KVM: s390: protvirt: Handle spec exception loops

SIE intercept code 8 is used only on exception loops for protected
guests. That means we need to stop the guest when we see it. This is
done by userspace.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/intercept.c

@@ -231,6 +231,13 @@ static int handle_prog(struct kvm_vcpu *vcpu)
 
 	vcpu->stat.exit_program_interruption++;
 
+	/*
+	 * Intercept 8 indicates a loop of specification exceptions
+	 * for protected guests.
+	 */
+	if (kvm_s390_pv_cpu_is_protected(vcpu))
+		return -EOPNOTSUPP;
+
 	if (guestdbg_enabled(vcpu) && per_event(vcpu)) {
 		rc = kvm_s390_handle_per_event(vcpu);
 		if (rc)