diff --git a/MAINTAINERS b/MAINTAINERS
index 797236befd279bef6bf7c0c074b132d4bf6f9380..3b738cb8bdeb3da510fef852a74b9cd3612fe7da 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11177,6 +11177,13 @@ L: netdev@vger.kernel.org
S: Maintained
F: drivers/net/ethernet/via/via-velocity.*
+VIRT LIB
+M: Alex Williamson <alex.williamson@redhat.com>
+M: Paolo Bonzini <pbonzini@redhat.com>
+L: kvm@vger.kernel.org
+S: Supported
+F: virt/lib/
+
VIVID VIRTUAL VIDEO DRIVER
M: Hans Verkuil <hverkuil@xs4all.nl>
L: linux-media@vger.kernel.org
diff --git a/include/linux/irqbypass.h b/include/linux/irqbypass.h
new file mode 100644
index 0000000000000000000000000000000000000000..1551b5b2f4c2a9ecb639bd6fe67be91f2e6d5bc6
--- /dev/null
+++ b/include/linux/irqbypass.h
@@ -0,0 +1,90 @@
+/*
+ * IRQ offload/bypass manager
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (c) 2015 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef IRQBYPASS_H
+#define IRQBYPASS_H
+
+#include <linux/list.h>
+
+struct irq_bypass_consumer;
+
+/*
+ * Theory of operation
+ *
+ * The IRQ bypass manager is a simple set of lists and callbacks that allows
+ * IRQ producers (ex. physical interrupt sources) to be matched to IRQ
+ * consumers (ex. virtualization hardware that allows IRQ bypass or offload)
+ * via a shared token (ex. eventfd_ctx). Producers and consumers register
+ * independently. When a token match is found, the optional @stop callback
+ * will be called for each participant. The pair will then be connected via
+ * the @add_* callbacks, and finally the optional @start callback will allow
+ * any final coordination. When either participant is unregistered, the
+ * process is repeated using the @del_* callbacks in place of the @add_*
+ * callbacks. Match tokens must be unique per producer/consumer, 1:N pairings
+ * are not supported.
+ */
+
+/**
+ * struct irq_bypass_producer - IRQ bypass producer definition
+ * @node: IRQ bypass manager private list management
+ * @token: opaque token to match between producer and consumer
+ * @irq: Linux IRQ number for the producer device
+ * @add_consumer: Connect the IRQ producer to an IRQ consumer (optional)
+ * @del_consumer: Disconnect the IRQ producer from an IRQ consumer (optional)
+ * @stop: Perform any quiesce operations necessary prior to add/del (optional)
+ * @start: Perform any startup operations necessary after add/del (optional)
+ *
+ * The IRQ bypass producer structure represents an interrupt source for
+ * participation in possible host bypass, for instance an interrupt vector
+ * for a physical device assigned to a VM.
+ */
+struct irq_bypass_producer {
+ struct list_head node;
+ void *token;
+ int irq;
+ int (*add_consumer)(struct irq_bypass_producer *,
+ struct irq_bypass_consumer *);
+ void (*del_consumer)(struct irq_bypass_producer *,
+ struct irq_bypass_consumer *);
+ void (*stop)(struct irq_bypass_producer *);
+ void (*start)(struct irq_bypass_producer *);
+};
+
+/**
+ * struct irq_bypass_consumer - IRQ bypass consumer definition
+ * @node: IRQ bypass manager private list management
+ * @token: opaque token to match between producer and consumer
+ * @add_producer: Connect the IRQ consumer to an IRQ producer
+ * @del_producer: Disconnect the IRQ consumer from an IRQ producer
+ * @stop: Perform any quiesce operations necessary prior to add/del (optional)
+ * @start: Perform any startup operations necessary after add/del (optional)
+ *
+ * The IRQ bypass consumer structure represents an interrupt sink for
+ * participation in possible host bypass, for instance a hypervisor may
+ * support offloads to allow bypassing the host entirely or offload
+ * portions of the interrupt handling to the VM.
