &utime, &stime);

	return div_u64(utime + stime, 100);
}

static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
{
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);

	if (unlikely(!host && !hv_check_msr_access(hv_vcpu, msr)))
		return 1;

	switch (msr) {
	case HV_X64_MSR_VP_INDEX: {
		struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
		u32 new_vp_index = (u32)data;

		if (!host || new_vp_index >= KVM_MAX_VCPUS)
			return 1;

		if (new_vp_index == hv_vcpu->vp_index)
			return 0;

		/*
		 * The VP index is initialized to vcpu_index by
		 * kvm_hv_vcpu_postcreate so they initially match.  Now the
		 * VP index is changing, adjust num_mismatched_vp_indexes if
		 * it now matches or no longer matches vcpu_idx.
		 */
		if (hv_vcpu->vp_index == vcpu->vcpu_idx)
			atomic_inc(&hv->num_mismatched_vp_indexes);
		else if (new_vp_index == vcpu->vcpu_idx)
			atomic_dec(&hv->num_mismatched_vp_indexes);

		hv_vcpu->vp_index = new_vp_index;
		break;
	}
	case HV_X64_MSR_VP_ASSIST_PAGE: {
		u64 gfn;
		unsigned long addr;

		if (!(data & HV_X64_MSR_VP_ASSIST_PAGE_ENABLE)) {
			hv_vcpu->hv_vapic = data;
			if (kvm_lapic_enable_pv_eoi(vcpu, 0, 0))
				return 1;
			break;
		}
		gfn = data >> HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT;
		addr = kvm_vcpu_gfn_to_hva(vcpu, gfn);
		if (kvm_is_error_hva(addr))
			return 1;

		/*
		 * Clear apic_assist portion of struct hv_vp_assist_page
		 * only, there can be valuable data in the rest which needs
		 * to be preserved e.g. on migration.
		 */
		if (__put_user(0, (u32 __user *)addr))
			return 1;
		hv_vcpu->hv_vapic = data;
		kvm_vcpu_mark_page_dirty(vcpu, gfn);
		if (kvm_lapic_enable_pv_eoi(vcpu,
					    gfn_to_gpa(gfn) | KVM_MSR_ENABLED,
					    sizeof(struct hv_vp_assist_page)))
			return 1;
		break;
	}
	case HV_X64_MSR_EOI:
		return kvm_hv_vapic_msr_write(vcpu, APIC_EOI, data);
	case HV_X64_MSR_ICR:
		return kvm_hv_vapic_msr_write(vcpu, APIC_ICR, data);
	case HV_X64_MSR_TPR:
		return kvm_hv_vapic_msr_write(vcpu, APIC_TASKPRI, data);
	case HV_X64_MSR_VP_RUNTIME:
		if (!host)
			return 1;
		hv_vcpu->runtime_offset = data - current_task_runtime_100ns();
		break;
	case HV_X64_MSR_SCONTROL:
	case HV_X64_MSR_SVERSION:
	case HV_X64_MSR_SIEFP:
	case HV_X64_MSR_SIMP:
	case HV_X64_MSR_EOM:
	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
		return synic_set_msr(to_hv_synic(vcpu), msr, data, host);
	case HV_X64_MSR_STIMER0_CONFIG:
	case HV_X64_MSR_STIMER1_CONFIG:
	case HV_X64_MSR_STIMER2_CONFIG:
	case HV_X64_MSR_STIMER3_CONFIG: {
		int timer_index = (msr - HV_X64_MSR_STIMER0_CONFIG)/2;

		return stimer_set_config(to_hv_stimer(vcpu, timer_index),
					 data, host);
	}
	case HV_X64_MSR_STIMER0_COUNT:
	case HV_X64_MSR_STIMER1_COUNT:
	case HV_X64_MSR_STIMER2_COUNT:
	case HV_X64_MSR_STIMER3_COUNT: {
		int timer_index = (msr - HV_X64_MSR_STIMER0_COUNT)/2;

		return stimer_set_count(to_hv_stimer(vcpu, timer_index),
					data, host);
	}
	case HV_X64_MSR_TSC_FREQUENCY:
	case HV_X64_MSR_APIC_FREQUENCY:
		/* read-only, but still ignore it if host-initiated */
		if (!host)
			return 1;
		break;
	default:
		vcpu_unimpl(vcpu, "Hyper-V unhandled wrmsr: 0x%x data 0x%llx\n",
			    msr, data);
		return 1;
	}

	return 0;
}

static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
			     bool host)
{
	u64 data = 0;
	struct kvm *kvm = vcpu->kvm;
	struct kvm_hv *hv = to_kvm_hv(kvm);

	if (unlikely(!host && !hv_check_msr_access(to_hv_vcpu(vcpu), msr)))
		return 1;

