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 d0a97e8088284ec8380c2092f2244ad5a15cafda..683bf5057e7a19f9ad1f7f958f85a3b5bcf26f83 100644 (file)
--- 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