KVM: s390: selftests: Add regression tests for SORTL and DFLTCC CPU subfunctions

KVM: s390: selftests: Add regression tests for SORTL and DFLTCC CPU subfunctions

Introduce new regression tests to verify the ASM inline block in the SORTL
and DFLTCC CPU subfunctions for the s390x architecture. These tests ensure
that future changes to the ASM code are properly validated.

The test procedure:

1. Create a VM and request the KVM_S390_VM_CPU_MACHINE_SUBFUNC attribute
   from the KVM_S390_VM_CPU_MODEL group for this VM. This SUBFUNC attribute
   contains the results of all CPU subfunction instructions.
2. For each tested subfunction (SORTL and DFLTCC), execute the
   corresponding ASM instruction and capture the result array.
3. Perform a memory comparison between the results stored in the SUBFUNC
   attribute (obtained in step 1) and the ASM instruction results (obtained
   in step 2) for each tested subfunction.

This process ensures that the KVM implementation accurately reflects the
behavior of the actual CPU instructions for the tested subfunctions.

Suggested-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Hariharan Mari <hari55@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Link: https://lore.kernel.org/r/20240823130947.38323-2-hari55@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20240823130947.38323-2-hari55@linux.ibm.com>