KVM: Avoid double interrupt injection with vapic

After an interrupt injection, the PPR changes, and we have to reflect that
into the vapic.  This causes a KVM_REQ_EVENT to be set, which causes the
whole interrupt injection routine to be run again (harmlessly).

Optimize by only setting KVM_REQ_EVENT if the ppr was lowered; otherwise
there is no chance that a new injection is needed.

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 413f8973a855..93cf9d0d3653 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -277,7 +277,8 @@ static void apic_update_ppr(struct kvm_lapic *apic)
 
         if (old_ppr != ppr) {
                 apic_set_reg(apic, APIC_PROCPRI, ppr);
-                kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
+                if (ppr < old_ppr)
+                        kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
         }
 }