diff mbox

KVM: Don't update PPR on any APIC read

Message ID 1342968060-23683-1-git-send-email-avi@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Avi Kivity July 22, 2012, 2:41 p.m. UTC
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>
---
 arch/x86/kvm/lapic.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Marcelo Tosatti July 30, 2012, 11:48 p.m. UTC | #1
On Sun, Jul 22, 2012 at 05:41:00PM +0300, Avi Kivity wrote:
> 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>

Applied, thanks.

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diff mbox

Patch

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ce87878..a7b8fa2 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -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;
 	}