KVM: PIC: enhance IPI avoidance

[linux-kernel-docs/linux-2.6.git] / arch / x86 / kvm / i8259.c

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index 71e3eee..17e41e1 100644 (file)
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -33,6 +33,14 @@
 static void pic_clear_isr(struct kvm_kpic_state *s, int irq)
 {
        s->isr &= ~(1 << irq);
+       s->isr_ack |= (1 << irq);
+}
+
+void kvm_pic_clear_isr_ack(struct kvm *kvm)
+{
+       struct kvm_pic *s = pic_irqchip(kvm);
+       s->pics[0].isr_ack = 0xff;
+       s->pics[1].isr_ack = 0xff;
 }
 
 /*
@@ -213,6 +221,7 @@ void kvm_pic_reset(struct kvm_kpic_state *s)
        s->irr = 0;
        s->imr = 0;
        s->isr = 0;
+       s->isr_ack = 0xff;
        s->priority_add = 0;
        s->irq_base = 0;
        s->read_reg_select = 0;
@@ -444,10 +453,14 @@ static void pic_irq_request(void *opaque, int level)
 {
        struct kvm *kvm = opaque;
        struct kvm_vcpu *vcpu = kvm->vcpus[0];
+       struct kvm_pic *s = pic_irqchip(kvm);
+       int irq = pic_get_irq(&s->pics[0]);
 
-       pic_irqchip(kvm)->output = level;
-       if (vcpu)
+       s->output = level;
+       if (vcpu && level && (s->pics[0].isr_ack & (1 << irq))) {
+               s->pics[0].isr_ack &= ~(1 << irq);
                kvm_vcpu_kick(vcpu);
+       }
 }
 
 struct kvm_pic *kvm_create_pic(struct kvm *kvm)