Some migration tests need to be run with shmem, the rest by default use
anonymous memory.
Introduce MemType and replace use_shmem with such a enumeration. This
prepares for a 3rd type of memory to be tested for migration.
Careful readers may also already notice that MigrateStart has another field
called memory_backend, which makes the whole "memory type" definition
convoluted. That'll be merged into MemType soon in a follow up patch.
When doing this, introduce some migrate_mem_type_*() helpers to do the
work for each memory type.
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20251117223908.415965-2-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>