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KVM: Don't update PPR on any APIC read 

The current code will update the PPR on almost any APIC read; however
that's only required if we read the PPR.

kvm_update_ppr() shows up in some profiles, albeit with a low usage (~1%).
This should reduce it further (it will still be called during interrupt
processing).

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2012-07-22 17:41:00 +03:00 committed by Marcelo Tosatti
parent ade38c311a
commit 4a4541a40e
1 changed files with 4 additions and 2 deletions
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6
arch/x86/kvm/lapic.c
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@ -696,12 +696,14 @@ static u32 __apic_read(struct kvm_lapic *apic, unsigned int offset)
val = apic_get_tmcct(apic);
break;
case APIC_PROCPRI:
apic_update_ppr(apic);
val = apic_get_reg(apic, offset);
break;
case APIC_TASKPRI:
report_tpr_access(apic, false);
/* fall thru */
default:
apic_update_ppr(apic);
val = apic_get_reg(apic, offset);
break;
}