diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index bee9512..01e3c61 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -2,7 +2,7 @@
 EXTRA_CFLAGS += -Ivirt/kvm -Iarch/x86/kvm
 
 kvm-y			+= $(addprefix ../../../virt/kvm/, kvm_main.o ioapic.o \
-				coalesced_mmio.o irq_comm.o)
+				coalesced_mmio.o irq_comm.o eventfd.o)
 kvm-$(CONFIG_KVM_TRACE)	+= $(addprefix ../../../virt/kvm/, kvm_trace.o)
 kvm-$(CONFIG_IOMMU_API)	+= $(addprefix ../../../virt/kvm/, iommu.o)
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7978d32..98c2434 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1084,6 +1084,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_REINJECT_CONTROL:
 	case KVM_CAP_IRQ_INJECT_STATUS:
 	case KVM_CAP_ASSIGN_DEV_IRQ:
+	case KVM_CAP_IRQFD:
 		r = 1;
 		break;
 	case KVM_CAP_COALESCED_MMIO:
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 7b17141..8f53f24 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -418,6 +418,7 @@ struct kvm_trace_rec {
 #ifdef __KVM_HAVE_MCE
 #define KVM_CAP_MCE 31
 #endif
+#define KVM_CAP_IRQFD 32
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -470,6 +471,15 @@ struct kvm_x86_mce {
 };
 #endif
 
+#define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
+
+struct kvm_irqfd {
+	__u32 fd;
+	__u32 gsi;
+	__u32 flags;
+	__u8  pad[20];
+};
+
 /*
  * ioctls for VM fds
  */
@@ -514,6 +524,7 @@ struct kvm_x86_mce {
 #define KVM_ASSIGN_SET_MSIX_ENTRY \
 			_IOW(KVMIO, 0x74, struct kvm_assigned_msix_entry)
 #define KVM_DEASSIGN_DEV_IRQ       _IOW(KVMIO, 0x75, struct kvm_assigned_irq)
+#define KVM_IRQFD                  _IOW(KVMIO, 0x76, struct kvm_irqfd)
 
 /*
  * ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8f410d3..3b6caf5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -134,6 +134,7 @@ struct kvm {
 	struct list_head vm_list;
 	struct kvm_io_bus mmio_bus;
 	struct kvm_io_bus pio_bus;
+	struct list_head irqfds;
 	struct kvm_vm_stat stat;
 	struct kvm_arch arch;
 	atomic_t users_count;
@@ -528,4 +529,7 @@ static inline void kvm_free_irq_routing(struct kvm *kvm) {}
 
