diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 95fa45c..59c2d93 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1212,6 +1212,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_IRQ_INJECT_STATUS:
 	case KVM_CAP_ASSIGN_DEV_IRQ:
 	case KVM_CAP_IRQFD:
+	case KVM_CAP_IOEVENTFD:
 	case KVM_CAP_PIT2:
 		r = 1;
 		break;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 76c6408..22d0eb7 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -307,6 +307,28 @@ struct kvm_guest_debug {
 	struct kvm_guest_debug_arch arch;
 };
 
+enum {
+	kvm_ioeventfd_flag_nr_datamatch,
+	kvm_ioeventfd_flag_nr_pio,
+	kvm_ioeventfd_flag_nr_deassign,
+	kvm_ioeventfd_flag_nr_max,
+};
+
+#define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
+#define KVM_IOEVENTFD_FLAG_PIO       (1 << kvm_ioeventfd_flag_nr_pio)
+#define KVM_IOEVENTFD_FLAG_DEASSIGN  (1 << kvm_ioeventfd_flag_nr_deassign)
+
+#define KVM_IOEVENTFD_VALID_FLAG_MASK  ((1 << kvm_ioeventfd_flag_nr_max) - 1)
+
+struct kvm_ioeventfd {
+	__u64 datamatch;
+	__u64 addr;        /* legal pio/mmio address */
+	__u32 len;         /* 1, 2, 4, or 8 bytes    */
+	__s32 fd;
+	__u32 flags;
+	__u8  pad[36];
+};
+
 #define KVM_TRC_SHIFT           16
 /*
  * kvm trace categories
@@ -409,6 +431,7 @@ struct kvm_guest_debug {
 #define KVM_CAP_PIT2 33
 #endif
 #define KVM_CAP_SET_BOOT_CPU_ID 34
+#define KVM_CAP_IOEVENTFD 35
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -517,6 +540,7 @@ struct kvm_irqfd {
 #define KVM_IRQFD                  _IOW(KVMIO, 0x76, struct kvm_irqfd)
 #define KVM_CREATE_PIT2		   _IOW(KVMIO, 0x77, struct kvm_pit_config)
 #define KVM_SET_BOOT_CPU_ID        _IO(KVMIO, 0x78)
+#define KVM_IOEVENTFD             _IOW(KVMIO, 0x79, struct kvm_ioeventfd)
 
 /*
  * ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 306bc67..0347d59 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -154,6 +154,7 @@ struct kvm {
 		spinlock_t        lock;
 		struct list_head  items;
 	} irqfds;
+	struct list_head ioeventfds;
 #endif
 	struct kvm_vm_stat stat;
 	struct kvm_arch arch;
@@ -532,19 +533,24 @@ static inline void kvm_free_irq_routing(struct kvm *kvm) {}
 
 #ifdef CONFIG_HAVE_KVM_EVENTFD
 
-void kvm_irqfd_init(struct kvm *kvm);
+void kvm_eventfd_init(struct kvm *kvm);
 int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags);
 void kvm_irqfd_release(struct kvm *kvm);
+int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args);
 
 #else
 
-static inline void kvm_irqfd_init(struct kvm *kvm) {}
+static inline void kvm_eventfd_init(struct kvm *kvm) {}
 static inline int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)
 {
 	return -EINVAL;
 }
 
 static inline void kvm_irqfd_release(struct kvm *kvm) {}
+static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+	return -ENOSYS;
+}
 
 #endif /* CONFIG_HAVE_KVM_EVENTFD */
 
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 4092b8d..eee8edb 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -21,6 +21,7 @@
  */
 
 #include <linux/kvm_host.h>
+#include <linux/kvm.h>
 #include <linux/workqueue.h>
 #include <linux/syscalls.h>
 #include <linux/wait.h>
@@ -28,6 +29,9 @@
 #include <linux/file.h>
 #include <linux/list.h>
 #include <linux/eventfd.h>
+#include <linux/kernel.h>
+
+#include "iodev.h"
 
