Re: [PATCH net-next v21 06/13] virtio_net: Create a FF group for ethtool steering

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

On Mon, Aug 03, 2026 at 05:07:14PM +0300, Shahar Shitrit wrote:
> From: Daniel Jurgens <danielj@nvidia.com>
> 
> All ethtool steering rules will go in one group, create it during
> initialization.
> 
> Signed-off-by: Daniel Jurgens <danielj@nvidia.com>
> Reviewed-by: Parav Pandit <parav@nvidia.com>
> Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Signed-off-by: Shahar Shitrit <shshitrit@nvidia.com>
> ---
>  drivers/net/virtio_net.c           | 29 +++++++++++++++++++++++++++++
>  include/uapi/linux/virtio_net_ff.h | 15 +++++++++++++++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 0d1f5a6cfd12..e11e42583243 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -287,6 +287,9 @@ static const struct virtnet_stat_desc virtnet_stats_tx_speed_desc_qstat[] = {
>  	VIRTNET_STATS_DESC_TX_QSTAT(speed, ratelimit_packets, hw_drop_ratelimits),
>  };
>  
> +#define VIRTNET_FF_ETHTOOL_GROUP_PRIORITY 1

why 1 and not 0?

> +#define VIRTNET_FF_MAX_GROUPS 1
> +
>  struct virtnet_ff {
>  	struct virtio_device *vdev;
>  	bool ff_supported;
> @@ -5749,6 +5752,7 @@ static int virtnet_ff_init(struct virtnet_ff *ff, struct virtio_device *vdev)
>  	size_t ff_mask_size = sizeof(struct virtio_net_ff_cap_mask_data) +
>  			      sizeof(struct virtio_net_ff_selector) *
>  			      VIRTIO_NET_FF_MASK_TYPE_MAX;
> +	struct virtio_net_resource_obj_ff_group ethtool_group = {};
>  	struct virtio_admin_cmd_query_cap_id_result *cap_id_list;
>  	struct virtio_net_ff_selector *sel;
>  	unsigned long sel_types = 0;
> @@ -5839,6 +5843,12 @@ static int virtnet_ff_init(struct virtnet_ff *ff, struct virtio_device *vdev)
>  	ff->ff_actions->count = min_t(u8, ff->ff_actions->count,
>  				      VIRTIO_NET_FF_ACTION_MAX);
>  
> +	if (le32_to_cpu(ff->ff_caps->groups_limit) < VIRTNET_FF_MAX_GROUPS) {
> +		err = -ENOSPC;
> +		goto err_ff_action;
> +	}
> +	ff->ff_caps->groups_limit = cpu_to_le32(VIRTNET_FF_MAX_GROUPS);
> +
>  	err = virtio_admin_cap_set(vdev,
>  				   VIRTIO_NET_FF_RESOURCE_CAP,
>  				   ff->ff_caps,
> @@ -5886,6 +5896,19 @@ static int virtnet_ff_init(struct virtnet_ff *ff, struct virtio_device *vdev)
>  	if (err)
>  		goto err_ff_action;
>  
> +	ethtool_group.group_priority = cpu_to_le16(VIRTNET_FF_ETHTOOL_GROUP_PRIORITY);
> +
> +	/* Use priority for the object ID. */

and how is this ok?
spec says:
 Each resource object has a unique resource object ID - a driver-assigned number
  in the range of 0 to \field{limit - 1}, where the \field{limit} is the maximum
  number set by the driver for this resource object type.

and limit here is 1, right?

> +	err = virtio_admin_obj_create(vdev,
> +				      VIRTIO_NET_RESOURCE_OBJ_FF_GROUP,
> +				      VIRTNET_FF_ETHTOOL_GROUP_PRIORITY,
> +				      VIRTIO_ADMIN_GROUP_TYPE_SELF,
> +				      0,
> +				      &ethtool_group,
> +				      sizeof(ethtool_group));
> +	if (err)
> +		goto err_ff_action;
> +
>  	ff->vdev = vdev;
>  	ff->ff_supported = true;
>  
> @@ -5913,6 +5936,12 @@ static void virtnet_ff_cleanup(struct virtnet_ff *ff)
>  	if (!ff->ff_supported)
>  		return;
>  
> +	virtio_admin_obj_destroy(ff->vdev,
> +				 VIRTIO_NET_RESOURCE_OBJ_FF_GROUP,
> +				 VIRTNET_FF_ETHTOOL_GROUP_PRIORITY,
> +				 VIRTIO_ADMIN_GROUP_TYPE_SELF,
> +				 0);
> +
>  	kfree(ff->ff_actions);
>  	kfree(ff->ff_mask);
>  	kfree(ff->ff_caps);
> diff --git a/include/uapi/linux/virtio_net_ff.h b/include/uapi/linux/virtio_net_ff.h
> index f9e771a0baff..b0780e49df9f 100644
> --- a/include/uapi/linux/virtio_net_ff.h
> +++ b/include/uapi/linux/virtio_net_ff.h
> @@ -12,6 +12,8 @@
>  #define VIRTIO_NET_FF_SELECTOR_CAP 0x801
>  #define VIRTIO_NET_FF_ACTION_CAP 0x802
>  
> +#define VIRTIO_NET_RESOURCE_OBJ_FF_GROUP 0x0200
> +
>  /**
>   * struct virtio_net_ff_cap_data - Flow filter resource capability limits
>   * @groups_limit: maximum number of flow filter groups supported by the device
> @@ -88,4 +90,17 @@ struct virtio_net_ff_actions {
>  	__u8 reserved[7];
>  	__u8 actions[] __counted_by(count);
>  };
> +
> +/**
> + * struct virtio_net_resource_obj_ff_group - Flow filter group object
> + * @group_priority: priority of the group used to order evaluation
> + *
> + * This structure is the payload for the VIRTIO_NET_RESOURCE_OBJ_FF_GROUP
> + * administrative object. Devices use @group_priority to order flow filter
> + * groups. Multi-byte fields are little-endian.
> + */
> +struct virtio_net_resource_obj_ff_group {
> +	__le16 group_priority;
> +};
> +
>  #endif
> -- 
> 2.49.0