KVM: s390: protvirt: Handle spec exception loops

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>