Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2582 insertions, 0 deletions

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
new file mode 100644
index 000000000..04cca46fe
--- /dev/null
+++ b/arch/x86/kvm/hyperv.c
@@ -0,0 +1,2582 @@
+// 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"
+
+#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);
+	bool 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_empty(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_empty(synic->auto_eoi_bitmap, 256);
+
+	if (auto_eoi_old == auto_eoi_new)
+		return;
+
+	if (!enable_apicv)
+		return;
+
+	down_write(&vcpu->kvm->arch.apicv_update_lock);
+
+	if (auto_eoi_new)
+		hv->synic_auto_eoi_used++;
+	else
+		hv->synic_auto_eoi_used--;
+
+	/*
+	 * Inhibit APICv if any vCPU is using SynIC's AutoEOI, which relies on
+	 * the hypervisor to manually inject IRQs.
+	 */
+	__kvm_set_or_clear_apicv_inhibit(vcpu->kvm,
+					 APICV_INHIBIT_REASON_HYPERV,
+					 !!hv->synic_auto_eoi_used);
+
+	up_write(&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;
+	unsigned long 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);
+}
+
+int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
+	int i;
+
+	if (hv_vcpu)
+		return 0;
+
+	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;
+
+	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);
+
+	mutex_lock(&hv->hv_lock);
+
+	if (hv->hv_tsc_page_status == HV_TSC_PAGE_BROKEN ||
+	    hv->hv_tsc_page_status == HV_TSC_PAGE_SET ||
+	    hv->hv_tsc_page_status == HV_TSC_PAGE_UNSET)
+		goto out_unlock;
+
+	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_request_tsc_page_update(struct kvm *kvm)
+{
+	struct kvm_hv *hv = to_kvm_hv(kvm);
+
+	mutex_lock(&hv->hv_lock);
+
+	if (hv->hv_tsc_page_status == HV_TSC_PAGE_SET &&
+	    !tsc_page_update_unsafe(hv))
+		hv->hv_tsc_page_status = HV_TSC_PAGE_HOST_CHANGED;
+
+	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_set_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_set_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 (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 (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 void sparse_set_to_vcpu_mask(struct kvm *kvm, u64 *sparse_banks,
+				    u64 valid_bank_mask, unsigned long *vcpu_mask)
+{
+	struct kvm_hv *hv = to_kvm_hv(kvm);
+	bool has_mismatch = atomic_read(&hv->num_mismatched_vp_indexes);
+	u64 vp_bitmap[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
+	struct kvm_vcpu *vcpu;
+	int bank, sbank = 0;
+	unsigned long i;
+	u64 *bitmap;
+
+	BUILD_BUG_ON(sizeof(vp_bitmap) >
+		     sizeof(*vcpu_mask) * BITS_TO_LONGS(KVM_MAX_VCPUS));
+
+	/*
+	 * If vp_index == vcpu_idx for all vCPUs, fill vcpu_mask directly, else
+	 * fill a temporary buffer and manually test each vCPU's VP index.
+	 */
+	if (likely(!has_mismatch))
+		bitmap = (u64 *)vcpu_mask;
+	else
+		bitmap = vp_bitmap;
+
+	/*
+	 * Each set of 64 VPs is packed into sparse_banks, with valid_bank_mask
+	 * having a '1' for each bank that exists in sparse_banks.  Sets must
+	 * be in ascending order, i.e. bank0..bankN.
+	 */
+	memset(bitmap, 0, sizeof(vp_bitmap));
+	for_each_set_bit(bank, (unsigned long *)&valid_bank_mask,
+			 KVM_HV_MAX_SPARSE_VCPU_SET_BITS)
+		bitmap[bank] = sparse_banks[sbank++];
+
+	if (likely(!has_mismatch))
+		return;
+
+	bitmap_zero(vcpu_mask, 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_mask);
+	}
+}
+
+struct kvm_hv_hcall {
+	u64 param;
+	u64 ingpa;
+	u64 outgpa;
+	u16 code;
+	u16 var_cnt;
+	u16 rep_cnt;
+	u16 rep_idx;
+	bool fast;
+	bool rep;
+	sse128_t xmm[HV_HYPERCALL_MAX_XMM_REGISTERS];
+};
+
+static u64 kvm_get_sparse_vp_set(struct kvm *kvm, struct kvm_hv_hcall *hc,
+				 int consumed_xmm_halves,
+				 u64 *sparse_banks, gpa_t offset)
+{
+	u16 var_cnt;
+	int i;
+
+	if (hc->var_cnt > 64)
+		return -EINVAL;
+
+	/* Ignore banks that cannot possibly contain a legal VP index. */
+	var_cnt = min_t(u16, hc->var_cnt, KVM_HV_MAX_SPARSE_VCPU_SET_BITS);
+
+	if (hc->fast) {
+		/*
+		 * Each XMM holds two sparse banks, but do not count halves that
+		 * have already been consumed for hypercall parameters.
