Re: [PATCH 3/6] vDPA/ifcvf: support userspace to query device feature bits

[Jason Wang <jasowang@redhat.com>]

On Thu, Jun 2, 2022 at 10:48 AM Zhu Lingshan <lingshan.zhu@intel.com> wrote:
>
> This commit supports userspace to query device feature bits
> by filling the relevant netlink attribute.
>
> There are two types of netlink attributes:
> VDPA_ATTR_DEV_XXXX work for virtio devices config space, and
> VDPA_ATTR_MGMTDEV_XXXX work for the management devices.
>
> This commit fixes a misuse of VDPA_ATTR_DEV_SUPPORTED_FEATURES,
> this attr is for a virtio device, not management devices.
>
> Thus VDPA_ATTR_MGMTDEV_SUPPORTED_FEATURES is introduced for
> reporting management device features, and VDPA_ATTR_DEV_SUPPORTED_FEATURES
> for virtio devices feature bits.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
>  drivers/vdpa/vdpa.c       | 15 ++++++++++-----
>  include/uapi/linux/vdpa.h |  1 +
>  2 files changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 2b75c00b1005..c820dd2b0307 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -508,7 +508,7 @@ static int vdpa_mgmtdev_fill(const struct vdpa_mgmt_dev *mdev, struct sk_buff *m
>                 err = -EMSGSIZE;
>                 goto msg_err;
>         }
> -       if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES,
> +       if (nla_put_u64_64bit(msg, VDPA_ATTR_MGMTDEV_SUPPORTED_FEATURES,

Adding Eli and Parav.

If I understand correctly, we can't provision virtio features right
now. This means, the vDPA instance should have the same features as
its parent (management device).

And it seems to me if we can do things like this, we need first allow
the features to be provisioned. (And this change breaks uABI)

Thanks


>                               mdev->supported_features, VDPA_ATTR_PAD)) {
>                 err = -EMSGSIZE;
>                 goto msg_err;
> @@ -827,7 +827,7 @@ 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));
> @@ -844,12 +844,17 @@ 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;
>
> -       return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> +       features_device = vdev->config->get_device_features(vdev);
> +       if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_SUPPORTED_FEATURES, features_device,
> +                             VDPA_ATTR_PAD))
> +               return -EMSGSIZE;
> +
> +       return vdpa_dev_net_mq_config_fill(vdev, msg, features_device, &config);
>  }
>
>  static int
> diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> index 1061d8d2d09d..70a3672c288f 100644
> --- a/include/uapi/linux/vdpa.h
> +++ b/include/uapi/linux/vdpa.h
> @@ -30,6 +30,7 @@ enum vdpa_attr {
>         VDPA_ATTR_MGMTDEV_BUS_NAME,             /* string */
>         VDPA_ATTR_MGMTDEV_DEV_NAME,             /* string */
>         VDPA_ATTR_MGMTDEV_SUPPORTED_CLASSES,    /* u64 */
> +       VDPA_ATTR_MGMTDEV_SUPPORTED_FEATURES,   /* u64 */
>
>         VDPA_ATTR_DEV_NAME,                     /* string */
>         VDPA_ATTR_DEV_ID,                       /* u32 */
> --
> 2.31.1
>