support vduse feature provisioning in vdpa netlink command

[RFC 2/2] vduse: allow to specify device-specific features if it's multiclass

Posted by Eugenio Pérez 2 months, 2 weeks ago

Even if the device supports more than one class, there are ways to solve
the ambiguity of which device are we creating.  In the VDUSE case it is
the name, for example.

RFC: I fon't understand 100% the motivation of this limitation, as the
backend should be the one filtering out the invalid features if any.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 drivers/vdpa/vdpa.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 34874beb0152..0fc32f3bd66f 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -688,15 +688,6 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
 		err = -EINVAL;
 		goto err;
 	}
-	if (!(config.mask & VDPA_DEV_NET_ATTRS_MASK) &&
-	    config.mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES) &&
-	    classes & BIT_ULL(VIRTIO_ID_NET) && ncls > 1 &&
-	    config.device_features & VIRTIO_DEVICE_F_MASK) {
-		NL_SET_ERR_MSG_MOD(info->extack,
-				   "Management device supports multi-class while device features specified are ambiguous");
-		err = -EINVAL;
-		goto err;
-	}

 	err = mdev->ops->dev_add(mdev, name, &config);
 err:
--
2.51.0

Re: [RFC 2/2] vduse: allow to specify device-specific features if it's multiclass

Posted by Jason Wang 2 months, 1 week ago

On Thu, Oct 2, 2025 at 6:36 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Even if the device supports more than one class, there are ways to solve
> the ambiguity of which device are we creating.  In the VDUSE case it is
> the name, for example.

This may only work for VDUSE but not other parents.

>
> RFC: I fon't understand 100% the motivation of this limitation, as the
> backend should be the one filtering out the invalid features if any.

I think we can avoid these tricks. Currently, there's a one single
mgmt device, this seems to be in-convenient. Could we have a per
device mgmt device? For example, if user space creates vduse0, vdpa
mgmtdev show may see vduse0 so we won't have this issue.

>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  drivers/vdpa/vdpa.c | 9 ---------
>  1 file changed, 9 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 34874beb0152..0fc32f3bd66f 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -688,15 +688,6 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
>                 err = -EINVAL;
>                 goto err;
>         }
> -       if (!(config.mask & VDPA_DEV_NET_ATTRS_MASK) &&
> -           config.mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES) &&
> -           classes & BIT_ULL(VIRTIO_ID_NET) && ncls > 1 &&
> -           config.device_features & VIRTIO_DEVICE_F_MASK) {
> -               NL_SET_ERR_MSG_MOD(info->extack,
> -                                  "Management device supports multi-class while device features specified are ambiguous");
> -               err = -EINVAL;
> -               goto err;
> -       }
>
>         err = mdev->ops->dev_add(mdev, name, &config);
>  err:
> --
> 2.51.0
>

Thanks

Re: [RFC 2/2] vduse: allow to specify device-specific features if it's multiclass

Posted by Jason Wang 2 months, 1 week ago

On Fri, Oct 10, 2025 at 9:39 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Thu, Oct 2, 2025 at 6:36 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > Even if the device supports more than one class, there are ways to solve
> > the ambiguity of which device are we creating.  In the VDUSE case it is
> > the name, for example.
>
> This may only work for VDUSE but not other parents.
>
> >
> > RFC: I fon't understand 100% the motivation of this limitation, as the
> > backend should be the one filtering out the invalid features if any.
>
> I think we can avoid these tricks. Currently, there's a one single
> mgmt device, this seems to be in-convenient. Could we have a per
> device mgmt device? For example, if user space creates vduse0, vdpa
> mgmtdev show may see vduse0 so we won't have this issue.

Or if we specify the class, there won't be ambiguity.

Thanks

>
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  drivers/vdpa/vdpa.c | 9 ---------
> >  1 file changed, 9 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > index 34874beb0152..0fc32f3bd66f 100644
> > --- a/drivers/vdpa/vdpa.c
> > +++ b/drivers/vdpa/vdpa.c
> > @@ -688,15 +688,6 @@ static int vdpa_nl_cmd_dev_add_set_doit(struct sk_buff *skb, struct genl_info *i
> >                 err = -EINVAL;
> >                 goto err;
> >         }
> > -       if (!(config.mask & VDPA_DEV_NET_ATTRS_MASK) &&
> > -           config.mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES) &&
> > -           classes & BIT_ULL(VIRTIO_ID_NET) && ncls > 1 &&
> > -           config.device_features & VIRTIO_DEVICE_F_MASK) {
> > -               NL_SET_ERR_MSG_MOD(info->extack,
> > -                                  "Management device supports multi-class while device features specified are ambiguous");
> > -               err = -EINVAL;
> > -               goto err;
> > -       }
> >
> >         err = mdev->ops->dev_add(mdev, name, &config);
> >  err:
> > --
> > 2.51.0
> >
>
> Thanks