 /*
  * --------------------------------------------------------------------
@@ -234,10 +238,11 @@ fail:
 }
 
 void
-kvm_irqfd_init(struct kvm *kvm)
+kvm_eventfd_init(struct kvm *kvm)
 {
 	spin_lock_init(&kvm->irqfds.lock);
 	INIT_LIST_HEAD(&kvm->irqfds.items);
+	INIT_LIST_HEAD(&kvm->ioeventfds);
 }
 
 /*
@@ -327,3 +332,248 @@ static void __exit irqfd_module_exit(void)
 
 module_init(irqfd_module_init);
 module_exit(irqfd_module_exit);
+
+/*
+ * --------------------------------------------------------------------
+ * ioeventfd: translate a PIO/MMIO memory write to an eventfd signal.
+ *
+ * userspace can register a PIO/MMIO address with an eventfd for receiving
+ * notification when the memory has been touched.
+ * --------------------------------------------------------------------
+ */
+
+struct _ioeventfd {
+	struct list_head     list;
+	u64                  addr;
+	int                  length;
+	struct eventfd_ctx  *eventfd;
+	u64                  datamatch;
+	struct kvm_io_device dev;
+	bool                 wildcard;
+};
+
+static inline struct _ioeventfd *
+to_ioeventfd(struct kvm_io_device *dev)
+{
+	return container_of(dev, struct _ioeventfd, dev);
+}
+
+static void
+ioeventfd_release(struct _ioeventfd *p)
+{
+	eventfd_ctx_put(p->eventfd);
+	list_del(&p->list);
+	kfree(p);
+}
+
+static bool
+ioeventfd_in_range(struct _ioeventfd *p, gpa_t addr, int len, const void *val)
+{
+	u64 _val;
+
+	if (!(addr == p->addr && len == p->length))
+		/* address-range must be precise for a hit */
+		return false;
+
+	if (p->wildcard)
+		/* all else equal, wildcard is always a hit */
+		return true;
+
+	/* otherwise, we have to actually compare the data */
+
+	BUG_ON(!IS_ALIGNED((unsigned long)val, len));
+
+	switch (len) {
+	case 1:
+		_val = *(u8 *)val;
+		break;
+	case 2:
+		_val = *(u16 *)val;
+		break;
+	case 4:
+		_val = *(u32 *)val;
+		break;
+	case 8:
+		_val = *(u64 *)val;
+		break;
+	default:
+		return false;
+	}
+
+	return _val == p->datamatch ? true : false;
+}
+
+/* MMIO/PIO writes trigger an event if the addr/val match */
+static int
+ioeventfd_write(struct kvm_io_device *this, gpa_t addr, int len,
+		const void *val)
+{
+	struct _ioeventfd *p = to_ioeventfd(this);
+
+	if (!ioeventfd_in_range(p, addr, len, val))
+		return -EOPNOTSUPP;
+
+	eventfd_signal(p->eventfd, 1);
+	return 0;
+}
+
+/*
+ * This function is called as KVM is completely shutting down.  We do not
+ * need to worry about locking just nuke anything we have as quickly as possible
+ */
+static void
+ioeventfd_destructor(struct kvm_io_device *this)
+{
+	struct _ioeventfd *p = to_ioeventfd(this);
+
+	ioeventfd_release(p);
+}
+
+static const struct kvm_io_device_ops ioeventfd_ops = {
+	.write      = ioeventfd_write,
+	.destructor = ioeventfd_destructor,
+};
+
+/* assumes kvm->slots_lock held */
+static bool
+ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p)
+{
+	struct _ioeventfd *_p;
+
+	list_for_each_entry(_p, &kvm->ioeventfds, list)
+		if (_p->addr == p->addr && _p->length == p->length &&
+		    (_p->wildcard || p->wildcard ||
+		     _p->datamatch == p->datamatch))
+			return true;
+
+	return false;
+}
+
+static int
+kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+	int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
+	struct kvm_io_bus        *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
