KVM: s390: Disallow invalid bits in kvm_valid_regs and kvm_dirty_regs

KVM: s390: Disallow invalid bits in kvm_valid_regs and kvm_dirty_regs

If unknown bits are set in kvm_valid_regs or kvm_dirty_regs, this
clearly indicates that something went wrong in the KVM userspace
application. The x86 variant of KVM already contains a check for
bad bits, so let's do the same on s390x now, too.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/lkml/20190904085200.29021-2-thuth@redhat.com/
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>