Re: [Qemu-devel] [PATCH v7 22/42] migrate_start_postcopy: Command to trigger transition to postcopy

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Once postcopy is enabled (with migrate_set_capability), the migration
> will still start on precopy mode.  To cause a transition into postcopy
> the:
>
>   migrate_start_postcopy
>
> command must be issued.  Postcopy will start sometime after this
> (when it's next checked in the migration loop).
>
> Issuing the command before migration has started will error,
> and issuing after it has finished is ignored.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> Reviewed-by: Eric Blake <address@hidden>

> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index a5951ac..e973490 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -111,6 +111,9 @@ struct MigrationState
>      int64_t xbzrle_cache_size;
>      int64_t setup_time;
>      int64_t dirty_sync_count;
> +
> +    /* Flag set once the migration has been asked to enter postcopy */
> +    bool start_postcopy;
>  };
>  
>  void process_incoming_migration(QEMUFile *f);
> diff --git a/migration/migration.c b/migration/migration.c
> index e77b8b4..6fc47f9 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -465,6 +465,28 @@ void qmp_migrate_set_parameters(bool has_compress_level,
>      }
>  }
>  
> +void qmp_migrate_start_postcopy(Error **errp)
> +{
> +    MigrationState *s = migrate_get_current();
> +
> +    if (!migrate_postcopy_ram()) {
> +        error_setg(errp, "Enable postcopy with migration_set_capability 
> before"
> +                         " the start of migration");
> +        return;
> +    }
> +
> +    if (s->state == MIGRATION_STATUS_NONE) {

I would claim that this check should be:

    if (s->state != MIGRATION_STATUS_ACTIVE) {
??

FAILED, COMPLETED, CANCELL* don't make sense, right?

Thanks, Juan.