diff options
Diffstat (limited to 'kernel/virt/lib/irqbypass.c')
| -rw-r--r-- | kernel/virt/lib/irqbypass.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/kernel/virt/lib/irqbypass.c b/kernel/virt/lib/irqbypass.c new file mode 100644 index 000000000..09a03b5a2 --- /dev/null +++ b/kernel/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); |