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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>
This commit is contained in:
Avi Kivity 2010-10-25 15:23:55 +02:00
parent 82ca2d108b
commit 83bcacb1a5
1 changed files with 2 additions and 1 deletions
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1
arch/x86/kvm/lapic.c
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@ -277,6 +277,7 @@ static void apic_update_ppr(struct kvm_lapic *apic)
if (old_ppr != ppr) { if (old_ppr != ppr) {
apic_set_reg(apic, APIC_PROCPRI, ppr); apic_set_reg(apic, APIC_PROCPRI, ppr);
if (ppr < old_ppr)
kvm_make_request(KVM_REQ_EVENT, apic->vcpu); kvm_make_request(KVM_REQ_EVENT, apic->vcpu);
} }
} }