Re: [PATCH v4 10/10] migration: block incoming colo when capability is disabled

[Lukas Straub]

On Fri, 28 Apr 2023 22:49:28 +0300
Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> wrote:

> We generally require same set of capabilities on source and target.
> Let's require x-colo capability to use COLO on target.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

Good patch, this is needed anyway for COLO with multifd.

Also, it allows to remove a some code, like
migration_incoming_enable_colo(), qemu_savevm_send_colo_enable() etc.
I will send patches for that. Or you can do it if you like.

Please update the docs like below, then:
Reviewed-by: Lukas Straub <lukasstraub2@web.de>

diff --git a/docs/COLO-FT.txt b/docs/COLO-FT.txt
index 8ec653f81c..2e760a4aee 100644
--- a/docs/COLO-FT.txt
+++ b/docs/COLO-FT.txt
@@ -210,6 +210,7 @@ children.0=childs0 \
 
 3. On Secondary VM's QEMU monitor, issue command
 {"execute":"qmp_capabilities"}
+{"execute": "migrate-set-capabilities", "arguments": {"capabilities": [ 
{"capability": "x-colo", "state": true } ] } }
 {"execute": "nbd-server-start", "arguments": {"addr": {"type": "inet", "data": 
{"host": "0.0.0.0", "port": "9999"} } } }
 {"execute": "nbd-server-add", "arguments": {"device": "parent0", "writable": 
true } }


> ---
>  migration/migration.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/migration/migration.c b/migration/migration.c
> index 8c5bbf3e94..5e162c0622 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -395,6 +395,12 @@ int migration_incoming_enable_colo(void)
>      return -ENOTSUP;
>  #endif
>  
> +    if (!migrate_colo()) {
> +        error_report("ENABLE_COLO command come in migration stream, but 
> c-colo "
> +                     "capability is not set");
> +        return -EINVAL;
> +    }
> +
>      if (ram_block_discard_disable(true)) {
>          error_report("COLO: cannot disable RAM discard");
>          return -EBUSY;



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