Re: [PATCH 1/2] vDPA: allow userspace to query features of a vDPA device

["Zhu, Lingshan" <lingshan.zhu@xxxxxxxxx>]

On 8/16/2022 2:15 AM, Si-Wei Liu wrote:
> On 8/15/2022 2:26 AM, Zhu Lingshan wrote:
> > This commit adds a new vDPA netlink attribution
> > VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES. Userspace can query
> > features of vDPA devices through this new attr.
> >
> > Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
> > ---
> >   drivers/vdpa/vdpa.c       | 17 +++++++++++++----
> >   include/uapi/linux/vdpa.h |  3 +++
> >   2 files changed, 16 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> > index c06c02704461..efb55a06e961 100644
> > --- a/drivers/vdpa/vdpa.c
> > +++ b/drivers/vdpa/vdpa.c
> > @@ -491,6 +491,8 @@ static int vdpa_mgmtdev_fill(const struct 
> > vdpa_mgmt_dev *mdev, struct sk_buff *m
> >           err = -EMSGSIZE;
> >           goto msg_err;
> >       }
> > +
> > +    /* report features of a vDPA management device through 
> > VDPA_ATTR_DEV_SUPPORTED_FEATURES */
> >       if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
> >                     mdev->supported_features, VDPA_ATTR_PAD)) {
> >           err = -EMSGSIZE;
> > @@ -815,7 +817,7 @@ static int vdpa_dev_net_mq_config_fill(struct 
> > vdpa_device *vdev,
> >   static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, 
> > struct sk_buff *msg)
> >   {
> >       struct virtio_net_config config = {};
> > -    u64 features;
> > +    u64 features_device, features_driver;
> >       u16 val_u16;
> >         vdpa_get_config_unlocked(vdev, 0, &config, sizeof(config));
> > @@ -832,12 +834,19 @@ static int vdpa_dev_net_config_fill(struct 
> > vdpa_device *vdev, struct sk_buff *ms
> >       if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
> >           return -EMSGSIZE;
> >   -    features = vdev->config->get_driver_features(vdev);
> > -    if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, 
> > features,
> > +    features_driver = vdev->config->get_driver_features(vdev);
> > +    if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, 
> > features_driver,
> > +                  VDPA_ATTR_PAD))
> > +        return -EMSGSIZE;
> > +
> > +    features_device = vdev->config->get_device_features(vdev);
> > +
> > +    /* report features of a vDPA device through 
> > VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES */
> > +    if (nla_put_u64_64bit(msg, 
> > VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, features_device,
> >                     VDPA_ATTR_PAD))
> >           return -EMSGSIZE;
> >   -    return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> > +    return vdpa_dev_net_mq_config_fill(vdev, msg, features_driver, 
> > &config);
> >   }
> >     static int
> > diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> > index 25c55cab3d7c..d171b92ef522 100644
> > --- a/include/uapi/linux/vdpa.h
> > +++ b/include/uapi/linux/vdpa.h
> > @@ -46,7 +46,10 @@ enum vdpa_attr {
> >         VDPA_ATTR_DEV_NEGOTIATED_FEATURES,    /* u64 */
> >       VDPA_ATTR_DEV_MGMTDEV_MAX_VQS,        /* u32 */
> > +    /* features of a vDPA management device */
> >       VDPA_ATTR_DEV_SUPPORTED_FEATURES,    /* u64 */
> > +    /* features of a vDPA device, e.g., /dev/vhost-vdpa0 */
> > +    VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES,    /* u64 */
> Append to the end, please. Otherwise it breaks userspace ABI.
OK, will fix it in V2
> -Siwei
>
> > VDPA_ATTR_DEV_QUEUE_INDEX,              /* u32 */
> >       VDPA_ATTR_DEV_VENDOR_ATTR_NAME,        /* string */