From: Andrew Jones <drjones@redhat.com>
Date: Wed, 15 Jan 2014 12:39:59 +0000 (+0100)
Subject: kvm: x86: fix apic_base enable check
X-Git-Tag: v3.10.29~103
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d934d91ae3399d562849d5da096cf93d08ddc9c4;p=thirdparty%2Fkernel%2Fstable.git

kvm: x86: fix apic_base enable check

commit 0dce7cd67fd9055c4a2ff278f8af1431e646d346 upstream.

Commit e66d2ae7c67bd moved the assignment
vcpu->arch.apic_base = value above a condition with
(vcpu->arch.apic_base ^ value), causing that check
to always fail. Use old_value, vcpu->arch.apic_base's
old value, in the condition instead.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index d0a97e8088284..683bf5057e7a1 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1369,7 +1369,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value)
 	vcpu->arch.apic_base = value;
 
 	/* update jump label if enable bit changes */
-	if ((vcpu->arch.apic_base ^ value) & MSR_IA32_APICBASE_ENABLE) {
+	if ((old_value ^ value) & MSR_IA32_APICBASE_ENABLE) {
 		if (value & MSR_IA32_APICBASE_ENABLE)
 			static_key_slow_dec_deferred(&apic_hw_disabled);
 		else