Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 6160 insertions, 0 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
new file mode 100644
index 000000000..8123f4d15
--- /dev/null
+++ b/virt/kvm/kvm_main.c
@@ -0,0 +1,6160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kernel-based Virtual Machine driver for Linux
+ *
+ * This module enables machines with Intel VT-x extensions to run virtual
+ * machines without emulation or binary translation.
+ *
+ * Copyright (C) 2006 Qumranet, Inc.
+ * Copyright 2010 Red Hat, Inc. and/or its affiliates.
+ *
+ * Authors:
+ *   Avi Kivity   <avi@qumranet.com>
+ *   Yaniv Kamay  <yaniv@qumranet.com>
+ */
+
+#include <kvm/iodev.h>
+
+#include <linux/kvm_host.h>
+#include <linux/kvm.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/percpu.h>
+#include <linux/mm.h>
+#include <linux/miscdevice.h>
+#include <linux/vmalloc.h>
+#include <linux/reboot.h>
+#include <linux/debugfs.h>
+#include <linux/highmem.h>
+#include <linux/file.h>
+#include <linux/syscore_ops.h>
+#include <linux/cpu.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/stat.h>
+#include <linux/cpumask.h>
+#include <linux/smp.h>
+#include <linux/anon_inodes.h>
+#include <linux/profile.h>
+#include <linux/kvm_para.h>
+#include <linux/pagemap.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/bitops.h>
+#include <linux/spinlock.h>
+#include <linux/compat.h>
+#include <linux/srcu.h>
+#include <linux/hugetlb.h>
+#include <linux/slab.h>
+#include <linux/sort.h>
+#include <linux/bsearch.h>
+#include <linux/io.h>
+#include <linux/lockdep.h>
+#include <linux/kthread.h>
+#include <linux/suspend.h>
+
+#include <asm/processor.h>
+#include <asm/ioctl.h>
+#include <linux/uaccess.h>
+
+#include "coalesced_mmio.h"
+#include "async_pf.h"
+#include "kvm_mm.h"
+#include "vfio.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/kvm.h>
+
+#include <linux/kvm_dirty_ring.h>
+
+/* Worst case buffer size needed for holding an integer. */
+#define ITOA_MAX_LEN 12
+
+MODULE_AUTHOR("Qumranet");
+MODULE_LICENSE("GPL");
+
+/* Architectures should define their poll value according to the halt latency */
+unsigned int halt_poll_ns = KVM_HALT_POLL_NS_DEFAULT;
+module_param(halt_poll_ns, uint, 0644);
+EXPORT_SYMBOL_GPL(halt_poll_ns);
+
+/* Default doubles per-vcpu halt_poll_ns. */
+unsigned int halt_poll_ns_grow = 2;
+module_param(halt_poll_ns_grow, uint, 0644);
+EXPORT_SYMBOL_GPL(halt_poll_ns_grow);
+
+/* The start value to grow halt_poll_ns from */
+unsigned int halt_poll_ns_grow_start = 10000; /* 10us */
+module_param(halt_poll_ns_grow_start, uint, 0644);
+EXPORT_SYMBOL_GPL(halt_poll_ns_grow_start);
+
+/* Default resets per-vcpu halt_poll_ns . */
+unsigned int halt_poll_ns_shrink;
+module_param(halt_poll_ns_shrink, uint, 0644);
+EXPORT_SYMBOL_GPL(halt_poll_ns_shrink);
+
+/*
+ * Ordering of locks:
+ *
+ *	kvm->lock --> kvm->slots_lock --> kvm->irq_lock
+ */
+
+DEFINE_MUTEX(kvm_lock);
+static DEFINE_RAW_SPINLOCK(kvm_count_lock);
+LIST_HEAD(vm_list);
+
+static cpumask_var_t cpus_hardware_enabled;
+static int kvm_usage_count;
+static atomic_t hardware_enable_failed;
+
+static struct kmem_cache *kvm_vcpu_cache;
+
+static __read_mostly struct preempt_ops kvm_preempt_ops;
+static DEFINE_PER_CPU(struct kvm_vcpu *, kvm_running_vcpu);
+
+struct dentry *kvm_debugfs_dir;
+EXPORT_SYMBOL_GPL(kvm_debugfs_dir);
+
+static const struct file_operations stat_fops_per_vm;
+
+static struct file_operations kvm_chardev_ops;
+
+static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
+			   unsigned long arg);
+#ifdef CONFIG_KVM_COMPAT
+static long kvm_vcpu_compat_ioctl(struct file *file, unsigned int ioctl,
+				  unsigned long arg);
+#define KVM_COMPAT(c)	.compat_ioctl	= (c)
+#else
+/*
+ * For architectures that don't implement a compat infrastructure,
+ * adopt a double line of defense:
+ * - Prevent a compat task from opening /dev/kvm
+ * - If the open has been done by a 64bit task, and the KVM fd
+ *   passed to a compat task, let the ioctls fail.
+ */
+static long kvm_no_compat_ioctl(struct file *file, unsigned int ioctl,
+				unsigned long arg) { return -EINVAL; }
+
+static int kvm_no_compat_open(struct inode *inode, struct file *file)
+{
+	return is_compat_task() ? -ENODEV : 0;
+}
+#define KVM_COMPAT(c)	.compat_ioctl	= kvm_no_compat_ioctl,	\
+			.open		= kvm_no_compat_open
+#endif
+static int hardware_enable_all(void);
+static void hardware_disable_all(void);
+
+static void kvm_io_bus_destroy(struct kvm_io_bus *bus);
+
+__visible bool kvm_rebooting;
+EXPORT_SYMBOL_GPL(kvm_rebooting);
+
+#define KVM_EVENT_CREATE_VM 0
+#define KVM_EVENT_DESTROY_VM 1
+static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm);
+static unsigned long long kvm_createvm_count;
+static unsigned long long kvm_active_vms;
+
+static DEFINE_PER_CPU(cpumask_var_t, cpu_kick_mask);
+
+__weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
+						   unsigned long start, unsigned long end)
+{
+}
+
+__weak void kvm_arch_guest_memory_reclaimed(struct kvm *kvm)
+{
+}
+
+bool kvm_is_zone_device_page(struct page *page)
+{
+	/*
+	 * The metadata used by is_zone_device_page() to determine whether or
+	 * not a page is ZONE_DEVICE is guaranteed to be valid if and only if
+	 * the device has been pinned, e.g. by get_user_pages().  WARN if the
+	 * page_count() is zero to help detect bad usage of this helper.
+	 */
+	if (WARN_ON_ONCE(!page_count(page)))
+		return false;
+
+	return is_zone_device_page(page);
+}
+
+/*
+ * Returns a 'struct page' if the pfn is "valid" and backed by a refcounted
+ * page, NULL otherwise.  Note, the list of refcounted PG_reserved page types
+ * is likely incomplete, it has been compiled purely through people wanting to
+ * back guest with a certain type of memory and encountering issues.
+ */
+struct page *kvm_pfn_to_refcounted_page(kvm_pfn_t pfn)
+{
+	struct page *page;
+
+	if (!pfn_valid(pfn))
+		return NULL;
+
+	page = pfn_to_page(pfn);
+	if (!PageReserved(page))
+		return page;
+
+	/* The ZERO_PAGE(s) is marked PG_reserved, but is refcounted. */
+	if (is_zero_pfn(pfn))
+		return page;
+
+	/*
+	 * ZONE_DEVICE pages currently set PG_reserved, but from a refcounting
+	 * perspective they are "normal" pages, albeit with slightly different
+	 * usage rules.
+	 */
+	if (kvm_is_zone_device_page(page))
+		return page;
+
+	return NULL;
+}
+
+/*
+ * Switches to specified vcpu, until a matching vcpu_put()
+ */
+void vcpu_load(struct kvm_vcpu *vcpu)
+{
+	int cpu = get_cpu();
+
+	__this_cpu_write(kvm_running_vcpu, vcpu);
+	preempt_notifier_register(&vcpu->preempt_notifier);
+	kvm_arch_vcpu_load(vcpu, cpu);
+	put_cpu();
+}
+EXPORT_SYMBOL_GPL(vcpu_load);
+
+void vcpu_put(struct kvm_vcpu *vcpu)
+{
+	preempt_disable();
+	kvm_arch_vcpu_put(vcpu);
+	preempt_notifier_unregister(&vcpu->preempt_notifier);
+	__this_cpu_write(kvm_running_vcpu, NULL);
+	preempt_enable();
+}
+EXPORT_SYMBOL_GPL(vcpu_put);
+
+/* TODO: merge with kvm_arch_vcpu_should_kick */
+static bool kvm_request_needs_ipi(struct kvm_vcpu *vcpu, unsigned req)
+{
+	int mode = kvm_vcpu_exiting_guest_mode(vcpu);
+
+	/*
+	 * We need to wait for the VCPU to reenable interrupts and get out of
+	 * READING_SHADOW_PAGE_TABLES mode.
+	 */
+	if (req & KVM_REQUEST_WAIT)
+		return mode != OUTSIDE_GUEST_MODE;
+
+	/*
+	 * Need to kick a running VCPU, but otherwise there is nothing to do.
+	 */
+	return mode == IN_GUEST_MODE;
+}
+
+static void ack_kick(void *_completed)
+{
+}
+
+static inline bool kvm_kick_many_cpus(struct cpumask *cpus, bool wait)
+{
+	if (cpumask_empty(cpus))
+		return false;
+
+	smp_call_function_many(cpus, ack_kick, NULL, wait);
+	return true;
+}
+
+static void kvm_make_vcpu_request(struct kvm_vcpu *vcpu, unsigned int req,
+				  struct cpumask *tmp, int current_cpu)
+{
+	int cpu;
+
+	if (likely(!(req & KVM_REQUEST_NO_ACTION)))
+		__kvm_make_request(req, vcpu);
+
+	if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu))
+		return;
+
+	/*
+	 * Note, the vCPU could get migrated to a different pCPU at any point
+	 * after kvm_request_needs_ipi(), which could result in sending an IPI
+	 * to the previous pCPU.  But, that's OK because the purpose of the IPI
+	 * is to ensure the vCPU returns to OUTSIDE_GUEST_MODE, which is
+	 * satisfied if the vCPU migrates. Entering READING_SHADOW_PAGE_TABLES
+	 * after this point is also OK, as the requirement is only that KVM wait
+	 * for vCPUs that were reading SPTEs _before_ any changes were
+	 * finalized. See kvm_vcpu_kick() for more details on handling requests.
+	 */
+	if (kvm_request_needs_ipi(vcpu, req)) {
+		cpu = READ_ONCE(vcpu->cpu);
+		if (cpu != -1 && cpu != current_cpu)
+			__cpumask_set_cpu(cpu, tmp);
+	}
+}
+
+bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
+				 unsigned long *vcpu_bitmap)
+{
+	struct kvm_vcpu *vcpu;
+	struct cpumask *cpus;
+	int i, me;
+	bool called;
+
+	me = get_cpu();
+
+	cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
+	cpumask_clear(cpus);
+
+	for_each_set_bit(i, vcpu_bitmap, KVM_MAX_VCPUS) {
+		vcpu = kvm_get_vcpu(kvm, i);
+		if (!vcpu)
+			continue;
+		kvm_make_vcpu_request(vcpu, req, cpus, me);
+	}
+
+	called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
+	put_cpu();
+
+	return called;
+}
+
+bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req,
+				      struct kvm_vcpu *except)
+{
+	struct kvm_vcpu *vcpu;
+	struct cpumask *cpus;
+	unsigned long i;
+	bool called;
+	int me;
+
+	me = get_cpu();
+
+	cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
+	cpumask_clear(cpus);
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		if (vcpu == except)
+			continue;
+		kvm_make_vcpu_request(vcpu, req, cpus, me);
+	}
+
+	called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
+	put_cpu();
+
+	return called;
+}
+
+bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req)
+{
+	return kvm_make_all_cpus_request_except(kvm, req, NULL);
+}
+EXPORT_SYMBOL_GPL(kvm_make_all_cpus_request);
+
+#ifndef CONFIG_HAVE_KVM_ARCH_TLB_FLUSH_ALL
+void kvm_flush_remote_tlbs(struct kvm *kvm)
+{
+	++kvm->stat.generic.remote_tlb_flush_requests;
+
+	/*
+	 * We want to publish modifications to the page tables before reading
+	 * mode. Pairs with a memory barrier in arch-specific code.
+	 * - x86: smp_mb__after_srcu_read_unlock in vcpu_enter_guest
+	 * and smp_mb in walk_shadow_page_lockless_begin/end.
+	 * - powerpc: smp_mb in kvmppc_prepare_to_enter.
+	 *
+	 * There is already an smp_mb__after_atomic() before
+	 * kvm_make_all_cpus_request() reads vcpu->mode. We reuse that
+	 * barrier here.
+	 */
+	if (!kvm_arch_flush_remote_tlb(kvm)
+	    || kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH))
+		++kvm->stat.generic.remote_tlb_flush;
+}
+EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
+#endif
+
+static void kvm_flush_shadow_all(struct kvm *kvm)
+{
+	kvm_arch_flush_shadow_all(kvm);
+	kvm_arch_guest_memory_reclaimed(kvm);
+}
+
+#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
+static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
+					       gfp_t gfp_flags)
+{
+	gfp_flags |= mc->gfp_zero;
+
+	if (mc->kmem_cache)
+		return kmem_cache_alloc(mc->kmem_cache, gfp_flags);
+	else
+		return (void *)__get_free_page(gfp_flags);
+}
+
+int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int capacity, int min)
+{
+	gfp_t gfp = mc->gfp_custom ? mc->gfp_custom : GFP_KERNEL_ACCOUNT;
+	void *obj;
+
+	if (mc->nobjs >= min)
+		return 0;
+
+	if (unlikely(!mc->objects)) {
+		if (WARN_ON_ONCE(!capacity))
+			return -EIO;
+
+		mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
+		if (!mc->objects)
+			return -ENOMEM;
+
+		mc->capacity = capacity;
+	}
+
+	/* It is illegal to request a different capacity across topups. */
+	if (WARN_ON_ONCE(mc->capacity != capacity))
+		return -EIO;
+
+	while (mc->nobjs < mc->capacity) {
+		obj = mmu_memory_cache_alloc_obj(mc, gfp);
+		if (!obj)
+			return mc->nobjs >= min ? 0 : -ENOMEM;
+		mc->objects[mc->nobjs++] = obj;
+	}
+	return 0;
+}
+
+int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
+{
+	return __kvm_mmu_topup_memory_cache(mc, KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, min);
+}
+
+int kvm_mmu_memory_cache_nr_free_objects(struct kvm_mmu_memory_cache *mc)
+{
+	return mc->nobjs;
+}
+
+void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
+{
+	while (mc->nobjs) {
+		if (mc->kmem_cache)
+			kmem_cache_free(mc->kmem_cache, mc->objects[--mc->nobjs]);
+		else
+			free_page((unsigned long)mc->objects[--mc->nobjs]);
+	}
+
+	kvfree(mc->objects);
+
+	mc->objects = NULL;
+	mc->capacity = 0;
+}
+
+void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
+{
+	void *p;
+
+	if (WARN_ON(!mc->nobjs))
+		p = mmu_memory_cache_alloc_obj(mc, GFP_ATOMIC | __GFP_ACCOUNT);
+	else
+		p = mc->objects[--mc->nobjs];
+	BUG_ON(!p);
+	return p;
+}
+#endif
+
+static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
+{
+	mutex_init(&vcpu->mutex);
+	vcpu->cpu = -1;
+	vcpu->kvm = kvm;
+	vcpu->vcpu_id = id;
+	vcpu->pid = NULL;
+#ifndef __KVM_HAVE_ARCH_WQP
+	rcuwait_init(&vcpu->wait);
+#endif
+	kvm_async_pf_vcpu_init(vcpu);
+
+	kvm_vcpu_set_in_spin_loop(vcpu, false);
+	kvm_vcpu_set_dy_eligible(vcpu, false);
+	vcpu->preempted = false;
+	vcpu->ready = false;
+	preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
+	vcpu->last_used_slot = NULL;
+
+	/* Fill the stats id string for the vcpu */
+	snprintf(vcpu->stats_id, sizeof(vcpu->stats_id), "kvm-%d/vcpu-%d",
+		 task_pid_nr(current), id);
+}
+
+static void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
+{
+	kvm_arch_vcpu_destroy(vcpu);
+	kvm_dirty_ring_free(&vcpu->dirty_ring);
+
+	/*
+	 * No need for rcu_read_lock as VCPU_RUN is the only place that changes
+	 * the vcpu->pid pointer, and at destruction time all file descriptors
+	 * are already gone.
+	 */
+	put_pid(rcu_dereference_protected(vcpu->pid, 1));
+
+	free_page((unsigned long)vcpu->run);
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
+}
+
+void kvm_destroy_vcpus(struct kvm *kvm)
+{
+	unsigned long i;
+	struct kvm_vcpu *vcpu;
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		kvm_vcpu_destroy(vcpu);
+		xa_erase(&kvm->vcpu_array, i);
+	}
+
+	atomic_set(&kvm->online_vcpus, 0);
+}
+EXPORT_SYMBOL_GPL(kvm_destroy_vcpus);
+
+#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
+static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn)
+{
+	return container_of(mn, struct kvm, mmu_notifier);
+}
+
+static void kvm_mmu_notifier_invalidate_range(struct mmu_notifier *mn,
+					      struct mm_struct *mm,
+					      unsigned long start, unsigned long end)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	int idx;
+
+	idx = srcu_read_lock(&kvm->srcu);
+	kvm_arch_mmu_notifier_invalidate_range(kvm, start, end);
+	srcu_read_unlock(&kvm->srcu, idx);
+}
+
+typedef bool (*hva_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range);
+
+typedef void (*on_lock_fn_t)(struct kvm *kvm, unsigned long start,
+			     unsigned long end);
+
+typedef void (*on_unlock_fn_t)(struct kvm *kvm);
+
+struct kvm_hva_range {
+	unsigned long start;
+	unsigned long end;
+	pte_t pte;
+	hva_handler_t handler;
+	on_lock_fn_t on_lock;
+	on_unlock_fn_t on_unlock;
+	bool flush_on_ret;
+	bool may_block;
+};
+
+/*
+ * Use a dedicated stub instead of NULL to indicate that there is no callback
+ * function/handler.  The compiler technically can't guarantee that a real
+ * function will have a non-zero address, and so it will generate code to
+ * check for !NULL, whereas comparing against a stub will be elided at compile
+ * time (unless the compiler is getting long in the tooth, e.g. gcc 4.9).
+ */
+static void kvm_null_fn(void)
+{
+
+}
+#define IS_KVM_NULL_FN(fn) ((fn) == (void *)kvm_null_fn)
+
+/* Iterate over each memslot intersecting [start, last] (inclusive) range */
+#define kvm_for_each_memslot_in_hva_range(node, slots, start, last)	     \
+	for (node = interval_tree_iter_first(&slots->hva_tree, start, last); \
+	     node;							     \
+	     node = interval_tree_iter_next(node, start, last))	     \
+
+static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
+						  const struct kvm_hva_range *range)
+{
+	bool ret = false, locked = false;
+	struct kvm_gfn_range gfn_range;
+	struct kvm_memory_slot *slot;
+	struct kvm_memslots *slots;
+	int i, idx;
+
+	if (WARN_ON_ONCE(range->end <= range->start))
+		return 0;
+
+	/* A null handler is allowed if and only if on_lock() is provided. */
+	if (WARN_ON_ONCE(IS_KVM_NULL_FN(range->on_lock) &&
+			 IS_KVM_NULL_FN(range->handler)))
+		return 0;
+
+	idx = srcu_read_lock(&kvm->srcu);
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		struct interval_tree_node *node;
+
+		slots = __kvm_memslots(kvm, i);
+		kvm_for_each_memslot_in_hva_range(node, slots,
+						  range->start, range->end - 1) {
+			unsigned long hva_start, hva_end;
+
+			slot = container_of(node, struct kvm_memory_slot, hva_node[slots->node_idx]);
+			hva_start = max(range->start, slot->userspace_addr);
+			hva_end = min(range->end, slot->userspace_addr +
+						  (slot->npages << PAGE_SHIFT));
+
+			/*
+			 * To optimize for the likely case where the address
+			 * range is covered by zero or one memslots, don't
+			 * bother making these conditional (to avoid writes on
+			 * the second or later invocation of the handler).
+			 */
+			gfn_range.pte = range->pte;
+			gfn_range.may_block = range->may_block;
+
+			/*
+			 * {gfn(page) | page intersects with [hva_start, hva_end)} =
+			 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
+			 */
+			gfn_range.start = hva_to_gfn_memslot(hva_start, slot);
+			gfn_range.end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, slot);
+			gfn_range.slot = slot;
+
+			if (!locked) {
+				locked = true;
+				KVM_MMU_LOCK(kvm);
+				if (!IS_KVM_NULL_FN(range->on_lock))
+					range->on_lock(kvm, range->start, range->end);
+				if (IS_KVM_NULL_FN(range->handler))
+					break;
+			}
+			ret |= range->handler(kvm, &gfn_range);
+		}
+	}
+
+	if (range->flush_on_ret && ret)
+		kvm_flush_remote_tlbs(kvm);
+
+	if (locked) {
+		KVM_MMU_UNLOCK(kvm);
+		if (!IS_KVM_NULL_FN(range->on_unlock))
+			range->on_unlock(kvm);
+	}
+
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	/* The notifiers are averse to booleans. :-( */
+	return (int)ret;
+}
+
+static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn,
+						unsigned long start,
+						unsigned long end,
+						pte_t pte,
+						hva_handler_t handler)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	const struct kvm_hva_range range = {
+		.start		= start,
+		.end		= end,
+		.pte		= pte,
+		.handler	= handler,
+		.on_lock	= (void *)kvm_null_fn,
+		.on_unlock	= (void *)kvm_null_fn,
+		.flush_on_ret	= true,
+		.may_block	= false,
+	};
+
+	return __kvm_handle_hva_range(kvm, &range);
+}
+
+static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn,
+							 unsigned long start,
+							 unsigned long end,
+							 hva_handler_t handler)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	const struct kvm_hva_range range = {
+		.start		= start,
+		.end		= end,
+		.pte		= __pte(0),
+		.handler	= handler,
+		.on_lock	= (void *)kvm_null_fn,
+		.on_unlock	= (void *)kvm_null_fn,
+		.flush_on_ret	= false,
+		.may_block	= false,
+	};
+
+	return __kvm_handle_hva_range(kvm, &range);
+}
+
+static bool kvm_change_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
+{
+	/*
+	 * Skipping invalid memslots is correct if and only change_pte() is
+	 * surrounded by invalidate_range_{start,end}(), which is currently
+	 * guaranteed by the primary MMU.  If that ever changes, KVM needs to
+	 * unmap the memslot instead of skipping the memslot to ensure that KVM
+	 * doesn't hold references to the old PFN.
+	 */
+	WARN_ON_ONCE(!READ_ONCE(kvm->mn_active_invalidate_count));
+
+	if (range->slot->flags & KVM_MEMSLOT_INVALID)
+		return false;
+
+	return kvm_set_spte_gfn(kvm, range);
+}
+
+static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
+					struct mm_struct *mm,
+					unsigned long address,
+					pte_t pte)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+
+	trace_kvm_set_spte_hva(address);
+
+	/*
+	 * .change_pte() must be surrounded by .invalidate_range_{start,end}().
+	 * If mmu_invalidate_in_progress is zero, then no in-progress
+	 * invalidations, including this one, found a relevant memslot at
+	 * start(); rechecking memslots here is unnecessary.  Note, a false
+	 * positive (count elevated by a different invalidation) is sub-optimal
+	 * but functionally ok.
+	 */
+	WARN_ON_ONCE(!READ_ONCE(kvm->mn_active_invalidate_count));
+	if (!READ_ONCE(kvm->mmu_invalidate_in_progress))
+		return;
+
+	kvm_handle_hva_range(mn, address, address + 1, pte, kvm_change_spte_gfn);
+}
+
+void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start,
+			      unsigned long end)
+{
+	/*
+	 * The count increase must become visible at unlock time as no
+	 * spte can be established without taking the mmu_lock and
+	 * count is also read inside the mmu_lock critical section.
+	 */
+	kvm->mmu_invalidate_in_progress++;
+	if (likely(kvm->mmu_invalidate_in_progress == 1)) {
+		kvm->mmu_invalidate_range_start = start;
+		kvm->mmu_invalidate_range_end = end;
+	} else {
+		/*
+		 * Fully tracking multiple concurrent ranges has diminishing
+		 * returns. Keep things simple and just find the minimal range
+		 * which includes the current and new ranges. As there won't be
+		 * enough information to subtract a range after its invalidate
+		 * completes, any ranges invalidated concurrently will
+		 * accumulate and persist until all outstanding invalidates
+		 * complete.
