Re: [PATCH V4 12/14] vfio: allow cpr-reboot migration if suspended

["Cédric Le Goater" <clg@redhat.com>]

On 2/22/24 18:28, Steve Sistare wrote:
> Allow cpr-reboot for vfio if the guest is in the suspended runstate.  The
> guest drivers' suspend methods flush outstanding requests and re-initialize
> the devices, and thus there is no device state to save and restore.  The
> user is responsible for suspending the guest before initiating cpr, such as
> by issuing guest-suspend-ram to the qemu guest agent.
> 
> Relax the vfio blocker so it does not apply to cpr, and add a notifier that
> verifies the guest is suspended.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>


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

Thanks,

C.




> ---
>   hw/vfio/common.c                      |  2 +-
>   hw/vfio/cpr.c                         | 20 ++++++++++++++++++++
>   hw/vfio/migration.c                   |  2 +-
>   include/hw/vfio/vfio-container-base.h |  1 +
>   4 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 059bfdc..ff88c3f 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -128,7 +128,7 @@ int vfio_block_multiple_devices_migration(VFIODevice *vbasedev, Error **errp)
>       error_setg(&multiple_devices_migration_blocker,
>                  "Multiple VFIO devices migration is supported only if all of "
>                  "them support P2P migration");
> -    ret = migrate_add_blocker(&multiple_devices_migration_blocker, errp);
> +    ret = migrate_add_blocker_normal(&multiple_devices_migration_blocker, errp);
>   
>       return ret;
>   }
> diff --git a/hw/vfio/cpr.c b/hw/vfio/cpr.c
> index 3bede54..392c2dd 100644
> --- a/hw/vfio/cpr.c
> +++ b/hw/vfio/cpr.c
> @@ -7,13 +7,33 @@
>   
>   #include "qemu/osdep.h"
>   #include "hw/vfio/vfio-common.h"
> +#include "migration/misc.h"
>   #include "qapi/error.h"
> +#include "sysemu/runstate.h"
> +
> +static int vfio_cpr_reboot_notifier(NotifierWithReturn *notifier,
> +                                    MigrationEvent *e, Error **errp)
> +{
> +    if (e->type == MIG_EVENT_PRECOPY_SETUP &&
> +        !runstate_check(RUN_STATE_SUSPENDED) && !vm_get_suspended()) {
> +
> +        error_setg(errp,
> +            "VFIO device only supports cpr-reboot for runstate suspended");
> +
> +        return -1;
> +    }
> +    return 0;
> +}
>   
>   int vfio_cpr_register_container(VFIOContainerBase *bcontainer, Error **errp)
>   {
> +    migration_add_notifier_mode(&bcontainer->cpr_reboot_notifier,
> +                                vfio_cpr_reboot_notifier,
> +                                MIG_MODE_CPR_REBOOT);
>       return 0;
>   }
>   
>   void vfio_cpr_unregister_container(VFIOContainerBase *bcontainer)
>   {
> +    migration_remove_notifier(&bcontainer->cpr_reboot_notifier);
>   }
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 50140ed..2050ac8 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -889,7 +889,7 @@ static int vfio_block_migration(VFIODevice *vbasedev, Error *err, Error **errp)
>       vbasedev->migration_blocker = error_copy(err);
>       error_free(err);
>   
> -    return migrate_add_blocker(&vbasedev->migration_blocker, errp);
> +    return migrate_add_blocker_normal(&vbasedev->migration_blocker, errp);
>   }
>   
>   /* ---------------------------------------------------------------------- */
> diff --git a/include/hw/vfio/vfio-container-base.h b/include/hw/vfio/vfio-container-base.h
> index b2813b0..3582d5f 100644
> --- a/include/hw/vfio/vfio-container-base.h
> +++ b/include/hw/vfio/vfio-container-base.h
> @@ -49,6 +49,7 @@ typedef struct VFIOContainerBase {
>       QLIST_ENTRY(VFIOContainerBase) next;
>       QLIST_HEAD(, VFIODevice) device_list;
>       GList *iova_ranges;
> +    NotifierWithReturn cpr_reboot_notifier;
>   } VFIOContainerBase;
>   
>   typedef struct VFIOGuestIOMMU {