Subject: Re: [PATCH net-next v11 10/12] virtio_net: Add support for IPv6 ethtool steering

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 18 Nov 2025 16:48:21 -0500

On Tue, Nov 18, 2025 at 08:39:00AM -0600, Daniel Jurgens wrote:
> Implement support for IPV6_USER_FLOW type rules.
> 
> Example:
> $ ethtool -U ens9 flow-type ip6 src-ip fe80::2 dst-ip fe80::4 action 3
> Added rule with ID 0
> 
> The example rule will forward packets with the specified source and
> destination IP addresses to RX ring 3.
> 
> 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: commit message typo
> ---
>  drivers/net/virtio_net.c | 89 ++++++++++++++++++++++++++++++++++++----
>  1 file changed, 81 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index c1adba60b6a8..78fc8f01b6c4 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -6932,6 +6932,34 @@ static bool validate_ip4_mask(const struct virtnet_ff *ff,
>  	return true;
>  }
>  
> +static bool validate_ip6_mask(const struct virtnet_ff *ff,
> +			      const struct virtio_net_ff_selector *sel,
> +			      const struct virtio_net_ff_selector *sel_cap)
> +{
> +	bool partial_mask = !!(sel_cap->flags & VIRTIO_NET_FF_MASK_F_PARTIAL_MASK);
> +	struct ipv6hdr *cap, *mask;
> +
> +	cap = (struct ipv6hdr *)&sel_cap->mask;
> +	mask = (struct ipv6hdr *)&sel->mask;
> +
> +	if (!ipv6_addr_any(&mask->saddr) &&
> +	    !check_mask_vs_cap(&mask->saddr, &cap->saddr,
> +			       sizeof(cap->saddr), partial_mask))
> +		return false;
> +
> +	if (!ipv6_addr_any(&mask->daddr) &&
> +	    !check_mask_vs_cap(&mask->daddr, &cap->daddr,
> +			       sizeof(cap->daddr), partial_mask))
> +		return false;
> +
> +	if (mask->nexthdr &&
> +	    !check_mask_vs_cap(&mask->nexthdr, &cap->nexthdr,
> +	    sizeof(cap->nexthdr), partial_mask))

indent sizeof here please - align on ( not on !.

> +		return false;
> +
> +	return true;
> +}
> +
>  static bool validate_mask(const struct virtnet_ff *ff,
>  			  const struct virtio_net_ff_selector *sel)
>  {
> @@ -6946,6 +6974,9 @@ static bool validate_mask(const struct virtnet_ff *ff,
>  
>  	case VIRTIO_NET_FF_MASK_TYPE_IPV4:
>  		return validate_ip4_mask(ff, sel, sel_cap);
> +
> +	case VIRTIO_NET_FF_MASK_TYPE_IPV6:
> +		return validate_ip6_mask(ff, sel, sel_cap);
>  	}
>  
>  	return false;
> @@ -6968,11 +6999,38 @@ static void parse_ip4(struct iphdr *mask, struct iphdr *key,
>  	}
>  }
>  
> +static void parse_ip6(struct ipv6hdr *mask, struct ipv6hdr *key,
> +		      const struct ethtool_rx_flow_spec *fs)
> +{
> +	const struct ethtool_usrip6_spec *l3_mask = &fs->m_u.usr_ip6_spec;
> +	const struct ethtool_usrip6_spec *l3_val  = &fs->h_u.usr_ip6_spec;
> +
> +	if (!ipv6_addr_any((struct in6_addr *)l3_mask->ip6src)) {
> +		memcpy(&mask->saddr, l3_mask->ip6src, sizeof(mask->saddr));
> +		memcpy(&key->saddr, l3_val->ip6src, sizeof(key->saddr));
> +	}

so this checks mask then copies but parse_ip4 copies unconditionally?
why?

> +
> +	if (!ipv6_addr_any((struct in6_addr *)l3_mask->ip6dst)) {
> +		memcpy(&mask->daddr, l3_mask->ip6dst, sizeof(mask->daddr));
> +		memcpy(&key->daddr, l3_val->ip6dst, sizeof(key->daddr));
> +	}
> +
> +	if (l3_mask->l4_proto) {
> +		mask->nexthdr = l3_mask->l4_proto;
> +		key->nexthdr = l3_val->l4_proto;
> +	}
> +}
> +
>  static bool has_ipv4(u32 flow_type)
>  {
>  	return flow_type == IP_USER_FLOW;
>  }
>  
> +static bool has_ipv6(u32 flow_type)
> +{
> +	return flow_type == IPV6_USER_FLOW;
> +}
> +
>  static int setup_classifier(struct virtnet_ff *ff,
>  			    struct virtnet_classifier **c)
>  {
> @@ -7108,6 +7166,7 @@ static bool supported_flow_type(const struct ethtool_rx_flow_spec *fs)
>  	switch (fs->flow_type) {
>  	case ETHER_FLOW:
>  	case IP_USER_FLOW:
> +	case IPV6_USER_FLOW:
>  		return true;
>  	}
>  
> @@ -7150,7 +7209,8 @@ static void calculate_flow_sizes(struct ethtool_rx_flow_spec *fs,
>  	++(*num_hdrs);
>  	if (has_ipv4(fs->flow_type))
>  		size += sizeof(struct iphdr);
> -
> +	else if (has_ipv6(fs->flow_type))
> +		size += sizeof(struct ipv6hdr);
>  done:
>  	*key_size = size;
>  	/*
> @@ -7187,18 +7247,31 @@ static int setup_ip_key_mask(struct virtio_net_ff_selector *selector,
>  			     u8 *key,
>  			     const struct ethtool_rx_flow_spec *fs)
>  {
> +	struct ipv6hdr *v6_m = (struct ipv6hdr *)&selector->mask;
>  	struct iphdr *v4_m = (struct iphdr *)&selector->mask;
> +	struct ipv6hdr *v6_k = (struct ipv6hdr *)key;
>  	struct iphdr *v4_k = (struct iphdr *)key;
>  
> -	selector->type = VIRTIO_NET_FF_MASK_TYPE_IPV4;
> -	selector->length = sizeof(struct iphdr);
> +	if (has_ipv6(fs->flow_type)) {
> +		selector->type = VIRTIO_NET_FF_MASK_TYPE_IPV6;
> +		selector->length = sizeof(struct ipv6hdr);
>  
> -	if (fs->h_u.usr_ip4_spec.l4_4_bytes ||
> -	    fs->h_u.usr_ip4_spec.tos ||
> -	    fs->h_u.usr_ip4_spec.ip_ver != ETH_RX_NFC_IP4)
> -		return -EOPNOTSUPP;
> +		if (fs->h_u.usr_ip6_spec.l4_4_bytes ||
> +		    fs->h_u.usr_ip6_spec.tclass)
> +			return -EOPNOTSUPP;
>  
> -	parse_ip4(v4_m, v4_k, fs);
> +		parse_ip6(v6_m, v6_k, fs);
> +	} else {
> +		selector->type = VIRTIO_NET_FF_MASK_TYPE_IPV4;
> +		selector->length = sizeof(struct iphdr);
> +
> +		if (fs->h_u.usr_ip4_spec.l4_4_bytes ||
> +		    fs->h_u.usr_ip4_spec.tos ||
> +		    fs->h_u.usr_ip4_spec.ip_ver != ETH_RX_NFC_IP4)
> +			return -EOPNOTSUPP;
> +
> +		parse_ip4(v4_m, v4_k, fs);
> +	}
>  
>  	return 0;
>  }
> -- 
> 2.50.1