+		 */
+		kvm->mmu_invalidate_range_start =
+			min(kvm->mmu_invalidate_range_start, start);
+		kvm->mmu_invalidate_range_end =
+			max(kvm->mmu_invalidate_range_end, end);
+	}
+}
+
+static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
+					const struct mmu_notifier_range *range)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	const struct kvm_hva_range hva_range = {
+		.start		= range->start,
+		.end		= range->end,
+		.pte		= __pte(0),
+		.handler	= kvm_unmap_gfn_range,
+		.on_lock	= kvm_mmu_invalidate_begin,
+		.on_unlock	= kvm_arch_guest_memory_reclaimed,
+		.flush_on_ret	= true,
+		.may_block	= mmu_notifier_range_blockable(range),
+	};
+
+	trace_kvm_unmap_hva_range(range->start, range->end);
+
+	/*
+	 * Prevent memslot modification between range_start() and range_end()
+	 * so that conditionally locking provides the same result in both
+	 * functions.  Without that guarantee, the mmu_invalidate_in_progress
+	 * adjustments will be imbalanced.
+	 *
+	 * Pairs with the decrement in range_end().
+	 */
+	spin_lock(&kvm->mn_invalidate_lock);
+	kvm->mn_active_invalidate_count++;
+	spin_unlock(&kvm->mn_invalidate_lock);
+
+	/*
+	 * Invalidate pfn caches _before_ invalidating the secondary MMUs, i.e.
+	 * before acquiring mmu_lock, to avoid holding mmu_lock while acquiring
+	 * each cache's lock.  There are relatively few caches in existence at
+	 * any given time, and the caches themselves can check for hva overlap,
+	 * i.e. don't need to rely on memslot overlap checks for performance.
+	 * Because this runs without holding mmu_lock, the pfn caches must use
+	 * mn_active_invalidate_count (see above) instead of
+	 * mmu_invalidate_in_progress.
+	 */
+	gfn_to_pfn_cache_invalidate_start(kvm, range->start, range->end,
+					  hva_range.may_block);
+
+	__kvm_handle_hva_range(kvm, &hva_range);
+
+	return 0;
+}
+
+void kvm_mmu_invalidate_end(struct kvm *kvm, unsigned long start,
+			    unsigned long end)
+{
+	/*
+	 * This sequence increase will notify the kvm page fault that
+	 * the page that is going to be mapped in the spte could have
+	 * been freed.
+	 */
+	kvm->mmu_invalidate_seq++;
+	smp_wmb();
+	/*
+	 * The above sequence increase must be visible before the
+	 * below count decrease, which is ensured by the smp_wmb above
+	 * in conjunction with the smp_rmb in mmu_invalidate_retry().
+	 */
+	kvm->mmu_invalidate_in_progress--;
+}
+
+static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
+					const struct mmu_notifier_range *range)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	const struct kvm_hva_range hva_range = {
+		.start		= range->start,
+		.end		= range->end,
+		.pte		= __pte(0),
+		.handler	= (void *)kvm_null_fn,
+		.on_lock	= kvm_mmu_invalidate_end,
+		.on_unlock	= (void *)kvm_null_fn,
+		.flush_on_ret	= false,
+		.may_block	= mmu_notifier_range_blockable(range),
+	};
+	bool wake;
+
+	__kvm_handle_hva_range(kvm, &hva_range);
+
+	/* Pairs with the increment in range_start(). */
+	spin_lock(&kvm->mn_invalidate_lock);
+	wake = (--kvm->mn_active_invalidate_count == 0);
+	spin_unlock(&kvm->mn_invalidate_lock);
+
+	/*
+	 * There can only be one waiter, since the wait happens under
+	 * slots_lock.
+	 */
+	if (wake)
+		rcuwait_wake_up(&kvm->mn_memslots_update_rcuwait);
+
+	BUG_ON(kvm->mmu_invalidate_in_progress < 0);
+}
+
+static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
+					      struct mm_struct *mm,
+					      unsigned long start,
+					      unsigned long end)
+{
+	trace_kvm_age_hva(start, end);
+
+	return kvm_handle_hva_range(mn, start, end, __pte(0), kvm_age_gfn);
+}
+
+static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
+					struct mm_struct *mm,
+					unsigned long start,
+					unsigned long end)
+{
+	trace_kvm_age_hva(start, end);
+
+	/*
+	 * Even though we do not flush TLB, this will still adversely
+	 * affect performance on pre-Haswell Intel EPT, where there is
+	 * no EPT Access Bit to clear so that we have to tear down EPT
+	 * tables instead. If we find this unacceptable, we can always
+	 * add a parameter to kvm_age_hva so that it effectively doesn't
+	 * do anything on clear_young.
+	 *
+	 * Also note that currently we never issue secondary TLB flushes
+	 * from clear_young, leaving this job up to the regular system
+	 * cadence. If we find this inaccurate, we might come up with a
+	 * more sophisticated heuristic later.
+	 */
+	return kvm_handle_hva_range_no_flush(mn, start, end, kvm_age_gfn);
+}
+
+static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
+				       struct mm_struct *mm,
+				       unsigned long address)
+{
+	trace_kvm_test_age_hva(address);
+
+	return kvm_handle_hva_range_no_flush(mn, address, address + 1,
+					     kvm_test_age_gfn);
+}
+
+static void kvm_mmu_notifier_release(struct mmu_notifier *mn,
+				     struct mm_struct *mm)
+{
+	struct kvm *kvm = mmu_notifier_to_kvm(mn);
+	int idx;
+
+	idx = srcu_read_lock(&kvm->srcu);
+	kvm_flush_shadow_all(kvm);
+	srcu_read_unlock(&kvm->srcu, idx);
+}
+
+static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
+	.invalidate_range	= kvm_mmu_notifier_invalidate_range,
+	.invalidate_range_start	= kvm_mmu_notifier_invalidate_range_start,
+	.invalidate_range_end	= kvm_mmu_notifier_invalidate_range_end,
+	.clear_flush_young	= kvm_mmu_notifier_clear_flush_young,
+	.clear_young		= kvm_mmu_notifier_clear_young,
+	.test_young		= kvm_mmu_notifier_test_young,
+	.change_pte		= kvm_mmu_notifier_change_pte,
+	.release		= kvm_mmu_notifier_release,
+};
+
+static int kvm_init_mmu_notifier(struct kvm *kvm)
+{
+	kvm->mmu_notifier.ops = &kvm_mmu_notifier_ops;
+	return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
+}
+
+#else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */
+
+static int kvm_init_mmu_notifier(struct kvm *kvm)
+{
+	return 0;
+}
+
+#endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
+
+#ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
+static int kvm_pm_notifier_call(struct notifier_block *bl,
+				unsigned long state,
+				void *unused)
+{
+	struct kvm *kvm = container_of(bl, struct kvm, pm_notifier);
+
+	return kvm_arch_pm_notifier(kvm, state);
+}
+
+static void kvm_init_pm_notifier(struct kvm *kvm)
+{
+	kvm->pm_notifier.notifier_call = kvm_pm_notifier_call;
+	/* Suspend KVM before we suspend ftrace, RCU, etc. */
+	kvm->pm_notifier.priority = INT_MAX;
+	register_pm_notifier(&kvm->pm_notifier);
+}
+
+static void kvm_destroy_pm_notifier(struct kvm *kvm)
+{
+	unregister_pm_notifier(&kvm->pm_notifier);
+}
+#else /* !CONFIG_HAVE_KVM_PM_NOTIFIER */
+static void kvm_init_pm_notifier(struct kvm *kvm)
+{
+}
+
+static void kvm_destroy_pm_notifier(struct kvm *kvm)
+{
+}
+#endif /* CONFIG_HAVE_KVM_PM_NOTIFIER */
+
+static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
+{
+	if (!memslot->dirty_bitmap)
+		return;
+
+	kvfree(memslot->dirty_bitmap);
+	memslot->dirty_bitmap = NULL;
+}
+
+/* This does not remove the slot from struct kvm_memslots data structures */
+static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
+{
+	kvm_destroy_dirty_bitmap(slot);
+
+	kvm_arch_free_memslot(kvm, slot);
+
+	kfree(slot);
+}
+
+static void kvm_free_memslots(struct kvm *kvm, struct kvm_memslots *slots)
+{
+	struct hlist_node *idnode;
+	struct kvm_memory_slot *memslot;
+	int bkt;
+
+	/*
+	 * The same memslot objects live in both active and inactive sets,
+	 * arbitrarily free using index '1' so the second invocation of this
+	 * function isn't operating over a structure with dangling pointers
+	 * (even though this function isn't actually touching them).
+	 */
+	if (!slots->node_idx)
+		return;
+
+	hash_for_each_safe(slots->id_hash, bkt, idnode, memslot, id_node[1])
+		kvm_free_memslot(kvm, memslot);
+}
+
+static umode_t kvm_stats_debugfs_mode(const struct _kvm_stats_desc *pdesc)
+{
+	switch (pdesc->desc.flags & KVM_STATS_TYPE_MASK) {
+	case KVM_STATS_TYPE_INSTANT:
+		return 0444;
+	case KVM_STATS_TYPE_CUMULATIVE:
+	case KVM_STATS_TYPE_PEAK:
+	default:
+		return 0644;
+	}
+}
+
+
+static void kvm_destroy_vm_debugfs(struct kvm *kvm)
+{
+	int i;
+	int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
+				      kvm_vcpu_stats_header.num_desc;
+
+	if (IS_ERR(kvm->debugfs_dentry))
+		return;
+
+	debugfs_remove_recursive(kvm->debugfs_dentry);
+
+	if (kvm->debugfs_stat_data) {
+		for (i = 0; i < kvm_debugfs_num_entries; i++)
+			kfree(kvm->debugfs_stat_data[i]);
+		kfree(kvm->debugfs_stat_data);
+	}
+}
+
+static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
+{
+	static DEFINE_MUTEX(kvm_debugfs_lock);
+	struct dentry *dent;
+	char dir_name[ITOA_MAX_LEN * 2];
+	struct kvm_stat_data *stat_data;
+	const struct _kvm_stats_desc *pdesc;
+	int i, ret = -ENOMEM;
+	int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
+				      kvm_vcpu_stats_header.num_desc;
+
+	if (!debugfs_initialized())
+		return 0;
+
+	snprintf(dir_name, sizeof(dir_name), "%d-%s", task_pid_nr(current), fdname);
+	mutex_lock(&kvm_debugfs_lock);
+	dent = debugfs_lookup(dir_name, kvm_debugfs_dir);
+	if (dent) {
+		pr_warn_ratelimited("KVM: debugfs: duplicate directory %s\n", dir_name);
+		dput(dent);
+		mutex_unlock(&kvm_debugfs_lock);
+		return 0;
+	}
+	dent = debugfs_create_dir(dir_name, kvm_debugfs_dir);
+	mutex_unlock(&kvm_debugfs_lock);
+	if (IS_ERR(dent))
+		return 0;
+
+	kvm->debugfs_dentry = dent;
+	kvm->debugfs_stat_data = kcalloc(kvm_debugfs_num_entries,
+					 sizeof(*kvm->debugfs_stat_data),
+					 GFP_KERNEL_ACCOUNT);
+	if (!kvm->debugfs_stat_data)
+		goto out_err;
+
+	for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) {
+		pdesc = &kvm_vm_stats_desc[i];
+		stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT);
+		if (!stat_data)
+			goto out_err;
+
+		stat_data->kvm = kvm;
+		stat_data->desc = pdesc;
+		stat_data->kind = KVM_STAT_VM;
+		kvm->debugfs_stat_data[i] = stat_data;
+		debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
+				    kvm->debugfs_dentry, stat_data,
+				    &stat_fops_per_vm);
+	}
+
+	for (i = 0; i < kvm_vcpu_stats_header.num_desc; ++i) {
+		pdesc = &kvm_vcpu_stats_desc[i];
+		stat_data = kzalloc(sizeof(*stat_data), GFP_KERNEL_ACCOUNT);
+		if (!stat_data)
+			goto out_err;
+
+		stat_data->kvm = kvm;
+		stat_data->desc = pdesc;
+		stat_data->kind = KVM_STAT_VCPU;
+		kvm->debugfs_stat_data[i + kvm_vm_stats_header.num_desc] = stat_data;
+		debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
+				    kvm->debugfs_dentry, stat_data,
+				    &stat_fops_per_vm);
+	}
+
+	ret = kvm_arch_create_vm_debugfs(kvm);
+	if (ret)
+		goto out_err;
+
+	return 0;
+out_err:
+	kvm_destroy_vm_debugfs(kvm);
+	return ret;
+}
+
+/*
+ * Called after the VM is otherwise initialized, but just before adding it to
+ * the vm_list.
+ */
+int __weak kvm_arch_post_init_vm(struct kvm *kvm)
+{
+	return 0;
+}
+
+/*
+ * Called just after removing the VM from the vm_list, but before doing any
+ * other destruction.
+ */
+void __weak kvm_arch_pre_destroy_vm(struct kvm *kvm)
+{
+}
+
+/*
+ * Called after per-vm debugfs created.  When called kvm->debugfs_dentry should
+ * be setup already, so we can create arch-specific debugfs entries under it.
+ * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so
+ * a per-arch destroy interface is not needed.
+ */
+int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm)
+{
+	return 0;
+}
+
+static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
+{
+	struct kvm *kvm = kvm_arch_alloc_vm();
+	struct kvm_memslots *slots;
+	int r = -ENOMEM;
+	int i, j;
+
+	if (!kvm)
+		return ERR_PTR(-ENOMEM);
+
+	/* KVM is pinned via open("/dev/kvm"), the fd passed to this ioctl(). */
+	__module_get(kvm_chardev_ops.owner);
+
+	KVM_MMU_LOCK_INIT(kvm);
+	mmgrab(current->mm);
+	kvm->mm = current->mm;
+	kvm_eventfd_init(kvm);
+	mutex_init(&kvm->lock);
+	mutex_init(&kvm->irq_lock);
+	mutex_init(&kvm->slots_lock);
+	mutex_init(&kvm->slots_arch_lock);
+	spin_lock_init(&kvm->mn_invalidate_lock);
+	rcuwait_init(&kvm->mn_memslots_update_rcuwait);
+	xa_init(&kvm->vcpu_array);
+
+	INIT_LIST_HEAD(&kvm->gpc_list);
+	spin_lock_init(&kvm->gpc_lock);
+
+	INIT_LIST_HEAD(&kvm->devices);
+	kvm->max_vcpus = KVM_MAX_VCPUS;
+
+	BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX);
+
+	/*
+	 * Force subsequent debugfs file creations to fail if the VM directory
+	 * is not created (by kvm_create_vm_debugfs()).
+	 */
+	kvm->debugfs_dentry = ERR_PTR(-ENOENT);
+
+	snprintf(kvm->stats_id, sizeof(kvm->stats_id), "kvm-%d",
+		 task_pid_nr(current));
+
+	if (init_srcu_struct(&kvm->srcu))
+		goto out_err_no_srcu;
+	if (init_srcu_struct(&kvm->irq_srcu))
+		goto out_err_no_irq_srcu;
+
+	refcount_set(&kvm->users_count, 1);
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		for (j = 0; j < 2; j++) {
+			slots = &kvm->__memslots[i][j];
+
+			atomic_long_set(&slots->last_used_slot, (unsigned long)NULL);
+			slots->hva_tree = RB_ROOT_CACHED;
+			slots->gfn_tree = RB_ROOT;
+			hash_init(slots->id_hash);
+			slots->node_idx = j;
+
+			/* Generations must be different for each address space. */
+			slots->generation = i;
+		}
+
+		rcu_assign_pointer(kvm->memslots[i], &kvm->__memslots[i][0]);
+	}
+
+	for (i = 0; i < KVM_NR_BUSES; i++) {
+		rcu_assign_pointer(kvm->buses[i],
+			kzalloc(sizeof(struct kvm_io_bus), GFP_KERNEL_ACCOUNT));
+		if (!kvm->buses[i])
+			goto out_err_no_arch_destroy_vm;
+	}
+
+	r = kvm_arch_init_vm(kvm, type);
+	if (r)
+		goto out_err_no_arch_destroy_vm;
+
+	r = hardware_enable_all();
+	if (r)
+		goto out_err_no_disable;
+
+#ifdef CONFIG_HAVE_KVM_IRQFD
+	INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
+#endif
+
+	r = kvm_init_mmu_notifier(kvm);
+	if (r)
+		goto out_err_no_mmu_notifier;
+
+	r = kvm_coalesced_mmio_init(kvm);
+	if (r < 0)
+		goto out_no_coalesced_mmio;
+
+	r = kvm_create_vm_debugfs(kvm, fdname);
+	if (r)
+		goto out_err_no_debugfs;
+
+	r = kvm_arch_post_init_vm(kvm);
+	if (r)
+		goto out_err;
+
+	mutex_lock(&kvm_lock);
+	list_add(&kvm->vm_list, &vm_list);
+	mutex_unlock(&kvm_lock);
+
+	preempt_notifier_inc();
+	kvm_init_pm_notifier(kvm);
+
+	return kvm;
+
+out_err:
+	kvm_destroy_vm_debugfs(kvm);
+out_err_no_debugfs:
+	kvm_coalesced_mmio_free(kvm);
+out_no_coalesced_mmio:
+#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
+	if (kvm->mmu_notifier.ops)
+		mmu_notifier_unregister(&kvm->mmu_notifier, current->mm);
+#endif
+out_err_no_mmu_notifier:
+	hardware_disable_all();
+out_err_no_disable:
+	kvm_arch_destroy_vm(kvm);
+out_err_no_arch_destroy_vm:
+	WARN_ON_ONCE(!refcount_dec_and_test(&kvm->users_count));
+	for (i = 0; i < KVM_NR_BUSES; i++)
+		kfree(kvm_get_bus(kvm, i));
+	cleanup_srcu_struct(&kvm->irq_srcu);
+out_err_no_irq_srcu:
+	cleanup_srcu_struct(&kvm->srcu);
+out_err_no_srcu:
+	kvm_arch_free_vm(kvm);
+	mmdrop(current->mm);
+	module_put(kvm_chardev_ops.owner);
+	return ERR_PTR(r);
+}
+
+static void kvm_destroy_devices(struct kvm *kvm)
+{
+	struct kvm_device *dev, *tmp;
+
+	/*
+	 * We do not need to take the kvm->lock here, because nobody else
+	 * has a reference to the struct kvm at this point and therefore
+	 * cannot access the devices list anyhow.
+	 */
+	list_for_each_entry_safe(dev, tmp, &kvm->devices, vm_node) {
+		list_del(&dev->vm_node);
+		dev->ops->destroy(dev);
+	}
+}
+
+static void kvm_destroy_vm(struct kvm *kvm)
+{
+	int i;
+	struct mm_struct *mm = kvm->mm;
+
+	kvm_destroy_pm_notifier(kvm);
+	kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm);
+	kvm_destroy_vm_debugfs(kvm);
+	kvm_arch_sync_events(kvm);
+	mutex_lock(&kvm_lock);
+	list_del(&kvm->vm_list);
+	mutex_unlock(&kvm_lock);
+	kvm_arch_pre_destroy_vm(kvm);
+
+	kvm_free_irq_routing(kvm);
+	for (i = 0; i < KVM_NR_BUSES; i++) {
+		struct kvm_io_bus *bus = kvm_get_bus(kvm, i);
+
+		if (bus)
+			kvm_io_bus_destroy(bus);
+		kvm->buses[i] = NULL;
+	}
+	kvm_coalesced_mmio_free(kvm);
+#if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
+	mmu_notifier_unregister(&kvm->mmu_notifier, kvm->mm);
+	/*
+	 * At this point, pending calls to invalidate_range_start()
+	 * have completed but no more MMU notifiers will run, so
+	 * mn_active_invalidate_count may remain unbalanced.
+	 * No threads can be waiting in install_new_memslots as the
+	 * last reference on KVM has been dropped, but freeing
+	 * memslots would deadlock without this manual intervention.
+	 */
+	WARN_ON(rcuwait_active(&kvm->mn_memslots_update_rcuwait));
+	kvm->mn_active_invalidate_count = 0;
+#else
+	kvm_flush_shadow_all(kvm);
+#endif
+	kvm_arch_destroy_vm(kvm);
+	kvm_destroy_devices(kvm);
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		kvm_free_memslots(kvm, &kvm->__memslots[i][0]);
+		kvm_free_memslots(kvm, &kvm->__memslots[i][1]);
+	}
+	cleanup_srcu_struct(&kvm->irq_srcu);
+	cleanup_srcu_struct(&kvm->srcu);
+	kvm_arch_free_vm(kvm);
+	preempt_notifier_dec();
+	hardware_disable_all();
+	mmdrop(mm);
+	module_put(kvm_chardev_ops.owner);
+}
+
+void kvm_get_kvm(struct kvm *kvm)
+{
+	refcount_inc(&kvm->users_count);
+}
+EXPORT_SYMBOL_GPL(kvm_get_kvm);
+
+/*
+ * Make sure the vm is not during destruction, which is a safe version of
+ * kvm_get_kvm().  Return true if kvm referenced successfully, false otherwise.
+ */
+bool kvm_get_kvm_safe(struct kvm *kvm)
+{
+	return refcount_inc_not_zero(&kvm->users_count);
+}
+EXPORT_SYMBOL_GPL(kvm_get_kvm_safe);
+
+void kvm_put_kvm(struct kvm *kvm)
+{
+	if (refcount_dec_and_test(&kvm->users_count))
+		kvm_destroy_vm(kvm);
+}
+EXPORT_SYMBOL_GPL(kvm_put_kvm);
+
+/*
+ * Used to put a reference that was taken on behalf of an object associated
+ * with a user-visible file descriptor, e.g. a vcpu or device, if installation
+ * of the new file descriptor fails and the reference cannot be transferred to
+ * its final owner.  In such cases, the caller is still actively using @kvm and
+ * will fail miserably if the refcount unexpectedly hits zero.
+ */
+void kvm_put_kvm_no_destroy(struct kvm *kvm)
+{
+	WARN_ON(refcount_dec_and_test(&kvm->users_count));
+}
+EXPORT_SYMBOL_GPL(kvm_put_kvm_no_destroy);
+
+static int kvm_vm_release(struct inode *inode, struct file *filp)
+{
+	struct kvm *kvm = filp->private_data;
+
+	kvm_irqfd_release(kvm);
+
+	kvm_put_kvm(kvm);
+	return 0;
+}
+
+/*
+ * Allocation size is twice as large as the actual dirty bitmap size.
+ * See kvm_vm_ioctl_get_dirty_log() why this is needed.
+ */
+static int kvm_alloc_dirty_bitmap(struct kvm_memory_slot *memslot)
+{
+	unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot);
+
+	memslot->dirty_bitmap = __vcalloc(2, dirty_bytes, GFP_KERNEL_ACCOUNT);
+	if (!memslot->dirty_bitmap)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static struct kvm_memslots *kvm_get_inactive_memslots(struct kvm *kvm, int as_id)
+{
+	struct kvm_memslots *active = __kvm_memslots(kvm, as_id);
+	int node_idx_inactive = active->node_idx ^ 1;
+
+	return &kvm->__memslots[as_id][node_idx_inactive];
+}
+
+/*
+ * Helper to get the address space ID when one of memslot pointers may be NULL.
+ * This also serves as a sanity that at least one of the pointers is non-NULL,
+ * and that their address space IDs don't diverge.
+ */
+static int kvm_memslots_get_as_id(struct kvm_memory_slot *a,
+				  struct kvm_memory_slot *b)
+{
+	if (WARN_ON_ONCE(!a && !b))
+		return 0;
+
+	if (!a)
+		return b->as_id;
+	if (!b)
+		return a->as_id;
+
+	WARN_ON_ONCE(a->as_id != b->as_id);
+	return a->as_id;
+}
+
+static void kvm_insert_gfn_node(struct kvm_memslots *slots,
+				struct kvm_memory_slot *slot)
+{
+	struct rb_root *gfn_tree = &slots->gfn_tree;
+	struct rb_node **node, *parent;
+	int idx = slots->node_idx;
+
+	parent = NULL;
+	for (node = &gfn_tree->rb_node; *node; ) {
+		struct kvm_memory_slot *tmp;
+
+		tmp = container_of(*node, struct kvm_memory_slot, gfn_node[idx]);
+		parent = *node;
+		if (slot->base_gfn < tmp->base_gfn)
+			node = &(*node)->rb_left;
+		else if (slot->base_gfn > tmp->base_gfn)
+			node = &(*node)->rb_right;
+		else
+			BUG();
+	}
+
+	rb_link_node(&slot->gfn_node[idx], parent, node);
+	rb_insert_color(&slot->gfn_node[idx], gfn_tree);
+}
+
+static void kvm_erase_gfn_node(struct kvm_memslots *slots,
+			       struct kvm_memory_slot *slot)
+{
+	rb_erase(&slot->gfn_node[slots->node_idx], &slots->gfn_tree);
+}
+
+static void kvm_replace_gfn_node(struct kvm_memslots *slots,
+				 struct kvm_memory_slot *old,
+				 struct kvm_memory_slot *new)
+{
+	int idx = slots->node_idx;
+
+	WARN_ON_ONCE(old->base_gfn != new->base_gfn);
+
+	rb_replace_node(&old->gfn_node[idx], &new->gfn_node[idx],
+			&slots->gfn_tree);
+}
+
+/*
+ * Replace @old with @new in the inactive memslots.
