Patchwork [1/2] KVM: Distangle eventfd code from irqchip

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Submitter Alexander Graf
Date Oct. 15, 2012, 12:02 p.m.
Message ID <1350302566-28889-2-git-send-email-agraf@suse.de>
Download mbox | patch
Permalink /patch/191551/
State New
Headers show

Comments

Alexander Graf - Oct. 15, 2012, 12:02 p.m.
The current eventfd code assumes that when we have eventfd, we also have
irqfd for in-kernel interrupt delivery. This is not necessarily true. On
PPC we don't have an in-kernel irqchip yet, but we can still support easily
support eventfd.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 include/linux/kvm_host.h |   12 +++++++++++-
 virt/kvm/eventfd.c       |    6 ++++++
 2 files changed, 17 insertions(+), 1 deletions(-)
Avi Kivity - Oct. 16, 2012, 10:57 a.m.
On 10/15/2012 02:02 PM, Alexander Graf wrote:
> The current eventfd code assumes that when we have eventfd, we also have
> irqfd for in-kernel interrupt delivery. This is not necessarily true. On
> PPC we don't have an in-kernel irqchip yet, but we can still support easily
> support eventfd.
> 

Don't you need, in addition, to reject PIO space for ioeventfd?
Alexander Graf - Oct. 16, 2012, 11:01 a.m.
On 16.10.2012, at 12:57, Avi Kivity wrote:

> On 10/15/2012 02:02 PM, Alexander Graf wrote:
>> The current eventfd code assumes that when we have eventfd, we also have
>> irqfd for in-kernel interrupt delivery. This is not necessarily true. On
>> PPC we don't have an in-kernel irqchip yet, but we can still support easily
>> support eventfd.
>> 
> 
> Don't you need, in addition, to reject PIO space for ioeventfd?

Yeah, we could tell user space that it's doing something stupid. Not sure how critical it is - right now it would just register it and never get triggered, because the bus doesn't exist. But sanity checks are a good thing usually.


Alex

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Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6afc5be..f2f5880 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -884,10 +884,20 @@  static inline void kvm_free_irq_routing(struct kvm *kvm) {}
 #ifdef CONFIG_HAVE_KVM_EVENTFD
 
 void kvm_eventfd_init(struct kvm *kvm);
+int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args);
+
+#ifdef CONFIG_HAVE_KVM_IRQCHIP
 int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args);
 void kvm_irqfd_release(struct kvm *kvm);
 void kvm_irq_routing_update(struct kvm *, struct kvm_irq_routing_table *);
-int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args);
+#else
+static inline int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args)
+{
+	return -EINVAL;
+}
+
+static inline void kvm_irqfd_release(struct kvm *kvm) {}
+#endif
 
 #else
 
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 9718e98..d7424c8 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -35,6 +35,7 @@ 
 
 #include "iodev.h"
 
+#ifdef __KVM_HAVE_IOAPIC
 /*
  * --------------------------------------------------------------------
  * irqfd: Allows an fd to be used to inject an interrupt to the guest
@@ -425,17 +426,21 @@  fail:
 	kfree(irqfd);
 	return ret;
 }
+#endif
 
 void
 kvm_eventfd_init(struct kvm *kvm)
 {
+#ifdef __KVM_HAVE_IOAPIC
 	spin_lock_init(&kvm->irqfds.lock);
 	INIT_LIST_HEAD(&kvm->irqfds.items);
 	INIT_LIST_HEAD(&kvm->irqfds.resampler_list);
 	mutex_init(&kvm->irqfds.resampler_lock);
+#endif
 	INIT_LIST_HEAD(&kvm->ioeventfds);
 }
 
+#ifdef __KVM_HAVE_IOAPIC
 /*
  * shutdown any irqfd's that match fd+gsi
  */
@@ -555,6 +560,7 @@  static void __exit irqfd_module_exit(void)
 
 module_init(irqfd_module_init);
 module_exit(irqfd_module_exit);
+#endif
 
 /*
  * --------------------------------------------------------------------