	switch (msr) {
	case HV_X64_MSR_GUEST_OS_ID:
		data = hv->hv_guest_os_id;
		break;
	case HV_X64_MSR_HYPERCALL:
		data = hv->hv_hypercall;
		break;
	case HV_X64_MSR_TIME_REF_COUNT:
		data = get_time_ref_counter(kvm);
		break;
	case HV_X64_MSR_REFERENCE_TSC:
		data = hv->hv_tsc_page;
		break;
	case HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4:
		return kvm_hv_msr_get_crash_data(kvm,
						 msr - HV_X64_MSR_CRASH_P0,
						 pdata);
	case HV_X64_MSR_CRASH_CTL:
		return kvm_hv_msr_get_crash_ctl(kvm, pdata);
	case HV_X64_MSR_RESET:
		data = 0;
		break;
	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
		data = hv->hv_reenlightenment_control;
		break;
	case HV_X64_MSR_TSC_EMULATION_CONTROL:
		data = hv->hv_tsc_emulation_control;
		break;
	case HV_X64_MSR_TSC_EMULATION_STATUS:
		data = hv->hv_tsc_emulation_status;
		break;
	case HV_X64_MSR_SYNDBG_OPTIONS:
	case HV_X64_MSR_SYNDBG_CONTROL ... HV_X64_MSR_SYNDBG_PENDING_BUFFER:
		return syndbg_get_msr(vcpu, msr, pdata, host);
	default:
		vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
		return 1;
	}

	*pdata = data;
	return 0;
}

static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
			  bool host)
{
	u64 data = 0;
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);

	if (unlikely(!host && !hv_check_msr_access(hv_vcpu, msr)))
		return 1;

	switch (msr) {
	case HV_X64_MSR_VP_INDEX:
		data = hv_vcpu->vp_index;
		break;
	case HV_X64_MSR_EOI:
		return kvm_hv_vapic_msr_read(vcpu, APIC_EOI, pdata);
	case HV_X64_MSR_ICR:
		return kvm_hv_vapic_msr_read(vcpu, APIC_ICR, pdata);
	case HV_X64_MSR_TPR:
		return kvm_hv_vapic_msr_read(vcpu, APIC_TASKPRI, pdata);
	case HV_X64_MSR_VP_ASSIST_PAGE:
		data = hv_vcpu->hv_vapic;
		break;
	case HV_X64_MSR_VP_RUNTIME:
		data = current_task_runtime_100ns() + hv_vcpu->runtime_offset;
		break;
	case HV_X64_MSR_SCONTROL:
	case HV_X64_MSR_SVERSION:
	case HV_X64_MSR_SIEFP:
	case HV_X64_MSR_SIMP:
	case HV_X64_MSR_EOM:
	case HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15:
		return synic_get_msr(to_hv_synic(vcpu), msr, pdata, host);
	case HV_X64_MSR_STIMER0_CONFIG:
	case HV_X64_MSR_STIMER1_CONFIG:
	case HV_X64_MSR_STIMER2_CONFIG:
	case HV_X64_MSR_STIMER3_CONFIG: {
		int timer_index = (msr - HV_X64_MSR_STIMER0_CONFIG)/2;

		return stimer_get_config(to_hv_stimer(vcpu, timer_index),
					 pdata);
	}
	case HV_X64_MSR_STIMER0_COUNT:
	case HV_X64_MSR_STIMER1_COUNT:
	case HV_X64_MSR_STIMER2_COUNT:
	case HV_X64_MSR_STIMER3_COUNT: {
		int timer_index = (msr - HV_X64_MSR_STIMER0_COUNT)/2;

		return stimer_get_count(to_hv_stimer(vcpu, timer_index),
					pdata);
	}
	case HV_X64_MSR_TSC_FREQUENCY:
		data = (u64)vcpu->arch.virtual_tsc_khz * 1000;
		break;
	case HV_X64_MSR_APIC_FREQUENCY:
		data = APIC_BUS_FREQUENCY;
		break;
	default:
		vcpu_unimpl(vcpu, "Hyper-V unhandled rdmsr: 0x%x\n", msr);
		return 1;
	}
	*pdata = data;
	return 0;
}

int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
{
	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);

	if (!host && !vcpu->arch.hyperv_enabled)
		return 1;

	if (!to_hv_vcpu(vcpu)) {
		if (kvm_hv_vcpu_init(vcpu))
			return 1;
	}

	if (kvm_hv_msr_partition_wide(msr)) {
		int r;

		mutex_lock(&hv->hv_lock);
		r = kvm_hv_set_msr_pw(vcpu, msr, data, host);
		mutex_unlock(&hv->hv_lock);
		return r;
	} else
		return kvm_hv_set_msr(vcpu, msr, data, host);
}

int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
{
	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);

	if (!host && !vcpu->arch.hyperv_enabled)
		return 1;

	if (!to_hv_vcpu(vcpu)) {
		if (kvm_hv_vcpu_init(vcpu))
			return 1;
	}

	if (kvm_hv_msr_partition_wide(msr)) {
		int r;

		mutex_lock(&hv->hv_lock);
		r = kvm_hv_get_msr_pw(vcpu, msr, pdata, host);
		mutex_unlock(&hv->hv_lock);
		return r;
	} else
		return kvm_hv_get_msr(vcpu, msr, pdata, host);
}

static __always_inline unsigned long *sparse_set_to_vcpu_mask(
	struct kvm *kvm, u64 *sparse_banks, u64 valid_bank_mask,
	u64 *vp_bitmap, unsigned long *vcpu_bitmap)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	struct kvm_vcpu *vcpu;
	int i, bank, sbank = 0;

	memset(vp_bitmap, 0,
	       KVM_HV_MAX_SPARSE_VCPU_SET_BITS * sizeof(*vp_bitmap));
	for_each_set_bit(bank, (unsigned long *)&valid_bank_mask,
			 KVM_HV_MAX_SPARSE_VCPU_SET_BITS)
		vp_bitmap[bank] = sparse_banks[sbank++];

	if (likely(!atomic_read(&hv->num_mismatched_vp_indexes))) {
		/* for all vcpus vp_index == vcpu_idx */
		return (unsigned long *)vp_bitmap;
	}

	bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS);
	kvm_for_each_vcpu(i, vcpu, kvm) {
		if (test_bit(kvm_hv_get_vpindex(vcpu), (unsigned long *)vp_bitmap))
			__set_bit(i, vcpu_bitmap);
	}
	return vcpu_bitmap;
}

struct kvm_hv_hcall {
	u64 param;
	u64 ingpa;
	u64 outgpa;
	u16 code;
	u16 rep_cnt;
	u16 rep_idx;
	bool fast;
	bool rep;
	sse128_t xmm[HV_HYPERCALL_MAX_XMM_REGISTERS];
};

static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
{
	int i;
	gpa_t gpa;
	struct kvm *kvm = vcpu->kvm;
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
	struct hv_tlb_flush_ex flush_ex;
	struct hv_tlb_flush flush;
	u64 vp_bitmap[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
	DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS);
	unsigned long *vcpu_mask;
	u64 valid_bank_mask;
	u64 sparse_banks[64];
	int sparse_banks_len;
	bool all_cpus;

	if (hc->code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST ||
	    hc->code == HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE) {
		if (hc->fast) {
			flush.address_space = hc->ingpa;
			flush.flags = hc->outgpa;
			flush.processor_mask = sse128_lo(hc->xmm[0]);
		} else {
			if (unlikely(kvm_read_guest(kvm, hc->ingpa,
						    &flush, sizeof(flush))))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
		}

		trace_kvm_hv_flush_tlb(flush.processor_mask,
				       flush.address_space, flush.flags);

		valid_bank_mask = BIT_ULL(0);
		sparse_banks[0] = flush.processor_mask;

		/*
		 * Work around possible WS2012 bug: it sends hypercalls
		 * with processor_mask = 0x0 and HV_FLUSH_ALL_PROCESSORS clear,
		 * while also expecting us to flush something and crashing if
		 * we don't. Let's treat processor_mask == 0 same as
		 * HV_FLUSH_ALL_PROCESSORS.
		 */
		all_cpus = (flush.flags & HV_FLUSH_ALL_PROCESSORS) ||
			flush.processor_mask == 0;
	} else {
		if (hc->fast) {
			flush_ex.address_space = hc->ingpa;
			flush_ex.flags = hc->outgpa;
			memcpy(&flush_ex.hv_vp_set,
			       &hc->xmm[0], sizeof(hc->xmm[0]));
		} else {
			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &flush_ex,
						    sizeof(flush_ex))))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
		}

		trace_kvm_hv_flush_tlb_ex(flush_ex.hv_vp_set.valid_bank_mask,
					  flush_ex.hv_vp_set.format,
					  flush_ex.address_space,
					  flush_ex.flags);

		valid_bank_mask = flush_ex.hv_vp_set.valid_bank_mask;
		all_cpus = flush_ex.hv_vp_set.format !=
			HV_GENERIC_SET_SPARSE_4K;

		sparse_banks_len = bitmap_weight((unsigned long *)&valid_bank_mask, 64);

		if (!sparse_banks_len && !all_cpus)
			goto ret_success;

		if (!all_cpus) {
			if (hc->fast) {
				/* XMM0 is already consumed, each XMM holds two sparse banks. */
				if (sparse_banks_len > 2 * (HV_HYPERCALL_MAX_XMM_REGISTERS - 1))
					return HV_STATUS_INVALID_HYPERCALL_INPUT;
				for (i = 0; i < sparse_banks_len; i += 2) {
					sparse_banks[i] = sse128_lo(hc->xmm[i / 2 + 1]);
					sparse_banks[i + 1] = sse128_hi(hc->xmm[i / 2 + 1]);
				}
			} else {
				gpa = hc->ingpa + offsetof(struct hv_tlb_flush_ex,
							   hv_vp_set.bank_contents);
				if (unlikely(kvm_read_guest(kvm, gpa, sparse_banks,
							    sparse_banks_len *
							    sizeof(sparse_banks[0]))))
					return HV_STATUS_INVALID_HYPERCALL_INPUT;
			}
		}
	}

	cpumask_clear(&hv_vcpu->tlb_flush);

