KVM: x86: preserve x2APIC LDR on INIT

Logical x2APIC stops working if we rewrite it with zeros. The best references are SDM April 2015: 10.12.10.1 Logical Destination Mode in x2APIC Mode [...], the LDR are initialized by hardware based on the value of x2APIC ID upon x2APIC state transitions. and SDM April 2015: 10.12.10.2 Deriving Logical x2APIC ID from the Local x2APIC ID The LDR initialization occurs whenever the x2APIC mode is enabled Signed-off-by: Radim KrÄ�mÃ¡Å™ <rkrcmar@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
git-mirror · May 28, 2015 · c028dd6 · c028dd6
1 parent 257b9a5
commit c028dd6
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
@@ -1594,7 +1594,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 	apic_set_reg(apic, APIC_DFR, 0xffffffffU);
 	apic_set_spiv(apic, 0xff);
 	apic_set_reg(apic, APIC_TASKPRI, 0);
-	kvm_apic_set_ldr(apic, 0);
+	if (!apic_x2apic_mode(apic))
+		kvm_apic_set_ldr(apic, 0);
 	apic_set_reg(apic, APIC_ESR, 0);
 	apic_set_reg(apic, APIC_ICR, 0);
 	apic_set_reg(apic, APIC_ICR2, 0);