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irqbypass: Take ownership of producer/consumer token tracking

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Move ownership of IRQ bypass token tracking into irqbypass.ko, and
explicitly require callers to pass an eventfd_ctx structure instead of a
completely opaque token.  Relying on producers and consumers to set the
token appropriately is error prone, and hiding the fact that the token must
be an eventfd_ctx pointer (for all intents and purposes) unnecessarily
obfuscates the code and makes it more brittle.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20250516230734.2564775-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2025-05-16 16:07:29 -07:00
parent 07fbc83c01
commit 2b521d86ee
6 changed files with 58 additions and 49 deletions
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7
virt/kvm/eventfd.c
View File

@@ -426,15 +426,14 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
#if IS_ENABLED(CONFIG_HAVE_KVM_IRQ_BYPASS)
if (kvm_arch_has_irq_bypass()) {
irqfd->consumer.token = (void *)irqfd->eventfd;
irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
irqfd->consumer.start = kvm_arch_irq_bypass_start;
ret = irq_bypass_register_consumer(&irqfd->consumer);
ret = irq_bypass_register_consumer(&irqfd->consumer, irqfd->eventfd);
if (ret)
pr_info("irq bypass consumer (token %p) registration fails: %d\n",
irqfd->consumer.token, ret);
pr_info("irq bypass consumer (eventfd %p) registration fails: %d\n",
irqfd->eventfd, ret);
}
#endif

44
virt/lib/irqbypass.c
View File

@@ -77,30 +77,32 @@ static void __disconnect(struct irq_bypass_producer *prod,
/**
* irq_bypass_register_producer - register IRQ bypass producer
* @producer: pointer to producer structure
* @eventfd: pointer to the eventfd context associated with the producer
*
* Add the provided IRQ producer to the list of producers and connect
* with any matching token found on the IRQ consumers list.
* with any matching eventfd found on the IRQ consumers list.
*/
int irq_bypass_register_producer(struct irq_bypass_producer *producer)
int irq_bypass_register_producer(struct irq_bypass_producer *producer,
struct eventfd_ctx *eventfd)
{
struct irq_bypass_producer *tmp;
struct irq_bypass_consumer *consumer;
int ret;
if (!producer->token)
if (WARN_ON_ONCE(producer->eventfd))
return -EINVAL;
mutex_lock(&lock);
list_for_each_entry(tmp, &producers, node) {
if (tmp->token == producer->token) {
if (tmp->eventfd == eventfd) {
ret = -EBUSY;
goto out_err;
}
}
list_for_each_entry(consumer, &consumers, node) {
if (consumer->token == producer->token) {
if (consumer->eventfd == eventfd) {
ret = __connect(producer, consumer);
if (ret)
goto out_err;
@@ -108,6 +110,7 @@ int irq_bypass_register_producer(struct irq_bypass_producer *producer)
}
}
producer->eventfd = eventfd;
list_add(&producer->node, &producers);
mutex_unlock(&lock);
@@ -131,26 +134,28 @@ void irq_bypass_unregister_producer(struct irq_bypass_producer *producer)
struct irq_bypass_producer *tmp;
struct irq_bypass_consumer *consumer;
if (!producer->token)
if (!producer->eventfd)
return;
mutex_lock(&lock);
list_for_each_entry(tmp, &producers, node) {
if (tmp->token != producer->token)
if (tmp->eventfd != producer->eventfd)
continue;
list_for_each_entry(consumer, &consumers, node) {
if (consumer->token == producer->token) {
if (consumer->eventfd == producer->eventfd) {
__disconnect(producer, consumer);
break;
}
}
producer->eventfd = NULL;
list_del(&producer->node);
break;
}
WARN_ON_ONCE(producer->eventfd);
mutex_unlock(&lock);
}
EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer);
@@ -158,31 +163,35 @@ EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer);
/**
* irq_bypass_register_consumer - register IRQ bypass consumer
* @consumer: pointer to consumer structure
* @eventfd: pointer to the eventfd context associated with the consumer
*
* Add the provided IRQ consumer to the list of consumers and connect
* with any matching token found on the IRQ producer list.
* with any matching eventfd found on the IRQ producer list.
*/
int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer)
int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer,
struct eventfd_ctx *eventfd)
{
struct irq_bypass_consumer *tmp;
struct irq_bypass_producer *producer;
int ret;
if (!consumer->token ||
!consumer->add_producer || !consumer->del_producer)
if (WARN_ON_ONCE(consumer->eventfd))
return -EINVAL;
if (!consumer->add_producer || !consumer->del_producer)
return -EINVAL;
mutex_lock(&lock);
list_for_each_entry(tmp, &consumers, node) {
if (tmp->token == consumer->token || tmp == consumer) {
if (tmp->eventfd == eventfd) {
ret = -EBUSY;
goto out_err;
}
}
list_for_each_entry(producer, &producers, node) {
if (producer->token == consumer->token) {
if (producer->eventfd == eventfd) {
ret = __connect(producer, consumer);
if (ret)
goto out_err;
@@ -190,6 +199,7 @@ int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer)
}
}
consumer->eventfd = eventfd;
list_add(&consumer->node, &consumers);
mutex_unlock(&lock);
@@ -213,7 +223,7 @@ void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer)
struct irq_bypass_consumer *tmp;
struct irq_bypass_producer *producer;
if (!consumer->token)
if (!consumer->eventfd)
return;
mutex_lock(&lock);
@@ -223,16 +233,18 @@ void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer)
continue;
list_for_each_entry(producer, &producers, node) {
if (producer->token == consumer->token) {
if (producer->eventfd == consumer->eventfd) {
__disconnect(producer, consumer);
break;
}
}
consumer->eventfd = NULL;
list_del(&consumer->node);
break;
}
WARN_ON_ONCE(consumer->eventfd);
mutex_unlock(&lock);
}
EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer);