[PATCH] Maybe avoid a IPI between the cpu cores

[yi li]

    The cpu inject the interrupt to vcpu which vcpu->cpu is the same as it.
    And it maybe  avoid a IPI between the cpu core.

    Signed-off-by: Yi Li <yiliker...@gmail.com>

--- linux/virt/kvm/irq_comm.c   2012-12-04 10:14:57.711024619 +0800
+++ linux/virt/kvm/irq_comm.c   2012-12-04 11:01:27.728859597 +0800
@@ -64,9 +64,10 @@ inline static bool kvm_is_dm_lowest_prio
 int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
                struct kvm_lapic_irq *irq)
 {
-       int i, r = -1;
+       int i, cpu, r = -1;
        struct kvm_vcpu *vcpu, *lowest = NULL;

+       cpu = get_cpu();
        if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
                        kvm_is_dm_lowest_prio(irq)) {
                printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
@@ -89,13 +90,17 @@ int kvm_irq_delivery_to_apic(struct kvm
                                r = 0;
                        r += kvm_apic_set_irq(vcpu, irq);
                } else if (kvm_lapic_enabled(vcpu)) {
-                       if (!lowest)
+                       if(vcpu->cpu == cpu) {
+                               lowest = vcpu;
+                               break;
+                       }
+                       else if (!lowest)
                                lowest = vcpu;
                        else if (kvm_apic_compare_prio(vcpu, lowest) < 0)
                                lowest = vcpu;
                }
        }
-
+       put_cpu();
        if (lowest)
                r = kvm_apic_set_irq(lowest, irq);


YiLi
Thanks
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