From e48258009d941891fca35348986b8d280caf31cd Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Wed, 24 Sep 2008 20:28:34 -0300 Subject: KVM: PIC: enhance IPI avoidance The PIC code makes little effort to avoid kvm_vcpu_kick(), resulting in unnecessary guest exits in some conditions. For example, if the timer interrupt is routed through the IOAPIC, IRR for IRQ 0 will get set but not cleared, since the APIC is handling the acks. This means that everytime an interrupt < 16 is triggered, the priority logic will find IRQ0 pending and send an IPI to vcpu0 (in case IRQ0 is not masked, which is Linux's case). Introduce a new variable isr_ack to represent the IRQ's for which the guest has been signalled / cleared the ISR. Use it to avoid more than one IPI per trigger-ack cycle, in addition to the avoidance when ISR is set in get_priority(). Signed-off-by: Marcelo Tosatti Signed-off-by: Avi Kivity --- arch/x86/kvm/irq.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kvm/irq.h') diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 479a3d2d5614..4748532fd1da 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -42,6 +42,7 @@ struct kvm_kpic_state { u8 irr; /* interrupt request register */ u8 imr; /* interrupt mask register */ u8 isr; /* interrupt service register */ + u8 isr_ack; /* interrupt ack detection */ u8 priority_add; /* highest irq priority */ u8 irq_base; u8 read_reg_select; @@ -70,6 +71,7 @@ struct kvm_pic *kvm_create_pic(struct kvm *kvm); void kvm_pic_set_irq(void *opaque, int irq, int level); int kvm_pic_read_irq(struct kvm *kvm); void kvm_pic_update_irq(struct kvm_pic *s); +void kvm_pic_clear_isr_ack(struct kvm *kvm); static inline struct kvm_pic *pic_irqchip(struct kvm *kvm) { -- cgit v1.2.3