+ */
+struct irq_bypass_consumer {
+ struct list_head node;
+ void *token;
+ int (*add_producer)(struct irq_bypass_consumer *,
+ struct irq_bypass_producer *);
+ void (*del_producer)(struct irq_bypass_consumer *,
+ struct irq_bypass_producer *);
+ void (*stop)(struct irq_bypass_consumer *);
+ void (*start)(struct irq_bypass_consumer *);
+};
+
+int irq_bypass_register_producer(struct irq_bypass_producer *);
+void irq_bypass_unregister_producer(struct irq_bypass_producer *);
+int irq_bypass_register_consumer(struct irq_bypass_consumer *);
+void irq_bypass_unregister_consumer(struct irq_bypass_consumer *);
+
+#endif /* IRQBYPASS_H */
diff --git a/virt/lib/Kconfig b/virt/lib/Kconfig
new file mode 100644
index 0000000000000000000000000000000000000000..89a414f815d244487bc19885047ded9d4f78f5d8
--- /dev/null
+++ b/virt/lib/Kconfig
@@ -0,0 +1,2 @@
+config IRQ_BYPASS_MANAGER
+ tristate
diff --git a/virt/lib/Makefile b/virt/lib/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..901228d1ffbc7118c4d1234b0ae2e3f53592aeaa
--- /dev/null
+++ b/virt/lib/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_IRQ_BYPASS_MANAGER) += irqbypass.o
diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c
new file mode 100644
index 0000000000000000000000000000000000000000..09a03b5a21ff239cb7f4afd36e9e0f723098a422
--- /dev/null
+++ b/virt/lib/irqbypass.c
@@ -0,0 +1,257 @@
+/*
+ * IRQ offload/bypass manager
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (c) 2015 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Various virtualization hardware acceleration techniques allow bypassing or
+ * offloading interrupts received from devices around the host kernel. Posted
+ * Interrupts on Intel VT-d systems can allow interrupts to be received
+ * directly by a virtual machine. ARM IRQ Forwarding allows forwarded physical
+ * interrupts to be directly deactivated by the guest. This manager allows
+ * interrupt producers and consumers to find each other to enable this sort of
+ * bypass.
+ */
+
+#include <linux/irqbypass.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("IRQ bypass manager utility module");
+
+static LIST_HEAD(producers);
+static LIST_HEAD(consumers);
+static DEFINE_MUTEX(lock);
+
+/* @lock must be held when calling connect */
+static int __connect(struct irq_bypass_producer *prod,
+ struct irq_bypass_consumer *cons)
+{
+ int ret = 0;
+
+ if (prod->stop)
+ prod->stop(prod);
+ if (cons->stop)
+ cons->stop(cons);
+
+ if (prod->add_consumer)
+ ret = prod->add_consumer(prod, cons);
+
+ if (!ret) {
+ ret = cons->add_producer(cons, prod);
+ if (ret && prod->del_consumer)
+ prod->del_consumer(prod, cons);
+ }
+
+ if (cons->start)
+ cons->start(cons);
+ if (prod->start)
+ prod->start(prod);
+
+ return ret;
+}
+
+/* @lock must be held when calling disconnect */
+static void __disconnect(struct irq_bypass_producer *prod,
+ struct irq_bypass_consumer *cons)
+{
+ if (prod->stop)
+ prod->stop(prod);
+ if (cons->stop)
+ cons->stop(cons);
+
+ cons->del_producer(cons, prod);
+
+ if (prod->del_consumer)
+ prod->del_consumer(prod, cons);
+
+ if (cons->start)
+ cons->start(cons);
+ if (prod->start)
+ prod->start(prod);
+}
+
+/**
+ * irq_bypass_register_producer - register IRQ bypass producer
+ * @producer: pointer to producer structure
+ *
+ * Add the provided IRQ producer to the list of producers and connect
+ * with any matching token found on the IRQ consumers list.
