linux-kernel - [PATCHv5 4/5] kvm: only sync when attention bits set

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Date:	Tue, 22 May 2012 17:05:42 +0300
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	x86@...nel.org, kvm@...r.kernel.org
Cc:	Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>,
	Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>, gleb@...hat.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCHv5 4/5] kvm: only sync when attention bits set

Commit eb0dc6d0368072236dcd086d7fdc17fd3c4574d4 introduced apic
attention bitmask but kvm still syncs lapic unconditionally.
As that commit suggested and in anticipation of adding more attention
bits, only sync lapic if(apic_attention).

Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
 arch/x86/kvm/x86.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 185a2b8..3e57566 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5370,7 +5370,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	if (unlikely(vcpu->arch.tsc_always_catchup))
 		kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
 
-	kvm_lapic_sync_from_vapic(vcpu);
+	if (unlikely(vcpu->arch.apic_attention))
+		kvm_lapic_sync_from_vapic(vcpu);
 
 	r = kvm_x86_ops->handle_exit(vcpu);
 out:
-- 
MST

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