diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 3f1490bfb938..f0c1a6a7eaa7 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_ACPI)			+= acpi.o
 obj-$(CONFIG_ACPI_NUMA)			+= acpi_numa.o
 obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL)	+= acpi_parking_protocol.o
 obj-$(CONFIG_PARAVIRT)			+= paravirt.o
+obj-$(CONFIG_KVM_GUEST)			+= kvm.o
 obj-$(CONFIG_RANDOMIZE_BASE)		+= kaslr.o
 obj-$(CONFIG_HIBERNATION)		+= hibernate.o hibernate-asm.o
 obj-$(CONFIG_KEXEC_CORE)		+= machine_kexec.o relocate_kernel.o	\
diff --git a/arch/arm64/kernel/kvm.c b/arch/arm64/kernel/kvm.c
new file mode 100644
index 000000000000..effe8dc7e921
--- /dev/null
+++ b/arch/arm64/kernel/kvm.c
@@ -0,0 +1,452 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Asynchronous page fault support.
+ *
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * Author(s): Gavin Shan <gshan@redhat.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/arm-smccc.h>
+#include <linux/kvm_para.h>
+#include <linux/arm_sdei.h>
+#include <linux/acpi.h>
+#include <linux/cpuhotplug.h>
+#include <linux/reboot.h>
+
+struct kvm_apf_task {
+	unsigned int		token;
+	struct task_struct	*task;
+	struct swait_queue_head	wq;
+};
+
+struct kvm_apf_table {
+	raw_spinlock_t		lock;
+	unsigned int		count;
+	struct kvm_apf_task	tasks[0];
+};
+
+static bool async_pf_available = true;
+static DEFINE_PER_CPU_DECRYPTED(struct kvm_vcpu_pv_apf_data, apf_data) __aligned(64);
+static struct kvm_apf_table __percpu *apf_tables;
+static unsigned int apf_tasks;
+static unsigned int apf_sdei_num;
+static unsigned int apf_ppi_num;
+static int apf_irq;
+
+static bool kvm_async_pf_add_task(struct task_struct *task,
+				  unsigned int token)
+{
+	struct kvm_apf_table *table = this_cpu_ptr(apf_tables);
+	unsigned int i, index = apf_tasks;
+	bool ret = false;
+
+	raw_spin_lock(&table->lock);
+
+	if (WARN_ON(table->count >= apf_tasks))
+		goto unlock;
+
+	for (i = 0; i < apf_tasks; i++) {
+		if (!table->tasks[i].task) {
+			if (index == apf_tasks) {
+				ret = true;
+				index = i;
+			}
+		} else if (table->tasks[i].task == task) {
+			WARN_ON(table->tasks[i].token != token);
+			ret = false;
+			break;
+		}
+	}
+
+	if (!ret)
+		goto unlock;
+
+	task->thread.data = &table->tasks[index].wq;
+	set_tsk_thread_flag(task, TIF_ASYNC_PF);
+
+	table->count++;
+	table->tasks[index].task = task;
+	table->tasks[index].token = token;
+
+unlock:
+	raw_spin_unlock(&table->lock);
+	return ret;
+}
+
+static inline void kvm_async_pf_remove_one_task(struct kvm_apf_table *table,
+						unsigned int index)
+{
+	clear_tsk_thread_flag(table->tasks[index].task, TIF_ASYNC_PF);
+	WRITE_ONCE(table->tasks[index].task->thread.data, NULL);
+
+	table->count--;
+	table->tasks[index].task = NULL;
+	table->tasks[index].token = 0;
+
+	swake_up_one(&table->tasks[index].wq);
+}
+
+static bool kvm_async_pf_remove_task(unsigned int token)
+{
+	struct kvm_apf_table *table = this_cpu_ptr(apf_tables);
+	unsigned int i;
+	bool ret = (token == UINT_MAX);
+
+	raw_spin_lock(&table->lock);
+
+	for (i = 0; i < apf_tasks; i++) {
+		if (!table->tasks[i].task)
+			continue;
+
+		/* Wakeup all */
+		if (token == UINT_MAX) {
+			kvm_async_pf_remove_one_task(table, i);
+			continue;
+		}
+
+		if (table->tasks[i].token == token) {
+			kvm_async_pf_remove_one_task(table, i);
+			ret = true;
+			break;
+		}
+	}
+
+	raw_spin_unlock(&table->lock);
+
+	return ret;
+}
+
+static int kvm_async_pf_sdei_handler(unsigned int event,
+				     struct pt_regs *regs,