+ */
+int irq_bypass_register_producer(struct irq_bypass_producer *producer)
+{
+ struct irq_bypass_producer *tmp;
+ struct irq_bypass_consumer *consumer;
+
+ might_sleep();
+
+ if (!try_module_get(THIS_MODULE))
+ return -ENODEV;
+
+ mutex_lock(&lock);
+
+ list_for_each_entry(tmp, &producers, node) {
+ if (tmp->token == producer->token) {
+ mutex_unlock(&lock);
+ module_put(THIS_MODULE);
+ return -EBUSY;
+ }
+ }
+
+ list_for_each_entry(consumer, &consumers, node) {
+ if (consumer->token == producer->token) {
+ int ret = __connect(producer, consumer);
+ if (ret) {
+ mutex_unlock(&lock);
+ module_put(THIS_MODULE);
+ return ret;
+ }
+ break;
+ }
+ }
+
+ list_add(&producer->node, &producers);
+
+ mutex_unlock(&lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(irq_bypass_register_producer);
+
+/**
+ * irq_bypass_unregister_producer - unregister IRQ bypass producer
+ * @producer: pointer to producer structure
+ *
+ * Remove a previously registered IRQ producer from the list of producers
+ * and disconnect it from any connected IRQ consumer.
+ */
+void irq_bypass_unregister_producer(struct irq_bypass_producer *producer)
+{
+ struct irq_bypass_producer *tmp;
+ struct irq_bypass_consumer *consumer;
+
+ might_sleep();
+
+ if (!try_module_get(THIS_MODULE))
+ return; /* nothing in the list anyway */
+
+ mutex_lock(&lock);
+
+ list_for_each_entry(tmp, &producers, node) {
+ if (tmp->token != producer->token)
+ continue;
+
+ list_for_each_entry(consumer, &consumers, node) {
+ if (consumer->token == producer->token) {
+ __disconnect(producer, consumer);
+ break;
+ }
+ }
+
+ list_del(&producer->node);
+ module_put(THIS_MODULE);
+ break;
+ }
+
+ mutex_unlock(&lock);
+
+ module_put(THIS_MODULE);
+}
+EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer);
+
+/**
+ * irq_bypass_register_consumer - register IRQ bypass consumer
+ * @consumer: pointer to consumer structure
+ *
+ * Add the provided IRQ consumer to the list of consumers and connect
+ * with any matching token found on the IRQ producer list.
+ */
+int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer)
+{
+ struct irq_bypass_consumer *tmp;
+ struct irq_bypass_producer *producer;
+
+ if (!consumer->add_producer || !consumer->del_producer)
+ return -EINVAL;
+
+ might_sleep();
+
+ if (!try_module_get(THIS_MODULE))
+ return -ENODEV;
+
+ mutex_lock(&lock);
+
+ list_for_each_entry(tmp, &consumers, node) {
+ if (tmp->token == consumer->token) {
+ mutex_unlock(&lock);
+ module_put(THIS_MODULE);
+ return -EBUSY;
+ }
+ }
+
+ list_for_each_entry(producer, &producers, node) {
+ if (producer->token == consumer->token) {
+ int ret = __connect(producer, consumer);
+ if (ret) {
+ mutex_unlock(&lock);
+ module_put(THIS_MODULE);
+ return ret;
+ }
+ break;
+ }
+ }
+
+ list_add(&consumer->node, &consumers);
+
+ mutex_unlock(&lock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(irq_bypass_register_consumer);
+
+/**
+ * irq_bypass_unregister_consumer - unregister IRQ bypass consumer
+ * @consumer: pointer to consumer structure
+ *
+ * Remove a previously registered IRQ consumer from the list of consumers
+ * and disconnect it from any connected IRQ producer.
+ */
+void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer)
+{
+ struct irq_bypass_consumer *tmp;
+ struct irq_bypass_producer *producer;
+
+ might_sleep();
+
+ if (!try_module_get(THIS_MODULE))
+ return; /* nothing in the list anyway */
+
+ mutex_lock(&lock);
+
+ list_for_each_entry(tmp, &consumers, node) {
+ if (tmp->token != consumer->token)
+ continue;
+
+ list_for_each_entry(producer, &producers, node) {
+ if (producer->token == consumer->token) {
+ __disconnect(producer, consumer);
+ break;
+ }
+ }
+
+ list_del(&consumer->node);
+ module_put(THIS_MODULE);
+ break;
+ }
+
+ mutex_unlock(&lock);
+
+ module_put(THIS_MODULE);
+}
+EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer);