KVM: LAPIC: Fix updating DFR missing apic map recalculation

There is missing apic map recalculation after updating DFR, if it is
INIT RESET, in x2apic mode, local apic is software enabled before.
This patch fix it by introducing the function kvm_apic_set_dfr() to
be called in INIT RESET handling path.
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Message-Id: <1597827327-25055-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -310,6 +310,12 @@ static inline void kvm_apic_set_ldr(struct kvm_lapic *apic, u32 id)
 	atomic_set_release(&apic->vcpu->kvm->arch.apic_map_dirty, DIRTY);
 }
 
+static inline void kvm_apic_set_dfr(struct kvm_lapic *apic, u32 val)
+{
+	kvm_lapic_set_reg(apic, APIC_DFR, val);
+	atomic_set_release(&apic->vcpu->kvm->arch.apic_map_dirty, DIRTY);
+}
+
 static inline u32 kvm_apic_calc_x2apic_ldr(u32 id)
 {
 	return ((id >> 4) << 16) | (1 << (id & 0xf));
@@ -1984,10 +1990,9 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 		break;
 
 	case APIC_DFR:
-		if (!apic_x2apic_mode(apic)) {
-			kvm_lapic_set_reg(apic, APIC_DFR, val | 0x0FFFFFFF);
-			atomic_set_release(&apic->vcpu->kvm->arch.apic_map_dirty, DIRTY);
-		} else
+		if (!apic_x2apic_mode(apic))
+			kvm_apic_set_dfr(apic, val | 0x0FFFFFFF);
+		else
 			ret = 1;
 		break;
 
@@ -2303,7 +2308,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 			     SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
 	apic_manage_nmi_watchdog(apic, kvm_lapic_get_reg(apic, APIC_LVT0));
 
-	kvm_lapic_set_reg(apic, APIC_DFR, 0xffffffffU);
+	kvm_apic_set_dfr(apic, 0xffffffffU);
 	apic_set_spiv(apic, 0xff);
 	kvm_lapic_set_reg(apic, APIC_TASKPRI, 0);
 	if (!apic_x2apic_mode(apic))