Re: [PATCH v3 15/24] migration/multifd: Add migration_has_device_state_support()

[Avihai Horon]

On 17/11/2024 21:20, Maciej S. Szmigiero wrote:
> External email: Use caution opening links or attachments
>
>
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
>
> Since device state transfer via multifd channels requires multifd
> channels with packets and is currently not compatible with multifd
> compression add an appropriate query function so device can learn
> whether it can actually make use of it.
>
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
> ---
>   include/migration/misc.h         | 1 +
>   migration/multifd-device-state.c | 7 +++++++
>   2 files changed, 8 insertions(+)
>
> diff --git a/include/migration/misc.h b/include/migration/misc.h
> index 118e205bbcc6..43558d9198f7 100644
> --- a/include/migration/misc.h
> +++ b/include/migration/misc.h
> @@ -112,5 +112,6 @@ bool migration_in_bg_snapshot(void);
>   /* migration/multifd-device-state.c */
>   bool multifd_queue_device_state(char *idstr, uint32_t instance_id,
>                                   char *data, size_t len);
> +bool migration_has_device_state_support(void);

Nit: maybe rename to multifd_device_state_supported or 
migration_multifd_device_state_supported, as it's specifically related 
to multifd?

Thanks.

>   #endif
> diff --git a/migration/multifd-device-state.c b/migration/multifd-device-state.c
> index 8cf5a6c2668c..bcbea926b6be 100644
> --- a/migration/multifd-device-state.c
> +++ b/migration/multifd-device-state.c
> @@ -11,6 +11,7 @@
>   #include "qemu/lockable.h"
>   #include "migration/misc.h"
>   #include "multifd.h"
> +#include "options.h"
>
>   static QemuMutex queue_job_mutex;
>
> @@ -99,3 +100,9 @@ bool multifd_queue_device_state(char *idstr, uint32_t 
> instance_id,
>
>       return true;
>   }
> +
> +bool migration_has_device_state_support(void)
> +{
> +    return migrate_multifd() && !migrate_mapped_ram() &&
> +        migrate_multifd_compression() == MULTIFD_COMPRESSION_NONE;
> +}