On 7/8/26 7:43 PM, Lucas Vargas Dias wrote:
> Hi Dumitru,
> 
> Looks good to me, thanks!
> 
> Acked-by: Lucas Vargas Dias <[email protected]>
> 

Hi Lucas, Lorenzo, Xavier,

Thanks for the reviews!  I applied this patch to main and 26.03.

Regards,
Dumitru

> Regards,
> Lucas
> 
> Em qua., 8 de jul. de 2026 às 09:01, Dumitru Ceara <[email protected]>
> escreveu:
> 
>> Commit 4f562e9346c2 ("ovn: Fix the invalid eth.dst and ip6.dst
>> set by nd_ns action for certain cases.") added priority-200
>> flows in lr_in_arp_request that pre-computed the solicited-node
>> multicast address for each IPv6 static route nexthop.  Those
>> flows were needed because pinctrl_handle_nd_ns() was using
>> ip_flow->ipv6_dst (the original packet's IPv6 destination)
>> instead of the nexthop from xxreg0 to derive the solicited-node
>> multicast.
>>
>> After d682437f99a7 ("pinctrl: Use correct IPv6 dst for nd_ns
>> action for IPv4 over v6.") fixed pinctrl to read xxreg0 for the
>> cross-AF case, extend pinctrl to ALWAYS read xxreg0.  This is
>> correct because the generic priority-100 nd_ns flow stores the
>> nexthop in xxreg0 for all cases, and compose_nd_ns() already
>> derives the solicited-node multicast internally when called
>> with multicast=true.
>>
>> Remove the now-redundant priority-200 flows from northd along
>> with their documentation.  Simplify pinctrl_handle_nd_ns() to
>> unconditionally read xxreg0, removing the dl_type branch and
>> the manual in6_addr_solicited_node() call.
>>
>> Assisted-by: Claude Opus 4.6, OpenCode
>> Signed-off-by: Dumitru Ceara <[email protected]>
>> ---
>>  Documentation/ref/ovn-logical-flows.7.rst | 15 ------
>>  controller/pinctrl.c                      | 37 +++++---------
>>  northd/northd.c                           | 47 +----------------
>>  tests/ovn-northd.at                       |  2 -
>>  tests/ovn.at                              | 62 +++++++++++++++++++++++
>>  5 files changed, 75 insertions(+), 88 deletions(-)
>>
>> diff --git a/Documentation/ref/ovn-logical-flows.7.rst
>> b/Documentation/ref/ovn-logical-flows.7.rst
>> index 3d9936414f..95f7e0d7e1 100644
>> --- a/Documentation/ref/ovn-logical-flows.7.rst
>> +++ b/Documentation/ref/ovn-logical-flows.7.rst
>> @@ -3585,21 +3585,6 @@ or IPv6 Neighbor Solicitation request.  It holds
>> the following flows:
>>            output;
>>        };
>>
>> -  Unknown MAC address.  For each IPv6 static route associated with the
>> router
>> -  with the nexthop IP: *G*, a priority-200 flow for IPv6 packets with
>> match
>> -  ``eth.dst == 00:00:00:00:00:00 && xxreg0 == G`` with the following
>> actions is
>> -  added::
>> -
>> -      nd_ns {
>> -          eth.dst = E;
>> -          ip6.dst = I
>> -          nd.target = G;
>> -          output;
>> -      };
>> -
>> -  Where *E* is the multicast mac derived from the Gateway IP, *I* is the
>> -  solicited-node multicast address corresponding to the target address
>> *G*.
>> -
>>    Unknown MAC address.  A priority-100 flow for IPv6 packets with match
>>    ``eth.dst == 00:00:00:00:00:00`` has the following actions::
>>
>> diff --git a/controller/pinctrl.c b/controller/pinctrl.c
>> index 1728aa7901..f898846285 100644
>> --- a/controller/pinctrl.c
>> +++ b/controller/pinctrl.c
>> @@ -6553,32 +6553,19 @@ pinctrl_handle_nd_ns(struct rconn *swconn, const
>> struct flow *ip_flow,
>>
>>      in6_generate_lla(ip_flow->dl_src, &ipv6_src);
>>
>> -    /* We might be here without actually currently handling an IPv6
>> packet.