+		 */
+		if (hc->var_cnt > 2 * HV_HYPERCALL_MAX_XMM_REGISTERS - consumed_xmm_halves)
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+		for (i = 0; i < var_cnt; i++) {
+			int j = i + consumed_xmm_halves;
+			if (j % 2)
+				sparse_banks[i] = sse128_hi(hc->xmm[j / 2]);
+			else
+				sparse_banks[i] = sse128_lo(hc->xmm[j / 2]);
+		}
+		return 0;
+	}
+
+	return kvm_read_guest(kvm, hc->ingpa + offset, sparse_banks,
+			      var_cnt * sizeof(*sparse_banks));
+}
+
+static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
+{
+	struct kvm *kvm = vcpu->kvm;
+	struct hv_tlb_flush_ex flush_ex;
+	struct hv_tlb_flush flush;
+	DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS);
+	u64 valid_bank_mask;
+	u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
+	bool all_cpus;
+
+	/*
+	 * The Hyper-V TLFS doesn't allow more than 64 sparse banks, e.g. the
+	 * valid mask is a u64.  Fail the build if KVM's max allowed number of
+	 * vCPUs (>4096) would exceed this limit, KVM will additional changes
+	 * for Hyper-V support to avoid setting the guest up to fail.
+	 */
+	BUILD_BUG_ON(KVM_HV_MAX_SPARSE_VCPU_SET_BITS > 64);
+
+	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;
+
+		if (hc->var_cnt != hweight64(valid_bank_mask))
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+		if (all_cpus)
+			goto do_flush;
+
+		if (!hc->var_cnt)
+			goto ret_success;
+
+		if (kvm_get_sparse_vp_set(kvm, hc, 2, sparse_banks,
+					  offsetof(struct hv_tlb_flush_ex,
+						   hv_vp_set.bank_contents)))
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+	}
+
+do_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 {
+		sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask);
+
+		kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST, vcpu_mask);
+	}
+
+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;
+	unsigned long 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;
+	DECLARE_BITMAP(vcpu_mask, KVM_MAX_VCPUS);
+	u64 valid_bank_mask;
+	u64 sparse_banks[KVM_HV_MAX_SPARSE_VCPU_SET_BITS];
+	u32 vector;
+	bool all_cpus;
+
+	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;
+		all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;
+
+		if (hc->var_cnt != hweight64(valid_bank_mask))
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+		if (all_cpus)
+			goto check_and_send_ipi;
+
+		if (!hc->var_cnt)
+			goto ret_success;
+
+		if (kvm_get_sparse_vp_set(kvm, hc, 1, sparse_banks,
+					  offsetof(struct hv_send_ipi_ex,
+						   vp_set.bank_contents)))
+			return HV_STATUS_INVALID_HYPERCALL_INPUT;
+	}
+
+check_and_send_ipi:
+	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))
+		return HV_STATUS_INVALID_HYPERCALL_INPUT;
+
+	if (all_cpus) {
+		kvm_send_ipi_to_many(kvm, vector, NULL);
+	} else {
+		sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask);
+
+		kvm_send_ipi_to_many(kvm, vector, vcpu_mask);
+	}
+
+ret_success:
+	return HV_STATUS_SUCCESS;
+}
+
+void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu, bool hyperv_enabled)
+{
+	struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
+	struct kvm_cpuid_entry2 *entry;
+
+	vcpu->arch.hyperv_enabled = hyperv_enabled;
+
+	if (!hv_vcpu) {
+		/*
+		 * KVM should have already allocated kvm_vcpu_hv if Hyper-V is
+		 * enabled in CPUID.
+		 */
+		WARN_ON_ONCE(vcpu->arch.hyperv_enabled);
+		return;
+	}
+
+	memset(&hv_vcpu->cpuid_cache, 0, sizeof(hv_vcpu->cpuid_cache));
+
+	if (!vcpu->arch.hyperv_enabled)
+		return;
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_FEATURES);
+	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;
+	}
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_ENLIGHTMENT_INFO);
+	if (entry) {
+		hv_vcpu->cpuid_cache.enlightenments_eax = entry->eax;
+		hv_vcpu->cpuid_cache.enlightenments_ebx = entry->ebx;
+	}
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES);
+	if (entry)
+		hv_vcpu->cpuid_cache.syndbg_cap_eax = entry->eax;
+
+	entry = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_NESTED_FEATURES);
+	if (entry) {
+		hv_vcpu->cpuid_cache.nested_eax = entry->eax;
+		hv_vcpu->cpuid_cache.nested_ebx = entry->ebx;
+	}
+}
+
+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;
+}
+
+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.var_cnt = (hc.param & HV_HYPERCALL_VARHEAD_MASK) >> HV_HYPERCALL_VARHEAD_OFFSET;
+	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.var_cnt, 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 (unlikely(hc.param & HV_HYPERCALL_RSVD_MASK)) {
+		ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+		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 || hc.var_cnt)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
+		kvm_vcpu_on_spin(vcpu, true);
+		break;
+	case HVCALL_SIGNAL_EVENT:
+		if (unlikely(hc.rep || hc.var_cnt)) {
+			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 || hc.var_cnt || !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:
+		if (unlikely(hc.var_cnt)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
+		fallthrough;
+	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:
+		if (unlikely(hc.var_cnt)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
+		fallthrough;
+	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:
+		if (unlikely(hc.var_cnt)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
+		fallthrough;
+	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);
+
+	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;
+			ent->eax |= HV_X64_NESTED_MSR_BITMAP;
+			ent->ebx |= HV_X64_NESTED_EVMCS1_PERF_GLOBAL_CTRL;
+			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;
+}