	/*
	 * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we can't
	 * analyze it here, flush TLB regardless of the specified address space.
	 */
	if (all_cpus) {
		kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH_GUEST);
	} else {
		vcpu_mask = sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask,
						    vp_bitmap, vcpu_bitmap);

		kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST,
					    NULL, vcpu_mask, &hv_vcpu->tlb_flush);
	}

ret_success:
	/* We always do full TLB flush, set 'Reps completed' = 'Rep Count' */
	return (u64)HV_STATUS_SUCCESS |
		((u64)hc->rep_cnt << HV_HYPERCALL_REP_COMP_OFFSET);
}

static void kvm_send_ipi_to_many(struct kvm *kvm, u32 vector,
				 unsigned long *vcpu_bitmap)
{
	struct kvm_lapic_irq irq = {
		.delivery_mode = APIC_DM_FIXED,
		.vector = vector
	};
	struct kvm_vcpu *vcpu;
	int i;

	kvm_for_each_vcpu(i, vcpu, kvm) {
		if (vcpu_bitmap && !test_bit(i, vcpu_bitmap))
			continue;

		/* We fail only when APIC is disabled */
		kvm_apic_set_irq(vcpu, &irq, NULL);
	}
}

static u64 kvm_hv_send_ipi(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
{
	struct kvm *kvm = vcpu->kvm;
	struct hv_send_ipi_ex send_ipi_ex;
	struct hv_send_ipi send_ipi;
	u64 vp_bitmap[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
	DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS);
	unsigned long *vcpu_mask;
	unsigned long valid_bank_mask;
	u64 sparse_banks[64];
	int sparse_banks_len;
	u32 vector;
	bool all_cpus;
	int i;

	if (hc->code == HVCALL_SEND_IPI) {
		if (!hc->fast) {
			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi,
						    sizeof(send_ipi))))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
			sparse_banks[0] = send_ipi.cpu_mask;
			vector = send_ipi.vector;
		} else {
			/* 'reserved' part of hv_send_ipi should be 0 */
			if (unlikely(hc->ingpa >> 32 != 0))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
			sparse_banks[0] = hc->outgpa;
			vector = (u32)hc->ingpa;
		}
		all_cpus = false;
		valid_bank_mask = BIT_ULL(0);

		trace_kvm_hv_send_ipi(vector, sparse_banks[0]);
	} else {
		if (!hc->fast) {
			if (unlikely(kvm_read_guest(kvm, hc->ingpa, &send_ipi_ex,
						    sizeof(send_ipi_ex))))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
		} else {
			send_ipi_ex.vector = (u32)hc->ingpa;
			send_ipi_ex.vp_set.format = hc->outgpa;
			send_ipi_ex.vp_set.valid_bank_mask = sse128_lo(hc->xmm[0]);
		}

		trace_kvm_hv_send_ipi_ex(send_ipi_ex.vector,
					 send_ipi_ex.vp_set.format,
					 send_ipi_ex.vp_set.valid_bank_mask);

		vector = send_ipi_ex.vector;
		valid_bank_mask = send_ipi_ex.vp_set.valid_bank_mask;
		sparse_banks_len = bitmap_weight(&valid_bank_mask, 64);

		all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;

		if (all_cpus)
			goto check_and_send_ipi;

		if (!sparse_banks_len)
			goto ret_success;

		if (!hc->fast) {
			if (kvm_read_guest(kvm,
					   hc->ingpa + offsetof(struct hv_send_ipi_ex,
								vp_set.bank_contents),
					   sparse_banks,
					   sparse_banks_len * sizeof(sparse_banks[0])))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
		} else {
			/*
			 * The lower half of XMM0 is already consumed, each XMM holds
			 * two sparse banks.
			 */
			if (sparse_banks_len > (2 * HV_HYPERCALL_MAX_XMM_REGISTERS - 1))
				return HV_STATUS_INVALID_HYPERCALL_INPUT;
			for (i = 0; i < sparse_banks_len; i++) {
				if (i % 2)
					sparse_banks[i] = sse128_lo(hc->xmm[(i + 1) / 2]);
				else
					sparse_banks[i] = sse128_hi(hc->xmm[i / 2]);
			}
		}
	}

check_and_send_ipi:
	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
		return HV_STATUS_INVALID_HYPERCALL_INPUT;

	vcpu_mask = all_cpus ? NULL :
		sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask,
					vp_bitmap, vcpu_bitmap);

	kvm_send_ipi_to_many(kvm, vector, vcpu_mask);

ret_success:
	return HV_STATUS_SUCCESS;
}

void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)
{
	struct kvm_cpuid_entry2 *entry;
	struct kvm_vcpu_hv *hv_vcpu;

	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_INTERFACE, 0);
	if (entry && entry->eax == HYPERV_CPUID_SIGNATURE_EAX) {
		vcpu->arch.hyperv_enabled = true;
	} else {
		vcpu->arch.hyperv_enabled = false;
		return;
	}

	if (!to_hv_vcpu(vcpu) && kvm_hv_vcpu_init(vcpu))
		return;

	hv_vcpu = to_hv_vcpu(vcpu);

