From: Avi Kivity <avi@redhat.com>
Date: Mon, 25 Oct 2010 13:23:55 +0000 (+0200)
Subject: KVM: Avoid double interrupt injection with vapic
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=83bcacb1a548d4d8df532376c981277761622bce;p=linux-beck.git

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>
---

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);
 	}
 }