Subject: Re: [PATCH net-next v11 12/12] virtio_net: Add get ethtool flow rules ops

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 18 Nov 2025 13:49:33 -0500

On Tue, Nov 18, 2025 at 08:39:02AM -0600, Daniel Jurgens wrote:
> - Get total number of rules. There's no user interface for this. It is
>   used to allocate an appropriately sized buffer for getting all the
>   rules.
> 
> - Get specific rule
> $ ethtool -u ens9 rule 0
> 	Filter: 0
> 		Rule Type: UDP over IPv4
> 		Src IP addr: 0.0.0.0 mask: 255.255.255.255
> 		Dest IP addr: 192.168.5.2 mask: 0.0.0.0
> 		TOS: 0x0 mask: 0xff
> 		Src port: 0 mask: 0xffff
> 		Dest port: 4321 mask: 0x0
> 		Action: Direct to queue 16
> 
> - Get all rules:
> $ ethtool -u ens9
> 31 RX rings available
> Total 2 rules
> 
> Filter: 0
>         Rule Type: UDP over IPv4
>         Src IP addr: 0.0.0.0 mask: 255.255.255.255
>         Dest IP addr: 192.168.5.2 mask: 0.0.0.0
> ...
> 
> Filter: 1
>         Flow Type: Raw Ethernet
>         Src MAC addr: 00:00:00:00:00:00 mask: FF:FF:FF:FF:FF:FF
>         Dest MAC addr: 08:11:22:33:44:54 mask: 00:00:00:00:00:00
> 
> Signed-off-by: Daniel Jurgens <[email-masked]>
> Reviewed-by: Parav Pandit <[email-masked]>
> Reviewed-by: Shahar Shitrit <[email-masked]>
> Reviewed-by: Xuan Zhuo <[email-masked]>
> ---
> v4: Answered questions about rules_limit overflow with no changes.
> ---
>  drivers/net/virtio_net.c | 78 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 17e33927f434..5823ba12f1eb 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -306,6 +306,13 @@ static int virtnet_ethtool_flow_insert(struct virtnet_ff *ff,
>  				       struct ethtool_rx_flow_spec *fs,
>  				       u16 curr_queue_pairs);
>  static int virtnet_ethtool_flow_remove(struct virtnet_ff *ff, int location);
> +static int virtnet_ethtool_get_flow_count(struct virtnet_ff *ff,
> +					  struct ethtool_rxnfc *info);
> +static int virtnet_ethtool_get_flow(struct virtnet_ff *ff,
> +				    struct ethtool_rxnfc *info);
> +static int
> +virtnet_ethtool_get_all_flows(struct virtnet_ff *ff,
> +			      struct ethtool_rxnfc *info, u32 *rule_locs);
>  
>  #define VIRTNET_Q_TYPE_RX 0
>  #define VIRTNET_Q_TYPE_TX 1
> @@ -5665,6 +5672,28 @@ static u32 virtnet_get_rx_ring_count(struct net_device *dev)
>  	return vi->curr_queue_pairs;
>  }
>  
> +static int virtnet_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info, u32 *rule_locs)
> +{
> +	struct virtnet_info *vi = netdev_priv(dev);
> +	int rc = 0;
> +
> +	switch (info->cmd) {
> +	case ETHTOOL_GRXCLSRLCNT:
> +		rc = virtnet_ethtool_get_flow_count(&vi->ff, info);
> +		break;
> +	case ETHTOOL_GRXCLSRULE:
> +		rc = virtnet_ethtool_get_flow(&vi->ff, info);
> +		break;
> +	case ETHTOOL_GRXCLSRLALL:
> +		rc = virtnet_ethtool_get_all_flows(&vi->ff, info, rule_locs);
> +		break;
> +	default:
> +		rc = -EOPNOTSUPP;
> +	}
> +
> +	return rc;
> +}
> +
>  static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
> @@ -5706,6 +5735,7 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
>  	.get_rxfh_fields = virtnet_get_hashflow,
>  	.set_rxfh_fields = virtnet_set_hashflow,
>  	.get_rx_ring_count = virtnet_get_rx_ring_count,
> +	.get_rxnfc = virtnet_get_rxnfc,
>  	.set_rxnfc = virtnet_set_rxnfc,
>  };
>  
> @@ -7625,6 +7655,54 @@ static int virtnet_ethtool_flow_remove(struct virtnet_ff *ff, int location)
>  	return err;
>  }
>  
> +static int virtnet_ethtool_get_flow_count(struct virtnet_ff *ff,
> +					  struct ethtool_rxnfc *info)
> +{
> +	if (!ff->ff_supported)
> +		return -EOPNOTSUPP;
> +
> +	info->rule_cnt = ff->ethtool.num_rules;
> +	info->data = le32_to_cpu(ff->ff_caps->rules_limit) | RX_CLS_LOC_SPECIAL;
> +
> +	return 0;
> +}
> +
> +static int virtnet_ethtool_get_flow(struct virtnet_ff *ff,
> +				    struct ethtool_rxnfc *info)
> +{
> +	struct virtnet_ethtool_rule *eth_rule;
> +
> +	if (!ff->ff_supported)
> +		return -EOPNOTSUPP;
> +
> +	eth_rule = xa_load(&ff->ethtool.rules, info->fs.location);
> +	if (!eth_rule)
> +		return -ENOENT;
> +
> +	info->fs = eth_rule->flow_spec;
> +
> +	return 0;
> +}
> +
> +static int
> +virtnet_ethtool_get_all_flows(struct virtnet_ff *ff,
> +			      struct ethtool_rxnfc *info, u32 *rule_locs)
> +{
> +	struct virtnet_ethtool_rule *eth_rule;
> +	unsigned long i = 0;
> +	int idx = 0;
> +
> +	if (!ff->ff_supported)
> +		return -EOPNOTSUPP;
> +
> +	xa_for_each(&ff->ethtool.rules, i, eth_rule)
> +		rule_locs[idx++] = i;
> +
> +	info->data = le32_to_cpu(ff->ff_caps->rules_limit);
> +
> +	return 0;
> +}

So I see

 * For %ETHTOOL_GRXCLSRLALL, @rule_cnt specifies the array size of the
 * user buffer for @rule_locs on entry.  On return, @data is the size
 * of the rule table, @rule_cnt is the number of defined rules, and
 * @rule_locs contains the locations of the defined rules.  Drivers
 * must use the second parameter to get_rxnfc() instead of @rule_locs.
 *

Should this set @rule_cnt?

> +
>  static size_t get_mask_size(u16 type)
>  {
>  	switch (type) {
> -- 
> 2.50.1