	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_FEATURES, 0);
	if (entry) {
		hv_vcpu->cpuid_cache.features_eax = entry->eax;
		hv_vcpu->cpuid_cache.features_ebx = entry->ebx;
		hv_vcpu->cpuid_cache.features_edx = entry->edx;
	} else {
		hv_vcpu->cpuid_cache.features_eax = 0;
		hv_vcpu->cpuid_cache.features_ebx = 0;
		hv_vcpu->cpuid_cache.features_edx = 0;
	}

	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_ENLIGHTMENT_INFO, 0);
	if (entry) {
		hv_vcpu->cpuid_cache.enlightenments_eax = entry->eax;
		hv_vcpu->cpuid_cache.enlightenments_ebx = entry->ebx;
	} else {
		hv_vcpu->cpuid_cache.enlightenments_eax = 0;
		hv_vcpu->cpuid_cache.enlightenments_ebx = 0;
	}

	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES, 0);
	if (entry)
		hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;
	else
		hv_vcpu->cpuid_cache.syndbg_cap_eax = 0;
}

int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)
{
	struct kvm_vcpu_hv *hv_vcpu;
	int ret = 0;

	if (!to_hv_vcpu(vcpu)) {
		if (enforce) {
			ret = kvm_hv_vcpu_init(vcpu);
			if (ret)
				return ret;
		} else {
			return 0;
		}
	}

	hv_vcpu = to_hv_vcpu(vcpu);
	hv_vcpu->enforce_cpuid = enforce;

	return ret;
}

bool kvm_hv_hypercall_enabled(struct kvm_vcpu *vcpu)
{
	return vcpu->arch.hyperv_enabled && to_kvm_hv(vcpu->kvm)->hv_guest_os_id;
}

static void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
{
	bool longmode;

	longmode = is_64_bit_hypercall(vcpu);
	if (longmode)
		kvm_rax_write(vcpu, result);
	else {
		kvm_rdx_write(vcpu, result >> 32);
		kvm_rax_write(vcpu, result & 0xffffffff);
	}
}

static int kvm_hv_hypercall_complete(struct kvm_vcpu *vcpu, u64 result)
{
	trace_kvm_hv_hypercall_done(result);
	kvm_hv_hypercall_set_result(vcpu, result);
	++vcpu->stat.hypercalls;
	return kvm_skip_emulated_instruction(vcpu);
}

static int kvm_hv_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
{
	return kvm_hv_hypercall_complete(vcpu, vcpu->run->hyperv.u.hcall.result);
}

static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
{
	struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
	struct eventfd_ctx *eventfd;

	if (unlikely(!hc->fast)) {
		int ret;
		gpa_t gpa = hc->ingpa;

		if ((gpa & (__alignof__(hc->ingpa) - 1)) ||
		    offset_in_page(gpa) + sizeof(hc->ingpa) > PAGE_SIZE)
			return HV_STATUS_INVALID_ALIGNMENT;

		ret = kvm_vcpu_read_guest(vcpu, gpa,
					  &hc->ingpa, sizeof(hc->ingpa));
		if (ret < 0)
			return HV_STATUS_INVALID_ALIGNMENT;
	}

	/*
	 * Per spec, bits 32-47 contain the extra "flag number".  However, we
	 * have no use for it, and in all known usecases it is zero, so just
	 * report lookup failure if it isn't.
	 */
	if (hc->ingpa & 0xffff00000000ULL)
		return HV_STATUS_INVALID_PORT_ID;
	/* remaining bits are reserved-zero */
	if (hc->ingpa & ~KVM_HYPERV_CONN_ID_MASK)
		return HV_STATUS_INVALID_HYPERCALL_INPUT;

	/* the eventfd is protected by vcpu->kvm->srcu, but conn_to_evt isn't */
	rcu_read_lock();
	eventfd = idr_find(&hv->conn_to_evt, hc->ingpa);
	rcu_read_unlock();
	if (!eventfd)
		return HV_STATUS_INVALID_PORT_ID;

	eventfd_signal(eventfd, 1);
	return HV_STATUS_SUCCESS;
}

static bool is_xmm_fast_hypercall(struct kvm_hv_hcall *hc)
{
	switch (hc->code) {
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
	case HVCALL_SEND_IPI_EX:
		return true;
	}

	return false;
}

static void kvm_hv_hypercall_read_xmm(struct kvm_hv_hcall *hc)
{
	int reg;

	kvm_fpu_get();
	for (reg = 0; reg < HV_HYPERCALL_MAX_XMM_REGISTERS; reg++)
		_kvm_read_sse_reg(reg, &hc->xmm[reg]);
	kvm_fpu_put();
}

static bool hv_check_hypercall_access(struct kvm_vcpu_hv *hv_vcpu, u16 code)
{
	if (!hv_vcpu->enforce_cpuid)
		return true;

