Subject: Re: [PATCH net-next v12 10/12] virtio_net: Add support for IPv6 ethtool steering

From: "Michael S. Tsirkin" <[email-masked]>
Date: Mon, 24 Nov 2025 16:59:14 -0500

On Wed, Nov 19, 2025 at 01:15:21PM -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
> 
> v12:
>   - refactor calculate_flow_sizes. MST
>   - Move parse_ip6 l3_mask check to TCP/UDP patch. MST
>   - Set eth proto to ipv6 as needed. MST
>   - Also check l4_4_bytes mask is 0 in setup_ip_key_mask. MST
>   - Remove tclass check in setup_ip_key_mask. If it's not suppored it
>     will be caught in validate_classifier_selectors.  MST
>   - Changed error return in setup_ip_key_mask to -EINVAL
> ---
> ---
>  drivers/net/virtio_net.c | 92 +++++++++++++++++++++++++++++++++++-----
>  1 file changed, 82 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index b0b9972fe624..bb8ec4265da5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -5922,6 +5922,34 @@ 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))
> +		return false;
> +
> +	return true;
> +}
> +
>  static bool validate_mask(const struct virtnet_ff *ff,
>  			  const struct virtio_net_ff_selector *sel)
>  {
> @@ -5936,6 +5964,9 @@ 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;
> @@ -5958,11 +5989,33 @@ 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)
> +{

I note logic wise it is different from ipv4, it is looking at the 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));
> +	}
> +
> +	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));
> +	}

Is this enough?
For example, what if user tries to set up a filter by 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)
>  {
> @@ -6099,6 +6152,7 @@ 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;
>  	}
>  
> @@ -6138,6 +6192,8 @@ 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);
>  	}
>  
>  	BUG_ON(size > 0xff);
> @@ -6165,7 +6221,10 @@ static void setup_eth_hdr_key_mask(struct virtio_net_ff_selector *selector,
>  
>  	if (num_hdrs > 1) {
>  		eth_m->h_proto = cpu_to_be16(0xffff);
> -		eth_k->h_proto = cpu_to_be16(ETH_P_IP);
> +		if (has_ipv4(fs->flow_type))
> +			eth_k->h_proto = cpu_to_be16(ETH_P_IP);
> +		else
> +			eth_k->h_proto = cpu_to_be16(ETH_P_IPV6);
>  	} else {
>  		memcpy(eth_m, &fs->m_u.ether_spec, sizeof(*eth_m));
>  		memcpy(eth_k, &fs->h_u.ether_spec, sizeof(*eth_k));
> @@ -6176,20 +6235,33 @@ 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.ip_ver != ETH_RX_NFC_IP4 ||
> -	    fs->m_u.usr_ip4_spec.l4_4_bytes ||
> -	    fs->m_u.usr_ip4_spec.ip_ver ||
> -	    fs->m_u.usr_ip4_spec.proto)
> -		return -EINVAL;
> +		if (fs->h_u.usr_ip6_spec.l4_4_bytes ||
> +		    fs->m_u.usr_ip6_spec.l4_4_bytes)
> +			return -EINVAL;
>  
> -	parse_ip4(v4_m, v4_k, fs);
> +		parse_ip6(v6_m, v6_k, fs);

why does ipv6 not check unsupported fields unlike ipv4?

> +	} 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.ip_ver != ETH_RX_NFC_IP4 ||
> +		    fs->m_u.usr_ip4_spec.l4_4_bytes ||
> +		    fs->m_u.usr_ip4_spec.ip_ver ||
> +		    fs->m_u.usr_ip4_spec.proto)
> +			return -EINVAL;
> +
> +		parse_ip4(v4_m, v4_k, fs);
> +	}
>  
>  	return 0;
>  }
> -- 
> 2.50.1