Re: [Qemu-devel] [PATCH RFC] vfio-ap: flag as compatible with balloon

[Cornelia Huck]

On Wed,  5 Dec 2018 15:51:31 +0100
Cornelia Huck <address@hidden> wrote:

> vfio-ap devices do not pin any pages in the host. Therefore, they
> are belived to be compatible with memory ballooning.
> 
> Flag them as compatible, so both vfio-ap and a balloon can be
> used simultaneously.
> 
> Signed-off-by: Cornelia Huck <address@hidden>
> ---
> 
> As briefly discussed on IRC. RFC as I do not have easy access to
> hardware I can test this with.
> 
> ---
>  hw/vfio/ap.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
> index 65de952f44..3bf48eed28 100644
> --- a/hw/vfio/ap.c
> +++ b/hw/vfio/ap.c
> @@ -104,6 +104,14 @@ static void vfio_ap_realize(DeviceState *dev, Error 
> **errp)
>      vapdev->vdev.name = g_strdup_printf("%s", mdevid);
>      vapdev->vdev.dev = dev;
>  
> +    /*
> +     * vfio-ap devices are believed to operate in a way compatible with
> +     * memory ballooning, as no pages are pinned in the host.
> +     * This needs to be set before vfio_get_device() for vfio common to
> +     * handle the balloon inhibitor.
> +     */
> +    vapdev->vdev.balloon_allowed = true;
> +
>      ret = vfio_get_device(vfio_group, mdevid, &vapdev->vdev, &local_err);
>      if (ret) {
>          goto out_get_dev_err;

Queued (with tweaked wording) to s390-next.