Re: [PATCH v6 29/36] vfio/migration: Multifd device state transfer support - config loading support

["Cédric Le Goater" <clg@redhat.com>]

On 3/4/25 23:03, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
> 
> Load device config received via multifd using the existing machinery
> behind vfio_load_device_config_state().
> 
> Also, make sure to process the relevant main migration channel flags.
> 
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>


Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.


> ---
>   hw/vfio/migration-multifd.c   | 49 +++++++++++++++++++++++++++++++++--
>   hw/vfio/migration.c           |  9 ++++++-
>   include/hw/vfio/vfio-common.h |  2 ++
>   3 files changed, 57 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/vfio/migration-multifd.c b/hw/vfio/migration-multifd.c
> index 2eef27604e4f..1d81233c755f 100644
> --- a/hw/vfio/migration-multifd.c
> +++ b/hw/vfio/migration-multifd.c
> @@ -17,6 +17,7 @@
>   #include "qemu/lockable.h"
>   #include "qemu/main-loop.h"
>   #include "qemu/thread.h"
> +#include "io/channel-buffer.h"
>   #include "migration/qemu-file.h"
>   #include "migration-multifd.h"
>   #include "trace.h"
> @@ -193,8 +194,52 @@ bool vfio_multifd_load_state_buffer(void *opaque, char *data, size_t data_size,
>   static bool vfio_load_bufs_thread_load_config(VFIODevice *vbasedev,
>                                                 Error **errp)
>   {
> -    error_setg(errp, "not yet there");
> -    return false;
> +    VFIOMigration *migration = vbasedev->migration;
> +    VFIOMultifd *multifd = migration->multifd;
> +    VFIOStateBuffer *lb;
> +    g_autoptr(QIOChannelBuffer) bioc = NULL;
> +    g_autoptr(QEMUFile) f_out = NULL, f_in = NULL;
> +    uint64_t mig_header;
> +    int ret;
> +
> +    assert(multifd->load_buf_idx == multifd->load_buf_idx_last);
> +    lb = vfio_state_buffers_at(&multifd->load_bufs, multifd->load_buf_idx);
> +    assert(lb->is_present);
> +
> +    bioc = qio_channel_buffer_new(lb->len);
> +    qio_channel_set_name(QIO_CHANNEL(bioc), "vfio-device-config-load");
> +
> +    f_out = qemu_file_new_output(QIO_CHANNEL(bioc));
> +    qemu_put_buffer(f_out, (uint8_t *)lb->data, lb->len);
> +
> +    ret = qemu_fflush(f_out);
> +    if (ret) {
> +        error_setg(errp, "%s: load config state flush failed: %d",
> +                   vbasedev->name, ret);
> +        return false;
> +    }
> +
> +    qio_channel_io_seek(QIO_CHANNEL(bioc), 0, 0, NULL);
> +    f_in = qemu_file_new_input(QIO_CHANNEL(bioc));
> +
> +    mig_header = qemu_get_be64(f_in);
> +    if (mig_header != VFIO_MIG_FLAG_DEV_CONFIG_STATE) {
> +        error_setg(errp, "%s: expected FLAG_DEV_CONFIG_STATE but got %" PRIx64,
> +                   vbasedev->name, mig_header);
> +        return false;
> +    }
> +
> +    bql_lock();
> +    ret = vfio_load_device_config_state(f_in, vbasedev);
> +    bql_unlock();
> +
> +    if (ret < 0) {
> +        error_setg(errp, "%s: vfio_load_device_config_state() failed: %d",
> +                   vbasedev->name, ret);
> +        return false;
> +    }
> +
> +    return true;
>   }
>   
>   static VFIOStateBuffer *vfio_load_state_buffer_get(VFIOMultifd *multifd)
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 0096344f74f9..f325a619c3ed 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -264,7 +264,7 @@ static int vfio_save_device_config_state(QEMUFile *f, void *opaque,
>       return ret;
>   }
>   
> -static int vfio_load_device_config_state(QEMUFile *f, void *opaque)
> +int vfio_load_device_config_state(QEMUFile *f, void *opaque)
>   {
>       VFIODevice *vbasedev = opaque;
>       uint64_t data;
> @@ -723,6 +723,13 @@ static int vfio_load_state(QEMUFile *f, void *opaque, int version_id)
>           switch (data) {
>           case VFIO_MIG_FLAG_DEV_CONFIG_STATE:
>           {
> +            if (vfio_multifd_transfer_enabled(vbasedev)) {
> +                error_report("%s: got DEV_CONFIG_STATE in main migration "
> +                             "channel but doing multifd transfer",
> +                             vbasedev->name);
> +                return -EINVAL;
> +            }
> +
>               return vfio_load_device_config_state(f, opaque);
>           }
>           case VFIO_MIG_FLAG_DEV_SETUP_STATE:
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 40382390692d..9d72ac1eae8a 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -298,6 +298,8 @@ void vfio_mig_add_bytes_transferred(unsigned long val);
>   bool vfio_device_state_is_running(VFIODevice *vbasedev);
>   bool vfio_device_state_is_precopy(VFIODevice *vbasedev);
>   
> +int vfio_load_device_config_state(QEMUFile *f, void *opaque);
> +
>   #ifdef CONFIG_LINUX
>   int vfio_get_region_info(VFIODevice *vbasedev, int index,
>                            struct vfio_region_info **info);
>