+ *
+ * With NULL @old this simply adds @new.
+ * With NULL @new this simply removes @old.
+ *
+ * If @new is non-NULL its hva_node[slots_idx] range has to be set
+ * appropriately.
+ */
+static void kvm_replace_memslot(struct kvm *kvm,
+				struct kvm_memory_slot *old,
+				struct kvm_memory_slot *new)
+{
+	int as_id = kvm_memslots_get_as_id(old, new);
+	struct kvm_memslots *slots = kvm_get_inactive_memslots(kvm, as_id);
+	int idx = slots->node_idx;
+
+	if (old) {
+		hash_del(&old->id_node[idx]);
+		interval_tree_remove(&old->hva_node[idx], &slots->hva_tree);
+
+		if ((long)old == atomic_long_read(&slots->last_used_slot))
+			atomic_long_set(&slots->last_used_slot, (long)new);
+
+		if (!new) {
+			kvm_erase_gfn_node(slots, old);
+			return;
+		}
+	}
+
+	/*
+	 * Initialize @new's hva range.  Do this even when replacing an @old
+	 * slot, kvm_copy_memslot() deliberately does not touch node data.
+	 */
+	new->hva_node[idx].start = new->userspace_addr;
+	new->hva_node[idx].last = new->userspace_addr +
+				  (new->npages << PAGE_SHIFT) - 1;
+
+	/*
+	 * (Re)Add the new memslot.  There is no O(1) interval_tree_replace(),
+	 * hva_node needs to be swapped with remove+insert even though hva can't
+	 * change when replacing an existing slot.
+	 */
+	hash_add(slots->id_hash, &new->id_node[idx], new->id);
+	interval_tree_insert(&new->hva_node[idx], &slots->hva_tree);
+
+	/*
+	 * If the memslot gfn is unchanged, rb_replace_node() can be used to
+	 * switch the node in the gfn tree instead of removing the old and
+	 * inserting the new as two separate operations. Replacement is a
+	 * single O(1) operation versus two O(log(n)) operations for
+	 * remove+insert.
+	 */
+	if (old && old->base_gfn == new->base_gfn) {
+		kvm_replace_gfn_node(slots, old, new);
+	} else {
+		if (old)
+			kvm_erase_gfn_node(slots, old);
+		kvm_insert_gfn_node(slots, new);
+	}
+}
+
+static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
+{
+	u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
+
+#ifdef __KVM_HAVE_READONLY_MEM
+	valid_flags |= KVM_MEM_READONLY;
+#endif
+
+	if (mem->flags & ~valid_flags)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void kvm_swap_active_memslots(struct kvm *kvm, int as_id)
+{
+	struct kvm_memslots *slots = kvm_get_inactive_memslots(kvm, as_id);
+
+	/* Grab the generation from the activate memslots. */
+	u64 gen = __kvm_memslots(kvm, as_id)->generation;
+
+	WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS);
+	slots->generation = gen | KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS;
+
+	/*
+	 * Do not store the new memslots while there are invalidations in
+	 * progress, otherwise the locking in invalidate_range_start and
+	 * invalidate_range_end will be unbalanced.
+	 */
+	spin_lock(&kvm->mn_invalidate_lock);
+	prepare_to_rcuwait(&kvm->mn_memslots_update_rcuwait);
+	while (kvm->mn_active_invalidate_count) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		spin_unlock(&kvm->mn_invalidate_lock);
+		schedule();
+		spin_lock(&kvm->mn_invalidate_lock);
+	}
+	finish_rcuwait(&kvm->mn_memslots_update_rcuwait);
+	rcu_assign_pointer(kvm->memslots[as_id], slots);
+	spin_unlock(&kvm->mn_invalidate_lock);
+
+	/*
+	 * Acquired in kvm_set_memslot. Must be released before synchronize
+	 * SRCU below in order to avoid deadlock with another thread
+	 * acquiring the slots_arch_lock in an srcu critical section.
+	 */
+	mutex_unlock(&kvm->slots_arch_lock);
+
+	synchronize_srcu_expedited(&kvm->srcu);
+
+	/*
+	 * Increment the new memslot generation a second time, dropping the
+	 * update in-progress flag and incrementing the generation based on
+	 * the number of address spaces.  This provides a unique and easily
+	 * identifiable generation number while the memslots are in flux.
+	 */
+	gen = slots->generation & ~KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS;
+
+	/*
+	 * Generations must be unique even across address spaces.  We do not need
+	 * a global counter for that, instead the generation space is evenly split
+	 * across address spaces.  For example, with two address spaces, address
+	 * space 0 will use generations 0, 2, 4, ... while address space 1 will
+	 * use generations 1, 3, 5, ...
+	 */
+	gen += KVM_ADDRESS_SPACE_NUM;
+
+	kvm_arch_memslots_updated(kvm, gen);
+
+	slots->generation = gen;
+}
+
+static int kvm_prepare_memory_region(struct kvm *kvm,
+				     const struct kvm_memory_slot *old,
+				     struct kvm_memory_slot *new,
+				     enum kvm_mr_change change)
+{
+	int r;
+
+	/*
+	 * If dirty logging is disabled, nullify the bitmap; the old bitmap
+	 * will be freed on "commit".  If logging is enabled in both old and
+	 * new, reuse the existing bitmap.  If logging is enabled only in the
+	 * new and KVM isn't using a ring buffer, allocate and initialize a
+	 * new bitmap.
+	 */
+	if (change != KVM_MR_DELETE) {
+		if (!(new->flags & KVM_MEM_LOG_DIRTY_PAGES))
+			new->dirty_bitmap = NULL;
+		else if (old && old->dirty_bitmap)
+			new->dirty_bitmap = old->dirty_bitmap;
+		else if (!kvm->dirty_ring_size) {
+			r = kvm_alloc_dirty_bitmap(new);
+			if (r)
+				return r;
+
+			if (kvm_dirty_log_manual_protect_and_init_set(kvm))
+				bitmap_set(new->dirty_bitmap, 0, new->npages);
+		}
+	}
+
+	r = kvm_arch_prepare_memory_region(kvm, old, new, change);
+
+	/* Free the bitmap on failure if it was allocated above. */
+	if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap))
+		kvm_destroy_dirty_bitmap(new);
+
+	return r;
+}
+
+static void kvm_commit_memory_region(struct kvm *kvm,
+				     struct kvm_memory_slot *old,
+				     const struct kvm_memory_slot *new,
+				     enum kvm_mr_change change)
+{
+	/*
+	 * Update the total number of memslot pages before calling the arch
+	 * hook so that architectures can consume the result directly.
+	 */
+	if (change == KVM_MR_DELETE)
+		kvm->nr_memslot_pages -= old->npages;
+	else if (change == KVM_MR_CREATE)
+		kvm->nr_memslot_pages += new->npages;
+
+	kvm_arch_commit_memory_region(kvm, old, new, change);
+
+	switch (change) {
+	case KVM_MR_CREATE:
+		/* Nothing more to do. */
+		break;
+	case KVM_MR_DELETE:
+		/* Free the old memslot and all its metadata. */
+		kvm_free_memslot(kvm, old);
+		break;
+	case KVM_MR_MOVE:
+	case KVM_MR_FLAGS_ONLY:
+		/*
+		 * Free the dirty bitmap as needed; the below check encompasses
+		 * both the flags and whether a ring buffer is being used)
+		 */
+		if (old->dirty_bitmap && !new->dirty_bitmap)
+			kvm_destroy_dirty_bitmap(old);
+
+		/*
+		 * The final quirk.  Free the detached, old slot, but only its
+		 * memory, not any metadata.  Metadata, including arch specific
+		 * data, may be reused by @new.
+		 */
+		kfree(old);
+		break;
+	default:
+		BUG();
+	}
+}
+
+/*
+ * Activate @new, which must be installed in the inactive slots by the caller,
+ * by swapping the active slots and then propagating @new to @old once @old is
+ * unreachable and can be safely modified.
+ *
+ * With NULL @old this simply adds @new to @active (while swapping the sets).
+ * With NULL @new this simply removes @old from @active and frees it
+ * (while also swapping the sets).
+ */
+static void kvm_activate_memslot(struct kvm *kvm,
+				 struct kvm_memory_slot *old,
+				 struct kvm_memory_slot *new)
+{
+	int as_id = kvm_memslots_get_as_id(old, new);
+
+	kvm_swap_active_memslots(kvm, as_id);
+
+	/* Propagate the new memslot to the now inactive memslots. */
+	kvm_replace_memslot(kvm, old, new);
+}
+
+static void kvm_copy_memslot(struct kvm_memory_slot *dest,
+			     const struct kvm_memory_slot *src)
+{
+	dest->base_gfn = src->base_gfn;
+	dest->npages = src->npages;
+	dest->dirty_bitmap = src->dirty_bitmap;
+	dest->arch = src->arch;
+	dest->userspace_addr = src->userspace_addr;
+	dest->flags = src->flags;
+	dest->id = src->id;
+	dest->as_id = src->as_id;
+}
+
+static void kvm_invalidate_memslot(struct kvm *kvm,
+				   struct kvm_memory_slot *old,
+				   struct kvm_memory_slot *invalid_slot)
+{
+	/*
+	 * Mark the current slot INVALID.  As with all memslot modifications,
+	 * this must be done on an unreachable slot to avoid modifying the
+	 * current slot in the active tree.
+	 */
+	kvm_copy_memslot(invalid_slot, old);
+	invalid_slot->flags |= KVM_MEMSLOT_INVALID;
+	kvm_replace_memslot(kvm, old, invalid_slot);
+
+	/*
+	 * Activate the slot that is now marked INVALID, but don't propagate
+	 * the slot to the now inactive slots. The slot is either going to be
+	 * deleted or recreated as a new slot.
+	 */
+	kvm_swap_active_memslots(kvm, old->as_id);
+
+	/*
+	 * From this point no new shadow pages pointing to a deleted, or moved,
+	 * memslot will be created.  Validation of sp->gfn happens in:
+	 *	- gfn_to_hva (kvm_read_guest, gfn_to_pfn)
+	 *	- kvm_is_visible_gfn (mmu_check_root)
+	 */
+	kvm_arch_flush_shadow_memslot(kvm, old);
+	kvm_arch_guest_memory_reclaimed(kvm);
+
+	/* Was released by kvm_swap_active_memslots, reacquire. */
+	mutex_lock(&kvm->slots_arch_lock);
+
+	/*
+	 * Copy the arch-specific field of the newly-installed slot back to the
+	 * old slot as the arch data could have changed between releasing
+	 * slots_arch_lock in install_new_memslots() and re-acquiring the lock
+	 * above.  Writers are required to retrieve memslots *after* acquiring
+	 * slots_arch_lock, thus the active slot's data is guaranteed to be fresh.
+	 */
+	old->arch = invalid_slot->arch;
+}
+
+static void kvm_create_memslot(struct kvm *kvm,
+			       struct kvm_memory_slot *new)
+{
+	/* Add the new memslot to the inactive set and activate. */
+	kvm_replace_memslot(kvm, NULL, new);
+	kvm_activate_memslot(kvm, NULL, new);
+}
+
+static void kvm_delete_memslot(struct kvm *kvm,
+			       struct kvm_memory_slot *old,
+			       struct kvm_memory_slot *invalid_slot)
+{
+	/*
+	 * Remove the old memslot (in the inactive memslots) by passing NULL as
+	 * the "new" slot, and for the invalid version in the active slots.
+	 */
+	kvm_replace_memslot(kvm, old, NULL);
+	kvm_activate_memslot(kvm, invalid_slot, NULL);
+}
+
+static void kvm_move_memslot(struct kvm *kvm,
+			     struct kvm_memory_slot *old,
+			     struct kvm_memory_slot *new,
+			     struct kvm_memory_slot *invalid_slot)
+{
+	/*
+	 * Replace the old memslot in the inactive slots, and then swap slots
+	 * and replace the current INVALID with the new as well.
+	 */
+	kvm_replace_memslot(kvm, old, new);
+	kvm_activate_memslot(kvm, invalid_slot, new);
+}
+
+static void kvm_update_flags_memslot(struct kvm *kvm,
+				     struct kvm_memory_slot *old,
+				     struct kvm_memory_slot *new)
+{
+	/*
+	 * Similar to the MOVE case, but the slot doesn't need to be zapped as
+	 * an intermediate step. Instead, the old memslot is simply replaced
+	 * with a new, updated copy in both memslot sets.
+	 */
+	kvm_replace_memslot(kvm, old, new);
+	kvm_activate_memslot(kvm, old, new);
+}
+
+static int kvm_set_memslot(struct kvm *kvm,
+			   struct kvm_memory_slot *old,
+			   struct kvm_memory_slot *new,
+			   enum kvm_mr_change change)
+{
+	struct kvm_memory_slot *invalid_slot;
+	int r;
+
+	/*
+	 * Released in kvm_swap_active_memslots.
+	 *
+	 * Must be held from before the current memslots are copied until
+	 * after the new memslots are installed with rcu_assign_pointer,
+	 * then released before the synchronize srcu in kvm_swap_active_memslots.
+	 *
+	 * When modifying memslots outside of the slots_lock, must be held
+	 * before reading the pointer to the current memslots until after all
+	 * changes to those memslots are complete.
+	 *
+	 * These rules ensure that installing new memslots does not lose
+	 * changes made to the previous memslots.
+	 */
+	mutex_lock(&kvm->slots_arch_lock);
+
+	/*
+	 * Invalidate the old slot if it's being deleted or moved.  This is
+	 * done prior to actually deleting/moving the memslot to allow vCPUs to
+	 * continue running by ensuring there are no mappings or shadow pages
+	 * for the memslot when it is deleted/moved.  Without pre-invalidation
+	 * (and without a lock), a window would exist between effecting the
+	 * delete/move and committing the changes in arch code where KVM or a
+	 * guest could access a non-existent memslot.
+	 *
+	 * Modifications are done on a temporary, unreachable slot.  The old
+	 * slot needs to be preserved in case a later step fails and the
+	 * invalidation needs to be reverted.
+	 */
+	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
+		invalid_slot = kzalloc(sizeof(*invalid_slot), GFP_KERNEL_ACCOUNT);
+		if (!invalid_slot) {
+			mutex_unlock(&kvm->slots_arch_lock);
+			return -ENOMEM;
+		}
+		kvm_invalidate_memslot(kvm, old, invalid_slot);
+	}
+
+	r = kvm_prepare_memory_region(kvm, old, new, change);
+	if (r) {
+		/*
+		 * For DELETE/MOVE, revert the above INVALID change.  No
+		 * modifications required since the original slot was preserved
+		 * in the inactive slots.  Changing the active memslots also
+		 * release slots_arch_lock.
+		 */
+		if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
+			kvm_activate_memslot(kvm, invalid_slot, old);
+			kfree(invalid_slot);
+		} else {
+			mutex_unlock(&kvm->slots_arch_lock);
+		}
+		return r;
+	}
+
+	/*
+	 * For DELETE and MOVE, the working slot is now active as the INVALID
+	 * version of the old slot.  MOVE is particularly special as it reuses
+	 * the old slot and returns a copy of the old slot (in working_slot).
+	 * For CREATE, there is no old slot.  For DELETE and FLAGS_ONLY, the
+	 * old slot is detached but otherwise preserved.
+	 */
+	if (change == KVM_MR_CREATE)
+		kvm_create_memslot(kvm, new);
+	else if (change == KVM_MR_DELETE)
+		kvm_delete_memslot(kvm, old, invalid_slot);
+	else if (change == KVM_MR_MOVE)
+		kvm_move_memslot(kvm, old, new, invalid_slot);
+	else if (change == KVM_MR_FLAGS_ONLY)
+		kvm_update_flags_memslot(kvm, old, new);
+	else
+		BUG();
+
+	/* Free the temporary INVALID slot used for DELETE and MOVE. */
+	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
+		kfree(invalid_slot);
+
+	/*
+	 * No need to refresh new->arch, changes after dropping slots_arch_lock
+	 * will directly hit the final, active memslot.  Architectures are
+	 * responsible for knowing that new->arch may be stale.
+	 */
+	kvm_commit_memory_region(kvm, old, new, change);
+
+	return 0;
+}
+
+static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
+				      gfn_t start, gfn_t end)
+{
+	struct kvm_memslot_iter iter;
+
+	kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
+		if (iter.slot->id != id)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * Allocate some memory and give it an address in the guest physical address
+ * space.
+ *
+ * Discontiguous memory is allowed, mostly for framebuffers.
+ *
+ * Must be called holding kvm->slots_lock for write.
+ */
+int __kvm_set_memory_region(struct kvm *kvm,
+			    const struct kvm_userspace_memory_region *mem)
+{
+	struct kvm_memory_slot *old, *new;
+	struct kvm_memslots *slots;
+	enum kvm_mr_change change;
+	unsigned long npages;
+	gfn_t base_gfn;
+	int as_id, id;
+	int r;
+
+	r = check_memory_region_flags(mem);
+	if (r)
+		return r;
+
+	as_id = mem->slot >> 16;
+	id = (u16)mem->slot;
+
+	/* General sanity checks */
+	if ((mem->memory_size & (PAGE_SIZE - 1)) ||
+	    (mem->memory_size != (unsigned long)mem->memory_size))
+		return -EINVAL;
+	if (mem->guest_phys_addr & (PAGE_SIZE - 1))
+		return -EINVAL;
+	/* We can read the guest memory with __xxx_user() later on. */
+	if ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
+	    (mem->userspace_addr != untagged_addr(mem->userspace_addr)) ||
+	     !access_ok((void __user *)(unsigned long)mem->userspace_addr,
+			mem->memory_size))
+		return -EINVAL;
+	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
+		return -EINVAL;
+	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
+		return -EINVAL;
+	if ((mem->memory_size >> PAGE_SHIFT) > KVM_MEM_MAX_NR_PAGES)
+		return -EINVAL;
+
+	slots = __kvm_memslots(kvm, as_id);
+
+	/*
+	 * Note, the old memslot (and the pointer itself!) may be invalidated
+	 * and/or destroyed by kvm_set_memslot().
+	 */
+	old = id_to_memslot(slots, id);
+
+	if (!mem->memory_size) {
+		if (!old || !old->npages)
+			return -EINVAL;
+
+		if (WARN_ON_ONCE(kvm->nr_memslot_pages < old->npages))
+			return -EIO;
+
+		return kvm_set_memslot(kvm, old, NULL, KVM_MR_DELETE);
+	}
+
+	base_gfn = (mem->guest_phys_addr >> PAGE_SHIFT);
+	npages = (mem->memory_size >> PAGE_SHIFT);
+
+	if (!old || !old->npages) {
+		change = KVM_MR_CREATE;
+
+		/*
+		 * To simplify KVM internals, the total number of pages across
+		 * all memslots must fit in an unsigned long.
+		 */
+		if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
+			return -EINVAL;
+	} else { /* Modify an existing slot. */
+		if ((mem->userspace_addr != old->userspace_addr) ||
+		    (npages != old->npages) ||
+		    ((mem->flags ^ old->flags) & KVM_MEM_READONLY))
+			return -EINVAL;
+
+		if (base_gfn != old->base_gfn)
+			change = KVM_MR_MOVE;
+		else if (mem->flags != old->flags)
+			change = KVM_MR_FLAGS_ONLY;
+		else /* Nothing to change. */
+			return 0;
+	}
+
+	if ((change == KVM_MR_CREATE || change == KVM_MR_MOVE) &&
+	    kvm_check_memslot_overlap(slots, id, base_gfn, base_gfn + npages))
+		return -EEXIST;
+
+	/* Allocate a slot that will persist in the memslot. */
+	new = kzalloc(sizeof(*new), GFP_KERNEL_ACCOUNT);
+	if (!new)
+		return -ENOMEM;
+
+	new->as_id = as_id;
+	new->id = id;
+	new->base_gfn = base_gfn;
+	new->npages = npages;
+	new->flags = mem->flags;
+	new->userspace_addr = mem->userspace_addr;
+
+	r = kvm_set_memslot(kvm, old, new, change);
+	if (r)
+		kfree(new);
+	return r;
+}
+EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
+
+int kvm_set_memory_region(struct kvm *kvm,
+			  const struct kvm_userspace_memory_region *mem)
+{
+	int r;
+
+	mutex_lock(&kvm->slots_lock);
+	r = __kvm_set_memory_region(kvm, mem);
+	mutex_unlock(&kvm->slots_lock);
+	return r;
+}
+EXPORT_SYMBOL_GPL(kvm_set_memory_region);
+
+static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
+					  struct kvm_userspace_memory_region *mem)
+{
+	if ((u16)mem->slot >= KVM_USER_MEM_SLOTS)
+		return -EINVAL;
+
+	return kvm_set_memory_region(kvm, mem);
+}
+
+#ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+/**
+ * kvm_get_dirty_log - get a snapshot of dirty pages
+ * @kvm:	pointer to kvm instance
+ * @log:	slot id and address to which we copy the log
+ * @is_dirty:	set to '1' if any dirty pages were found
+ * @memslot:	set to the associated memslot, always valid on success
+ */
+int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
+		      int *is_dirty, struct kvm_memory_slot **memslot)
+{
+	struct kvm_memslots *slots;
+	int i, as_id, id;
+	unsigned long n;
+	unsigned long any = 0;
+
+	/* Dirty ring tracking is exclusive to dirty log tracking */
+	if (kvm->dirty_ring_size)
+		return -ENXIO;
+
+	*memslot = NULL;
+	*is_dirty = 0;
+
+	as_id = log->slot >> 16;
+	id = (u16)log->slot;
+	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
+		return -EINVAL;
+
+	slots = __kvm_memslots(kvm, as_id);
+	*memslot = id_to_memslot(slots, id);
+	if (!(*memslot) || !(*memslot)->dirty_bitmap)
+		return -ENOENT;
+
+	kvm_arch_sync_dirty_log(kvm, *memslot);
+
+	n = kvm_dirty_bitmap_bytes(*memslot);
+
+	for (i = 0; !any && i < n/sizeof(long); ++i)
+		any = (*memslot)->dirty_bitmap[i];
+
+	if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
+		return -EFAULT;
+
+	if (any)
+		*is_dirty = 1;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_get_dirty_log);
+
+#else /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
+/**
+ * kvm_get_dirty_log_protect - get a snapshot of dirty pages
+ *	and reenable dirty page tracking for the corresponding pages.
+ * @kvm:	pointer to kvm instance
+ * @log:	slot id and address to which we copy the log
+ *
+ * We need to keep it in mind that VCPU threads can write to the bitmap
+ * concurrently. So, to avoid losing track of dirty pages we keep the
+ * following order:
+ *
+ *    1. Take a snapshot of the bit and clear it if needed.
+ *    2. Write protect the corresponding page.
+ *    3. Copy the snapshot to the userspace.
+ *    4. Upon return caller flushes TLB's if needed.
+ *
+ * Between 2 and 4, the guest may write to the page using the remaining TLB
+ * entry.  This is not a problem because the page is reported dirty using
+ * the snapshot taken before and step 4 ensures that writes done after
+ * exiting to userspace will be logged for the next call.
+ *
+ */
+static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	int i, as_id, id;
+	unsigned long n;
+	unsigned long *dirty_bitmap;
+	unsigned long *dirty_bitmap_buffer;
+	bool flush;
+
+	/* Dirty ring tracking is exclusive to dirty log tracking */
+	if (kvm->dirty_ring_size)
+		return -ENXIO;
+
+	as_id = log->slot >> 16;
+	id = (u16)log->slot;
+	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
+		return -EINVAL;
+
+	slots = __kvm_memslots(kvm, as_id);
+	memslot = id_to_memslot(slots, id);
+	if (!memslot || !memslot->dirty_bitmap)
+		return -ENOENT;
+
+	dirty_bitmap = memslot->dirty_bitmap;
+
+	kvm_arch_sync_dirty_log(kvm, memslot);
+
+	n = kvm_dirty_bitmap_bytes(memslot);
+	flush = false;
+	if (kvm->manual_dirty_log_protect) {
+		/*
+		 * Unlike kvm_get_dirty_log, we always return false in *flush,
+		 * because no flush is needed until KVM_CLEAR_DIRTY_LOG.  There
+		 * is some code duplication between this function and
+		 * kvm_get_dirty_log, but hopefully all architecture
+		 * transition to kvm_get_dirty_log_protect and kvm_get_dirty_log
+		 * can be eliminated.