>> -     * This can happen in the case where we route IPv4 packets over an
>> IPv6
>> -     * link (e.g. RFC 5549 / BGP unnumbered, where an IPv4 destination is
>> -     * resolved via an IPv6 link-local nexthop).
>> -     *
>> -     * In that case we have no destination IPv6 address in the trigger
>> packet
>> -     * to reuse. compose_nd_ns() needs a valid destination so it can
>> derive
>> -     * the correct solicited-node multicast (ff02::1:ff{addr[13:16]}) for
>> -     * eth.dst and ip6.dst -- userdata only sets nd.target on the new
>> packet
>> -     * and does not rewrite ip6.dst, so a wrong ipv6_dst here egresses on
>> the
>> -     * wire as-is.
>> -     *
>> -     * The fallback nd_ns logical flow in S_ROUTER_IN_ARP_REQUEST stores
>> the
>> -     * actual IPv6 nexthop in xxreg0 (REG_NEXT_HOP_IPV6) before invoking
>> the
>> -     * nd_ns action, so for the IPv4-over-IPv6 case read xxreg0 from the
>> -     * trigger packet's flow metadata. */
>> -    struct in6_addr ipv6_dst = IN6ADDR_EXACT_INIT;
>> -    if (get_dl_type(ip_flow) == htons(ETH_TYPE_IPV6)) {
>> -        ipv6_dst = ip_flow->ipv6_dst;
>> -    } else {
>> -        ovs_be128 nexthop_be =
>> -            hton128(flow_get_xxreg(&pin->flow_metadata.flow, 0));
>> -        memcpy(&ipv6_dst, &nexthop_be, sizeof ipv6_dst);
>> -    }
>> +    /* The nd_ns logical flow in S_ROUTER_IN_ARP_REQUEST stores the actual
>> +     * IPv6 nexthop in xxreg0 (REG_NEXT_HOP_IPV6) before invoking the
>> +     * nd_ns action.  Read the nexthop and pass it to compose_nd_ns()
>> +     * which derives the solicited-node multicast for eth.dst and
>> +     * ip6.dst. */
>> +    struct in6_addr ipv6_nh = IN6ADDR_EXACT_INIT;
>> +
>> +    ovs_be128 nexthop_be =
>> +        hton128(flow_get_xxreg(&pin->flow_metadata.flow, 0));
>> +    memcpy(&ipv6_nh, &nexthop_be, sizeof ipv6_nh);
>> +
>>      compose_nd_ns(&packet, true, ip_flow->dl_src, eth_addr_zero,
>> &ipv6_src,
>> -                  &ipv6_dst);
>> +                  &ipv6_nh);
>>
>>      /* Reload previous packet metadata and set actions from userdata. */
>>      set_actions_and_enqueue_msg(swconn, &packet,
>> diff --git a/northd/northd.c b/northd/northd.c
>> index 62270893ab..e4cd93969a 100644
>> --- a/northd/northd.c
>> +++ b/northd/northd.c
>> @@ -16458,53 +16458,10 @@ build_lr_gateway_redirect_flows_for_nats(
>>  static void
>>  build_arp_request_flows_for_lrouter(
>>          struct ovn_datapath *od, struct lflow_table *lflows,
>> -        struct ds *match, struct ds *actions,
>>          const struct shash *meter_groups,
>>          struct lflow_ref *lflow_ref)
>>  {
>>      ovs_assert(od->nbr);
>> -    for (int i = 0; i < od->nbr->n_static_routes; i++) {
>> -        const struct nbrec_logical_router_static_route *route;
>> -
>> -        route = od->nbr->static_routes[i];
>> -        struct in6_addr gw_ip6;
>> -        unsigned int plen;
>> -        char *error = ipv6_parse_cidr(route->nexthop, &gw_ip6, &plen);
>> -        if (error || plen != 128) {
>> -            free(error);
>> -            continue;
>> -        }
>> -
>> -        ds_clear(match);
>> -        ds_put_format(match, "eth.dst == 00:00:00:00:00:00 && "
>> -                      REGBIT_NEXTHOP_IS_IPV4" == 0 && "
>> -                      REG_NEXT_HOP_IPV6 " == %s",
>> -                      route->nexthop);
>> -        struct in6_addr sn_addr;
