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

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Nov 06, 2023 at 03:35:54PM +0400, marcandre.lureau@redhat.com wrote:
> 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

I think this kind of thing is better deferred to the next release -
unless you have something specific in mind this fixes?

> 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