+		 */
+		dirty_bitmap_buffer = dirty_bitmap;
+	} else {
+		dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
+		memset(dirty_bitmap_buffer, 0, n);
+
+		KVM_MMU_LOCK(kvm);
+		for (i = 0; i < n / sizeof(long); i++) {
+			unsigned long mask;
+			gfn_t offset;
+
+			if (!dirty_bitmap[i])
+				continue;
+
+			flush = true;
+			mask = xchg(&dirty_bitmap[i], 0);
+			dirty_bitmap_buffer[i] = mask;
+
+			offset = i * BITS_PER_LONG;
+			kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
+								offset, mask);
+		}
+		KVM_MMU_UNLOCK(kvm);
+	}
+
+	if (flush)
+		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
+
+	if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
+		return -EFAULT;
+	return 0;
+}
+
+
+/**
+ * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
+ * @kvm: kvm instance
+ * @log: slot id and address to which we copy the log
+ *
+ * Steps 1-4 below provide general overview of dirty page logging. See
+ * kvm_get_dirty_log_protect() function description for additional details.
+ *
+ * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
+ * always flush the TLB (step 4) even if previous step failed  and the dirty
+ * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
+ * does not preclude user space subsequent dirty log read. Flushing TLB ensures
+ * writes will be marked dirty for next log read.
+ *
+ *   1. Take a snapshot of the bit and clear it if needed.
+ *   2. Write protect the corresponding page.
+ *   3. Copy the snapshot to the userspace.
+ *   4. Flush TLB's if needed.
+ */
+static int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
+				      struct kvm_dirty_log *log)
+{
+	int r;
+
+	mutex_lock(&kvm->slots_lock);
+
+	r = kvm_get_dirty_log_protect(kvm, log);
+
+	mutex_unlock(&kvm->slots_lock);
+	return r;
+}
+
+/**
+ * kvm_clear_dirty_log_protect - clear dirty bits in the bitmap
+ *	and reenable dirty page tracking for the corresponding pages.
+ * @kvm:	pointer to kvm instance
+ * @log:	slot id and address from which to fetch the bitmap of dirty pages
+ */
+static int kvm_clear_dirty_log_protect(struct kvm *kvm,
+				       struct kvm_clear_dirty_log *log)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	int as_id, id;
+	gfn_t offset;
+	unsigned long i, n;
+	unsigned long *dirty_bitmap;
+	unsigned long *dirty_bitmap_buffer;
+	bool flush;
+
+	/* Dirty ring tracking is exclusive to dirty log tracking */
+	if (kvm->dirty_ring_size)
+		return -ENXIO;
+
+	as_id = log->slot >> 16;
+	id = (u16)log->slot;
+	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
+		return -EINVAL;
+
+	if (log->first_page & 63)
+		return -EINVAL;
+
+	slots = __kvm_memslots(kvm, as_id);
+	memslot = id_to_memslot(slots, id);
+	if (!memslot || !memslot->dirty_bitmap)
+		return -ENOENT;
+
+	dirty_bitmap = memslot->dirty_bitmap;
+
+	n = ALIGN(log->num_pages, BITS_PER_LONG) / 8;
+
+	if (log->first_page > memslot->npages ||
+	    log->num_pages > memslot->npages - log->first_page ||
+	    (log->num_pages < memslot->npages - log->first_page && (log->num_pages & 63)))
+	    return -EINVAL;
+
+	kvm_arch_sync_dirty_log(kvm, memslot);
+
+	flush = false;
+	dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
+	if (copy_from_user(dirty_bitmap_buffer, log->dirty_bitmap, n))
+		return -EFAULT;
+
+	KVM_MMU_LOCK(kvm);
+	for (offset = log->first_page, i = offset / BITS_PER_LONG,
+		 n = DIV_ROUND_UP(log->num_pages, BITS_PER_LONG); n--;
+	     i++, offset += BITS_PER_LONG) {
+		unsigned long mask = *dirty_bitmap_buffer++;
+		atomic_long_t *p = (atomic_long_t *) &dirty_bitmap[i];
+		if (!mask)
+			continue;
+
+		mask &= atomic_long_fetch_andnot(mask, p);
+
+		/*
+		 * mask contains the bits that really have been cleared.  This
+		 * never includes any bits beyond the length of the memslot (if
+		 * the length is not aligned to 64 pages), therefore it is not
+		 * a problem if userspace sets them in log->dirty_bitmap.
+		*/
+		if (mask) {
+			flush = true;
+			kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
+								offset, mask);
+		}
+	}
+	KVM_MMU_UNLOCK(kvm);
+
+	if (flush)
+		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
+
+	return 0;
+}
+
+static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
+					struct kvm_clear_dirty_log *log)
+{
+	int r;
+
+	mutex_lock(&kvm->slots_lock);
+
+	r = kvm_clear_dirty_log_protect(kvm, log);
+
+	mutex_unlock(&kvm->slots_lock);
+	return r;
+}
+#endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
+
+struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
+{
+	return __gfn_to_memslot(kvm_memslots(kvm), gfn);
+}
+EXPORT_SYMBOL_GPL(gfn_to_memslot);
+
+struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	struct kvm_memslots *slots = kvm_vcpu_memslots(vcpu);
+	u64 gen = slots->generation;
+	struct kvm_memory_slot *slot;
+
+	/*
+	 * This also protects against using a memslot from a different address space,
+	 * since different address spaces have different generation numbers.
+	 */
+	if (unlikely(gen != vcpu->last_used_slot_gen)) {
+		vcpu->last_used_slot = NULL;
+		vcpu->last_used_slot_gen = gen;
+	}
+
+	slot = try_get_memslot(vcpu->last_used_slot, gfn);
+	if (slot)
+		return slot;
+
+	/*
+	 * Fall back to searching all memslots. We purposely use
+	 * search_memslots() instead of __gfn_to_memslot() to avoid
+	 * thrashing the VM-wide last_used_slot in kvm_memslots.
+	 */
+	slot = search_memslots(slots, gfn, false);
+	if (slot) {
+		vcpu->last_used_slot = slot;
+		return slot;
+	}
+
+	return NULL;
+}
+
+bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
+{
+	struct kvm_memory_slot *memslot = gfn_to_memslot(kvm, gfn);
+
+	return kvm_is_visible_memslot(memslot);
+}
+EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
+
+bool kvm_vcpu_is_visible_gfn(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	struct kvm_memory_slot *memslot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+
+	return kvm_is_visible_memslot(memslot);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_is_visible_gfn);
+
+unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	struct vm_area_struct *vma;
+	unsigned long addr, size;
+
+	size = PAGE_SIZE;
+
+	addr = kvm_vcpu_gfn_to_hva_prot(vcpu, gfn, NULL);
+	if (kvm_is_error_hva(addr))
+		return PAGE_SIZE;
+
+	mmap_read_lock(current->mm);
+	vma = find_vma(current->mm, addr);
+	if (!vma)
+		goto out;
+
+	size = vma_kernel_pagesize(vma);
+
+out:
+	mmap_read_unlock(current->mm);
+
+	return size;
+}
+
+static bool memslot_is_readonly(const struct kvm_memory_slot *slot)
+{
+	return slot->flags & KVM_MEM_READONLY;
+}
+
+static unsigned long __gfn_to_hva_many(const struct kvm_memory_slot *slot, gfn_t gfn,
+				       gfn_t *nr_pages, bool write)
+{
+	if (!slot || slot->flags & KVM_MEMSLOT_INVALID)
+		return KVM_HVA_ERR_BAD;
+
+	if (memslot_is_readonly(slot) && write)
+		return KVM_HVA_ERR_RO_BAD;
+
+	if (nr_pages)
+		*nr_pages = slot->npages - (gfn - slot->base_gfn);
+
+	return __gfn_to_hva_memslot(slot, gfn);
+}
+
+static unsigned long gfn_to_hva_many(struct kvm_memory_slot *slot, gfn_t gfn,
+				     gfn_t *nr_pages)
+{
+	return __gfn_to_hva_many(slot, gfn, nr_pages, true);
+}
+
+unsigned long gfn_to_hva_memslot(struct kvm_memory_slot *slot,
+					gfn_t gfn)
+{
+	return gfn_to_hva_many(slot, gfn, NULL);
+}
+EXPORT_SYMBOL_GPL(gfn_to_hva_memslot);
+
+unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
+{
+	return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL);
+}
+EXPORT_SYMBOL_GPL(gfn_to_hva);
+
+unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	return gfn_to_hva_many(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, NULL);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_hva);
+
+/*
+ * Return the hva of a @gfn and the R/W attribute if possible.
+ *
+ * @slot: the kvm_memory_slot which contains @gfn
+ * @gfn: the gfn to be translated
+ * @writable: used to return the read/write attribute of the @slot if the hva
+ * is valid and @writable is not NULL
+ */
+unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot,
+				      gfn_t gfn, bool *writable)
+{
+	unsigned long hva = __gfn_to_hva_many(slot, gfn, NULL, false);
+
+	if (!kvm_is_error_hva(hva) && writable)
+		*writable = !memslot_is_readonly(slot);
+
+	return hva;
+}
+
+unsigned long gfn_to_hva_prot(struct kvm *kvm, gfn_t gfn, bool *writable)
+{
+	struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
+
+	return gfn_to_hva_memslot_prot(slot, gfn, writable);
+}
+
+unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable)
+{
+	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+
+	return gfn_to_hva_memslot_prot(slot, gfn, writable);
+}
+
+static inline int check_user_page_hwpoison(unsigned long addr)
+{
+	int rc, flags = FOLL_HWPOISON | FOLL_WRITE;
+
+	rc = get_user_pages(addr, 1, flags, NULL, NULL);
+	return rc == -EHWPOISON;
+}
+
+/*
+ * The fast path to get the writable pfn which will be stored in @pfn,
+ * true indicates success, otherwise false is returned.  It's also the
+ * only part that runs if we can in atomic context.
+ */
+static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
+			    bool *writable, kvm_pfn_t *pfn)
+{
+	struct page *page[1];
+
+	/*
+	 * Fast pin a writable pfn only if it is a write fault request
+	 * or the caller allows to map a writable pfn for a read fault
+	 * request.
+	 */
+	if (!(write_fault || writable))
+		return false;
+
+	if (get_user_page_fast_only(addr, FOLL_WRITE, page)) {
+		*pfn = page_to_pfn(page[0]);
+
+		if (writable)
+			*writable = true;
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * The slow path to get the pfn of the specified host virtual address,
+ * 1 indicates success, -errno is returned if error is detected.
+ */
+static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
+			   bool *writable, kvm_pfn_t *pfn)
+{
+	unsigned int flags = FOLL_HWPOISON;
+	struct page *page;
+	int npages;
+
+	might_sleep();
+
+	if (writable)
+		*writable = write_fault;
+
+	if (write_fault)
+		flags |= FOLL_WRITE;
+	if (async)
+		flags |= FOLL_NOWAIT;
+
+	npages = get_user_pages_unlocked(addr, 1, &page, flags);
+	if (npages != 1)
+		return npages;
+
+	/* map read fault as writable if possible */
+	if (unlikely(!write_fault) && writable) {
+		struct page *wpage;
+
+		if (get_user_page_fast_only(addr, FOLL_WRITE, &wpage)) {
+			*writable = true;
+			put_page(page);
+			page = wpage;
+		}
+	}
+	*pfn = page_to_pfn(page);
+	return npages;
+}
+
+static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault)
+{
+	if (unlikely(!(vma->vm_flags & VM_READ)))
+		return false;
+
+	if (write_fault && (unlikely(!(vma->vm_flags & VM_WRITE))))
+		return false;
+
+	return true;
+}
+
+static int kvm_try_get_pfn(kvm_pfn_t pfn)
+{
+	struct page *page = kvm_pfn_to_refcounted_page(pfn);
+
+	if (!page)
+		return 1;
+
+	return get_page_unless_zero(page);
+}
+
+static int hva_to_pfn_remapped(struct vm_area_struct *vma,
+			       unsigned long addr, bool write_fault,
+			       bool *writable, kvm_pfn_t *p_pfn)
+{
+	kvm_pfn_t pfn;
+	pte_t *ptep;
+	spinlock_t *ptl;
+	int r;
+
+	r = follow_pte(vma->vm_mm, addr, &ptep, &ptl);
+	if (r) {
+		/*
+		 * get_user_pages fails for VM_IO and VM_PFNMAP vmas and does
+		 * not call the fault handler, so do it here.
+		 */
+		bool unlocked = false;
+		r = fixup_user_fault(current->mm, addr,
+				     (write_fault ? FAULT_FLAG_WRITE : 0),
+				     &unlocked);
+		if (unlocked)
+			return -EAGAIN;
+		if (r)
+			return r;
+
+		r = follow_pte(vma->vm_mm, addr, &ptep, &ptl);
+		if (r)
+			return r;
+	}
+
+	if (write_fault && !pte_write(*ptep)) {
+		pfn = KVM_PFN_ERR_RO_FAULT;
+		goto out;
+	}
+
+	if (writable)
+		*writable = pte_write(*ptep);
+	pfn = pte_pfn(*ptep);
+
+	/*
+	 * Get a reference here because callers of *hva_to_pfn* and
+	 * *gfn_to_pfn* ultimately call kvm_release_pfn_clean on the
+	 * returned pfn.  This is only needed if the VMA has VM_MIXEDMAP
+	 * set, but the kvm_try_get_pfn/kvm_release_pfn_clean pair will
+	 * simply do nothing for reserved pfns.
+	 *
+	 * Whoever called remap_pfn_range is also going to call e.g.
+	 * unmap_mapping_range before the underlying pages are freed,
+	 * causing a call to our MMU notifier.
+	 *
+	 * Certain IO or PFNMAP mappings can be backed with valid
+	 * struct pages, but be allocated without refcounting e.g.,
+	 * tail pages of non-compound higher order allocations, which
+	 * would then underflow the refcount when the caller does the
+	 * required put_page. Don't allow those pages here.
+	 */ 
+	if (!kvm_try_get_pfn(pfn))
+		r = -EFAULT;
+
+out:
+	pte_unmap_unlock(ptep, ptl);
+	*p_pfn = pfn;
+
+	return r;
+}
+
+/*
+ * Pin guest page in memory and return its pfn.
+ * @addr: host virtual address which maps memory to the guest
+ * @atomic: whether this function can sleep
+ * @async: whether this function need to wait IO complete if the
+ *         host page is not in the memory
+ * @write_fault: whether we should get a writable host page
+ * @writable: whether it allows to map a writable host page for !@write_fault
+ *
+ * The function will map a writable host page for these two cases:
+ * 1): @write_fault = true
+ * 2): @write_fault = false && @writable, @writable will tell the caller
+ *     whether the mapping is writable.
+ */
+kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
+		     bool write_fault, bool *writable)
+{
+	struct vm_area_struct *vma;
+	kvm_pfn_t pfn;
+	int npages, r;
+
+	/* we can do it either atomically or asynchronously, not both */
+	BUG_ON(atomic && async);
+
+	if (hva_to_pfn_fast(addr, write_fault, writable, &pfn))
+		return pfn;
+
+	if (atomic)
+		return KVM_PFN_ERR_FAULT;
+
+	npages = hva_to_pfn_slow(addr, async, write_fault, writable, &pfn);
+	if (npages == 1)
+		return pfn;
+
+	mmap_read_lock(current->mm);
+	if (npages == -EHWPOISON ||
+	      (!async && check_user_page_hwpoison(addr))) {
+		pfn = KVM_PFN_ERR_HWPOISON;
+		goto exit;
+	}
+
+retry:
+	vma = vma_lookup(current->mm, addr);
+
+	if (vma == NULL)
+		pfn = KVM_PFN_ERR_FAULT;
+	else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) {
+		r = hva_to_pfn_remapped(vma, addr, write_fault, writable, &pfn);
+		if (r == -EAGAIN)
+			goto retry;
+		if (r < 0)
+			pfn = KVM_PFN_ERR_FAULT;
+	} else {
+		if (async && vma_is_valid(vma, write_fault))
+			*async = true;
+		pfn = KVM_PFN_ERR_FAULT;
+	}
+exit:
+	mmap_read_unlock(current->mm);
+	return pfn;
+}
+
+kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn,
+			       bool atomic, bool *async, bool write_fault,
+			       bool *writable, hva_t *hva)
+{
+	unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault);
+
+	if (hva)
+		*hva = addr;
+
+	if (addr == KVM_HVA_ERR_RO_BAD) {
+		if (writable)
+			*writable = false;
+		return KVM_PFN_ERR_RO_FAULT;
+	}
+
+	if (kvm_is_error_hva(addr)) {
+		if (writable)
+			*writable = false;
+		return KVM_PFN_NOSLOT;
+	}
+
+	/* Do not map writable pfn in the readonly memslot. */
+	if (writable && memslot_is_readonly(slot)) {
+		*writable = false;
+		writable = NULL;
+	}
+
+	return hva_to_pfn(addr, atomic, async, write_fault,
+			  writable);
+}
+EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot);
+
+kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
+		      bool *writable)
+{
+	return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL,
+				    write_fault, writable, NULL);
+}
+EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
+
+kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot);
+
+kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gfn_t gfn)
+{
+	return __gfn_to_pfn_memslot(slot, gfn, true, NULL, true, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic);
+
+kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	return gfn_to_pfn_memslot_atomic(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn_atomic);
+
+kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+{
+	return gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn);
+}
+EXPORT_SYMBOL_GPL(gfn_to_pfn);
+
+kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	return gfn_to_pfn_memslot(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn);
+
+int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
+			    struct page **pages, int nr_pages)
+{
+	unsigned long addr;
+	gfn_t entry = 0;
+
+	addr = gfn_to_hva_many(slot, gfn, &entry);
+	if (kvm_is_error_hva(addr))
+		return -1;
+
+	if (entry < nr_pages)
+		return 0;
+
+	return get_user_pages_fast_only(addr, nr_pages, FOLL_WRITE, pages);
+}
+EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
+
+/*
+ * Do not use this helper unless you are absolutely certain the gfn _must_ be
+ * backed by 'struct page'.  A valid example is if the backing memslot is
+ * controlled by KVM.  Note, if the returned page is valid, it's refcount has
+ * been elevated by gfn_to_pfn().
+ */
+struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
+{
+	struct page *page;
+	kvm_pfn_t pfn;
+
+	pfn = gfn_to_pfn(kvm, gfn);
+
+	if (is_error_noslot_pfn(pfn))
+		return KVM_ERR_PTR_BAD_PAGE;
+
+	page = kvm_pfn_to_refcounted_page(pfn);
+	if (!page)
+		return KVM_ERR_PTR_BAD_PAGE;
+
+	return page;
+}
+EXPORT_SYMBOL_GPL(gfn_to_page);
+
+void kvm_release_pfn(kvm_pfn_t pfn, bool dirty)
+{
+	if (dirty)
+		kvm_release_pfn_dirty(pfn);
+	else
+		kvm_release_pfn_clean(pfn);
+}
+
+int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
+{
+	kvm_pfn_t pfn;
+	void *hva = NULL;
+	struct page *page = KVM_UNMAPPED_PAGE;
+
+	if (!map)
+		return -EINVAL;
+
+	pfn = gfn_to_pfn(vcpu->kvm, gfn);
+	if (is_error_noslot_pfn(pfn))
+		return -EINVAL;
+
+	if (pfn_valid(pfn)) {
+		page = pfn_to_page(pfn);
+		hva = kmap(page);
+#ifdef CONFIG_HAS_IOMEM
+	} else {
+		hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
+#endif
+	}
+
+	if (!hva)
+		return -EFAULT;
+
+	map->page = page;
+	map->hva = hva;
+	map->pfn = pfn;
+	map->gfn = gfn;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_map);
+
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
+{
+	if (!map)
+		return;
+
+	if (!map->hva)
+		return;
+
+	if (map->page != KVM_UNMAPPED_PAGE)
+		kunmap(map->page);
+#ifdef CONFIG_HAS_IOMEM
+	else
+		memunmap(map->hva);
+#endif
+
+	if (dirty)
+		kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
+
+	kvm_release_pfn(map->pfn, dirty);
+
+	map->hva = NULL;
+	map->page = NULL;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
+
+static bool kvm_is_ad_tracked_page(struct page *page)
+{
+	/*
+	 * Per page-flags.h, pages tagged PG_reserved "should in general not be
+	 * touched (e.g. set dirty) except by its owner".
+	 */
+	return !PageReserved(page);
+}
+
+static void kvm_set_page_dirty(struct page *page)
+{
+	if (kvm_is_ad_tracked_page(page))
+		SetPageDirty(page);
+}
+
+static void kvm_set_page_accessed(struct page *page)
+{
+	if (kvm_is_ad_tracked_page(page))
+		mark_page_accessed(page);
+}
+
+void kvm_release_page_clean(struct page *page)
+{
+	WARN_ON(is_error_page(page));
+
+	kvm_set_page_accessed(page);
+	put_page(page);
+}
+EXPORT_SYMBOL_GPL(kvm_release_page_clean);
+
+void kvm_release_pfn_clean(kvm_pfn_t pfn)
+{
+	struct page *page;
+
+	if (is_error_noslot_pfn(pfn))
+		return;
+
+	page = kvm_pfn_to_refcounted_page(pfn);
+	if (!page)
+		return;
+
+	kvm_release_page_clean(page);
+}
+EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
+
+void kvm_release_page_dirty(struct page *page)
+{
+	WARN_ON(is_error_page(page));
+
+	kvm_set_page_dirty(page);
+	kvm_release_page_clean(page);
+}
+EXPORT_SYMBOL_GPL(kvm_release_page_dirty);
+
+void kvm_release_pfn_dirty(kvm_pfn_t pfn)
+{
+	struct page *page;
+
+	if (is_error_noslot_pfn(pfn))
+		return;
+
+	page = kvm_pfn_to_refcounted_page(pfn);
+	if (!page)
+		return;
+
+	kvm_release_page_dirty(page);
+}
+EXPORT_SYMBOL_GPL(kvm_release_pfn_dirty);
+
+/*
+ * Note, checking for an error/noslot pfn is the caller's responsibility when
+ * directly marking a page dirty/accessed.  Unlike the "release" helpers, the
+ * "set" helpers are not to be used when the pfn might point at garbage.
