Re: [PATCH v2 09/24] vhost: introduce vhost_dev_virtqueue_stop()

[Kangjie Xu]

在 2022/8/23 15:52, Jason Wang 写道:
> 在 2022/8/16 09:06, Kangjie Xu 写道:
> > Introduce vhost_dev_virtqueue_stop(), which can ummap the
> > vrings and the desc of it.
> >
> > Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >   hw/virtio/vhost.c         | 9 +++++++++
> >   include/hw/virtio/vhost.h | 3 +++
> >   2 files changed, 12 insertions(+)
> >
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index e467dfc7bc..1bca9ff48d 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -1904,3 +1904,12 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
> >         return -ENOSYS;
> >   }
> > +
> > +void vhost_dev_virtqueue_stop(struct vhost_dev *hdev, VirtIODevice 
> > *vdev,
> > +                              int idx)
> > +{
> > +    vhost_virtqueue_unmap(hdev,
> > +                          vdev,
> > +                          hdev->vqs + idx,
> > +                          idx);
>
> So I think the unmap is not sufficient, we need backend specific 
> support. E.g for vhost kernel, need a SET_BACKEND here?
> Thanks
But SET_BACKEND of vhost-net needs a parameter fd in vhost_vring_file: 
that is net->backend of VHostNetState.
If we add the fd parameter or struct vhost_vring_file to 
vhost_dev_virtqueue_stop/restart, it exposes some implementation details 
in the parameter list.
And that seems not good? So I put SET_BACKEND in the vhost-net module. 
The workflow is similar to vhost_net_start_one().
Thanks

> > +}
> > diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> > index a346f23d13..574888440c 100644
> > --- a/include/hw/virtio/vhost.h
> > +++ b/include/hw/virtio/vhost.h
> > @@ -288,4 +288,7 @@ int vhost_dev_set_inflight(struct vhost_dev *dev,
> >                              struct vhost_inflight *inflight);
> >   int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size,
> >                              struct vhost_inflight *inflight);
> > +
> > +void vhost_dev_virtqueue_stop(struct vhost_dev *hdev, VirtIODevice 
> > *vdev,
> > +                              int idx);
> >   #endif