Re: [PATCH V2 2/3] vdpa_sim_net: support feature provisioning

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Sep 22, 2022 at 05:13:59AM +0000, Eli Cohen wrote:
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Thursday, 22 September 2022 5:43
> > To: mst@redhat.com; jasowang@redhat.com
> > Cc: Eli Cohen <elic@nvidia.com>; si-wei.liu@oracle.com; Parav Pandit
> > <parav@nvidia.com>; wuzongyong@linux.alibaba.com;
> > virtualization@lists.linux-foundation.org; linux-kernel@vger.kernel.org;
> > eperezma@redhat.com; lingshan.zhu@intel.com; gdawar@xilinx.com;
> > lulu@redhat.com; xieyongji@bytedance.com
> > Subject: [PATCH V2 2/3] vdpa_sim_net: support feature provisioning
> > 
> > This patch implements features provisioning for vdpa_sim_net.
> > 
> > 1) validating the provisioned features to be a subset of the parent
> >    features.
> > 2) clearing the features that is not wanted by the userspace
> > 
> > For example:
> > 
> > # vdpa mgmtdev show
> > vdpasim_net:
> >   supported_classes net
> >   max_supported_vqs 3
> >   dev_features MTU MAC CTRL_VQ CTRL_MAC_ADDR ANY_LAYOUT
> > VERSION_1 ACCESS_PLATFORM
> > 
> > 1) provision vDPA device with all features that are supported by the
> >    net simulator
> > 
> > # vdpa dev add name dev1 mgmtdev vdpasim_net
> > # vdpa dev config show
> > dev1: mac 00:00:00:00:00:00 link up link_announce false mtu 1500
> >   negotiated_features MTU MAC CTRL_VQ CTRL_MAC_ADDR VERSION_1
> > ACCESS_PLATFORM
> > 
> > 2) provision vDPA device with a subset of the features
> > 
> > # vdpa dev add name dev1 mgmtdev vdpasim_net device_features
> > 0x300020000
> 
> How about "features_mask" instead of "device_features"? Could avoid confusion.

Not sure I agree.
features_mask to me would mean it is & with features. Not the case here.

> > # vdpa dev config show
> > dev1: mac 00:00:00:00:00:00 link up link_announce false mtu 1500
> >   negotiated_features CTRL_VQ VERSION_1 ACCESS_PLATFORM
> > 
> > Reviewed-by: Eli Cohen <elic@nvidia.com>
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > ---
> >  drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> > b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> > index 886449e88502..a9ba02be378b 100644
> > --- a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> > +++ b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> > @@ -254,6 +254,14 @@ static int vdpasim_net_dev_add(struct
> > vdpa_mgmt_dev *mdev, const char *name,
> >  	dev_attr.work_fn = vdpasim_net_work;
> >  	dev_attr.buffer_size = PAGE_SIZE;
> > 
> > +	if (config->mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES)) {
> > +		if (config->device_features &
> > +		    ~dev_attr.supported_features)
> > +			return -EINVAL;
> > +		dev_attr.supported_features &=
> > +			 config->device_features;
> > +	}
> > +
> >  	simdev = vdpasim_create(&dev_attr);
> >  	if (IS_ERR(simdev))
> >  		return PTR_ERR(simdev);
> > @@ -294,7 +302,8 @@ static struct vdpa_mgmt_dev mgmt_dev = {
> >  	.id_table = id_table,
> >  	.ops = &vdpasim_net_mgmtdev_ops,
> >  	.config_attr_mask = (1 << VDPA_ATTR_DEV_NET_CFG_MACADDR |
> > -			     1 << VDPA_ATTR_DEV_NET_CFG_MTU),
> > +			     1 << VDPA_ATTR_DEV_NET_CFG_MTU |
> > +		             1 << VDPA_ATTR_DEV_FEATURES),
> >  	.max_supported_vqs = VDPASIM_NET_VQ_NUM,
> >  	.supported_features = VDPASIM_NET_FEATURES,
> >  };
> > --
> > 2.25.1
>