Re: [RFC 2/2] vhost: IFC VF vdpa layer

[Jason Wang]

On 2019/10/22 äå2:53, Zhu Lingshan wrote:
> On 10/21/2019 6:19 PM, Jason Wang wrote:
> > On 2019/10/21 äå5:53, Zhu, Lingshan wrote:
> > > On 10/16/2019 6:19 PM, Jason Wang wrote:
> > > > On 2019/10/16 äå9:30, Zhu Lingshan wrote:
> > > > > This commit introduced IFC VF operations for vdpa, which complys to
> > > > > vhost_mdev interfaces, handles IFC VF initialization,
> > > > > configuration and removal.
> > > > >
> > > > > Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> > > > > ---


[...]


> > > > > +}
> > > > > +
> > > > > +static int ifcvf_mdev_set_features(struct mdev_device *mdev, u64 
> > > > > features)
> > > > > +{
> > > > > +ÂÂÂ struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
> > > > > +ÂÂÂ struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
> > > > > +
> > > > > +ÂÂÂ vf->req_features = features;
> > > > > +
> > > > > +ÂÂÂ return 0;
> > > > > +}
> > > > > +
> > > > > +static u64 ifcvf_mdev_get_vq_state(struct mdev_device *mdev, u16 
> > > > > qid)
> > > > > +{
> > > > > +ÂÂÂ struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
> > > > > +ÂÂÂ struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
> > > > > +
> > > > > +ÂÂÂ return vf->vring[qid].last_avail_idx;
> > > >
> > > >
> > > > Does this really work? I'd expect it should be fetched from hw 
> > > > since it's an internal state.
> > > for now, it's working, we intend to support LM in next version drivers.
> >
> >
> > I'm not sure I understand here, I don't see any synchronization 
> > between the hardware and last_avail_idx, so last_avail_idx should not 
> > change.
> >
> > Btw, what did "LM" mean :) ?
>
> I can add bar IO operations here, LM = live migration, sorry for the 
> abbreviation.


Just make sure I understand here, I believe you mean reading 
last_avail_idx through IO bar here?

Thanks