s390x/tcg: add basic MSA features

s390x/tcg: add basic MSA features

The STFLE bits for the MSA (extension) facilities simply indicate that
the respective instructions can be executed. The QUERY subfunction can then
be used to identify which features exactly are available.

Availability of subfunctions can also vary on real hardware. For now, we
simply implement a CPU model without any available subfunctions except
QUERY (which is always around).

As all MSA functions behave quite similarly, we can use one translation
handler for now. Prepare the code for implementation of actual subfunctions.

At least MSA is helpful for now, as older Linux kernels require this
facility when compiled for a z9 model. Allow to enable the facilities
for the qemu cpu model.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170920153016.3858-4-david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>