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

[Stefano Garzarella]

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'.

Thanks,
Stefano