selftests: kvm: s390: Add test fixture and simple VM setup tests

selftests: kvm: s390: Add test fixture and simple VM setup tests

Add a uc_kvm fixture to create and destroy a ucontrol VM.

* uc_sie_assertions asserts basic settings in the SIE as setup by the
  kernel.
* uc_attr_mem_limit asserts the memory limit is max value and cannot be
  set (not supported).
* uc_no_dirty_log asserts dirty log is not supported.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20240807154512.316936-5-schlameuss@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20240807154512.316936-5-schlameuss@linux.ibm.com>