+	struct _ioeventfd        *p;
+	struct eventfd_ctx       *eventfd;
+	int                       ret;
+
+	/* must be natural-word sized */
+	switch (args->len) {
+	case 1:
+	case 2:
+	case 4:
+	case 8:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* check for range overflow */
+	if (args->addr + args->len < args->addr)
+		return -EINVAL;
+
+	/* check for extra flags that we don't understand */
+	if (args->flags & ~KVM_IOEVENTFD_VALID_FLAG_MASK)
+		return -EINVAL;
+
+	eventfd = eventfd_ctx_fdget(args->fd);
+	if (IS_ERR(eventfd))
+		return PTR_ERR(eventfd);
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	INIT_LIST_HEAD(&p->list);
+	p->addr    = args->addr;
+	p->length  = args->len;
+	p->eventfd = eventfd;
+
+	/* The datamatch feature is optional, otherwise this is a wildcard */
+	if (args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH)
+		p->datamatch = args->datamatch;
+	else
+		p->wildcard = true;
+
+	down_write(&kvm->slots_lock);
+
+	/* Verify that there isnt a match already */
+	if (ioeventfd_check_collision(kvm, p)) {
+		ret = -EEXIST;
+		goto unlock_fail;
+	}
+
+	kvm_iodevice_init(&p->dev, &ioeventfd_ops);
+
+	ret = __kvm_io_bus_register_dev(bus, &p->dev);
+	if (ret < 0)
+		goto unlock_fail;
+
+	list_add_tail(&p->list, &kvm->ioeventfds);
+
+	up_write(&kvm->slots_lock);
+
+	return 0;
+
+unlock_fail:
+	up_write(&kvm->slots_lock);
+
+fail:
+	kfree(p);
+	eventfd_ctx_put(eventfd);
+
+	return ret;
+}
+
+static int
+kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+	int                       pio = args->flags & KVM_IOEVENTFD_FLAG_PIO;
+	struct kvm_io_bus        *bus = pio ? &kvm->pio_bus : &kvm->mmio_bus;
+	struct _ioeventfd        *p, *tmp;
+	struct eventfd_ctx       *eventfd;
+	int                       ret = -ENOENT;
+
+	eventfd = eventfd_ctx_fdget(args->fd);
+	if (IS_ERR(eventfd))
+		return PTR_ERR(eventfd);
+
+	down_write(&kvm->slots_lock);
+
+	list_for_each_entry_safe(p, tmp, &kvm->ioeventfds, list) {
+		bool wildcard = args->flags & KVM_IOEVENTFD_FLAG_DATAMATCH ?
+			true : false;
+
+		if (p->eventfd != eventfd  ||
+		    p->addr != args->addr  ||
+		    p->length != args->len ||
+		    p->wildcard != wildcard)
+			continue;
+
+		if (!p->wildcard && p->datamatch != args->datamatch)
+			continue;
+
+		__kvm_io_bus_unregister_dev(bus, &p->dev);
+		ioeventfd_release(p);
+		ret = 0;
+		break;
+	}
+
+	up_write(&kvm->slots_lock);
+
+	eventfd_ctx_put(eventfd);
+
+	return ret;
+}
+
+int
+kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
+{
+	if (args->flags & KVM_IOEVENTFD_FLAG_DEASSIGN)
+		return kvm_deassign_ioeventfd(kvm, args);
+
+	return kvm_assign_ioeventfd(kvm, args);
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index dd92b44..14e1f32 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -979,7 +979,7 @@ static struct kvm *kvm_create_vm(void)
 	spin_lock_init(&kvm->mmu_lock);
 	spin_lock_init(&kvm->requests_lock);
 	kvm_io_bus_init(&kvm->pio_bus);
-	kvm_irqfd_init(kvm);
+	kvm_eventfd_init(kvm);
 	mutex_init(&kvm->lock);
 	mutex_init(&kvm->irq_lock);
 	kvm_io_bus_init(&kvm->mmio_bus);
@@ -2271,6 +2271,15 @@ static long kvm_vm_ioctl(struct file *filp,
 		r = kvm_irqfd(kvm, data.fd, data.gsi, data.flags);
 		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_KVM_APIC_ARCHITECTURE
 	case KVM_SET_BOOT_CPU_ID:
 		r = 0;