+ */
+void kvm_set_pfn_dirty(kvm_pfn_t pfn)
+{
+	if (WARN_ON(is_error_noslot_pfn(pfn)))
+		return;
+
+	if (pfn_valid(pfn))
+		kvm_set_page_dirty(pfn_to_page(pfn));
+}
+EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
+
+void kvm_set_pfn_accessed(kvm_pfn_t pfn)
+{
+	if (WARN_ON(is_error_noslot_pfn(pfn)))
+		return;
+
+	if (pfn_valid(pfn))
+		kvm_set_page_accessed(pfn_to_page(pfn));
+}
+EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);
+
+static int next_segment(unsigned long len, int offset)
+{
+	if (len > PAGE_SIZE - offset)
+		return PAGE_SIZE - offset;
+	else
+		return len;
+}
+
+static int __kvm_read_guest_page(struct kvm_memory_slot *slot, gfn_t gfn,
+				 void *data, int offset, int len)
+{
+	int r;
+	unsigned long addr;
+
+	addr = gfn_to_hva_memslot_prot(slot, gfn, NULL);
+	if (kvm_is_error_hva(addr))
+		return -EFAULT;
+	r = __copy_from_user(data, (void __user *)addr + offset, len);
+	if (r)
+		return -EFAULT;
+	return 0;
+}
+
+int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
+			int len)
+{
+	struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
+
+	return __kvm_read_guest_page(slot, gfn, data, offset, len);
+}
+EXPORT_SYMBOL_GPL(kvm_read_guest_page);
+
+int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data,
+			     int offset, int len)
+{
+	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+
+	return __kvm_read_guest_page(slot, gfn, data, offset, len);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_page);
+
+int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len)
+{
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	int seg;
+	int offset = offset_in_page(gpa);
+	int ret;
+
+	while ((seg = next_segment(len, offset)) != 0) {
+		ret = kvm_read_guest_page(kvm, gfn, data, offset, seg);
+		if (ret < 0)
+			return ret;
+		offset = 0;
+		len -= seg;
+		data += seg;
+		++gfn;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_read_guest);
+
+int kvm_vcpu_read_guest(struct kvm_vcpu *vcpu, gpa_t gpa, void *data, unsigned long len)
+{
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	int seg;
+	int offset = offset_in_page(gpa);
+	int ret;
+
+	while ((seg = next_segment(len, offset)) != 0) {
+		ret = kvm_vcpu_read_guest_page(vcpu, gfn, data, offset, seg);
+		if (ret < 0)
+			return ret;
+		offset = 0;
+		len -= seg;
+		data += seg;
+		++gfn;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest);
+
+static int __kvm_read_guest_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
+			           void *data, int offset, unsigned long len)
+{
+	int r;
+	unsigned long addr;
+
+	addr = gfn_to_hva_memslot_prot(slot, gfn, NULL);
+	if (kvm_is_error_hva(addr))
+		return -EFAULT;
+	pagefault_disable();
+	r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
+	pagefault_enable();
+	if (r)
+		return -EFAULT;
+	return 0;
+}
+
+int kvm_vcpu_read_guest_atomic(struct kvm_vcpu *vcpu, gpa_t gpa,
+			       void *data, unsigned long len)
+{
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+	int offset = offset_in_page(gpa);
+
+	return __kvm_read_guest_atomic(slot, gfn, data, offset, len);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_atomic);
+
+static int __kvm_write_guest_page(struct kvm *kvm,
+				  struct kvm_memory_slot *memslot, gfn_t gfn,
+			          const void *data, int offset, int len)
+{
+	int r;
+	unsigned long addr;
+
+	addr = gfn_to_hva_memslot(memslot, gfn);
+	if (kvm_is_error_hva(addr))
+		return -EFAULT;
+	r = __copy_to_user((void __user *)addr + offset, data, len);
+	if (r)
+		return -EFAULT;
+	mark_page_dirty_in_slot(kvm, memslot, gfn);
+	return 0;
+}
+
+int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn,
+			 const void *data, int offset, int len)
+{
+	struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
+
+	return __kvm_write_guest_page(kvm, slot, gfn, data, offset, len);
+}
+EXPORT_SYMBOL_GPL(kvm_write_guest_page);
+
+int kvm_vcpu_write_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn,
+			      const void *data, int offset, int len)
+{
+	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+
+	return __kvm_write_guest_page(vcpu->kvm, slot, gfn, data, offset, len);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest_page);
+
+int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
+		    unsigned long len)
+{
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	int seg;
+	int offset = offset_in_page(gpa);
+	int ret;
+
+	while ((seg = next_segment(len, offset)) != 0) {
+		ret = kvm_write_guest_page(kvm, gfn, data, offset, seg);
+		if (ret < 0)
+			return ret;
+		offset = 0;
+		len -= seg;
+		data += seg;
+		++gfn;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_write_guest);
+
+int kvm_vcpu_write_guest(struct kvm_vcpu *vcpu, gpa_t gpa, const void *data,
+		         unsigned long len)
+{
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	int seg;
+	int offset = offset_in_page(gpa);
+	int ret;
+
+	while ((seg = next_segment(len, offset)) != 0) {
+		ret = kvm_vcpu_write_guest_page(vcpu, gfn, data, offset, seg);
+		if (ret < 0)
+			return ret;
+		offset = 0;
+		len -= seg;
+		data += seg;
+		++gfn;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest);
+
+static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
+				       struct gfn_to_hva_cache *ghc,
+				       gpa_t gpa, unsigned long len)
+{
+	int offset = offset_in_page(gpa);
+	gfn_t start_gfn = gpa >> PAGE_SHIFT;
+	gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
+	gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
+	gfn_t nr_pages_avail;
+
+	/* Update ghc->generation before performing any error checks. */
+	ghc->generation = slots->generation;
+
+	if (start_gfn > end_gfn) {
+		ghc->hva = KVM_HVA_ERR_BAD;
+		return -EINVAL;
+	}
+
+	/*
+	 * If the requested region crosses two memslots, we still
+	 * verify that the entire region is valid here.
+	 */
+	for ( ; start_gfn <= end_gfn; start_gfn += nr_pages_avail) {
+		ghc->memslot = __gfn_to_memslot(slots, start_gfn);
+		ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
+					   &nr_pages_avail);
+		if (kvm_is_error_hva(ghc->hva))
+			return -EFAULT;
+	}
+
+	/* Use the slow path for cross page reads and writes. */
+	if (nr_pages_needed == 1)
+		ghc->hva += offset;
+	else
+		ghc->memslot = NULL;
+
+	ghc->gpa = gpa;
+	ghc->len = len;
+	return 0;
+}
+
+int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+			      gpa_t gpa, unsigned long len)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	return __kvm_gfn_to_hva_cache_init(slots, ghc, gpa, len);
+}
+EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
+
+int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+				  void *data, unsigned int offset,
+				  unsigned long len)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	int r;
+	gpa_t gpa = ghc->gpa + offset;
+
+	if (WARN_ON_ONCE(len + offset > ghc->len))
+		return -EINVAL;
+
+	if (slots->generation != ghc->generation) {
+		if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
+			return -EFAULT;
+	}
+
+	if (kvm_is_error_hva(ghc->hva))
+		return -EFAULT;
+
+	if (unlikely(!ghc->memslot))
+		return kvm_write_guest(kvm, gpa, data, len);
+
+	r = __copy_to_user((void __user *)ghc->hva + offset, data, len);
+	if (r)
+		return -EFAULT;
+	mark_page_dirty_in_slot(kvm, ghc->memslot, gpa >> PAGE_SHIFT);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_write_guest_offset_cached);
+
+int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+			   void *data, unsigned long len)
+{
+	return kvm_write_guest_offset_cached(kvm, ghc, data, 0, len);
+}
+EXPORT_SYMBOL_GPL(kvm_write_guest_cached);
+
+int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+				 void *data, unsigned int offset,
+				 unsigned long len)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	int r;
+	gpa_t gpa = ghc->gpa + offset;
+
+	if (WARN_ON_ONCE(len + offset > ghc->len))
+		return -EINVAL;
+
+	if (slots->generation != ghc->generation) {
+		if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
+			return -EFAULT;
+	}
+
+	if (kvm_is_error_hva(ghc->hva))
+		return -EFAULT;
+
+	if (unlikely(!ghc->memslot))
+		return kvm_read_guest(kvm, gpa, data, len);
+
+	r = __copy_from_user(data, (void __user *)ghc->hva + offset, len);
+	if (r)
+		return -EFAULT;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_read_guest_offset_cached);
+
+int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+			  void *data, unsigned long len)
+{
+	return kvm_read_guest_offset_cached(kvm, ghc, data, 0, len);
+}
+EXPORT_SYMBOL_GPL(kvm_read_guest_cached);
+
+int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
+{
+	const void *zero_page = (const void *) __va(page_to_phys(ZERO_PAGE(0)));
+	gfn_t gfn = gpa >> PAGE_SHIFT;
+	int seg;
+	int offset = offset_in_page(gpa);
+	int ret;
+
+	while ((seg = next_segment(len, offset)) != 0) {
+		ret = kvm_write_guest_page(kvm, gfn, zero_page, offset, len);
+		if (ret < 0)
+			return ret;
+		offset = 0;
+		len -= seg;
+		++gfn;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_clear_guest);
+
+void mark_page_dirty_in_slot(struct kvm *kvm,
+			     const struct kvm_memory_slot *memslot,
+		 	     gfn_t gfn)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+#ifdef CONFIG_HAVE_KVM_DIRTY_RING
+	if (WARN_ON_ONCE(!vcpu) || WARN_ON_ONCE(vcpu->kvm != kvm))
+		return;
+#endif
+
+	if (memslot && kvm_slot_dirty_track_enabled(memslot)) {
+		unsigned long rel_gfn = gfn - memslot->base_gfn;
+		u32 slot = (memslot->as_id << 16) | memslot->id;
+
+		if (kvm->dirty_ring_size)
+			kvm_dirty_ring_push(&vcpu->dirty_ring,
+					    slot, rel_gfn);
+		else
+			set_bit_le(rel_gfn, memslot->dirty_bitmap);
+	}
+}
+EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot);
+
+void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
+{
+	struct kvm_memory_slot *memslot;
+
+	memslot = gfn_to_memslot(kvm, gfn);
+	mark_page_dirty_in_slot(kvm, memslot, gfn);
+}
+EXPORT_SYMBOL_GPL(mark_page_dirty);
+
+void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn)
+{
+	struct kvm_memory_slot *memslot;
+
+	memslot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
+	mark_page_dirty_in_slot(vcpu->kvm, memslot, gfn);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty);
+
+void kvm_sigset_activate(struct kvm_vcpu *vcpu)
+{
+	if (!vcpu->sigset_active)
+		return;
+
+	/*
+	 * This does a lockless modification of ->real_blocked, which is fine
+	 * because, only current can change ->real_blocked and all readers of
+	 * ->real_blocked don't care as long ->real_blocked is always a subset
+	 * of ->blocked.
+	 */
+	sigprocmask(SIG_SETMASK, &vcpu->sigset, &current->real_blocked);
+}
+
+void kvm_sigset_deactivate(struct kvm_vcpu *vcpu)
+{
+	if (!vcpu->sigset_active)
+		return;
+
+	sigprocmask(SIG_SETMASK, &current->real_blocked, NULL);
+	sigemptyset(&current->real_blocked);
+}
+
+static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
+{
+	unsigned int old, val, grow, grow_start;
+
+	old = val = vcpu->halt_poll_ns;
+	grow_start = READ_ONCE(halt_poll_ns_grow_start);
+	grow = READ_ONCE(halt_poll_ns_grow);
+	if (!grow)
+		goto out;
+
+	val *= grow;
+	if (val < grow_start)
+		val = grow_start;
+
+	vcpu->halt_poll_ns = val;
+out:
+	trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
+}
+
+static void shrink_halt_poll_ns(struct kvm_vcpu *vcpu)
+{
+	unsigned int old, val, shrink, grow_start;
+
+	old = val = vcpu->halt_poll_ns;
+	shrink = READ_ONCE(halt_poll_ns_shrink);
+	grow_start = READ_ONCE(halt_poll_ns_grow_start);
+	if (shrink == 0)
+		val = 0;
+	else
+		val /= shrink;
+
+	if (val < grow_start)
+		val = 0;
+
+	vcpu->halt_poll_ns = val;
+	trace_kvm_halt_poll_ns_shrink(vcpu->vcpu_id, val, old);
+}
+
+static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
+{
+	int ret = -EINTR;
+	int idx = srcu_read_lock(&vcpu->kvm->srcu);
+
+	if (kvm_arch_vcpu_runnable(vcpu))
+		goto out;
+	if (kvm_cpu_has_pending_timer(vcpu))
+		goto out;
+	if (signal_pending(current))
+		goto out;
+	if (kvm_check_request(KVM_REQ_UNBLOCK, vcpu))
+		goto out;
+
+	ret = 0;
+out:
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+	return ret;
+}
+
+/*
+ * Block the vCPU until the vCPU is runnable, an event arrives, or a signal is
+ * pending.  This is mostly used when halting a vCPU, but may also be used
+ * directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI.
+ */
+bool kvm_vcpu_block(struct kvm_vcpu *vcpu)
+{
+	struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
+	bool waited = false;
+
+	vcpu->stat.generic.blocking = 1;
+
+	preempt_disable();
+	kvm_arch_vcpu_blocking(vcpu);
+	prepare_to_rcuwait(wait);
+	preempt_enable();
+
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		if (kvm_vcpu_check_block(vcpu) < 0)
+			break;
+
+		waited = true;
+		schedule();
+	}
+
+	preempt_disable();
+	finish_rcuwait(wait);
+	kvm_arch_vcpu_unblocking(vcpu);
+	preempt_enable();
+
+	vcpu->stat.generic.blocking = 0;
+
+	return waited;
+}
+
+static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,
+					  ktime_t end, bool success)
+{
+	struct kvm_vcpu_stat_generic *stats = &vcpu->stat.generic;
+	u64 poll_ns = ktime_to_ns(ktime_sub(end, start));
+
+	++vcpu->stat.generic.halt_attempted_poll;
+
+	if (success) {
+		++vcpu->stat.generic.halt_successful_poll;
+
+		if (!vcpu_valid_wakeup(vcpu))
+			++vcpu->stat.generic.halt_poll_invalid;
+
+		stats->halt_poll_success_ns += poll_ns;
+		KVM_STATS_LOG_HIST_UPDATE(stats->halt_poll_success_hist, poll_ns);
+	} else {
+		stats->halt_poll_fail_ns += poll_ns;
+		KVM_STATS_LOG_HIST_UPDATE(stats->halt_poll_fail_hist, poll_ns);
+	}
+}
+
+static unsigned int kvm_vcpu_max_halt_poll_ns(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = vcpu->kvm;
+
+	if (kvm->override_halt_poll_ns) {
+		/*
+		 * Ensure kvm->max_halt_poll_ns is not read before
+		 * kvm->override_halt_poll_ns.
+		 *
+		 * Pairs with the smp_wmb() when enabling KVM_CAP_HALT_POLL.
+		 */
+		smp_rmb();
+		return READ_ONCE(kvm->max_halt_poll_ns);
+	}
+
+	return READ_ONCE(halt_poll_ns);
+}
+
+/*
+ * Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc...  If halt
+ * polling is enabled, busy wait for a short time before blocking to avoid the
+ * expensive block+unblock sequence if a wake event arrives soon after the vCPU
+ * is halted.
+ */
+void kvm_vcpu_halt(struct kvm_vcpu *vcpu)
+{
+	unsigned int max_halt_poll_ns = kvm_vcpu_max_halt_poll_ns(vcpu);
+	bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);
+	ktime_t start, cur, poll_end;
+	bool waited = false;
+	bool do_halt_poll;
+	u64 halt_ns;
+
+	if (vcpu->halt_poll_ns > max_halt_poll_ns)
+		vcpu->halt_poll_ns = max_halt_poll_ns;
+
+	do_halt_poll = halt_poll_allowed && vcpu->halt_poll_ns;
+
+	start = cur = poll_end = ktime_get();
+	if (do_halt_poll) {
+		ktime_t stop = ktime_add_ns(start, vcpu->halt_poll_ns);
+
+		do {
+			/*
+			 * This sets KVM_REQ_UNHALT if an interrupt
+			 * arrives.
+			 */
+			if (kvm_vcpu_check_block(vcpu) < 0)
+				goto out;
+			cpu_relax();
+			poll_end = cur = ktime_get();
+		} while (kvm_vcpu_can_poll(cur, stop));
+	}
+
+	waited = kvm_vcpu_block(vcpu);
+
+	cur = ktime_get();
+	if (waited) {
+		vcpu->stat.generic.halt_wait_ns +=
+			ktime_to_ns(cur) - ktime_to_ns(poll_end);
+		KVM_STATS_LOG_HIST_UPDATE(vcpu->stat.generic.halt_wait_hist,
+				ktime_to_ns(cur) - ktime_to_ns(poll_end));
+	}
+out:
+	/* The total time the vCPU was "halted", including polling time. */
+	halt_ns = ktime_to_ns(cur) - ktime_to_ns(start);
+
+	/*
+	 * Note, halt-polling is considered successful so long as the vCPU was
+	 * never actually scheduled out, i.e. even if the wake event arrived
+	 * after of the halt-polling loop itself, but before the full wait.
+	 */
+	if (do_halt_poll)
+		update_halt_poll_stats(vcpu, start, poll_end, !waited);
+
+	if (halt_poll_allowed) {
+		/* Recompute the max halt poll time in case it changed. */
+		max_halt_poll_ns = kvm_vcpu_max_halt_poll_ns(vcpu);
+
+		if (!vcpu_valid_wakeup(vcpu)) {
+			shrink_halt_poll_ns(vcpu);
+		} else if (max_halt_poll_ns) {
+			if (halt_ns <= vcpu->halt_poll_ns)
+				;
+			/* we had a long block, shrink polling */
+			else if (vcpu->halt_poll_ns &&
+				 halt_ns > max_halt_poll_ns)
+				shrink_halt_poll_ns(vcpu);
+			/* we had a short halt and our poll time is too small */
+			else if (vcpu->halt_poll_ns < max_halt_poll_ns &&
+				 halt_ns < max_halt_poll_ns)
+				grow_halt_poll_ns(vcpu);
+		} else {
+			vcpu->halt_poll_ns = 0;
+		}
+	}
+
+	trace_kvm_vcpu_wakeup(halt_ns, waited, vcpu_valid_wakeup(vcpu));
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_halt);
+
+bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
+{
+	if (__kvm_vcpu_wake_up(vcpu)) {
+		WRITE_ONCE(vcpu->ready, true);
+		++vcpu->stat.generic.halt_wakeup;
+		return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_wake_up);
+
+#ifndef CONFIG_S390
+/*
+ * Kick a sleeping VCPU, or a guest VCPU in guest mode, into host kernel mode.
+ */
+void kvm_vcpu_kick(struct kvm_vcpu *vcpu)
+{
+	int me, cpu;
+
+	if (kvm_vcpu_wake_up(vcpu))
+		return;
+
+	me = get_cpu();
+	/*
+	 * The only state change done outside the vcpu mutex is IN_GUEST_MODE
+	 * to EXITING_GUEST_MODE.  Therefore the moderately expensive "should
+	 * kick" check does not need atomic operations if kvm_vcpu_kick is used
+	 * within the vCPU thread itself.
+	 */
+	if (vcpu == __this_cpu_read(kvm_running_vcpu)) {
+		if (vcpu->mode == IN_GUEST_MODE)
+			WRITE_ONCE(vcpu->mode, EXITING_GUEST_MODE);
+		goto out;
+	}
+
+	/*
+	 * Note, the vCPU could get migrated to a different pCPU at any point
+	 * after kvm_arch_vcpu_should_kick(), which could result in sending an
+	 * IPI to the previous pCPU.  But, that's ok because the purpose of the
+	 * IPI is to force the vCPU to leave IN_GUEST_MODE, and migrating the
+	 * vCPU also requires it to leave IN_GUEST_MODE.
+	 */
+	if (kvm_arch_vcpu_should_kick(vcpu)) {
+		cpu = READ_ONCE(vcpu->cpu);
+		if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu))
+			smp_send_reschedule(cpu);
+	}
+out:
+	put_cpu();
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_kick);
+#endif /* !CONFIG_S390 */
+
+int kvm_vcpu_yield_to(struct kvm_vcpu *target)
+{
+	struct pid *pid;
+	struct task_struct *task = NULL;
+	int ret = 0;
+
+	rcu_read_lock();
+	pid = rcu_dereference(target->pid);
+	if (pid)
+		task = get_pid_task(pid, PIDTYPE_PID);
+	rcu_read_unlock();
+	if (!task)
+		return ret;
+	ret = yield_to(task, 1);
+	put_task_struct(task);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_yield_to);
+
+/*
+ * Helper that checks whether a VCPU is eligible for directed yield.
+ * Most eligible candidate to yield is decided by following heuristics:
+ *
+ *  (a) VCPU which has not done pl-exit or cpu relax intercepted recently
+ *  (preempted lock holder), indicated by @in_spin_loop.
+ *  Set at the beginning and cleared at the end of interception/PLE handler.
+ *
+ *  (b) VCPU which has done pl-exit/ cpu relax intercepted but did not get
+ *  chance last time (mostly it has become eligible now since we have probably
+ *  yielded to lockholder in last iteration. This is done by toggling
+ *  @dy_eligible each time a VCPU checked for eligibility.)
+ *
+ *  Yielding to a recently pl-exited/cpu relax intercepted VCPU before yielding
+ *  to preempted lock-holder could result in wrong VCPU selection and CPU
+ *  burning. Giving priority for a potential lock-holder increases lock
+ *  progress.
+ *
+ *  Since algorithm is based on heuristics, accessing another VCPU data without
+ *  locking does not harm. It may result in trying to yield to  same VCPU, fail
+ *  and continue with next VCPU and so on.
+ */
+static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
+{
+#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
+	bool eligible;
+
+	eligible = !vcpu->spin_loop.in_spin_loop ||
+		    vcpu->spin_loop.dy_eligible;
+
+	if (vcpu->spin_loop.in_spin_loop)
+		kvm_vcpu_set_dy_eligible(vcpu, !vcpu->spin_loop.dy_eligible);
+
+	return eligible;
+#else
+	return true;
+#endif
+}
+
+/*
+ * Unlike kvm_arch_vcpu_runnable, this function is called outside
+ * a vcpu_load/vcpu_put pair.  However, for most architectures
+ * kvm_arch_vcpu_runnable does not require vcpu_load.
+ */
+bool __weak kvm_arch_dy_runnable(struct kvm_vcpu *vcpu)
+{
+	return kvm_arch_vcpu_runnable(vcpu);
+}
+
+static bool vcpu_dy_runnable(struct kvm_vcpu *vcpu)
+{
+	if (kvm_arch_dy_runnable(vcpu))
+		return true;
+
+#ifdef CONFIG_KVM_ASYNC_PF
+	if (!list_empty_careful(&vcpu->async_pf.done))
+		return true;
+#endif
+
+	return false;
+}
+
+bool __weak kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu)
+{
+	return false;
+}
+
+void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
+{
+	struct kvm *kvm = me->kvm;
+	struct kvm_vcpu *vcpu;
+	int last_boosted_vcpu = me->kvm->last_boosted_vcpu;
+	unsigned long i;
+	int yielded = 0;
+	int try = 3;
+	int pass;
+
+	kvm_vcpu_set_in_spin_loop(me, true);
+	/*
+	 * We boost the priority of a VCPU that is runnable but not
+	 * currently running, because it got preempted by something
+	 * else and called schedule in __vcpu_run.  Hopefully that
+	 * VCPU is holding the lock that we need and will release it.
+	 * We approximate round-robin by starting at the last boosted VCPU.
+	 */
+	for (pass = 0; pass < 2 && !yielded && try; pass++) {
+		kvm_for_each_vcpu(i, vcpu, kvm) {
+			if (!pass && i <= last_boosted_vcpu) {
+				i = last_boosted_vcpu;
+				continue;
+			} else if (pass && i > last_boosted_vcpu)
+				break;
+			if (!READ_ONCE(vcpu->ready))
+				continue;
+			if (vcpu == me)
+				continue;
+			if (kvm_vcpu_is_blocking(vcpu) && !vcpu_dy_runnable(vcpu))
+				continue;
+			if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
+			    !kvm_arch_dy_has_pending_interrupt(vcpu) &&
+			    !kvm_arch_vcpu_in_kernel(vcpu))
+				continue;
+			if (!kvm_vcpu_eligible_for_directed_yield(vcpu))
+				continue;
+
+			yielded = kvm_vcpu_yield_to(vcpu);
+			if (yielded > 0) {
+				kvm->last_boosted_vcpu = i;
+				break;
+			} else if (yielded < 0) {
+				try--;
+				if (!try)
+					break;
+			}
+		}
+	}
+	kvm_vcpu_set_in_spin_loop(me, false);
+
+	/* Ensure vcpu is not eligible during next spinloop */
+	kvm_vcpu_set_dy_eligible(me, false);
+}
+EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);
+
+static bool kvm_page_in_dirty_ring(struct kvm *kvm, unsigned long pgoff)
+{
+#ifdef CONFIG_HAVE_KVM_DIRTY_RING
+	return (pgoff >= KVM_DIRTY_LOG_PAGE_OFFSET) &&
+	    (pgoff < KVM_DIRTY_LOG_PAGE_OFFSET +
+	     kvm->dirty_ring_size / PAGE_SIZE);
+#else
+	return false;
+#endif
+}
+
+static vm_fault_t kvm_vcpu_fault(struct vm_fault *vmf)
+{
+	struct kvm_vcpu *vcpu = vmf->vma->vm_file->private_data;
+	struct page *page;
+
+	if (vmf->pgoff == 0)
+		page = virt_to_page(vcpu->run);
+#ifdef CONFIG_X86
+	else if (vmf->pgoff == KVM_PIO_PAGE_OFFSET)
+		page = virt_to_page(vcpu->arch.pio_data);
+#endif
+#ifdef CONFIG_KVM_MMIO
+	else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET)
+		page = virt_to_page(vcpu->kvm->coalesced_mmio_ring);
+#endif
+	else if (kvm_page_in_dirty_ring(vcpu->kvm, vmf->pgoff))
+		page = kvm_dirty_ring_get_page(
+		    &vcpu->dirty_ring,
+		    vmf->pgoff - KVM_DIRTY_LOG_PAGE_OFFSET);
+	else
+		return kvm_arch_vcpu_fault(vcpu, vmf);
+	get_page(page);
+	vmf->page = page;
+	return 0;
+}
+
+static const struct vm_operations_struct kvm_vcpu_vm_ops = {
+	.fault = kvm_vcpu_fault,
+};
+
+static int kvm_vcpu_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct kvm_vcpu *vcpu = file->private_data;
+	unsigned long pages = vma_pages(vma);
+
+	if ((kvm_page_in_dirty_ring(vcpu->kvm, vma->vm_pgoff) ||
+	     kvm_page_in_dirty_ring(vcpu->kvm, vma->vm_pgoff + pages - 1)) &&
+	    ((vma->vm_flags & VM_EXEC) || !(vma->vm_flags & VM_SHARED)))
+		return -EINVAL;
+
+	vma->vm_ops = &kvm_vcpu_vm_ops;
+	return 0;
+}
+
+static int kvm_vcpu_release(struct inode *inode, struct file *filp)
+{
+	struct kvm_vcpu *vcpu = filp->private_data;
+
+	kvm_put_kvm(vcpu->kvm);
+	return 0;
+}
+
+static const struct file_operations kvm_vcpu_fops = {
+	.release        = kvm_vcpu_release,
+	.unlocked_ioctl = kvm_vcpu_ioctl,
+	.mmap           = kvm_vcpu_mmap,
+	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_vcpu_compat_ioctl),
+};
+
+/*
+ * Allocates an inode for the vcpu.
+ */
+static int create_vcpu_fd(struct kvm_vcpu *vcpu)
+{
+	char name[8 + 1 + ITOA_MAX_LEN + 1];
+
+	snprintf(name, sizeof(name), "kvm-vcpu:%d", vcpu->vcpu_id);
+	return anon_inode_getfd(name, &kvm_vcpu_fops, vcpu, O_RDWR | O_CLOEXEC);
+}
+
+#ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS
+static int vcpu_get_pid(void *data, u64 *val)
+{
+	struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data;
+	*val = pid_nr(rcu_access_pointer(vcpu->pid));
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(vcpu_get_pid_fops, vcpu_get_pid, NULL, "%llu\n");
+
+static void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu)
+{
+	struct dentry *debugfs_dentry;
+	char dir_name[ITOA_MAX_LEN * 2];
+
+	if (!debugfs_initialized())
+		return;
+
+	snprintf(dir_name, sizeof(dir_name), "vcpu%d", vcpu->vcpu_id);
+	debugfs_dentry = debugfs_create_dir(dir_name,
+					    vcpu->kvm->debugfs_dentry);
+	debugfs_create_file("pid", 0444, debugfs_dentry, vcpu,
+			    &vcpu_get_pid_fops);
+
+	kvm_arch_create_vcpu_debugfs(vcpu, debugfs_dentry);
+}
+#endif
+
+/*
+ * Creates some virtual cpus.  Good luck creating more than one.
+ */
+static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
+{
+	int r;
+	struct kvm_vcpu *vcpu;
+	struct page *page;
+
+	if (id >= KVM_MAX_VCPU_IDS)
+		return -EINVAL;
+
+	mutex_lock(&kvm->lock);
+	if (kvm->created_vcpus >= kvm->max_vcpus) {
+		mutex_unlock(&kvm->lock);
+		return -EINVAL;
+	}
+
+	r = kvm_arch_vcpu_precreate(kvm, id);
+	if (r) {
+		mutex_unlock(&kvm->lock);
+		return r;
+	}
+
+	kvm->created_vcpus++;
+	mutex_unlock(&kvm->lock);
+
+	vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL_ACCOUNT);
+	if (!vcpu) {
+		r = -ENOMEM;
+		goto vcpu_decrement;
+	}
+
+	BUILD_BUG_ON(sizeof(struct kvm_run) > PAGE_SIZE);
+	page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	if (!page) {
+		r = -ENOMEM;
+		goto vcpu_free;
+	}
+	vcpu->run = page_address(page);
+
+	kvm_vcpu_init(vcpu, kvm, id);
+
+	r = kvm_arch_vcpu_create(vcpu);
+	if (r)
+		goto vcpu_free_run_page;
+
+	if (kvm->dirty_ring_size) {
+		r = kvm_dirty_ring_alloc(&vcpu->dirty_ring,
+					 id, kvm->dirty_ring_size);
+		if (r)
+			goto arch_vcpu_destroy;
+	}
+
+	mutex_lock(&kvm->lock);
+	if (kvm_get_vcpu_by_id(kvm, id)) {
+		r = -EEXIST;
+		goto unlock_vcpu_destroy;
+	}
+
+	vcpu->vcpu_idx = atomic_read(&kvm->online_vcpus);
+	r = xa_reserve(&kvm->vcpu_array, vcpu->vcpu_idx, GFP_KERNEL_ACCOUNT);
+	if (r)
+		goto unlock_vcpu_destroy;
+
+	/* Now it's all set up, let userspace reach it */
+	kvm_get_kvm(kvm);
+	r = create_vcpu_fd(vcpu);
+	if (r < 0)
+		goto kvm_put_xa_release;
+
+	if (KVM_BUG_ON(!!xa_store(&kvm->vcpu_array, vcpu->vcpu_idx, vcpu, 0), kvm)) {
+		r = -EINVAL;
+		goto kvm_put_xa_release;
+	}
+
+	/*
+	 * Pairs with smp_rmb() in kvm_get_vcpu.  Store the vcpu
+	 * pointer before kvm->online_vcpu's incremented value.
+	 */
+	smp_wmb();
+	atomic_inc(&kvm->online_vcpus);
+
+	mutex_unlock(&kvm->lock);
+	kvm_arch_vcpu_postcreate(vcpu);
+	kvm_create_vcpu_debugfs(vcpu);
+	return r;
+
+kvm_put_xa_release:
+	kvm_put_kvm_no_destroy(kvm);
+	xa_release(&kvm->vcpu_array, vcpu->vcpu_idx);
+unlock_vcpu_destroy:
+	mutex_unlock(&kvm->lock);
+	kvm_dirty_ring_free(&vcpu->dirty_ring);
+arch_vcpu_destroy:
+	kvm_arch_vcpu_destroy(vcpu);
+vcpu_free_run_page:
+	free_page((unsigned long)vcpu->run);
+vcpu_free:
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
+vcpu_decrement:
+	mutex_lock(&kvm->lock);
+	kvm->created_vcpus--;
+	mutex_unlock(&kvm->lock);
+	return r;
+}
+
+static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
+{
+	if (sigset) {
+		sigdelsetmask(sigset, sigmask(SIGKILL)|sigmask(SIGSTOP));
+		vcpu->sigset_active = 1;
+		vcpu->sigset = *sigset;
+	} else
+		vcpu->sigset_active = 0;
+	return 0;
+}
+
+static ssize_t kvm_vcpu_stats_read(struct file *file, char __user *user_buffer,
+			      size_t size, loff_t *offset)
+{
+	struct kvm_vcpu *vcpu = file->private_data;
+
+	return kvm_stats_read(vcpu->stats_id, &kvm_vcpu_stats_header,
+			&kvm_vcpu_stats_desc[0], &vcpu->stat,
+			sizeof(vcpu->stat), user_buffer, size, offset);
+}
+
+static int kvm_vcpu_stats_release(struct inode *inode, struct file *file)
+{
+	struct kvm_vcpu *vcpu = file->private_data;
+
+	kvm_put_kvm(vcpu->kvm);
+	return 0;
+}
+
+static const struct file_operations kvm_vcpu_stats_fops = {
+	.read = kvm_vcpu_stats_read,
+	.release = kvm_vcpu_stats_release,
+	.llseek = noop_llseek,
+};
+
+static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu)
+{
+	int fd;
+	struct file *file;
+	char name[15 + ITOA_MAX_LEN + 1];
+
+	snprintf(name, sizeof(name), "kvm-vcpu-stats:%d", vcpu->vcpu_id);
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	file = anon_inode_getfile(name, &kvm_vcpu_stats_fops, vcpu, O_RDONLY);
+	if (IS_ERR(file)) {
+		put_unused_fd(fd);
+		return PTR_ERR(file);
+	}
+
+	kvm_get_kvm(vcpu->kvm);
+
+	file->f_mode |= FMODE_PREAD;
+	fd_install(fd, file);
+
+	return fd;
+}
+
+static long kvm_vcpu_ioctl(struct file *filp,
+			   unsigned int ioctl, unsigned long arg)
+{
+	struct kvm_vcpu *vcpu = filp->private_data;
+	void __user *argp = (void __user *)arg;
+	int r;
+	struct kvm_fpu *fpu = NULL;
+	struct kvm_sregs *kvm_sregs = NULL;
+
+	if (vcpu->kvm->mm != current->mm || vcpu->kvm->vm_dead)
+		return -EIO;
+
+	if (unlikely(_IOC_TYPE(ioctl) != KVMIO))
+		return -EINVAL;
+
+	/*
+	 * Some architectures have vcpu ioctls that are asynchronous to vcpu
+	 * execution; mutex_lock() would break them.
+	 */
+	r = kvm_arch_vcpu_async_ioctl(filp, ioctl, arg);
+	if (r != -ENOIOCTLCMD)
+		return r;
+
+	if (mutex_lock_killable(&vcpu->mutex))
+		return -EINTR;
+	switch (ioctl) {
+	case KVM_RUN: {
+		struct pid *oldpid;
+		r = -EINVAL;
+		if (arg)
+			goto out;
+		oldpid = rcu_access_pointer(vcpu->pid);
+		if (unlikely(oldpid != task_pid(current))) {
+			/* The thread running this VCPU changed. */
+			struct pid *newpid;
+
+			r = kvm_arch_vcpu_run_pid_change(vcpu);
+			if (r)
+				break;
+
+			newpid = get_task_pid(current, PIDTYPE_PID);
+			rcu_assign_pointer(vcpu->pid, newpid);
+			if (oldpid)
+				synchronize_rcu();
+			put_pid(oldpid);
+		}
+		r = kvm_arch_vcpu_ioctl_run(vcpu);
+		trace_kvm_userspace_exit(vcpu->run->exit_reason, r);
+		break;
+	}
+	case KVM_GET_REGS: {
+		struct kvm_regs *kvm_regs;
+
+		r = -ENOMEM;
+		kvm_regs = kzalloc(sizeof(struct kvm_regs), GFP_KERNEL_ACCOUNT);
+		if (!kvm_regs)
+			goto out;
+		r = kvm_arch_vcpu_ioctl_get_regs(vcpu, kvm_regs);
+		if (r)
+			goto out_free1;
+		r = -EFAULT;
+		if (copy_to_user(argp, kvm_regs, sizeof(struct kvm_regs)))
+			goto out_free1;
+		r = 0;
+out_free1:
+		kfree(kvm_regs);
+		break;
+	}
+	case KVM_SET_REGS: {
+		struct kvm_regs *kvm_regs;
+
+		kvm_regs = memdup_user(argp, sizeof(*kvm_regs));
+		if (IS_ERR(kvm_regs)) {
+			r = PTR_ERR(kvm_regs);
+			goto out;
+		}
+		r = kvm_arch_vcpu_ioctl_set_regs(vcpu, kvm_regs);
+		kfree(kvm_regs);
+		break;
+	}
+	case KVM_GET_SREGS: {
+		kvm_sregs = kzalloc(sizeof(struct kvm_sregs),
+				    GFP_KERNEL_ACCOUNT);
+		r = -ENOMEM;
+		if (!kvm_sregs)
+			goto out;
+		r = kvm_arch_vcpu_ioctl_get_sregs(vcpu, kvm_sregs);
+		if (r)
+			goto out;
+		r = -EFAULT;
+		if (copy_to_user(argp, kvm_sregs, sizeof(struct kvm_sregs)))
+			goto out;
+		r = 0;
+		break;
+	}
+	case KVM_SET_SREGS: {
+		kvm_sregs = memdup_user(argp, sizeof(*kvm_sregs));
+		if (IS_ERR(kvm_sregs)) {
+			r = PTR_ERR(kvm_sregs);
+			kvm_sregs = NULL;
+			goto out;
+		}
+		r = kvm_arch_vcpu_ioctl_set_sregs(vcpu, kvm_sregs);
+		break;
+	}
+	case KVM_GET_MP_STATE: {
+		struct kvm_mp_state mp_state;
+
+		r = kvm_arch_vcpu_ioctl_get_mpstate(vcpu, &mp_state);
+		if (r)
+			goto out;
+		r = -EFAULT;
+		if (copy_to_user(argp, &mp_state, sizeof(mp_state)))
+			goto out;
+		r = 0;
+		break;
+	}
+	case KVM_SET_MP_STATE: {
+		struct kvm_mp_state mp_state;
+
+		r = -EFAULT;
+		if (copy_from_user(&mp_state, argp, sizeof(mp_state)))
+			goto out;
+		r = kvm_arch_vcpu_ioctl_set_mpstate(vcpu, &mp_state);
+		break;
+	}
+	case KVM_TRANSLATE: {
+		struct kvm_translation tr;
+
+		r = -EFAULT;
+		if (copy_from_user(&tr, argp, sizeof(tr)))
+			goto out;
+		r = kvm_arch_vcpu_ioctl_translate(vcpu, &tr);
+		if (r)
+			goto out;
+		r = -EFAULT;
+		if (copy_to_user(argp, &tr, sizeof(tr)))
+			goto out;
+		r = 0;
+		break;
+	}
+	case KVM_SET_GUEST_DEBUG: {
+		struct kvm_guest_debug dbg;
+
+		r = -EFAULT;
+		if (copy_from_user(&dbg, argp, sizeof(dbg)))
+			goto out;
+		r = kvm_arch_vcpu_ioctl_set_guest_debug(vcpu, &dbg);
+		break;
+	}
+	case KVM_SET_SIGNAL_MASK: {
+		struct kvm_signal_mask __user *sigmask_arg = argp;
+		struct kvm_signal_mask kvm_sigmask;
+		sigset_t sigset, *p;
+
+		p = NULL;
+		if (argp) {
+			r = -EFAULT;
+			if (copy_from_user(&kvm_sigmask, argp,
+					   sizeof(kvm_sigmask)))
+				goto out;
+			r = -EINVAL;
+			if (kvm_sigmask.len != sizeof(sigset))
+				goto out;
+			r = -EFAULT;
+			if (copy_from_user(&sigset, sigmask_arg->sigset,
+					   sizeof(sigset)))
+				goto out;
+			p = &sigset;
+		}
+		r = kvm_vcpu_ioctl_set_sigmask(vcpu, p);
+		break;
+	}
+	case KVM_GET_FPU: {
+		fpu = kzalloc(sizeof(struct kvm_fpu), GFP_KERNEL_ACCOUNT);
+		r = -ENOMEM;
+		if (!fpu)
+			goto out;
+		r = kvm_arch_vcpu_ioctl_get_fpu(vcpu, fpu);
+		if (r)
+			goto out;
+		r = -EFAULT;
+		if (copy_to_user(argp, fpu, sizeof(struct kvm_fpu)))
+			goto out;
+		r = 0;
+		break;
+	}
+	case KVM_SET_FPU: {
+		fpu = memdup_user(argp, sizeof(*fpu));
+		if (IS_ERR(fpu)) {
+			r = PTR_ERR(fpu);
+			fpu = NULL;
+			goto out;
+		}
+		r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu);
+		break;
+	}
+	case KVM_GET_STATS_FD: {
+		r = kvm_vcpu_ioctl_get_stats_fd(vcpu);
+		break;
+	}
+	default:
+		r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
+	}
+out:
+	mutex_unlock(&vcpu->mutex);
+	kfree(fpu);
+	kfree(kvm_sregs);
+	return r;
+}
+
+#ifdef CONFIG_KVM_COMPAT
+static long kvm_vcpu_compat_ioctl(struct file *filp,
+				  unsigned int ioctl, unsigned long arg)
+{
+	struct kvm_vcpu *vcpu = filp->private_data;
+	void __user *argp = compat_ptr(arg);
+	int r;
+
+	if (vcpu->kvm->mm != current->mm || vcpu->kvm->vm_dead)
+		return -EIO;
+
+	switch (ioctl) {
+	case KVM_SET_SIGNAL_MASK: {
+		struct kvm_signal_mask __user *sigmask_arg = argp;
+		struct kvm_signal_mask kvm_sigmask;
+		sigset_t sigset;
+
+		if (argp) {
+			r = -EFAULT;
+			if (copy_from_user(&kvm_sigmask, argp,
+					   sizeof(kvm_sigmask)))
+				goto out;
+			r = -EINVAL;
+			if (kvm_sigmask.len != sizeof(compat_sigset_t))
+				goto out;
+			r = -EFAULT;
+			if (get_compat_sigset(&sigset,
+					      (compat_sigset_t __user *)sigmask_arg->sigset))
+				goto out;
+			r = kvm_vcpu_ioctl_set_sigmask(vcpu, &sigset);
+		} else
+			r = kvm_vcpu_ioctl_set_sigmask(vcpu, NULL);
+		break;
+	}
+	default:
+		r = kvm_vcpu_ioctl(filp, ioctl, arg);
+	}
+
+out:
+	return r;
+}
+#endif
+
+static int kvm_device_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct kvm_device *dev = filp->private_data;
+
+	if (dev->ops->mmap)
+		return dev->ops->mmap(dev, vma);
+
+	return -ENODEV;
+}
+
+static int kvm_device_ioctl_attr(struct kvm_device *dev,
+				 int (*accessor)(struct kvm_device *dev,
+						 struct kvm_device_attr *attr),
+				 unsigned long arg)
+{
+	struct kvm_device_attr attr;
+
+	if (!accessor)
+		return -EPERM;
+
+	if (copy_from_user(&attr, (void __user *)arg, sizeof(attr)))
+		return -EFAULT;
+
+	return accessor(dev, &attr);
+}
+
+static long kvm_device_ioctl(struct file *filp, unsigned int ioctl,
+			     unsigned long arg)
+{
+	struct kvm_device *dev = filp->private_data;
+
+	if (dev->kvm->mm != current->mm || dev->kvm->vm_dead)
+		return -EIO;
+
+	switch (ioctl) {
+	case KVM_SET_DEVICE_ATTR:
+		return kvm_device_ioctl_attr(dev, dev->ops->set_attr, arg);
+	case KVM_GET_DEVICE_ATTR:
+		return kvm_device_ioctl_attr(dev, dev->ops->get_attr, arg);
+	case KVM_HAS_DEVICE_ATTR:
+		return kvm_device_ioctl_attr(dev, dev->ops->has_attr, arg);
+	default:
+		if (dev->ops->ioctl)
+			return dev->ops->ioctl(dev, ioctl, arg);
+
+		return -ENOTTY;
+	}
+}
+
+static int kvm_device_release(struct inode *inode, struct file *filp)
+{
+	struct kvm_device *dev = filp->private_data;
+	struct kvm *kvm = dev->kvm;
+
+	if (dev->ops->release) {
+		mutex_lock(&kvm->lock);
+		list_del(&dev->vm_node);
+		dev->ops->release(dev);
+		mutex_unlock(&kvm->lock);
+	}
+
+	kvm_put_kvm(kvm);
+	return 0;
+}
+
+static const struct file_operations kvm_device_fops = {
+	.unlocked_ioctl = kvm_device_ioctl,
+	.release = kvm_device_release,
+	KVM_COMPAT(kvm_device_ioctl),
+	.mmap = kvm_device_mmap,
+};
+
+struct kvm_device *kvm_device_from_filp(struct file *filp)
+{
+	if (filp->f_op != &kvm_device_fops)
+		return NULL;
+
+	return filp->private_data;
+}
+
+static const struct kvm_device_ops *kvm_device_ops_table[KVM_DEV_TYPE_MAX] = {
+#ifdef CONFIG_KVM_MPIC
+	[KVM_DEV_TYPE_FSL_MPIC_20]	= &kvm_mpic_ops,
+	[KVM_DEV_TYPE_FSL_MPIC_42]	= &kvm_mpic_ops,
+#endif
+};
+
+int kvm_register_device_ops(const struct kvm_device_ops *ops, u32 type)
+{
+	if (type >= ARRAY_SIZE(kvm_device_ops_table))
+		return -ENOSPC;
+
+	if (kvm_device_ops_table[type] != NULL)
+		return -EEXIST;
+
+	kvm_device_ops_table[type] = ops;
+	return 0;
+}
+
+void kvm_unregister_device_ops(u32 type)
+{
+	if (kvm_device_ops_table[type] != NULL)
+		kvm_device_ops_table[type] = NULL;
+}
+
+static int kvm_ioctl_create_device(struct kvm *kvm,
+				   struct kvm_create_device *cd)
+{
+	const struct kvm_device_ops *ops;
+	struct kvm_device *dev;
+	bool test = cd->flags & KVM_CREATE_DEVICE_TEST;
+	int type;
+	int ret;
+
+	if (cd->type >= ARRAY_SIZE(kvm_device_ops_table))
+		return -ENODEV;
+
+	type = array_index_nospec(cd->type, ARRAY_SIZE(kvm_device_ops_table));
+	ops = kvm_device_ops_table[type];
+	if (ops == NULL)
+		return -ENODEV;
+
+	if (test)
+		return 0;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL_ACCOUNT);
+	if (!dev)
+		return -ENOMEM;
+
+	dev->ops = ops;
+	dev->kvm = kvm;
+
+	mutex_lock(&kvm->lock);
+	ret = ops->create(dev, type);
+	if (ret < 0) {
+		mutex_unlock(&kvm->lock);
+		kfree(dev);
+		return ret;
+	}
+	list_add(&dev->vm_node, &kvm->devices);
+	mutex_unlock(&kvm->lock);
+
+	if (ops->init)
+		ops->init(dev);
+
+	kvm_get_kvm(kvm);
+	ret = anon_inode_getfd(ops->name, &kvm_device_fops, dev, O_RDWR | O_CLOEXEC);
+	if (ret < 0) {
+		kvm_put_kvm_no_destroy(kvm);
+		mutex_lock(&kvm->lock);
+		list_del(&dev->vm_node);
+		if (ops->release)
+			ops->release(dev);
+		mutex_unlock(&kvm->lock);
+		if (ops->destroy)
+			ops->destroy(dev);
+		return ret;
+	}
+
+	cd->fd = ret;
+	return 0;
+}
+
+static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
+{
+	switch (arg) {
+	case KVM_CAP_USER_MEMORY:
+	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
+	case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS:
+	case KVM_CAP_INTERNAL_ERROR_DATA:
+#ifdef CONFIG_HAVE_KVM_MSI
+	case KVM_CAP_SIGNAL_MSI:
+#endif
+#ifdef CONFIG_HAVE_KVM_IRQFD
+	case KVM_CAP_IRQFD:
+	case KVM_CAP_IRQFD_RESAMPLE:
+#endif
+	case KVM_CAP_IOEVENTFD_ANY_LENGTH:
+	case KVM_CAP_CHECK_EXTENSION_VM:
+	case KVM_CAP_ENABLE_CAP_VM:
+	case KVM_CAP_HALT_POLL:
+		return 1;
+#ifdef CONFIG_KVM_MMIO
+	case KVM_CAP_COALESCED_MMIO:
+		return KVM_COALESCED_MMIO_PAGE_OFFSET;
+	case KVM_CAP_COALESCED_PIO:
+		return 1;
+#endif
+#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2:
+		return KVM_DIRTY_LOG_MANUAL_CAPS;
+#endif
+#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
+	case KVM_CAP_IRQ_ROUTING:
+		return KVM_MAX_IRQ_ROUTES;
+#endif
+#if KVM_ADDRESS_SPACE_NUM > 1
+	case KVM_CAP_MULTI_ADDRESS_SPACE:
+		return KVM_ADDRESS_SPACE_NUM;
+#endif
+	case KVM_CAP_NR_MEMSLOTS:
+		return KVM_USER_MEM_SLOTS;
+	case KVM_CAP_DIRTY_LOG_RING:
+#ifdef CONFIG_HAVE_KVM_DIRTY_RING_TSO
+		return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn);
+#else
+		return 0;
+#endif
+	case KVM_CAP_DIRTY_LOG_RING_ACQ_REL:
+#ifdef CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL
+		return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn);
+#else
+		return 0;
+#endif
+	case KVM_CAP_BINARY_STATS_FD:
+	case KVM_CAP_SYSTEM_EVENT_DATA:
+		return 1;
+	default:
+		break;
+	}
+	return kvm_vm_ioctl_check_extension(kvm, arg);
+}
+
+static int kvm_vm_ioctl_enable_dirty_log_ring(struct kvm *kvm, u32 size)
+{
+	int r;
+
+	if (!KVM_DIRTY_LOG_PAGE_OFFSET)
+		return -EINVAL;
+
+	/* the size should be power of 2 */
+	if (!size || (size & (size - 1)))
+		return -EINVAL;
+
+	/* Should be bigger to keep the reserved entries, or a page */
+	if (size < kvm_dirty_ring_get_rsvd_entries() *
+	    sizeof(struct kvm_dirty_gfn) || size < PAGE_SIZE)
+		return -EINVAL;
+
+	if (size > KVM_DIRTY_RING_MAX_ENTRIES *
+	    sizeof(struct kvm_dirty_gfn))
+		return -E2BIG;
+
+	/* We only allow it to set once */
+	if (kvm->dirty_ring_size)
+		return -EINVAL;
+
+	mutex_lock(&kvm->lock);
+
+	if (kvm->created_vcpus) {
+		/* We don't allow to change this value after vcpu created */
+		r = -EINVAL;
+	} else {
+		kvm->dirty_ring_size = size;
+		r = 0;
+	}
+
+	mutex_unlock(&kvm->lock);
+	return r;
+}
+
+static int kvm_vm_ioctl_reset_dirty_pages(struct kvm *kvm)
+{
+	unsigned long i;
+	struct kvm_vcpu *vcpu;
+	int cleared = 0;
+
+	if (!kvm->dirty_ring_size)
+		return -EINVAL;
+
+	mutex_lock(&kvm->slots_lock);
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		cleared += kvm_dirty_ring_reset(vcpu->kvm, &vcpu->dirty_ring);
+
+	mutex_unlock(&kvm->slots_lock);
+
+	if (cleared)
+		kvm_flush_remote_tlbs(kvm);
+
+	return cleared;
+}
+
+int __attribute__((weak)) kvm_vm_ioctl_enable_cap(struct kvm *kvm,
+						  struct kvm_enable_cap *cap)
+{
+	return -EINVAL;
+}
+
+static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
+					   struct kvm_enable_cap *cap)
+{
+	switch (cap->cap) {
+#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2: {
+		u64 allowed_options = KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE;
+
+		if (cap->args[0] & KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE)
+			allowed_options = KVM_DIRTY_LOG_MANUAL_CAPS;
+
+		if (cap->flags || (cap->args[0] & ~allowed_options))
+			return -EINVAL;
+		kvm->manual_dirty_log_protect = cap->args[0];
+		return 0;
+	}
+#endif
+	case KVM_CAP_HALT_POLL: {
+		if (cap->flags || cap->args[0] != (unsigned int)cap->args[0])
+			return -EINVAL;
+
+		kvm->max_halt_poll_ns = cap->args[0];
+
+		/*
+		 * Ensure kvm->override_halt_poll_ns does not become visible
+		 * before kvm->max_halt_poll_ns.