+				     void *arg)
+{
+	unsigned int reason = __this_cpu_read(apf_data.reason);
+	unsigned int token = __this_cpu_read(apf_data.token);
+	bool ret;
+
+	if (reason != KVM_PV_REASON_PAGE_NOT_PRESENT) {
+		pr_warn("%s: Bogus notification (%d, 0x%08x)\n",
+			__func__, reason, token);
+		return -EINVAL;
+	}
+
+	ret = kvm_async_pf_add_task(current, token);
+	__this_cpu_write(apf_data.token, 0);
+	__this_cpu_write(apf_data.reason, 0);
+
+	if (!ret)
+		return -ENOSPC;
+
+	smp_send_reschedule(smp_processor_id());
+
+	return 0;
+}
+
+static irqreturn_t kvm_async_pf_irq_handler(int irq, void *dev_id)
+{
+	unsigned int reason = __this_cpu_read(apf_data.reason);
+	unsigned int token = __this_cpu_read(apf_data.token);
+	struct arm_smccc_res res;
+
+	if (reason != KVM_PV_REASON_PAGE_READY) {
+		pr_warn("%s: Bogus interrupt %d (%d, 0x%08x)\n",
+			__func__, irq, reason, token);
+		return IRQ_HANDLED;
+	}
+
+	kvm_async_pf_remove_task(token);
+
+	__this_cpu_write(apf_data.token, 0);
+	__this_cpu_write(apf_data.reason, 0);
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_IRQ_ACK, &res);
+
+	return IRQ_HANDLED;
+}
+
+static int __init kvm_async_pf_available(char *arg)
+{
+	async_pf_available = false;
+
+	return 0;
+}
+early_param("no-kvmapf", kvm_async_pf_available);
+
+static void kvm_async_pf_disable(void)
+{
+	struct arm_smccc_res res;
+	u32 enabled = __this_cpu_read(apf_data.enabled);
+
+	if (!enabled)
+		return;
+
+	/* Disable the functionality */
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_ENABLE,
+			     0, 0, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_warn("%s: Error %ld to disable on CPU%d\n",
+			__func__, res.a0, smp_processor_id());
+		return;
+	}
+
+	__this_cpu_write(apf_data.enabled, 0);
+
+	pr_info("Async PF disabled on CPU%d\n", smp_processor_id());
+}
+
+static void kvm_async_pf_enable(void)
+{
+	struct arm_smccc_res res;
+	u32 enabled = __this_cpu_read(apf_data.enabled);
+	u64 val = virt_to_phys(this_cpu_ptr(&apf_data));
+
+	if (enabled)
+		return;
+
+	val |= KVM_ASYNC_PF_ENABLED;
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_ENABLE,
+			     (u32)val, (u32)(val >> 32), &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_warn("%s: Error %ld to enable CPU%d\n",
+			__func__, res.a0, smp_processor_id());
+		return;
+	}
+
+	__this_cpu_write(apf_data.enabled, 1);
+
+	pr_info("Async PF enabled on CPU%d\n", smp_processor_id());
+}
+
+static void kvm_async_pf_cpu_disable(void *info)
+{
+	disable_percpu_irq(apf_irq);
+	kvm_async_pf_disable();
+}
+
+static void kvm_async_pf_cpu_enable(void *info)
+{
+	enable_percpu_irq(apf_irq, IRQ_TYPE_LEVEL_HIGH);
+	kvm_async_pf_enable();
+}
+
+static int kvm_async_pf_cpu_reboot_notify(struct notifier_block *nb,
+					  unsigned long code,
+					  void *unused)
+{
+	if (code == SYS_RESTART) {
+		sdei_event_disable(apf_sdei_num);
+		sdei_event_unregister(apf_sdei_num);
+
+		on_each_cpu(kvm_async_pf_cpu_disable, NULL, 1);
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kvm_async_pf_cpu_reboot_nb = {
+	.notifier_call = kvm_async_pf_cpu_reboot_notify,
+};
+
+static int kvm_async_pf_cpu_online(unsigned int cpu)
+{
+	kvm_async_pf_cpu_enable(NULL);
+
+	return 0;
+}
+
+static int kvm_async_pf_cpu_offline(unsigned int cpu)
+{
+	kvm_async_pf_cpu_disable(NULL);
+
+	return 0;
+}
+
+static int __init kvm_async_pf_check_version(void)
+{
+	struct arm_smccc_res res;
+
+	/*
+	 * Check the version and v1.0.0 or higher version is required
+	 * to support the functionality.
