[PATCH 2/2] kvm: Conditionally register IRQ bypass consumer

From: Alex Williamson
Date: Thu May 05 2016 - 13:58:46 EST


If we don't support a mechanism for bypassing IRQs, don't register as
a consumer. This eliminates meaningless dev_info()s when the connect
fails between producer and consumer, such as on AMD systems where
kvm_x86_ops->update_pi_irte is not implemented

Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 19 ++++++++-----------
include/linux/kvm_host.h | 1 +
virt/kvm/eventfd.c | 18 ++++++++++--------
3 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9b7798c..ac97a0e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8355,19 +8355,21 @@ bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
}
EXPORT_SYMBOL_GPL(kvm_arch_has_noncoherent_dma);

+bool kvm_arch_has_irq_bypass(void)
+{
+ return kvm_x86_ops->update_pi_irte != NULL;
+}
+
int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
struct irq_bypass_producer *prod)
{
struct kvm_kernel_irqfd *irqfd =
container_of(cons, struct kvm_kernel_irqfd, consumer);

- if (kvm_x86_ops->update_pi_irte) {
- irqfd->producer = prod;
- return kvm_x86_ops->update_pi_irte(irqfd->kvm,
- prod->irq, irqfd->gsi, 1);
- }
+ irqfd->producer = prod;

- return -EINVAL;
+ return kvm_x86_ops->update_pi_irte(irqfd->kvm,
+ prod->irq, irqfd->gsi, 1);
}

void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
@@ -8377,11 +8379,6 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
struct kvm_kernel_irqfd *irqfd =
container_of(cons, struct kvm_kernel_irqfd, consumer);

- if (!kvm_x86_ops->update_pi_irte) {
- WARN_ON(irqfd->producer != NULL);
- return;
- }
-
WARN_ON(irqfd->producer != prod);
irqfd->producer = NULL;

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5276fe0..3aa4aa6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1169,6 +1169,7 @@ static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)
#endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */

#ifdef CONFIG_HAVE_KVM_IRQ_BYPASS
+bool kvm_arch_has_irq_bypass(void);
int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *,
struct irq_bypass_producer *);
void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *,
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 46dbc0a..e469b60 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -408,15 +408,17 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
*/
fdput(f);
#ifdef CONFIG_HAVE_KVM_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);
- if (ret)
- pr_info("irq bypass consumer (token %p) registration fails: %d\n",
+ 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);
+ if (ret)
+ pr_info("irq bypass consumer (token %p) registration fails: %d\n",
irqfd->consumer.token, ret);
+ }
#endif

return 0;