Re: [PATCH v2 2/2] vdpa: Remove ioctl VHOST_VDPA_SET_CONFIG per spec compliance

[Jason Wang]

On Wed, Sep 4, 2024 at 1:59 PM Dragos Tatulea <dtatulea@xxxxxxxxxx> wrote:
>
>
>
> On 04.09.24 05:38, Jason Wang wrote:
> > On Wed, Sep 4, 2024 at 1:15 AM Carlos Bilbao
> > <carlos.bilbao.osdev@xxxxxxxxx> wrote:
> >>
> >> From: Carlos Bilbao <cbilbao@xxxxxxxxxxxxxxxx>
> >>
> >> Remove invalid ioctl VHOST_VDPA_SET_CONFIG and all its implementations
> >> with vdpa_config_ops->set_config(). This is needed per virtio spec
> >> requirements; virtio-spec v3.1 Sec 5.1.4 states that "All of the device
> >> configuration fields are read-only for the driver."
> >>
> >> Signed-off-by: Carlos Bilbao <cbilbao@xxxxxxxxxxxxxxxx>
> >
> > Note that only the config space of the modern device is read only. So
> > it should be fine to remove vp_vdpa which only works for modern
> > devices.
> Just out of curiosity: how will this work for devices that are not
> v1.3 compliant but are v1.2 compliant?

Devices don't know the version of the spec, it works with features.
For example, most devices mandate ACCESS_PLATFORM which implies a
mandatory VERSION_1. So they are modern devices.

> Or is this true of all devices
> except eni?

ENI depends on the virtio-pci legacy library, so we know it's a legacy
device implementation which allows mac address setting via config
space.

Thanks

>
> Thanks,
> Dragos
> >
> > And for eni, it is a legacy only device, so we should not move the
> > set_config there.
> >
> > For the rest, we need the acks for those maintainers.
> >
> > Thanks
> >
>