+		 *
+		 * Pairs with the smp_rmb() in kvm_vcpu_max_halt_poll_ns().
+		 */
+		smp_wmb();
+		kvm->override_halt_poll_ns = true;
+
+		return 0;
+	}
+	case KVM_CAP_DIRTY_LOG_RING:
+	case KVM_CAP_DIRTY_LOG_RING_ACQ_REL:
+		if (!kvm_vm_ioctl_check_extension_generic(kvm, cap->cap))
+			return -EINVAL;
+
+		return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]);
+	default:
+		return kvm_vm_ioctl_enable_cap(kvm, cap);
+	}
+}
+
+static ssize_t kvm_vm_stats_read(struct file *file, char __user *user_buffer,
+			      size_t size, loff_t *offset)
+{
+	struct kvm *kvm = file->private_data;
+
+	return kvm_stats_read(kvm->stats_id, &kvm_vm_stats_header,
+				&kvm_vm_stats_desc[0], &kvm->stat,
+				sizeof(kvm->stat), user_buffer, size, offset);
+}
+
+static int kvm_vm_stats_release(struct inode *inode, struct file *file)
+{
+	struct kvm *kvm = file->private_data;
+
+	kvm_put_kvm(kvm);
+	return 0;
+}
+
+static const struct file_operations kvm_vm_stats_fops = {
+	.read = kvm_vm_stats_read,
+	.release = kvm_vm_stats_release,
+	.llseek = noop_llseek,
+};
+
+static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm)
+{
+	int fd;
+	struct file *file;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	file = anon_inode_getfile("kvm-vm-stats",
+			&kvm_vm_stats_fops, kvm, O_RDONLY);
+	if (IS_ERR(file)) {
+		put_unused_fd(fd);
+		return PTR_ERR(file);
+	}
+
+	kvm_get_kvm(kvm);
+
+	file->f_mode |= FMODE_PREAD;
+	fd_install(fd, file);
+
+	return fd;
+}
+
+static long kvm_vm_ioctl(struct file *filp,
+			   unsigned int ioctl, unsigned long arg)
+{
+	struct kvm *kvm = filp->private_data;
+	void __user *argp = (void __user *)arg;
+	int r;
+
+	if (kvm->mm != current->mm || kvm->vm_dead)
+		return -EIO;
+	switch (ioctl) {
+	case KVM_CREATE_VCPU:
+		r = kvm_vm_ioctl_create_vcpu(kvm, arg);
+		break;
+	case KVM_ENABLE_CAP: {
+		struct kvm_enable_cap cap;
+
+		r = -EFAULT;
+		if (copy_from_user(&cap, argp, sizeof(cap)))
+			goto out;
+		r = kvm_vm_ioctl_enable_cap_generic(kvm, &cap);
+		break;
+	}
+	case KVM_SET_USER_MEMORY_REGION: {
+		struct kvm_userspace_memory_region kvm_userspace_mem;
+
+		r = -EFAULT;
+		if (copy_from_user(&kvm_userspace_mem, argp,
+						sizeof(kvm_userspace_mem)))
+			goto out;
+
+		r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem);
+		break;
+	}
+	case KVM_GET_DIRTY_LOG: {
+		struct kvm_dirty_log log;
+
+		r = -EFAULT;
+		if (copy_from_user(&log, argp, sizeof(log)))
+			goto out;
+		r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
+		break;
+	}
+#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	case KVM_CLEAR_DIRTY_LOG: {
+		struct kvm_clear_dirty_log log;
+
+		r = -EFAULT;
+		if (copy_from_user(&log, argp, sizeof(log)))
+			goto out;
+		r = kvm_vm_ioctl_clear_dirty_log(kvm, &log);
+		break;
+	}
+#endif
+#ifdef CONFIG_KVM_MMIO
+	case KVM_REGISTER_COALESCED_MMIO: {
+		struct kvm_coalesced_mmio_zone zone;
+
+		r = -EFAULT;
+		if (copy_from_user(&zone, argp, sizeof(zone)))
+			goto out;
+		r = kvm_vm_ioctl_register_coalesced_mmio(kvm, &zone);
+		break;
+	}
+	case KVM_UNREGISTER_COALESCED_MMIO: {
+		struct kvm_coalesced_mmio_zone zone;
+
+		r = -EFAULT;
+		if (copy_from_user(&zone, argp, sizeof(zone)))
+			goto out;
+		r = kvm_vm_ioctl_unregister_coalesced_mmio(kvm, &zone);
+		break;
+	}
+#endif
+	case KVM_IRQFD: {
+		struct kvm_irqfd data;
+
+		r = -EFAULT;
+		if (copy_from_user(&data, argp, sizeof(data)))
+			goto out;
+		r = kvm_irqfd(kvm, &data);
+		break;
+	}
+	case KVM_IOEVENTFD: {
+		struct kvm_ioeventfd data;
+
+		r = -EFAULT;
+		if (copy_from_user(&data, argp, sizeof(data)))
+			goto out;
+		r = kvm_ioeventfd(kvm, &data);
+		break;
+	}
+#ifdef CONFIG_HAVE_KVM_MSI
+	case KVM_SIGNAL_MSI: {
+		struct kvm_msi msi;
+
+		r = -EFAULT;
+		if (copy_from_user(&msi, argp, sizeof(msi)))
+			goto out;
+		r = kvm_send_userspace_msi(kvm, &msi);
+		break;
+	}
+#endif
+#ifdef __KVM_HAVE_IRQ_LINE
+	case KVM_IRQ_LINE_STATUS:
+	case KVM_IRQ_LINE: {
+		struct kvm_irq_level irq_event;
+
+		r = -EFAULT;
+		if (copy_from_user(&irq_event, argp, sizeof(irq_event)))
+			goto out;
+
+		r = kvm_vm_ioctl_irq_line(kvm, &irq_event,
+					ioctl == KVM_IRQ_LINE_STATUS);
+		if (r)
+			goto out;
+
+		r = -EFAULT;
+		if (ioctl == KVM_IRQ_LINE_STATUS) {
+			if (copy_to_user(argp, &irq_event, sizeof(irq_event)))
+				goto out;
+		}
+
+		r = 0;
+		break;
+	}
+#endif
+#ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
+	case KVM_SET_GSI_ROUTING: {
+		struct kvm_irq_routing routing;
+		struct kvm_irq_routing __user *urouting;
+		struct kvm_irq_routing_entry *entries = NULL;
+
+		r = -EFAULT;
+		if (copy_from_user(&routing, argp, sizeof(routing)))
+			goto out;
+		r = -EINVAL;
+		if (!kvm_arch_can_set_irq_routing(kvm))
+			goto out;
+		if (routing.nr > KVM_MAX_IRQ_ROUTES)
+			goto out;
+		if (routing.flags)
+			goto out;
+		if (routing.nr) {
+			urouting = argp;
+			entries = vmemdup_user(urouting->entries,
+					       array_size(sizeof(*entries),
+							  routing.nr));
+			if (IS_ERR(entries)) {
+				r = PTR_ERR(entries);
+				goto out;
+			}
+		}
+		r = kvm_set_irq_routing(kvm, entries, routing.nr,
+					routing.flags);
+		kvfree(entries);
+		break;
+	}
+#endif /* CONFIG_HAVE_KVM_IRQ_ROUTING */
+	case KVM_CREATE_DEVICE: {
+		struct kvm_create_device cd;
+
+		r = -EFAULT;
+		if (copy_from_user(&cd, argp, sizeof(cd)))
+			goto out;
+
+		r = kvm_ioctl_create_device(kvm, &cd);
+		if (r)
+			goto out;
+
+		r = -EFAULT;
+		if (copy_to_user(argp, &cd, sizeof(cd)))
+			goto out;
+
+		r = 0;
+		break;
+	}
+	case KVM_CHECK_EXTENSION:
+		r = kvm_vm_ioctl_check_extension_generic(kvm, arg);
+		break;
+	case KVM_RESET_DIRTY_RINGS:
+		r = kvm_vm_ioctl_reset_dirty_pages(kvm);
+		break;
+	case KVM_GET_STATS_FD:
+		r = kvm_vm_ioctl_get_stats_fd(kvm);
+		break;
+	default:
+		r = kvm_arch_vm_ioctl(filp, ioctl, arg);
+	}
+out:
+	return r;
+}
+
+#ifdef CONFIG_KVM_COMPAT
+struct compat_kvm_dirty_log {
+	__u32 slot;
+	__u32 padding1;
+	union {
+		compat_uptr_t dirty_bitmap; /* one bit per page */
+		__u64 padding2;
+	};
+};
+
+struct compat_kvm_clear_dirty_log {
+	__u32 slot;
+	__u32 num_pages;
+	__u64 first_page;
+	union {
+		compat_uptr_t dirty_bitmap; /* one bit per page */
+		__u64 padding2;
+	};
+};
+
+long __weak kvm_arch_vm_compat_ioctl(struct file *filp, unsigned int ioctl,
+				     unsigned long arg)
+{
+	return -ENOTTY;
+}
+
+static long kvm_vm_compat_ioctl(struct file *filp,
+			   unsigned int ioctl, unsigned long arg)
+{
+	struct kvm *kvm = filp->private_data;
+	int r;
+
+	if (kvm->mm != current->mm || kvm->vm_dead)
+		return -EIO;
+
+	r = kvm_arch_vm_compat_ioctl(filp, ioctl, arg);
+	if (r != -ENOTTY)
+		return r;
+
+	switch (ioctl) {
+#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	case KVM_CLEAR_DIRTY_LOG: {
+		struct compat_kvm_clear_dirty_log compat_log;
+		struct kvm_clear_dirty_log log;
+
+		if (copy_from_user(&compat_log, (void __user *)arg,
+				   sizeof(compat_log)))
+			return -EFAULT;
+		log.slot	 = compat_log.slot;
+		log.num_pages	 = compat_log.num_pages;
+		log.first_page	 = compat_log.first_page;
+		log.padding2	 = compat_log.padding2;
+		log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
+
+		r = kvm_vm_ioctl_clear_dirty_log(kvm, &log);
+		break;
+	}
+#endif
+	case KVM_GET_DIRTY_LOG: {
+		struct compat_kvm_dirty_log compat_log;
+		struct kvm_dirty_log log;
+
+		if (copy_from_user(&compat_log, (void __user *)arg,
+				   sizeof(compat_log)))
+			return -EFAULT;
+		log.slot	 = compat_log.slot;
+		log.padding1	 = compat_log.padding1;
+		log.padding2	 = compat_log.padding2;
+		log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
+
+		r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
+		break;
+	}
+	default:
+		r = kvm_vm_ioctl(filp, ioctl, arg);
+	}
+	return r;
+}
+#endif
+
+static const struct file_operations kvm_vm_fops = {
+	.release        = kvm_vm_release,
+	.unlocked_ioctl = kvm_vm_ioctl,
+	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_vm_compat_ioctl),
+};
+
+bool file_is_kvm(struct file *file)
+{
+	return file && file->f_op == &kvm_vm_fops;
+}
+EXPORT_SYMBOL_GPL(file_is_kvm);
+
+static int kvm_dev_ioctl_create_vm(unsigned long type)
+{
+	char fdname[ITOA_MAX_LEN + 1];
+	int r, fd;
+	struct kvm *kvm;
+	struct file *file;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	snprintf(fdname, sizeof(fdname), "%d", fd);
+
+	kvm = kvm_create_vm(type, fdname);
+	if (IS_ERR(kvm)) {
+		r = PTR_ERR(kvm);
+		goto put_fd;
+	}
+
+	file = anon_inode_getfile("kvm-vm", &kvm_vm_fops, kvm, O_RDWR);
+	if (IS_ERR(file)) {
+		r = PTR_ERR(file);
+		goto put_kvm;
+	}
+
+	/*
+	 * Don't call kvm_put_kvm anymore at this point; file->f_op is
+	 * already set, with ->release() being kvm_vm_release().  In error
+	 * cases it will be called by the final fput(file) and will take
+	 * care of doing kvm_put_kvm(kvm).
+	 */
+	kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm);
+
+	fd_install(fd, file);
+	return fd;
+
+put_kvm:
+	kvm_put_kvm(kvm);
+put_fd:
+	put_unused_fd(fd);
+	return r;
+}
+
+static long kvm_dev_ioctl(struct file *filp,
+			  unsigned int ioctl, unsigned long arg)
+{
+	long r = -EINVAL;
+
+	switch (ioctl) {
+	case KVM_GET_API_VERSION:
+		if (arg)
+			goto out;
+		r = KVM_API_VERSION;
+		break;
+	case KVM_CREATE_VM:
+		r = kvm_dev_ioctl_create_vm(arg);
+		break;
+	case KVM_CHECK_EXTENSION:
+		r = kvm_vm_ioctl_check_extension_generic(NULL, arg);
+		break;
+	case KVM_GET_VCPU_MMAP_SIZE:
+		if (arg)
+			goto out;
+		r = PAGE_SIZE;     /* struct kvm_run */
+#ifdef CONFIG_X86
+		r += PAGE_SIZE;    /* pio data page */
+#endif
+#ifdef CONFIG_KVM_MMIO
+		r += PAGE_SIZE;    /* coalesced mmio ring page */
+#endif
+		break;
+	case KVM_TRACE_ENABLE:
+	case KVM_TRACE_PAUSE:
+	case KVM_TRACE_DISABLE:
+		r = -EOPNOTSUPP;
+		break;
+	default:
+		return kvm_arch_dev_ioctl(filp, ioctl, arg);
+	}
+out:
+	return r;
+}
+
+static struct file_operations kvm_chardev_ops = {
+	.unlocked_ioctl = kvm_dev_ioctl,
+	.llseek		= noop_llseek,
+	KVM_COMPAT(kvm_dev_ioctl),
+};
+
+static struct miscdevice kvm_dev = {
+	KVM_MINOR,
+	"kvm",
+	&kvm_chardev_ops,
+};
+
+static void hardware_enable_nolock(void *junk)
+{
+	int cpu = raw_smp_processor_id();
+	int r;
+
+	if (cpumask_test_cpu(cpu, cpus_hardware_enabled))
+		return;
+
+	cpumask_set_cpu(cpu, cpus_hardware_enabled);
+
+	r = kvm_arch_hardware_enable();
+
+	if (r) {
+		cpumask_clear_cpu(cpu, cpus_hardware_enabled);
+		atomic_inc(&hardware_enable_failed);
+		pr_info("kvm: enabling virtualization on CPU%d failed\n", cpu);
+	}
+}
+
+static int kvm_starting_cpu(unsigned int cpu)
+{
+	raw_spin_lock(&kvm_count_lock);
+	if (kvm_usage_count)
+		hardware_enable_nolock(NULL);
+	raw_spin_unlock(&kvm_count_lock);
+	return 0;
+}
+
+static void hardware_disable_nolock(void *junk)
+{
+	int cpu = raw_smp_processor_id();
+
+	if (!cpumask_test_cpu(cpu, cpus_hardware_enabled))
+		return;
+	cpumask_clear_cpu(cpu, cpus_hardware_enabled);
+	kvm_arch_hardware_disable();
+}
+
+static int kvm_dying_cpu(unsigned int cpu)
+{
+	raw_spin_lock(&kvm_count_lock);
+	if (kvm_usage_count)
+		hardware_disable_nolock(NULL);
+	raw_spin_unlock(&kvm_count_lock);
+	return 0;
+}
+
+static void hardware_disable_all_nolock(void)
+{
+	BUG_ON(!kvm_usage_count);
+
+	kvm_usage_count--;
+	if (!kvm_usage_count)
+		on_each_cpu(hardware_disable_nolock, NULL, 1);
+}
+
+static void hardware_disable_all(void)
+{
+	raw_spin_lock(&kvm_count_lock);
+	hardware_disable_all_nolock();
+	raw_spin_unlock(&kvm_count_lock);
+}
+
+static int hardware_enable_all(void)
+{
+	int r = 0;
+
+	raw_spin_lock(&kvm_count_lock);
+
+	kvm_usage_count++;
+	if (kvm_usage_count == 1) {
+		atomic_set(&hardware_enable_failed, 0);
+		on_each_cpu(hardware_enable_nolock, NULL, 1);
+
+		if (atomic_read(&hardware_enable_failed)) {
+			hardware_disable_all_nolock();
+			r = -EBUSY;
+		}
+	}
+
+	raw_spin_unlock(&kvm_count_lock);
+
+	return r;
+}
+
+static int kvm_reboot(struct notifier_block *notifier, unsigned long val,
+		      void *v)
+{
+	/*
+	 * Some (well, at least mine) BIOSes hang on reboot if
+	 * in vmx root mode.
+	 *
+	 * And Intel TXT required VMX off for all cpu when system shutdown.
+	 */
+	pr_info("kvm: exiting hardware virtualization\n");
+	kvm_rebooting = true;
+	on_each_cpu(hardware_disable_nolock, NULL, 1);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block kvm_reboot_notifier = {
+	.notifier_call = kvm_reboot,
+	.priority = 0,
+};
+
+static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
+{
+	int i;
+
+	for (i = 0; i < bus->dev_count; i++) {
+		struct kvm_io_device *pos = bus->range[i].dev;
+
+		kvm_iodevice_destructor(pos);
+	}
+	kfree(bus);
+}
+
+static inline int kvm_io_bus_cmp(const struct kvm_io_range *r1,
+				 const struct kvm_io_range *r2)
+{
+	gpa_t addr1 = r1->addr;
+	gpa_t addr2 = r2->addr;
+
+	if (addr1 < addr2)
+		return -1;
+
+	/* If r2->len == 0, match the exact address.  If r2->len != 0,
+	 * accept any overlapping write.  Any order is acceptable for
+	 * overlapping ranges, because kvm_io_bus_get_first_dev ensures
+	 * we process all of them.
+	 */
+	if (r2->len) {
+		addr1 += r1->len;
+		addr2 += r2->len;
+	}
+
+	if (addr1 > addr2)
+		return 1;
+
+	return 0;
+}
+
+static int kvm_io_bus_sort_cmp(const void *p1, const void *p2)
+{
+	return kvm_io_bus_cmp(p1, p2);
+}
+
+static int kvm_io_bus_get_first_dev(struct kvm_io_bus *bus,
+			     gpa_t addr, int len)
+{
+	struct kvm_io_range *range, key;
+	int off;
+
+	key = (struct kvm_io_range) {
+		.addr = addr,
+		.len = len,
+	};
+
+	range = bsearch(&key, bus->range, bus->dev_count,
+			sizeof(struct kvm_io_range), kvm_io_bus_sort_cmp);
+	if (range == NULL)
+		return -ENOENT;
+
+	off = range - bus->range;
+
+	while (off > 0 && kvm_io_bus_cmp(&key, &bus->range[off-1]) == 0)
+		off--;
+
+	return off;
+}
+
+static int __kvm_io_bus_write(struct kvm_vcpu *vcpu, struct kvm_io_bus *bus,
+			      struct kvm_io_range *range, const void *val)
+{
+	int idx;
+
+	idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
+	if (idx < 0)
+		return -EOPNOTSUPP;
+
+	while (idx < bus->dev_count &&
+		kvm_io_bus_cmp(range, &bus->range[idx]) == 0) {
+		if (!kvm_iodevice_write(vcpu, bus->range[idx].dev, range->addr,
+					range->len, val))
+			return idx;
+		idx++;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+/* kvm_io_bus_write - called under kvm->slots_lock */
+int kvm_io_bus_write(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
+		     int len, const void *val)
+{
+	struct kvm_io_bus *bus;
+	struct kvm_io_range range;
+	int r;
+
+	range = (struct kvm_io_range) {
+		.addr = addr,
+		.len = len,
+	};
+
+	bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
+	if (!bus)
+		return -ENOMEM;
+	r = __kvm_io_bus_write(vcpu, bus, &range, val);
+	return r < 0 ? r : 0;
+}
+EXPORT_SYMBOL_GPL(kvm_io_bus_write);
+
+/* kvm_io_bus_write_cookie - called under kvm->slots_lock */
+int kvm_io_bus_write_cookie(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx,
+			    gpa_t addr, int len, const void *val, long cookie)
+{
+	struct kvm_io_bus *bus;
+	struct kvm_io_range range;
+
+	range = (struct kvm_io_range) {
+		.addr = addr,
+		.len = len,
+	};
+
+	bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
+	if (!bus)
+		return -ENOMEM;
+
+	/* First try the device referenced by cookie. */
+	if ((cookie >= 0) && (cookie < bus->dev_count) &&
+	    (kvm_io_bus_cmp(&range, &bus->range[cookie]) == 0))
+		if (!kvm_iodevice_write(vcpu, bus->range[cookie].dev, addr, len,
+					val))
+			return cookie;
+
+	/*
+	 * cookie contained garbage; fall back to search and return the
+	 * correct cookie value.
