KVM: s390: unintended fallthrough for external call

commit f346026e upstream.

We must not fallthrough if the conditions for external call are not met.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/s390/kvm/interrupt.c

@@ -43,6 +43,7 @@ static int __interrupt_is_deliverable(struct kvm_vcpu *vcpu,
 			return 0;
 		if (vcpu->arch.sie_block->gcr[0] & 0x2000ul)
 			return 1;
+		return 0;
 	case KVM_S390_INT_EMERGENCY:
 		if (psw_extint_disabled(vcpu))
 			return 0;