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

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

On Thu, Sep 22, 2022 at 07:47:40AM +0000, Eli Cohen wrote:
> 
> 
> > -----Original Message-----
> > From: Michael S. Tsirkin <mst@redhat.com>
> > Sent: Thursday, 22 September 2022 10:30
> > To: Eli Cohen <elic@nvidia.com>
> > Cc: Jason Wang <jasowang@redhat.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: Re: [PATCH V2 2/3] vdpa_sim_net: support feature provisioning
> > 
> > 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.
> > 
> 
> 
> See the code below
> 
> @@ -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;
> +	}
> +

Oh I didn't notice. It's unnecessary, isn't it?
Can just equivalently be

	dev_attr.supported_features = config->device_features;

right?


> > > > # 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
> > >
> 

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