KVM: only clear irq_source_id if irqchip is present

Otherwise kvm might attempt to dereference a NULL pointer.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

virt/kvm/irq_comm.c

@@ -243,6 +243,10 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
 		printk(KERN_ERR "kvm: IRQ source ID out of range!\n");
 		goto unlock;
 	}
+	clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
+	if (!irqchip_in_kernel(kvm))
+		goto unlock;
+
 	for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++) {
 		clear_bit(irq_source_id, &kvm->arch.vioapic->irq_states[i]);
 		if (i >= 16)
@@ -251,7 +255,6 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
 		clear_bit(irq_source_id, &pic_irqchip(kvm)->irq_states[i]);
 #endif
 	}
-	clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
 unlock:
 	mutex_unlock(&kvm->irq_lock);
 }