	switch (code) {
	case HVCALL_NOTIFY_LONG_SPIN_WAIT:
		return hv_vcpu->cpuid_cache.enlightenments_ebx &&
			hv_vcpu->cpuid_cache.enlightenments_ebx != U32_MAX;
	case HVCALL_POST_MESSAGE:
		return hv_vcpu->cpuid_cache.features_ebx & HV_POST_MESSAGES;
	case HVCALL_SIGNAL_EVENT:
		return hv_vcpu->cpuid_cache.features_ebx & HV_SIGNAL_EVENTS;
	case HVCALL_POST_DEBUG_DATA:
	case HVCALL_RETRIEVE_DEBUG_DATA:
	case HVCALL_RESET_DEBUG_SESSION:
		/*
		 * Return 'true' when SynDBG is disabled so the resulting code
		 * will be HV_STATUS_INVALID_HYPERCALL_CODE.
		 */
		return !kvm_hv_is_syndbg_enabled(hv_vcpu->vcpu) ||
			hv_vcpu->cpuid_cache.features_ebx & HV_DEBUGGING;
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
		if (!(hv_vcpu->cpuid_cache.enlightenments_eax &
		      HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
			return false;
		fallthrough;
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
		return hv_vcpu->cpuid_cache.enlightenments_eax &
			HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;
	case HVCALL_SEND_IPI_EX:
		if (!(hv_vcpu->cpuid_cache.enlightenments_eax &
		      HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED))
			return false;
		fallthrough;
	case HVCALL_SEND_IPI:
		return hv_vcpu->cpuid_cache.enlightenments_eax &
			HV_X64_CLUSTER_IPI_RECOMMENDED;
	default:
		break;
	}

	return true;
}

int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
{
	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
	struct kvm_hv_hcall hc;
	u64 ret = HV_STATUS_SUCCESS;

	/*
	 * hypercall generates UD from non zero cpl and real mode
	 * per HYPER-V spec
	 */
	if (static_call(kvm_x86_get_cpl)(vcpu) != 0 || !is_protmode(vcpu)) {
		kvm_queue_exception(vcpu, UD_VECTOR);
		return 1;
	}

#ifdef CONFIG_X86_64
	if (is_64_bit_hypercall(vcpu)) {
		hc.param = kvm_rcx_read(vcpu);
		hc.ingpa = kvm_rdx_read(vcpu);
		hc.outgpa = kvm_r8_read(vcpu);
	} else
#endif
	{
		hc.param = ((u64)kvm_rdx_read(vcpu) << 32) |
			    (kvm_rax_read(vcpu) & 0xffffffff);
		hc.ingpa = ((u64)kvm_rbx_read(vcpu) << 32) |
			    (kvm_rcx_read(vcpu) & 0xffffffff);
		hc.outgpa = ((u64)kvm_rdi_read(vcpu) << 32) |
			     (kvm_rsi_read(vcpu) & 0xffffffff);
	}

	hc.code = hc.param & 0xffff;
	hc.fast = !!(hc.param & HV_HYPERCALL_FAST_BIT);
	hc.rep_cnt = (hc.param >> HV_HYPERCALL_REP_COMP_OFFSET) & 0xfff;
	hc.rep_idx = (hc.param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
	hc.rep = !!(hc.rep_cnt || hc.rep_idx);

	trace_kvm_hv_hypercall(hc.code, hc.fast, hc.rep_cnt, hc.rep_idx,
			       hc.ingpa, hc.outgpa);

	if (unlikely(!hv_check_hypercall_access(hv_vcpu, hc.code))) {
		ret = HV_STATUS_ACCESS_DENIED;
		goto hypercall_complete;
	}

	if (hc.fast && is_xmm_fast_hypercall(&hc)) {
		if (unlikely(hv_vcpu->enforce_cpuid &&
			     !(hv_vcpu->cpuid_cache.features_edx &
			       HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE))) {
			kvm_queue_exception(vcpu, UD_VECTOR);
			return 1;
		}

		kvm_hv_hypercall_read_xmm(&hc);
	}

	switch (hc.code) {
	case HVCALL_NOTIFY_LONG_SPIN_WAIT:
		if (unlikely(hc.rep)) {
			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
			break;
		}
		kvm_vcpu_on_spin(vcpu, true);
		break;
	case HVCALL_SIGNAL_EVENT:
		if (unlikely(hc.rep)) {
			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
			break;
		}
		ret = kvm_hvcall_signal_event(vcpu, &hc);
		if (ret != HV_STATUS_INVALID_PORT_ID)
			break;
		fallthrough;	/* maybe userspace knows this conn_id */
	case HVCALL_POST_MESSAGE:
		/* don't bother userspace if it has no way to handle it */
		if (unlikely(hc.rep || !to_hv_synic(vcpu)->active)) {
			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
			break;
		}
		vcpu->run->exit_reason = KVM_EXIT_HYPERV;
		vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
		vcpu->run->hyperv.u.hcall.input = hc.param;
		vcpu->run->hyperv.u.hcall.params[0] = hc.ingpa;
		vcpu->run->hyperv.u.hcall.params[1] = hc.outgpa;
		vcpu->arch.complete_userspace_io =
				kvm_hv_hypercall_complete_userspace;
		return 0;
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
		if (unlikely(!hc.rep_cnt || hc.rep_idx)) {
			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
			break;
		}
		ret = kvm_hv_flush_tlb(vcpu, &hc);
		break;
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
	case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
		if (unlikely(hc.rep)) {
			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
			break;
		}
		ret = kvm_hv_flush_tlb(vcpu, &hc);
		break;
	case HVCALL_SEND_IPI:
	case HVCALL_SEND_IPI_EX:
		if (unlikely(hc.rep)) {
			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
			break;
		}
		ret = kvm_hv_send_ipi(vcpu, &hc);
		break;
	case HVCALL_POST_DEBUG_DATA:
	case HVCALL_RETRIEVE_DEBUG_DATA:
		if (unlikely(hc.fast)) {
			ret = HV_STATUS_INVALID_PARAMETER;
			break;
		}
		fallthrough;
	case HVCALL_RESET_DEBUG_SESSION: {
		struct kvm_hv_syndbg *syndbg = to_hv_syndbg(vcpu);