+	 */
+	return __kvm_io_bus_write(vcpu, bus, &range, val);
+}
+
+static int __kvm_io_bus_read(struct kvm_vcpu *vcpu, struct kvm_io_bus *bus,
+			     struct kvm_io_range *range, void *val)
+{
+	int idx;
+
+	idx = kvm_io_bus_get_first_dev(bus, range->addr, range->len);
+	if (idx < 0)
+		return -EOPNOTSUPP;
+
+	while (idx < bus->dev_count &&
+		kvm_io_bus_cmp(range, &bus->range[idx]) == 0) {
+		if (!kvm_iodevice_read(vcpu, bus->range[idx].dev, range->addr,
+				       range->len, val))
+			return idx;
+		idx++;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+/* kvm_io_bus_read - called under kvm->slots_lock */
+int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
+		    int len, void *val)
+{
+	struct kvm_io_bus *bus;
+	struct kvm_io_range range;
+	int r;
+
+	range = (struct kvm_io_range) {
+		.addr = addr,
+		.len = len,
+	};
+
+	bus = srcu_dereference(vcpu->kvm->buses[bus_idx], &vcpu->kvm->srcu);
+	if (!bus)
+		return -ENOMEM;
+	r = __kvm_io_bus_read(vcpu, bus, &range, val);
+	return r < 0 ? r : 0;
+}
+
+/* Caller must hold slots_lock. */
+int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
+			    int len, struct kvm_io_device *dev)
+{
+	int i;
+	struct kvm_io_bus *new_bus, *bus;
+	struct kvm_io_range range;
+
+	bus = kvm_get_bus(kvm, bus_idx);
+	if (!bus)
+		return -ENOMEM;
+
+	/* exclude ioeventfd which is limited by maximum fd */
+	if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1)
+		return -ENOSPC;
+
+	new_bus = kmalloc(struct_size(bus, range, bus->dev_count + 1),
+			  GFP_KERNEL_ACCOUNT);
+	if (!new_bus)
+		return -ENOMEM;
+
+	range = (struct kvm_io_range) {
+		.addr = addr,
+		.len = len,
+		.dev = dev,
+	};
+
+	for (i = 0; i < bus->dev_count; i++)
+		if (kvm_io_bus_cmp(&bus->range[i], &range) > 0)
+			break;
+
+	memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range));
+	new_bus->dev_count++;
+	new_bus->range[i] = range;
+	memcpy(new_bus->range + i + 1, bus->range + i,
+		(bus->dev_count - i) * sizeof(struct kvm_io_range));
+	rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
+	synchronize_srcu_expedited(&kvm->srcu);
+	kfree(bus);
+
+	return 0;
+}
+
+int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+			      struct kvm_io_device *dev)
+{
+	int i, j;
+	struct kvm_io_bus *new_bus, *bus;
+
+	lockdep_assert_held(&kvm->slots_lock);
+
+	bus = kvm_get_bus(kvm, bus_idx);
+	if (!bus)
+		return 0;
+
+	for (i = 0; i < bus->dev_count; i++) {
+		if (bus->range[i].dev == dev) {
+			break;
+		}
+	}
+
+	if (i == bus->dev_count)
+		return 0;
+
+	new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1),
+			  GFP_KERNEL_ACCOUNT);
+	if (new_bus) {
+		memcpy(new_bus, bus, struct_size(bus, range, i));
+		new_bus->dev_count--;
+		memcpy(new_bus->range + i, bus->range + i + 1,
+				flex_array_size(new_bus, range, new_bus->dev_count - i));
+	}
+
+	rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
+	synchronize_srcu_expedited(&kvm->srcu);
+
+	/* Destroy the old bus _after_ installing the (null) bus. */
+	if (!new_bus) {
+		pr_err("kvm: failed to shrink bus, removing it completely\n");
+		for (j = 0; j < bus->dev_count; j++) {
+			if (j == i)
+				continue;
+			kvm_iodevice_destructor(bus->range[j].dev);
+		}
+	}
+
+	kfree(bus);
+	return new_bus ? 0 : -ENOMEM;
+}
+
+struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+					 gpa_t addr)
+{
+	struct kvm_io_bus *bus;
+	int dev_idx, srcu_idx;
+	struct kvm_io_device *iodev = NULL;
+
+	srcu_idx = srcu_read_lock(&kvm->srcu);
+
+	bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
+	if (!bus)
+		goto out_unlock;
+
+	dev_idx = kvm_io_bus_get_first_dev(bus, addr, 1);
+	if (dev_idx < 0)
+		goto out_unlock;
+
+	iodev = bus->range[dev_idx].dev;
+
+out_unlock:
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+	return iodev;
+}
+EXPORT_SYMBOL_GPL(kvm_io_bus_get_dev);
+
+static int kvm_debugfs_open(struct inode *inode, struct file *file,
+			   int (*get)(void *, u64 *), int (*set)(void *, u64),
+			   const char *fmt)
+{
+	int ret;
+	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)
+					  inode->i_private;
+
+	/*
+	 * The debugfs files are a reference to the kvm struct which
+        * is still valid when kvm_destroy_vm is called.  kvm_get_kvm_safe
+        * avoids the race between open and the removal of the debugfs directory.
+	 */
+	if (!kvm_get_kvm_safe(stat_data->kvm))
+		return -ENOENT;
+
+	ret = simple_attr_open(inode, file, get,
+			       kvm_stats_debugfs_mode(stat_data->desc) & 0222
+			       ? set : NULL, fmt);
+	if (ret)
+		kvm_put_kvm(stat_data->kvm);
+
+	return ret;
+}
+
+static int kvm_debugfs_release(struct inode *inode, struct file *file)
+{
+	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)
+					  inode->i_private;
+
+	simple_attr_release(inode, file);
+	kvm_put_kvm(stat_data->kvm);
+
+	return 0;
+}
+
+static int kvm_get_stat_per_vm(struct kvm *kvm, size_t offset, u64 *val)
+{
+	*val = *(u64 *)((void *)(&kvm->stat) + offset);
+
+	return 0;
+}
+
+static int kvm_clear_stat_per_vm(struct kvm *kvm, size_t offset)
+{
+	*(u64 *)((void *)(&kvm->stat) + offset) = 0;
+
+	return 0;
+}
+
+static int kvm_get_stat_per_vcpu(struct kvm *kvm, size_t offset, u64 *val)
+{
+	unsigned long i;
+	struct kvm_vcpu *vcpu;
+
+	*val = 0;
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		*val += *(u64 *)((void *)(&vcpu->stat) + offset);
+
+	return 0;
+}
+
+static int kvm_clear_stat_per_vcpu(struct kvm *kvm, size_t offset)
+{
+	unsigned long i;
+	struct kvm_vcpu *vcpu;
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		*(u64 *)((void *)(&vcpu->stat) + offset) = 0;
+
+	return 0;
+}
+
+static int kvm_stat_data_get(void *data, u64 *val)
+{
+	int r = -EFAULT;
+	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
+
+	switch (stat_data->kind) {
+	case KVM_STAT_VM:
+		r = kvm_get_stat_per_vm(stat_data->kvm,
+					stat_data->desc->desc.offset, val);
+		break;
+	case KVM_STAT_VCPU:
+		r = kvm_get_stat_per_vcpu(stat_data->kvm,
+					  stat_data->desc->desc.offset, val);
+		break;
+	}
+
+	return r;
+}
+
+static int kvm_stat_data_clear(void *data, u64 val)
+{
+	int r = -EFAULT;
+	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
+
+	if (val)
+		return -EINVAL;
+
+	switch (stat_data->kind) {
+	case KVM_STAT_VM:
+		r = kvm_clear_stat_per_vm(stat_data->kvm,
+					  stat_data->desc->desc.offset);
+		break;
+	case KVM_STAT_VCPU:
+		r = kvm_clear_stat_per_vcpu(stat_data->kvm,
+					    stat_data->desc->desc.offset);
+		break;
+	}
+
+	return r;
+}
+
+static int kvm_stat_data_open(struct inode *inode, struct file *file)
+{
+	__simple_attr_check_format("%llu\n", 0ull);
+	return kvm_debugfs_open(inode, file, kvm_stat_data_get,
+				kvm_stat_data_clear, "%llu\n");
+}
+
+static const struct file_operations stat_fops_per_vm = {
+	.owner = THIS_MODULE,
+	.open = kvm_stat_data_open,
+	.release = kvm_debugfs_release,
+	.read = simple_attr_read,
+	.write = simple_attr_write,
+	.llseek = no_llseek,
+};
+
+static int vm_stat_get(void *_offset, u64 *val)
+{
+	unsigned offset = (long)_offset;
+	struct kvm *kvm;
+	u64 tmp_val;
+
+	*val = 0;
+	mutex_lock(&kvm_lock);
+	list_for_each_entry(kvm, &vm_list, vm_list) {
+		kvm_get_stat_per_vm(kvm, offset, &tmp_val);
+		*val += tmp_val;
+	}
+	mutex_unlock(&kvm_lock);
+	return 0;
+}
+
+static int vm_stat_clear(void *_offset, u64 val)
+{
+	unsigned offset = (long)_offset;
+	struct kvm *kvm;
+
+	if (val)
+		return -EINVAL;
+
+	mutex_lock(&kvm_lock);
+	list_for_each_entry(kvm, &vm_list, vm_list) {
+		kvm_clear_stat_per_vm(kvm, offset);
+	}
+	mutex_unlock(&kvm_lock);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(vm_stat_fops, vm_stat_get, vm_stat_clear, "%llu\n");
+DEFINE_SIMPLE_ATTRIBUTE(vm_stat_readonly_fops, vm_stat_get, NULL, "%llu\n");
+
+static int vcpu_stat_get(void *_offset, u64 *val)
+{
+	unsigned offset = (long)_offset;
+	struct kvm *kvm;
+	u64 tmp_val;
+
+	*val = 0;
+	mutex_lock(&kvm_lock);
+	list_for_each_entry(kvm, &vm_list, vm_list) {
+		kvm_get_stat_per_vcpu(kvm, offset, &tmp_val);
+		*val += tmp_val;
+	}
+	mutex_unlock(&kvm_lock);
+	return 0;
+}
+
+static int vcpu_stat_clear(void *_offset, u64 val)
+{
+	unsigned offset = (long)_offset;
+	struct kvm *kvm;
+
+	if (val)
+		return -EINVAL;
+
+	mutex_lock(&kvm_lock);
+	list_for_each_entry(kvm, &vm_list, vm_list) {
+		kvm_clear_stat_per_vcpu(kvm, offset);
+	}
+	mutex_unlock(&kvm_lock);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(vcpu_stat_fops, vcpu_stat_get, vcpu_stat_clear,
+			"%llu\n");
+DEFINE_SIMPLE_ATTRIBUTE(vcpu_stat_readonly_fops, vcpu_stat_get, NULL, "%llu\n");
+
+static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
+{
+	struct kobj_uevent_env *env;
+	unsigned long long created, active;
+
+	if (!kvm_dev.this_device || !kvm)
+		return;
+
+	mutex_lock(&kvm_lock);
+	if (type == KVM_EVENT_CREATE_VM) {
+		kvm_createvm_count++;
+		kvm_active_vms++;
+	} else if (type == KVM_EVENT_DESTROY_VM) {
+		kvm_active_vms--;
+	}
+	created = kvm_createvm_count;
+	active = kvm_active_vms;
+	mutex_unlock(&kvm_lock);
+
+	env = kzalloc(sizeof(*env), GFP_KERNEL_ACCOUNT);
+	if (!env)
+		return;
+
+	add_uevent_var(env, "CREATED=%llu", created);
+	add_uevent_var(env, "COUNT=%llu", active);
+
+	if (type == KVM_EVENT_CREATE_VM) {
+		add_uevent_var(env, "EVENT=create");
+		kvm->userspace_pid = task_pid_nr(current);
+	} else if (type == KVM_EVENT_DESTROY_VM) {
+		add_uevent_var(env, "EVENT=destroy");
+	}
+	add_uevent_var(env, "PID=%d", kvm->userspace_pid);
+
+	if (!IS_ERR(kvm->debugfs_dentry)) {
+		char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL_ACCOUNT);
+
+		if (p) {
+			tmp = dentry_path_raw(kvm->debugfs_dentry, p, PATH_MAX);
+			if (!IS_ERR(tmp))
+				add_uevent_var(env, "STATS_PATH=%s", tmp);
+			kfree(p);
+		}
+	}
+	/* no need for checks, since we are adding at most only 5 keys */
+	env->envp[env->envp_idx++] = NULL;
+	kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, env->envp);
+	kfree(env);
+}
+
+static void kvm_init_debug(void)
+{
+	const struct file_operations *fops;
+	const struct _kvm_stats_desc *pdesc;
+	int i;
+
+	kvm_debugfs_dir = debugfs_create_dir("kvm", NULL);
+
+	for (i = 0; i < kvm_vm_stats_header.num_desc; ++i) {
+		pdesc = &kvm_vm_stats_desc[i];
+		if (kvm_stats_debugfs_mode(pdesc) & 0222)
+			fops = &vm_stat_fops;
+		else
+			fops = &vm_stat_readonly_fops;
+		debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
+				kvm_debugfs_dir,
+				(void *)(long)pdesc->desc.offset, fops);
+	}
+
+	for (i = 0; i < kvm_vcpu_stats_header.num_desc; ++i) {
+		pdesc = &kvm_vcpu_stats_desc[i];
+		if (kvm_stats_debugfs_mode(pdesc) & 0222)
+			fops = &vcpu_stat_fops;
+		else
+			fops = &vcpu_stat_readonly_fops;
+		debugfs_create_file(pdesc->name, kvm_stats_debugfs_mode(pdesc),
+				kvm_debugfs_dir,
+				(void *)(long)pdesc->desc.offset, fops);
+	}
+}
+
+static int kvm_suspend(void)
+{
+	if (kvm_usage_count)
+		hardware_disable_nolock(NULL);
+	return 0;
+}
+
+static void kvm_resume(void)
+{
+	if (kvm_usage_count) {
+		lockdep_assert_not_held(&kvm_count_lock);
+		hardware_enable_nolock(NULL);
+	}
+}
+
+static struct syscore_ops kvm_syscore_ops = {
+	.suspend = kvm_suspend,
+	.resume = kvm_resume,
+};
+
+static inline
+struct kvm_vcpu *preempt_notifier_to_vcpu(struct preempt_notifier *pn)
+{
+	return container_of(pn, struct kvm_vcpu, preempt_notifier);
+}
+
+static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
+{
+	struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
+
+	WRITE_ONCE(vcpu->preempted, false);
+	WRITE_ONCE(vcpu->ready, false);
+
+	__this_cpu_write(kvm_running_vcpu, vcpu);
+	kvm_arch_sched_in(vcpu, cpu);
+	kvm_arch_vcpu_load(vcpu, cpu);
+}
+
+static void kvm_sched_out(struct preempt_notifier *pn,
+			  struct task_struct *next)
+{
+	struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
+
+	if (current->on_rq) {
+		WRITE_ONCE(vcpu->preempted, true);
+		WRITE_ONCE(vcpu->ready, true);
+	}
+	kvm_arch_vcpu_put(vcpu);
+	__this_cpu_write(kvm_running_vcpu, NULL);
+}
+
+/**
+ * kvm_get_running_vcpu - get the vcpu running on the current CPU.
+ *
+ * We can disable preemption locally around accessing the per-CPU variable,
+ * and use the resolved vcpu pointer after enabling preemption again,
+ * because even if the current thread is migrated to another CPU, reading
+ * the per-CPU value later will give us the same value as we update the
+ * per-CPU variable in the preempt notifier handlers.
+ */
+struct kvm_vcpu *kvm_get_running_vcpu(void)
+{
+	struct kvm_vcpu *vcpu;
+
+	preempt_disable();
+	vcpu = __this_cpu_read(kvm_running_vcpu);
+	preempt_enable();
+
+	return vcpu;
+}
+EXPORT_SYMBOL_GPL(kvm_get_running_vcpu);
+
+/**
+ * kvm_get_running_vcpus - get the per-CPU array of currently running vcpus.
+ */
+struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
+{
+        return &kvm_running_vcpu;
+}
+
+#ifdef CONFIG_GUEST_PERF_EVENTS
+static unsigned int kvm_guest_state(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned int state;
+
+	if (!kvm_arch_pmi_in_guest(vcpu))
+		return 0;
+
+	state = PERF_GUEST_ACTIVE;
+	if (!kvm_arch_vcpu_in_kernel(vcpu))
+		state |= PERF_GUEST_USER;
+
+	return state;
+}
+
+static unsigned long kvm_guest_get_ip(void)
+{
+	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+
+	/* Retrieving the IP must be guarded by a call to kvm_guest_state(). */
+	if (WARN_ON_ONCE(!kvm_arch_pmi_in_guest(vcpu)))
+		return 0;
+
+	return kvm_arch_vcpu_get_ip(vcpu);
+}
+
+static struct perf_guest_info_callbacks kvm_guest_cbs = {
+	.state			= kvm_guest_state,
+	.get_ip			= kvm_guest_get_ip,
+	.handle_intel_pt_intr	= NULL,
+};
+
+void kvm_register_perf_callbacks(unsigned int (*pt_intr_handler)(void))
+{
+	kvm_guest_cbs.handle_intel_pt_intr = pt_intr_handler;
+	perf_register_guest_info_callbacks(&kvm_guest_cbs);
+}
+void kvm_unregister_perf_callbacks(void)
+{
+	perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+}
+#endif
+
+struct kvm_cpu_compat_check {
+	void *opaque;
+	int *ret;
+};
+
+static void check_processor_compat(void *data)
+{
+	struct kvm_cpu_compat_check *c = data;
+
+	*c->ret = kvm_arch_check_processor_compat(c->opaque);
+}
+
+int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
+		  struct module *module)
+{
+	struct kvm_cpu_compat_check c;
+	int r;
+	int cpu;
+
+	r = kvm_arch_init(opaque);
+	if (r)
+		goto out_fail;
+
+	/*
+	 * kvm_arch_init makes sure there's at most one caller
+	 * for architectures that support multiple implementations,
+	 * like intel and amd on x86.
+	 * kvm_arch_init must be called before kvm_irqfd_init to avoid creating
+	 * conflicts in case kvm is already setup for another implementation.
+	 */
+	r = kvm_irqfd_init();
+	if (r)
+		goto out_irqfd;
+
+	if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) {
+		r = -ENOMEM;
+		goto out_free_0;
+	}
+
+	r = kvm_arch_hardware_setup(opaque);
+	if (r < 0)
+		goto out_free_1;
+
+	c.ret = &r;
+	c.opaque = opaque;
+	for_each_online_cpu(cpu) {
+		smp_call_function_single(cpu, check_processor_compat, &c, 1);
+		if (r < 0)
+			goto out_free_2;
+	}
+
+	r = cpuhp_setup_state_nocalls(CPUHP_AP_KVM_STARTING, "kvm/cpu:starting",
+				      kvm_starting_cpu, kvm_dying_cpu);
+	if (r)
+		goto out_free_2;
+	register_reboot_notifier(&kvm_reboot_notifier);
+
+	/* A kmem cache lets us meet the alignment requirements of fx_save. */
+	if (!vcpu_align)
+		vcpu_align = __alignof__(struct kvm_vcpu);
+	kvm_vcpu_cache =
+		kmem_cache_create_usercopy("kvm_vcpu", vcpu_size, vcpu_align,
+					   SLAB_ACCOUNT,
+					   offsetof(struct kvm_vcpu, arch),
+					   offsetofend(struct kvm_vcpu, stats_id)
+					   - offsetof(struct kvm_vcpu, arch),
+					   NULL);
+	if (!kvm_vcpu_cache) {
+		r = -ENOMEM;
+		goto out_free_3;
+	}
+
+	for_each_possible_cpu(cpu) {
+		if (!alloc_cpumask_var_node(&per_cpu(cpu_kick_mask, cpu),
+					    GFP_KERNEL, cpu_to_node(cpu))) {
+			r = -ENOMEM;
+			goto out_free_4;
+		}
+	}
+
+	r = kvm_async_pf_init();
+	if (r)
+		goto out_free_4;
+
+	kvm_chardev_ops.owner = module;
+
+	register_syscore_ops(&kvm_syscore_ops);
+
+	kvm_preempt_ops.sched_in = kvm_sched_in;
+	kvm_preempt_ops.sched_out = kvm_sched_out;
+
+	kvm_init_debug();
+
+	r = kvm_vfio_ops_init();
+	if (WARN_ON_ONCE(r))
+		goto err_vfio;
+
+	/*
+	 * Registration _must_ be the very last thing done, as this exposes
+	 * /dev/kvm to userspace, i.e. all infrastructure must be setup!
+	 */
+	r = misc_register(&kvm_dev);
+	if (r) {
+		pr_err("kvm: misc device register failed\n");
+		goto err_register;
+	}
+
+	return 0;
+
+err_register:
+	kvm_vfio_ops_exit();
+err_vfio:
+	kvm_async_pf_deinit();
+out_free_4:
+	for_each_possible_cpu(cpu)
+		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
+	kmem_cache_destroy(kvm_vcpu_cache);
+out_free_3:
+	unregister_reboot_notifier(&kvm_reboot_notifier);
+	cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING);
+out_free_2:
+	kvm_arch_hardware_unsetup();
+out_free_1:
+	free_cpumask_var(cpus_hardware_enabled);
+out_free_0:
+	kvm_irqfd_exit();
+out_irqfd:
+	kvm_arch_exit();
+out_fail:
+	return r;
+}
+EXPORT_SYMBOL_GPL(kvm_init);
+
+void kvm_exit(void)
+{
+	int cpu;
+
+	/*
+	 * Note, unregistering /dev/kvm doesn't strictly need to come first,
+	 * fops_get(), a.k.a. try_module_get(), prevents acquiring references
+	 * to KVM while the module is being stopped.
+	 */
+	misc_deregister(&kvm_dev);
+
+	debugfs_remove_recursive(kvm_debugfs_dir);
+	for_each_possible_cpu(cpu)
+		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
+	kmem_cache_destroy(kvm_vcpu_cache);
+	kvm_async_pf_deinit();
+	unregister_syscore_ops(&kvm_syscore_ops);
+	unregister_reboot_notifier(&kvm_reboot_notifier);
+	cpuhp_remove_state_nocalls(CPUHP_AP_KVM_STARTING);
+	on_each_cpu(hardware_disable_nolock, NULL, 1);
+	kvm_arch_hardware_unsetup();
+	kvm_arch_exit();
+	kvm_irqfd_exit();
+	free_cpumask_var(cpus_hardware_enabled);
+	kvm_vfio_ops_exit();
+}
+EXPORT_SYMBOL_GPL(kvm_exit);
+
+struct kvm_vm_worker_thread_context {
+	struct kvm *kvm;
+	struct task_struct *parent;
+	struct completion init_done;
+	kvm_vm_thread_fn_t thread_fn;
+	uintptr_t data;
+	int err;
+};
+
+static int kvm_vm_worker_thread(void *context)
+{
+	/*
+	 * The init_context is allocated on the stack of the parent thread, so
+	 * we have to locally copy anything that is needed beyond initialization
+	 */
+	struct kvm_vm_worker_thread_context *init_context = context;
+	struct task_struct *parent;
+	struct kvm *kvm = init_context->kvm;
+	kvm_vm_thread_fn_t thread_fn = init_context->thread_fn;
+	uintptr_t data = init_context->data;
+	int err;
+
+	err = kthread_park(current);
+	/* kthread_park(current) is never supposed to return an error */
+	WARN_ON(err != 0);
+	if (err)
+		goto init_complete;
+
+	err = cgroup_attach_task_all(init_context->parent, current);
+	if (err) {
+		kvm_err("%s: cgroup_attach_task_all failed with err %d\n",
+			__func__, err);
+		goto init_complete;
+	}
+
+	set_user_nice(current, task_nice(init_context->parent));
+
+init_complete:
+	init_context->err = err;
+	complete(&init_context->init_done);
+	init_context = NULL;
+
+	if (err)
+		goto out;
+
+	/* Wait to be woken up by the spawner before proceeding. */
+	kthread_parkme();
+
+	if (!kthread_should_stop())
+		err = thread_fn(kvm, data);
+
+out:
+	/*
+	 * Move kthread back to its original cgroup to prevent it lingering in
+	 * the cgroup of the VM process, after the latter finishes its
+	 * execution.
+	 *
+	 * kthread_stop() waits on the 'exited' completion condition which is
+	 * set in exit_mm(), via mm_release(), in do_exit(). However, the
+	 * kthread is removed from the cgroup in the cgroup_exit() which is
+	 * called after the exit_mm(). This causes the kthread_stop() to return
+	 * before the kthread actually quits the cgroup.
+	 */
+	rcu_read_lock();
+	parent = rcu_dereference(current->real_parent);
+	get_task_struct(parent);
+	rcu_read_unlock();
+	cgroup_attach_task_all(parent, current);
+	put_task_struct(parent);
+
+	return err;
+}
+
+int kvm_vm_create_worker_thread(struct kvm *kvm, kvm_vm_thread_fn_t thread_fn,
+				uintptr_t data, const char *name,
+				struct task_struct **thread_ptr)
+{
+	struct kvm_vm_worker_thread_context init_context = {};
+	struct task_struct *thread;
+
+	*thread_ptr = NULL;
+	init_context.kvm = kvm;
+	init_context.parent = current;
+	init_context.thread_fn = thread_fn;
+	init_context.data = data;
+	init_completion(&init_context.init_done);
+
+	thread = kthread_run(kvm_vm_worker_thread, &init_context,
+			     "%s-%d", name, task_pid_nr(current));
+	if (IS_ERR(thread))
+		return PTR_ERR(thread);
+
+	/* kthread_run is never supposed to return NULL */
+	WARN_ON(thread == NULL);
+
+	wait_for_completion(&init_context.init_done);
+
+	if (!init_context.err)
+		*thread_ptr = thread;
+
+	return init_context.err;
+}