To write kunit tests for preservation and restoration of liveupdate
state in various subsystems without triggering the actual kexec, the KHO
restore API needs to be mocked by the test writer. The mocking is done
to allow testing of the individual components or functions in isolation.

The patch series adds the following to support kunit testing when using the KHO
API:

- Add static stub hooks to mock the KHO restore API so the restore path
  can be tested without triggering kexec.
- Add helper function that can be used by the test writer to check if
  memory is preserved in KHO tree.

Finally, it adds a KUnit test for the KHO API that verifies the allocation of
preserved memory, and the preservation/restoration of pages and folios.

KHO Kunit test run:

 KTAP version 1
 1..1
     KTAP version 1
     # Subtest: kho_test
     # module: kexec_handover_test
     1..3
     ok 1 kho_test_alloc_preserve
     ok 2 kho_test_preserve_pages
     ok 3 kho_test_preserve_folio
 # kho_test: pass:3 fail:0 skip:0 total:3
 # Totals: pass:3 fail:0 skip:0 total:3
 ok 1 kho_test

v2:
 - Move kunit header includes above linux header includes.
 - Use the __kho_preserve_pages_order() to get the order of preserved
   pages instead of open order calculation math.

Samiullah Khawaja (3):
  kho: Add kunit static stubs
  kho: Add helper function to check if pages are preserved
  kho: Add kunit test to verify preserve/restore pages and folio

 include/linux/kexec_handover.h          |   5 +
 kernel/liveupdate/Kconfig               |  10 ++
 kernel/liveupdate/Makefile              |   1 +
 kernel/liveupdate/kexec_handover.c      |  63 +++++++++++-
 kernel/liveupdate/kexec_handover_test.c | 131 ++++++++++++++++++++++++
 5 files changed, 209 insertions(+), 1 deletion(-)
 create mode 100644 kernel/liveupdate/kexec_handover_test.c


base-commit: ec4084bc445027a52f600e30a976928be1ba1950
-- 
2.54.0.746.g67dd491aae-goog