>> -        struct eth_addr eth_dst;
>> -        in6_addr_solicited_node(&sn_addr, &gw_ip6);
>> -        ipv6_multicast_to_ethernet(&eth_dst, &sn_addr);
>> -
>> -        char sn_addr_s[INET6_ADDRSTRLEN + 1];
>> -        ipv6_string_mapped(sn_addr_s, &sn_addr);
>> -
>> -        ds_clear(actions);
>> -        ds_put_format(actions,
>> -                      "nd_ns { "
>> -                      "eth.dst = "ETH_ADDR_FMT"; "
>> -                      "ip6.dst = %s; "
>> -                      "nd.target = %s; "
>> -                      "output; "
>> -                      "}; next;", ETH_ADDR_ARGS(eth_dst), sn_addr_s,
>> -                      route->nexthop);
>> -
>> -        ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_REQUEST, 200,
>> -                      ds_cstr(match), ds_cstr(actions), lflow_ref,
>> -                      WITH_CTRL_METER(copp_meter_get(COPP_ND_NS_RESOLVE,
>> -                                                     od->nbr->copp,
>> -                                                     meter_groups)),
>> -                      WITH_HINT(&route->header_));
>> -    }
>>
>>      ovn_lflow_add(lflows, od, S_ROUTER_IN_ARP_REQUEST, 100,
>>                    "eth.dst == 00:00:00:00:00:00 && "
>> @@ -19716,9 +19673,7 @@ build_lswitch_and_lrouter_iterate_by_lr(struct
>> ovn_datapath *od,
>>      build_gateway_redirect_flows_for_lrouter(od, lsi->lflows, &lsi->match,
>>                                               &lsi->actions,
>>                                               od->datapath_lflows);
>> -    build_arp_request_flows_for_lrouter(od, lsi->lflows, &lsi->match,
>> -                                        &lsi->actions,
>> -                                        lsi->meter_groups,
>> +    build_arp_request_flows_for_lrouter(od, lsi->lflows,
>> lsi->meter_groups,
>>                                          od->datapath_lflows);
>>      build_ecmp_stateful_egr_flows_for_lrouter(od, lsi->lflows,
>>                                                od->datapath_lflows);
>> diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
>> index f82902c61d..886dd9aba0 100644
>> --- a/tests/ovn-northd.at
>> +++ b/tests/ovn-northd.at
>> @@ -7717,8 +7717,6 @@ AT_CHECK([grep -e "lr_in_arp_request" lr0flows |
>> ovn_strip_lflows], [0], [dnl
>>    table=??(lr_in_arp_request  ), priority=0    , match=(1), action=(next;)
>>    table=??(lr_in_arp_request  ), priority=100  , match=(eth.dst ==
>> 00:00:00:00:00:00 && reg9[[9]] == 0), action=(nd_ns { nd.target = xxreg0;
>> output; }; next;)
>>    table=??(lr_in_arp_request  ), priority=100  , match=(eth.dst ==
>> 00:00:00:00:00:00 && reg9[[9]] == 1), action=(arp { eth.dst =
>> ff:ff:ff:ff:ff:ff; arp.spa = reg5; arp.tpa = reg0; arp.op = 1; output; };
>> next;)
>> -  table=??(lr_in_arp_request  ), priority=200  , match=(eth.dst ==
>> 00:00:00:00:00:00 && reg9[[9]] == 0 && xxreg0 == 2001:db8::10),
>> action=(nd_ns { eth.dst = 33:33:ff:00:00:10; ip6.dst = ff02::1:ff00:10;
>> nd.target = 2001:db8::10; output; }; next;)
>> -  table=??(lr_in_arp_request  ), priority=200  , match=(eth.dst ==
>> 00:00:00:00:00:00 && reg9[[9]] == 0 && xxreg0 == 2001:db8::20),
>> action=(nd_ns { eth.dst = 33:33:ff:00:00:20; ip6.dst = ff02::1:ff00:20;
>> nd.target = 2001:db8::20; output; }; next;)
>>  ])
>>
>>  # ECMP symmetric reply with IPv4 prefix + IPv6 nexthop.
