--- /dev/null
+/*
+ * 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);
Code Review / kvmfornfv.git / blobdiff