Re: [RFC PATCH 01/10] vdpa: add get_config_size callback in vdpa_config_ops

[Jason Wang]

On 2021/3/2 10:15 下午, Stefano Garzarella wrote:
> On Tue, Mar 02, 2021 at 12:14:13PM +0800, Jason Wang wrote:
> > On 2021/2/16 5:44 下午, Stefano Garzarella wrote:
> > > This new callback is used to get the size of the configuration space
> > > of vDPA devices.
> > >
> > > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > > ---
> > >  include/linux/vdpa.h              | 4 ++++
> > >  drivers/vdpa/ifcvf/ifcvf_main.c   | 6 ++++++
> > >  drivers/vdpa/mlx5/net/mlx5_vnet.c | 6 ++++++
> > >  drivers/vdpa/vdpa_sim/vdpa_sim.c  | 9 +++++++++
> > >  4 files changed, 25 insertions(+)
> > >
> > > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> > > index 4ab5494503a8..fddf42b17573 100644
> > > --- a/include/linux/vdpa.h
> > > +++ b/include/linux/vdpa.h
> > > @@ -150,6 +150,9 @@ struct vdpa_iova_range {
> > >   * @set_status:            Set the device status
> > >   *                @vdev: vdpa device
> > >   *                @status: virtio device status
> > > + * @get_config_size:        Get the size of the configuration space
> > > + *                @vdev: vdpa device
> > > + *                Returns size_t: configuration size
> >
> >
> > Rethink about this, how much we could gain by introducing a dedicated 
> > ops here? E.g would it be simpler if we simply introduce a 
> > max_config_size to vdpa device?
>
> Mainly because in this way we don't have to add new parameters to the 
> vdpa_alloc_device() function.
>
> We do the same for example for 'get_device_id', 'get_vendor_id', 
> 'get_vq_num_max'. All of these are usually static, but we have ops.
> I think because it's easier to extend.
>
> I don't know if it's worth adding a new structure for these static 
> values at this point, like 'struct vdpa_config_params'.


Yes, that's the point. I think for any static values, it should be set 
during device allocation.

I'm fine with both.

Thanks


> Thanks,
> Stefano