>> diff --git a/tests/ovn.at b/tests/ovn.at
>> index abd12f0ddb..31a97aead9 100644
>> --- a/tests/ovn.at
>> +++ b/tests/ovn.at
>> @@ -46586,3 +46586,65 @@ OVN_CLEANUP([hv])
>>  AT_CLEANUP
>>  ])
>>
>> +OVN_FOR_EACH_NORTHD([
>> +AT_SETUP([IPv6 static route ND NS resolution])
>> +CHECK_SCAPY
>> +ovn_start
>> +
>> +net_add n1
>> +sim_add hv
>> +ovs-vsctl add-br br-phys
>> +ovn_attach n1 br-phys 192.168.0.1
>> +ovs-vsctl set open . external-ids:ovn-bridge-mappings=phys:br-phys
>> +
>> +check ovn-nbctl ls-add sw0
>> +check ovn-nbctl lsp-add sw0 sw0-port1
>> +check ovn-nbctl lsp-set-addresses sw0-port1 "50:54:00:00:00:01
>> 2001:db8::3"
>> +
>> +check ovn-nbctl lr-add lr0
>> +check ovn-nbctl lrp-add lr0 lr0-sw0 00:00:00:00:ff:01 2001:db8::1/64
>> +check ovn-nbctl lsp-add-router-port sw0 sw0-lr0 lr0-sw0
>> +
>> +check ovn-nbctl ls-add public
>> +check ovn-nbctl lrp-add lr0 lr0-public 00:00:20:20:12:13 2001:db8:1::1/64
>> +check ovn-nbctl lsp-add-router-port public public-lr0 lr0-public
>> +
>> +# localnet port
>> +check ovn-nbctl lsp-add-localnet-port public ln-public phys
>> +
>> +check ovn-nbctl lrp-set-gateway-chassis lr0-public hv 20
>> +
>> +# Add an IPv6 static route with an IPv6 nexthop whose MAC is unknown.
>> +check ovn-nbctl --wait=hv lr-route-add lr0 2001:db8:2::/64
>> 2001:db8:1::cafe
>> +
>> +ovs-vsctl -- add-port br-int vif1 -- \
>> +    set interface vif1 external-ids:iface-id=sw0-port1 \
>> +    options:tx_pcap=hv/vif1-tx.pcap \
>> +    options:rxq_pcap=hv/vif1-rx.pcap
>> +
>> +wait_for_ports_up
>> +
>> +# Send an IPv6 packet from sw0-port1 destined for an address behind the
>> +# static route.  The nexthop 2001:db8:1::cafe has no MAC binding, so the
>> +# router must emit an ND NS to resolve it.
>> +packet=$(fmt_pkt "Ether(dst='00:00:00:00:ff:01',
>> src='50:54:00:00:00:01')/ \
>> +                  IPv6(src='2001:db8::3', dst='2001:db8:2::42', hlim=64)/
>> \
>> +                  ICMPv6EchoRequest()")
>> +check as hv ovs-appctl netdev-dummy/receive vif1 $packet
>> +
>> +# Verify the ND NS has correct solicited-node multicast addresses derived
>> +# from the nexthop 2001:db8:1::cafe:
>> +#   eth.dst   = 33:33:ff:00:ca:fe  (multicast MAC from solicited-node)
>> +#   ip6.dst   = ff02::1:ff00:cafe  (solicited-node multicast)
>> +#   nd.target = 2001:db8:1::cafe   (the actual nexthop)
>> +nd_ns=$(fmt_pkt "Ether(dst='33:33:ff:00:ca:fe', src='00:00:20:20:12:13')/
>> \
>> +                       IPv6(src='fe80::200:20ff:fe20:1213', \
>> +
>>  dst='ff02::1:ff00:cafe')/ICMPv6ND_NS(tgt='2001:db8:1::cafe')/\
>> +                       ICMPv6NDOptSrcLLAddr(lladdr='00:00:20:20:12:13')")
>> +
>> +echo $nd_ns > expected_nd_ns
>> +OVN_CHECK_PACKETS_CONTAIN([hv/br-phys_n1-tx.pcap], [expected_nd_ns])
>> +
>> +OVN_CLEANUP([hv])
>> +AT_CLEANUP
>> +])
>> --
>> 2.54.0
>>
>>
> 

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