+	 */
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_VERSION, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_warn("%s: Error %ld to get version\n",
+			__func__, res.a0);
+		return -EPERM;
+	}
+
+	if ((res.a1 & 0xFFFFFFFFFF000000) ||
+	    ((res.a1 & 0xFF0000) >> 16) < 0x1) {
+		pr_warn("%s: Invalid version (0x%016lx)\n",
+			__func__, res.a1);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int __init kvm_async_pf_info(void)
+{
+	struct arm_smccc_res res;
+
+	/* Retrieve number of tokens */
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_SLOTS, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_warn("%s: Error %ld to get token number\n",
+			__func__, res.a0);
+		return -EPERM;
+	}
+
+	apf_tasks = res.a1 * 2;
+
+	/* Retrieve SDEI event number */
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_SDEI, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_warn("%s: Error %ld to get SDEI event number\n",
+			__func__, res.a0);
+		return -EPERM;
+	}
+
+	apf_sdei_num = res.a1;
+
+	/* Retrieve (PPI) interrupt number */
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_ASYNC_PF_FUNC_ID,
+			     ARM_SMCCC_KVM_FUNC_ASYNC_PF_IRQ, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS) {
+		pr_warn("%s: Error %ld to get IRQ\n",
+			__func__, res.a0);
+		return -EPERM;
+	}
+
+	apf_ppi_num = res.a1;
+
+	return 0;
+}
+
+static int __init kvm_async_pf_init(void)
+{
+	struct kvm_apf_table *table;
+	size_t size;
+	int cpu, i, ret;
+
+	if (!kvm_para_has_feature(KVM_FEATURE_ASYNC_PF) ||
+	    !async_pf_available)
+		return -EPERM;
+
+	ret = kvm_async_pf_check_version();
+	if (ret)
+		return ret;
+
+	ret = kvm_async_pf_info();
+	if (ret)
+		return ret;
+
+	/* Allocate and initialize the sleeper table */
+	size = sizeof(struct kvm_apf_table) +
+	       apf_tasks * sizeof(struct kvm_apf_task);
+	apf_tables = __alloc_percpu(size, 0);
+	if (!apf_tables) {
+		pr_warn("%s: Unable to alloc async PF table\n",
+			__func__);
+		return -ENOMEM;
+	}
+
+	for_each_possible_cpu(cpu) {
+		table = per_cpu_ptr(apf_tables, cpu);
+		raw_spin_lock_init(&table->lock);
+		for (i = 0; i < apf_tasks; i++)
+			init_swait_queue_head(&table->tasks[i].wq);
+	}
+
+	/*
+	 * Initialize SDEI event for page-not-present notification.
+	 * The SDEI event number should have been retrieved from
+	 * the host.
+	 */
+	ret = sdei_event_register(apf_sdei_num,
+				  kvm_async_pf_sdei_handler, NULL);
+	if (ret) {
+		pr_warn("%s: Error %d to register SDEI event\n",
+			__func__, ret);
+		ret = -EIO;
+		goto release_tables;
+	}
+
+	ret = sdei_event_enable(apf_sdei_num);
+	if (ret) {
+		pr_warn("%s: Error %d to enable SDEI event\n",
+			__func__, ret);
+		goto unregister_event;
+	}
+
+	/*
+	 * Initialize interrupt for page-ready notification. The
+	 * interrupt number and its properties should have been
+	 * retrieved from the ACPI:APFT table.
+	 */
+	apf_irq = acpi_register_gsi(NULL, apf_ppi_num,
+				    ACPI_LEVEL_SENSITIVE, ACPI_ACTIVE_HIGH);
+	if (apf_irq <= 0) {
+		ret = -EIO;
+		pr_warn("%s: Error %d to register IRQ\n",
+			__func__, apf_irq);
+		goto disable_event;
+	}
+
+	ret = request_percpu_irq(apf_irq, kvm_async_pf_irq_handler,
+				 "Asynchronous Page Fault", &apf_data);
+	if (ret) {
+		pr_warn("%s: Error %d to request IRQ\n",
+			__func__, ret);
+		goto unregister_irq;
+	}
+
+	register_reboot_notifier(&kvm_async_pf_cpu_reboot_nb);
+	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+			"arm/kvm:online", kvm_async_pf_cpu_online,
+			kvm_async_pf_cpu_offline);
+	if (ret < 0) {
+		pr_warn("%s: Error %d to install cpu hotplug callbacks\n",
+			__func__, ret);
+		goto release_irq;
+	}
+
+	/* Enable async PF on the online CPUs */
+	on_each_cpu(kvm_async_pf_cpu_enable, NULL, 1);
+
+	return 0;
+
+release_irq:
+	free_percpu_irq(apf_irq, &apf_data);
+unregister_irq:
+	acpi_unregister_gsi(apf_ppi_num);
+disable_event:
+	sdei_event_disable(apf_sdei_num);
+unregister_event:
+	sdei_event_unregister(apf_sdei_num);
+release_tables:
+	free_percpu(apf_tables);
+
+	return ret;
+}
+
+static int __init kvm_guest_init(void)
+{
+	return kvm_async_pf_init();
+}
+
+fs_initcall(kvm_guest_init);