 #endif
 
+int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags);
+void kvm_irqfd_release(struct kvm *kvm);
+
 #endif
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
new file mode 100644
index 0000000..72a282e
--- /dev/null
+++ b/virt/kvm/eventfd.c
@@ -0,0 +1,228 @@
+/*
+ * kvm eventfd support - use eventfd objects to signal various KVM events
+ *
+ * Copyright 2009 Novell.  All Rights Reserved.
+ *
+ * Author:
+ *	Gregory Haskins <ghaskins@novell.com>
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/workqueue.h>
+#include <linux/syscalls.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/list.h>
+
+/*
+ * --------------------------------------------------------------------
+ * irqfd: Allows an fd to be used to inject an interrupt to the guest
+ *
+ * Credit goes to Avi Kivity for the original idea.
+ * --------------------------------------------------------------------
+ */
+struct _irqfd {
+	struct kvm               *kvm;
+	int                       gsi;
+	struct file              *file;
+	struct list_head          list;
+	poll_table                pt;
+	wait_queue_head_t        *wqh;
+	wait_queue_t              wait;
+	struct work_struct        work;
+};
+
+static void
+irqfd_inject(struct work_struct *work)
+{
+	struct _irqfd *irqfd = container_of(work, struct _irqfd, work);
+	struct kvm *kvm = irqfd->kvm;
+
+	mutex_lock(&kvm->lock);
+	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
+	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
+	mutex_unlock(&kvm->lock);
+}
+
+static int
+irqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)
+{
+	struct _irqfd *irqfd = container_of(wait, struct _irqfd, wait);
+
+	/*
+	 * The wake_up is called with interrupts disabled.  Therefore we need
+	 * to defer the IRQ injection until later since we need to acquire the
+	 * kvm->lock to do so.
+	 */
+	schedule_work(&irqfd->work);
+
+	return 0;
+}
+
+static void
+irqfd_ptable_queue_proc(struct file *file, wait_queue_head_t *wqh,
+			poll_table *pt)
+{
+	struct _irqfd *irqfd = container_of(pt, struct _irqfd, pt);
+
+	irqfd->wqh = wqh;
+	add_wait_queue(wqh, &irqfd->wait);
+}
+
+static int
+kvm_assign_irqfd(struct kvm *kvm, int fd, int gsi)
+{
+	struct _irqfd *irqfd;
+	struct file *file = NULL;
+	int ret;
+
+	irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
+	if (!irqfd)
+		return -ENOMEM;
+
+	irqfd->kvm = kvm;
+	irqfd->gsi = gsi;
+	INIT_LIST_HEAD(&irqfd->list);
+	INIT_WORK(&irqfd->work, irqfd_inject);
+
+	/*
+	 * Embed the file* lifetime in the irqfd.
+	 */
+	file = fget(fd);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto fail;
+	}
+
+	/*
+	 * Install our own custom wake-up handling so we are notified via
+	 * a callback whenever someone signals the underlying eventfd
+	 */
+	init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
+	init_poll_funcptr(&irqfd->pt, irqfd_ptable_queue_proc);
+
+	ret = file->f_op->poll(file, &irqfd->pt);
+	if (ret < 0)
+		goto fail;
+
+	irqfd->file = file;
+
+	mutex_lock(&kvm->lock);
+	list_add_tail(&irqfd->list, &kvm->irqfds);
+	mutex_unlock(&kvm->lock);
+
+	return 0;
+
+fail:
+	if (irqfd->wqh)
+		remove_wait_queue(irqfd->wqh, &irqfd->wait);
+
+	if (file && !IS_ERR(file))
+		fput(file);
+
+	kfree(irqfd);
+	return ret;
+}
+
+static void
+irqfd_release(struct _irqfd *irqfd)
+{
+	/*
+	 * The ordering is important.  We must remove ourselves from the wqh
+	 * first to ensure no more event callbacks are issued, and then flush
+	 * any previously scheduled work prior to freeing the memory
+	 */
+	remove_wait_queue(irqfd->wqh, &irqfd->wait);
+
+	flush_work(&irqfd->work);
+
+	fput(irqfd->file);
+	kfree(irqfd);
+}
+
+static struct _irqfd *
+irqfd_remove(struct kvm *kvm, struct file *file, int gsi)
+{
+	struct _irqfd *irqfd;
+
+	mutex_lock(&kvm->lock);
+
+	/*
+	 * linear search isn't brilliant, but this should be an infrequent
+	 * slow-path operation, and the list should not grow very large
+	 */
+	list_for_each_entry(irqfd, &kvm->irqfds, list) {
+		if (irqfd->file != file || irqfd->gsi != gsi)
+			continue;
+
+		list_del(&irqfd->list);
+		mutex_unlock(&kvm->lock);
+
+		return irqfd;
+	}
+
+	mutex_unlock(&kvm->lock);
+
+	return NULL;
+}
+
+static int
+kvm_deassign_irqfd(struct kvm *kvm, int fd, int gsi)
+{
+	struct _irqfd *irqfd;
+	struct file *file;
+	int count = 0;
+
+	file = fget(fd);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+
+	while ((irqfd = irqfd_remove(kvm, file, gsi))) {
+		/*
+		 * We remove the item from the list under the lock, but we
+		 * free it outside the lock to avoid deadlocking with the
+		 * flush_work and the work_item taking the lock
+		 */
+		irqfd_release(irqfd);
+		count++;
+	}
+
+	fput(file);
+
+	return count ? count : -ENOENT;
+}
+
+int
+kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags)
+{
+	if (flags & KVM_IRQFD_FLAG_DEASSIGN)
+		return kvm_deassign_irqfd(kvm, fd, gsi);
+
+	return kvm_assign_irqfd(kvm, fd, gsi);
+}
+
+void
+kvm_irqfd_release(struct kvm *kvm)
+{
+	struct _irqfd *irqfd, *tmp;
+
+	/* don't bother with the lock..we are shutting down */
+	list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds, list) {
+		list_del(&irqfd->list);
+		irqfd_release(irqfd);
+	}
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index bebfe59..b58837d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -983,6 +983,7 @@ static struct kvm *kvm_create_vm(void)
 	atomic_inc(&kvm->mm->mm_count);
 	spin_lock_init(&kvm->mmu_lock);
 	kvm_io_bus_init(&kvm->pio_bus);
+	INIT_LIST_HEAD(&kvm->irqfds);
 	mutex_init(&kvm->lock);
 	kvm_io_bus_init(&kvm->mmio_bus);
 	init_rwsem(&kvm->slots_lock);
@@ -1034,6 +1035,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	spin_lock(&kvm_lock);
 	list_del(&kvm->vm_list);
 	spin_unlock(&kvm_lock);
+	kvm_irqfd_release(kvm);
 	kvm_free_irq_routing(kvm);
 	kvm_io_bus_destroy(&kvm->pio_bus);
 	kvm_io_bus_destroy(&kvm->mmio_bus);
@@ -2210,6 +2212,15 @@ static long kvm_vm_ioctl(struct file *filp,
 	}
 #endif
 #endif /* KVM_CAP_IRQ_ROUTING */
+	case KVM_IRQFD: {
+		struct kvm_irqfd data;
+
+		r = -EFAULT;
+		if (copy_from_user(&data, argp, sizeof data))
+			goto out;
+		r = kvm_irqfd(kvm, data.fd, data.gsi, data.flags);
+		break;
+	}
 	default:
 		r = kvm_arch_vm_ioctl(filp, ioctl, arg);
 	}
