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In-Reply-To: <1704919215-91319-8-git-send-email-steven.sistare@oracle.com>
From: Jason Wang <jasowang@redhat.com>
Date: Thu, 11 Jan 2024 11:09:20 +0800
Message-ID: <CACGkMEv8TXXTrCW=hf1sJ+V2a0eD3w1b1Yub4FnGZ0=Du-RbtQ@mail.gmail.com>
Subject: Re: [RFC V1 07/13] vhost-vdpa: flush workers on suspend
To: Steve Sistare <steven.sistare@oracle.com>
Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, 
	"Michael S. Tsirkin" <mst@redhat.com>, Si-Wei Liu <si-wei.liu@oracle.com>, 
	Eugenio Perez Martin <eperezma@redhat.com>, Xuan Zhuo <xuanzhuo@linux.alibaba.com>, 
	Dragos Tatulea <dtatulea@nvidia.com>, Eli Cohen <elic@nvidia.com>, 
	Xie Yongji <xieyongji@bytedance.com>
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On Thu, Jan 11, 2024 at 4:40=E2=80=AFAM Steve Sistare <steven.sistare@oracl=
e.com> wrote:
>
> To pass ownership of a live vdpa device to a new process, the user
> suspends the device, calls VHOST_NEW_OWNER to change the mm, and calls
> VHOST_IOTLB_REMAP to change the user virtual addresses to match the new
> mm.  Flush workers in suspend to guarantee that no worker sees the new
> mm and old VA in between.
>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  drivers/vhost/vdpa.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 8fe1562d24af..9673e8e20d11 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -591,10 +591,14 @@ static long vhost_vdpa_suspend(struct vhost_vdpa *v=
)
>  {
>         struct vdpa_device *vdpa =3D v->vdpa;
>         const struct vdpa_config_ops *ops =3D vdpa->config;
> +       struct vhost_dev *vdev =3D &v->vdev;
>
>         if (!ops->suspend)
>                 return -EOPNOTSUPP;
>
> +       if (vdev->use_worker)
> +               vhost_dev_flush(vdev);

It looks to me like it's better to check use_woker in vhost_dev_flush.

Thanks


> +
>         return ops->suspend(vdpa);
>  }
>
> --
> 2.39.3
>