KVM: x86: recalculate_apic_map after enabling apic

Currently, recalculate_apic_map ignores vcpus whose lapic is software disabled
through the spurious interrupt vector. However, once it is re-enabled, the map
is not recalculated. Therefore, if the guest OS configured DFR while lapic is
software-disabled, the map may be incorrect. This patch recalculates apic map
after software enabling the lapic.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -112,17 +112,6 @@ static inline int __apic_test_and_clear_vector(int vec, void *bitmap)
 struct static_key_deferred apic_hw_disabled __read_mostly;
 struct static_key_deferred apic_sw_disabled __read_mostly;
 
-static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
-{
-	if ((kvm_apic_get_reg(apic, APIC_SPIV) ^ val) & APIC_SPIV_APIC_ENABLED) {
-		if (val & APIC_SPIV_APIC_ENABLED)
-			static_key_slow_dec_deferred(&apic_sw_disabled);
-		else
-			static_key_slow_inc(&apic_sw_disabled.key);
-	}
-	apic_set_reg(apic, APIC_SPIV, val);
-}
-
 static inline int apic_enabled(struct kvm_lapic *apic)
 {
 	return kvm_apic_sw_enabled(apic) &&	kvm_apic_hw_enabled(apic);
@@ -210,6 +199,20 @@ static void recalculate_apic_map(struct kvm *kvm)
 	kvm_vcpu_request_scan_ioapic(kvm);
 }
 
+static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
+{
+	u32 prev = kvm_apic_get_reg(apic, APIC_SPIV);
+
+	apic_set_reg(apic, APIC_SPIV, val);
+	if ((prev ^ val) & APIC_SPIV_APIC_ENABLED) {
+		if (val & APIC_SPIV_APIC_ENABLED) {
+			static_key_slow_dec_deferred(&apic_sw_disabled);
+			recalculate_apic_map(apic->vcpu->kvm);
+		} else
+			static_key_slow_inc(&apic_sw_disabled.key);
+	}
+}
+
 static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
 {
 	apic_set_reg(apic, APIC_ID, id << 24);