KVM: s390: pfmf: handle address overflows

In theory, end could always end up being < start, if overflowing to 0.
Although very unlikely for now, let's just fix it.
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/priv.c

@@ -715,7 +715,7 @@ static int handle_pfmf(struct kvm_vcpu *vcpu)
 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 	}
 
-	while (start < end) {
+	while (start != end) {
 		unsigned long useraddr;
 
 		/* Translate guest address to host address */