[PATCH v3 0/6] migration: check required entries and sections are loaded

[marcandre . lureau]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Hi,

Surprisingly, the migration code doesn't check that required migration entries
and subsections are loaded. Either optional or required sections are both
ignored when missing. According to the documentation a "newer QEMU that knows
about a subsection can (with care) load a stream from an older QEMU that didn't
send the subsection". I propose this behaviour to be limited to "optional"
sections only.

This series has a few preliminary fixes, add new checks that entries are
loaded once and required ones have been loaded, add some tests and
documentation update.

thanks

v3:
 - rebased, drop RFC status
 - switch from tracepoint + returning an error to report for missing
   subsections, as we worry about potential regressions
 - add r-b tags

v2:
 - add "migration: rename vmstate_save_needed->vmstate_section_needed"
 - add "migration: set file error on subsection loading"
 - add subsection tests
 - update the documentation

Marc-André Lureau (6):
  block/fdc: 'phase' is not needed on load
  virtio: make endian_needed() work during loading
  migration: check required subsections are loaded, once
  migration: check required entries are loaded, once
  test-vmstate: add some subsection tests
  docs/migration: reflect the changes about needed subsections

 docs/devel/migration.rst  |  17 +++---
 hw/block/fdc.c            |   5 ++
 hw/virtio/virtio.c        |   6 +-
 migration/savevm.c        |  43 ++++++++++++++
 migration/vmstate.c       |  40 ++++++++++++-
 tests/unit/test-vmstate.c | 116 ++++++++++++++++++++++++++++++++++++++
 6 files changed, 215 insertions(+), 12 deletions(-)

-- 
2.41.0