From 4d82d12b39132e820b9ac4aa058ccc733db98917 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Sun, 18 Dec 2016 21:43:41 +0100 Subject: [PATCH] KVM: lapic: do not scan IRR when delivering an interrupt On interrupt delivery the PPR can only grow (except for auto-EOI), so it is impossible that non-auto-EOI interrupt delivery results in KVM_REQ_EVENT. We can therefore use __apic_update_ppr. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 457fb206647d..10a745faa659 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2115,6 +2115,7 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu) { int vector = kvm_apic_has_interrupt(vcpu); struct kvm_lapic *apic = vcpu->arch.apic; + u32 ppr; if (vector == -1) return -1; @@ -2126,13 +2127,23 @@ int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu) * because the process would deliver it through the IDT. */ - apic_set_isr(vector, apic); - apic_update_ppr(apic); apic_clear_irr(vector, apic); - if (test_bit(vector, vcpu_to_synic(vcpu)->auto_eoi_bitmap)) { - apic_clear_isr(vector, apic); + /* + * For auto-EOI interrupts, there might be another pending + * interrupt above PPR, so check whether to raise another + * KVM_REQ_EVENT. + */ apic_update_ppr(apic); + } else { + /* + * For normal interrupts, PPR has been raised and there cannot + * be a higher-priority pending interrupt---except if there was + * a concurrent interrupt injection, but that would have + * triggered KVM_REQ_EVENT already. + */ + apic_set_isr(vector, apic); + __apic_update_ppr(apic, &ppr); } return vector; -- 2.30.2