Re: [PATCH v2] vfio/migration: Use BE byte order for device state wire packets

["Cédric Le Goater" <clg@redhat.com>]

On 3/10/25 13:53, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
> 
> Wire data commonly use BE byte order (including in the existing migration
> protocol), use it also for for VFIO device state packets.
> 
> This will allow VFIO multifd device state transfer between hosts with
> different endianness.
> Although currently there is no such use case, it's good to have it now
> for completeness.
> 
> Reviewed-by: Avihai Horon <avihaih@nvidia.com>
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
> --->   hw/vfio/migration-multifd.c | 15 ++++++++++-----
>   1 file changed, 10 insertions(+), 5 deletions(-)



Applied to vfio-next.

Thanks,

C.



  
> diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c
> index a9d41b9f1cb1..e816461e1652 100644
> --- a/hw/vfio/migration-multifd.c
> +++ b/hw/vfio/migration-multifd.c
> @@ -13,6 +13,7 @@
>   #include "hw/vfio/vfio-common.h"
>   #include "migration/misc.h"
>   #include "qapi/error.h"
> +#include "qemu/bswap.h"
>   #include "qemu/error-report.h"
>   #include "qemu/lockable.h"
>   #include "qemu/main-loop.h"
> @@ -208,12 +209,16 @@ bool vfio_multifd_load_state_buffer(void *opaque, char *data, size_t data_size,
>           return false;
>       }
>   
> +    packet->version = be32_to_cpu(packet->version);
>       if (packet->version != VFIO_DEVICE_STATE_PACKET_VER_CURRENT) {
>           error_setg(errp, "%s: packet has unknown version %" PRIu32,
>                      vbasedev->name, packet->version);
>           return false;
>       }
>   
> +    packet->idx = be32_to_cpu(packet->idx);
> +    packet->flags = be32_to_cpu(packet->flags);
> +
>       if (packet->idx == UINT32_MAX) {
>           error_setg(errp, "%s: packet index is invalid", vbasedev->name);
>           return false;
> @@ -682,9 +687,9 @@ vfio_save_complete_precopy_thread_config_state(VFIODevice *vbasedev,
>   
>       packet_len = sizeof(*packet) + bioc->usage;
>       packet = g_malloc0(packet_len);
> -    packet->version = VFIO_DEVICE_STATE_PACKET_VER_CURRENT;
> -    packet->idx = idx;
> -    packet->flags = VFIO_DEVICE_STATE_CONFIG_STATE;
> +    packet->version = cpu_to_be32(VFIO_DEVICE_STATE_PACKET_VER_CURRENT);
> +    packet->idx = cpu_to_be32(idx);
> +    packet->flags = cpu_to_be32(VFIO_DEVICE_STATE_CONFIG_STATE);
>       memcpy(&packet->data, bioc->data, bioc->usage);
>   
>       if (!multifd_queue_device_state(idstr, instance_id,
> @@ -734,7 +739,7 @@ vfio_multifd_save_complete_precopy_thread(SaveLiveCompletePrecopyThreadData *d,
>       }
>   
>       packet = g_malloc0(sizeof(*packet) + migration->data_buffer_size);
> -    packet->version = VFIO_DEVICE_STATE_PACKET_VER_CURRENT;
> +    packet->version = cpu_to_be32(VFIO_DEVICE_STATE_PACKET_VER_CURRENT);
>   
>       for (idx = 0; ; idx++) {
>           ssize_t data_size;
> @@ -755,7 +760,7 @@ vfio_multifd_save_complete_precopy_thread(SaveLiveCompletePrecopyThreadData *d,
>               break;
>           }
>   
> -        packet->idx = idx;
> +        packet->idx = cpu_to_be32(idx);
>           packet_size = sizeof(*packet) + data_size;
>   
>           if (!multifd_queue_device_state(d->idstr, d->instance_id,
>