		if (!kvm_hv_is_syndbg_enabled(vcpu)) {
			ret = HV_STATUS_INVALID_HYPERCALL_CODE;
			break;
		}

		if (!(syndbg->options & HV_X64_SYNDBG_OPTION_USE_HCALLS)) {
			ret = HV_STATUS_OPERATION_DENIED;
			break;
		}
		vcpu->run->exit_reason = KVM_EXIT_HYPERV;
		vcpu->run->hyperv.type = KVM_EXIT_HYPERV_HCALL;
		vcpu->run->hyperv.u.hcall.input = hc.param;
		vcpu->run->hyperv.u.hcall.params[0] = hc.ingpa;
		vcpu->run->hyperv.u.hcall.params[1] = hc.outgpa;
		vcpu->arch.complete_userspace_io =
				kvm_hv_hypercall_complete_userspace;
		return 0;
	}
	default:
		ret = HV_STATUS_INVALID_HYPERCALL_CODE;
		break;
	}

hypercall_complete:
	return kvm_hv_hypercall_complete(vcpu, ret);
}

void kvm_hv_init_vm(struct kvm *kvm)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);

	mutex_init(&hv->hv_lock);
	idr_init(&hv->conn_to_evt);
}

void kvm_hv_destroy_vm(struct kvm *kvm)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	struct eventfd_ctx *eventfd;
	int i;

	idr_for_each_entry(&hv->conn_to_evt, eventfd, i)
		eventfd_ctx_put(eventfd);
	idr_destroy(&hv->conn_to_evt);
}

static int kvm_hv_eventfd_assign(struct kvm *kvm, u32 conn_id, int fd)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	struct eventfd_ctx *eventfd;
	int ret;

	eventfd = eventfd_ctx_fdget(fd);
	if (IS_ERR(eventfd))
		return PTR_ERR(eventfd);

	mutex_lock(&hv->hv_lock);
	ret = idr_alloc(&hv->conn_to_evt, eventfd, conn_id, conn_id + 1,
			GFP_KERNEL_ACCOUNT);
	mutex_unlock(&hv->hv_lock);

	if (ret >= 0)
		return 0;

	if (ret == -ENOSPC)
		ret = -EEXIST;
	eventfd_ctx_put(eventfd);
	return ret;
}

static int kvm_hv_eventfd_deassign(struct kvm *kvm, u32 conn_id)
{
	struct kvm_hv *hv = to_kvm_hv(kvm);
	struct eventfd_ctx *eventfd;

	mutex_lock(&hv->hv_lock);
	eventfd = idr_remove(&hv->conn_to_evt, conn_id);
	mutex_unlock(&hv->hv_lock);

	if (!eventfd)
		return -ENOENT;

	synchronize_srcu(&kvm->srcu);
	eventfd_ctx_put(eventfd);
	return 0;
}

int kvm_vm_ioctl_hv_eventfd(struct kvm *kvm, struct kvm_hyperv_eventfd *args)
{
	if ((args->flags & ~KVM_HYPERV_EVENTFD_DEASSIGN) ||
	    (args->conn_id & ~KVM_HYPERV_CONN_ID_MASK))
		return -EINVAL;

	if (args->flags == KVM_HYPERV_EVENTFD_DEASSIGN)
		return kvm_hv_eventfd_deassign(kvm, args->conn_id);
	return kvm_hv_eventfd_assign(kvm, args->conn_id, args->fd);
}

int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
		     struct kvm_cpuid_entry2 __user *entries)
{
	uint16_t evmcs_ver = 0;
	struct kvm_cpuid_entry2 cpuid_entries[] = {
		{ .function = HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS },
		{ .function = HYPERV_CPUID_INTERFACE },
		{ .function = HYPERV_CPUID_VERSION },
		{ .function = HYPERV_CPUID_FEATURES },
		{ .function = HYPERV_CPUID_ENLIGHTMENT_INFO },
		{ .function = HYPERV_CPUID_IMPLEMENT_LIMITS },
		{ .function = HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS },
		{ .function = HYPERV_CPUID_SYNDBG_INTERFACE },
		{ .function = HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES	},
		{ .function = HYPERV_CPUID_NESTED_FEATURES },
	};
	int i, nent = ARRAY_SIZE(cpuid_entries);

	if (kvm_x86_ops.nested_ops->get_evmcs_version)
		evmcs_ver = kvm_x86_ops.nested_ops->get_evmcs_version(vcpu);

