Re: [PATCH v6 8/9] vfio/migration: Don't block migration device dirty tracking is unsupported

[Eric Auger <eric.auger@redhat.com>]

On 7/22/24 23:13, Joao Martins wrote:
> By default VFIO migration is set to auto, which will support live
> migration if the migration capability is set *and* also dirty page
> tracking is supported.
>
> For testing purposes one can force enable without dirty page tracking
> via enable-migration=on, but that option is generally left for testing
> purposes.
>
> So starting with IOMMU dirty tracking it can use to accomodate the lack of
> VF dirty page tracking allowing us to minimize the VF requirements for
> migration and thus enabling migration by default for those too.
>
> While at it change the error messages to mention IOMMU dirty tracking as
> well.
>
> Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> ---
>  hw/vfio/migration.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index 34d4be2ce1b1..cbfaef7afffe 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -1036,16 +1036,16 @@ bool vfio_migration_realize(VFIODevice *vbasedev, Error **errp)
>          return !vfio_block_migration(vbasedev, err, errp);
>      }
>  
> -    if (!vbasedev->dirty_pages_supported) {
> +    if (!vbasedev->dirty_pages_supported && !vbasedev->iommu_dirty_tracking) {
>          if (vbasedev->enable_migration == ON_OFF_AUTO_AUTO) {
>              error_setg(&err,
> -                       "%s: VFIO device doesn't support device dirty tracking",
> -                       vbasedev->name);
nit: does support neither/nor writing may be better here and below but I
am not a native english speaker

Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> +                       "%s: VFIO device doesn't support device and "
> +                       "IOMMU dirty tracking", vbasedev->name);
>              goto add_blocker;
>          }
>  
> -        warn_report("%s: VFIO device doesn't support device dirty tracking",
> -                    vbasedev->name);
> +        warn_report("%s: VFIO device doesn't support device and "
> +                    "IOMMU dirty tracking", vbasedev->name);
>      }
>  
>      ret = vfio_block_multiple_devices_migration(vbasedev, errp);