path: root/virt/kvm/irq_comm.c
diff options
authorMichael S. Tsirkin <>2010-11-18 19:09:08 +0200
committerAvi Kivity <>2011-01-12 11:29:38 +0200
commitbd2b53b20fcd0d6c4c815b54e6d464e34429d3a4 (patch)
tree1f225ea8b74368056bc144de14a1015fa4ebde29 /virt/kvm/irq_comm.c
parent104f226bfd0a607ca0e804ae4907555374f72cd9 (diff)
KVM: fast-path msi injection with irqfd
Store irq routing table pointer in the irqfd object, and use that to inject MSI directly without bouncing out to a kernel thread. While we touch this structure, rearrange irqfd fields to make fastpath better packed for better cache utilization. This also adds some comments about locking rules and rcu usage in code. Some notes on the design: - Use pointer into the rt instead of copying an entry, to make it possible to use rcu, thus side-stepping locking complexities. We also save some memory this way. - Old workqueue code is still used for level irqs. I don't think we DTRT with level anyway, however, it seems easier to keep the code around as it has been thought through and debugged, and fix level later than rip out and re-instate it later. Signed-off-by: Michael S. Tsirkin <> Acked-by: Marcelo Tosatti <> Acked-by: Gregory Haskins <> Signed-off-by: Avi Kivity <>
Diffstat (limited to 'virt/kvm/irq_comm.c')
1 files changed, 4 insertions, 3 deletions
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 8edca9141b78..9f614b4e365f 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -114,8 +114,8 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
return r;
-static int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
- struct kvm *kvm, int irq_source_id, int level)
+int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
+ struct kvm *kvm, int irq_source_id, int level)
struct kvm_lapic_irq irq;
@@ -409,8 +409,9 @@ int kvm_set_irq_routing(struct kvm *kvm,
old = kvm->irq_routing;
- rcu_assign_pointer(kvm->irq_routing, new);
+ kvm_irq_routing_update(kvm, new);
new = old;