	/* Skip NESTED_FEATURES if eVMCS is not supported */
	if (!evmcs_ver)
		--nent;

	if (cpuid->nent < nent)
		return -E2BIG;

	if (cpuid->nent > nent)
		cpuid->nent = nent;

	for (i = 0; i < nent; i++) {
		struct kvm_cpuid_entry2 *ent = &cpuid_entries[i];
		u32 signature[3];

		switch (ent->function) {
		case HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS:
			memcpy(signature, "Linux KVM Hv", 12);

			ent->eax = HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES;
			ent->ebx = signature[0];
			ent->ecx = signature[1];
			ent->edx = signature[2];
			break;

		case HYPERV_CPUID_INTERFACE:
			ent->eax = HYPERV_CPUID_SIGNATURE_EAX;
			break;

		case HYPERV_CPUID_VERSION:
			/*
			 * We implement some Hyper-V 2016 functions so let's use
			 * this version.
			 */
			ent->eax = 0x00003839;
			ent->ebx = 0x000A0000;
			break;

		case HYPERV_CPUID_FEATURES:
			ent->eax |= HV_MSR_VP_RUNTIME_AVAILABLE;
			ent->eax |= HV_MSR_TIME_REF_COUNT_AVAILABLE;
			ent->eax |= HV_MSR_SYNIC_AVAILABLE;
			ent->eax |= HV_MSR_SYNTIMER_AVAILABLE;
			ent->eax |= HV_MSR_APIC_ACCESS_AVAILABLE;
			ent->eax |= HV_MSR_HYPERCALL_AVAILABLE;
			ent->eax |= HV_MSR_VP_INDEX_AVAILABLE;
			ent->eax |= HV_MSR_RESET_AVAILABLE;
			ent->eax |= HV_MSR_REFERENCE_TSC_AVAILABLE;
			ent->eax |= HV_ACCESS_FREQUENCY_MSRS;
			ent->eax |= HV_ACCESS_REENLIGHTENMENT;

			ent->ebx |= HV_POST_MESSAGES;
			ent->ebx |= HV_SIGNAL_EVENTS;

			ent->edx |= HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE;
			ent->edx |= HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
			ent->edx |= HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;

			ent->ebx |= HV_DEBUGGING;
			ent->edx |= HV_X64_GUEST_DEBUGGING_AVAILABLE;
			ent->edx |= HV_FEATURE_DEBUG_MSRS_AVAILABLE;

			/*
			 * Direct Synthetic timers only make sense with in-kernel
			 * LAPIC
			 */
			if (!vcpu || lapic_in_kernel(vcpu))
				ent->edx |= HV_STIMER_DIRECT_MODE_AVAILABLE;

			break;

		case HYPERV_CPUID_ENLIGHTMENT_INFO:
			ent->eax |= HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;
			ent->eax |= HV_X64_APIC_ACCESS_RECOMMENDED;
			ent->eax |= HV_X64_RELAXED_TIMING_RECOMMENDED;
			ent->eax |= HV_X64_CLUSTER_IPI_RECOMMENDED;
			ent->eax |= HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED;
			if (evmcs_ver)
				ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
			if (!cpu_smt_possible())
				ent->eax |= HV_X64_NO_NONARCH_CORESHARING;

			ent->eax |= HV_DEPRECATING_AEOI_RECOMMENDED;
			/*
			 * Default number of spinlock retry attempts, matches
			 * HyperV 2016.
			 */
			ent->ebx = 0x00000FFF;

			break;

		case HYPERV_CPUID_IMPLEMENT_LIMITS:
			/* Maximum number of virtual processors */
			ent->eax = KVM_MAX_VCPUS;
			/*
			 * Maximum number of logical processors, matches
			 * HyperV 2016.
			 */
			ent->ebx = 64;

			break;

		case HYPERV_CPUID_NESTED_FEATURES:
			ent->eax = evmcs_ver;

			break;

		case HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS:
			memcpy(signature, "Linux KVM Hv", 12);

			ent->eax = 0;
			ent->ebx = signature[0];
			ent->ecx = signature[1];
			ent->edx = signature[2];
			break;

		case HYPERV_CPUID_SYNDBG_INTERFACE:
			memcpy(signature, "VS#1\0\0\0\0\0\0\0\0", 12);
			ent->eax = signature[0];
			break;

		case HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES:
			ent->eax |= HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING;
			break;

		default:
			break;
		}
	}

	if (copy_to_user(entries, cpuid_entries,
			 nent * sizeof(struct kvm_cpuid_entry2)))
		return -EFAULT;

	return 0;
}