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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 <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-12-18 21:43:41 +01:00 committed by Radim Krčmář
parent 26fbbee581
commit 4d82d12b39
1 changed files with 15 additions and 4 deletions
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19
arch/x86/kvm/lapic.c
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@ -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;