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>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 457fb20..10a745f 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;