[PATCH net-next] net: airoha: bind WLAN-bound flows on PPE driver L2 cache miss
Lorenzo Bianconi
lorenzo at kernel.org
Mon May 25 09:32:31 PDT 2026
>
>
> On 5/26/26 00:19, Lorenzo Bianconi wrote:
> >>
> >>
> >> On 5/25/26 17:09, Lorenzo Bianconi wrote:
> >>>> The Linux bridge FDB can resolve a destination station to WDMA even when
> >>>> the Airoha PPE driver's L2 offload cache has no entry for that MAC pair.
> >>>> The normal bind path only checks the PPE driver's L2 offload cache, so an
> >>>> unbound PPE hit for WLAN egress can stay unbound even though the bridge
> >>>> already knows the right output path, unless a later offload event fills
> >>>> that PPE driver cache.
> >>>>
> >>>> This matters for bridge-visible WLAN egress, such as wired-to-WLAN
> >>>> forwarding or WLAN peer forwarding across another BSS, radio or MLO link.
> >>>> Same-link or same-radio intra-BSS forwarding can stay inside the WLAN
> >>>> datapath and is not covered.
> >>>
> >>> Hi Jihong,
> >>
> >> Hi, Lorenzo.
> >>
> >>>
> >>> In order to offload L2 flows, I assume you are using the OpenWrt bridger
> >>> package, right?
> >>
> >> Actually, no.
> >>
> >> I am using Fanboy's OpenWrt `test` build for the Lumen W1700K2,
> >> together with several of my other patches. It does not include the
> >> bridger package specifically. It now uses native nft-based offloading
> >> with `kmod-br-netfilter`.
> >
> > according to my understanding this is not merged yet, right? I guess the
> > patches should be based on official/accepted code.
> >
>
> Yes, you are right. I just checked current net-next and realized that the
> bridge/L2 nft_flow_offload pieces used in my test environment are not
> merged upstream yet. Sorry, I should have checked this before submitting
> the patch.
ack, no worries ;)
>
> Since I cannot properly test the current upstream code plus bridger at the
> moment, I will put this patch on hold.
>
> I will also check whether this should instead be fixed on the
> nft_flow_offload side.
ack.
Regards,
Lorenzo
>
>
> Sincerely,
> Jihong Min
>
> >>
> >>> IIUC the issue you want to resolve is we are not adding PPE L2 entries for
> >>> the specified cases (same-link or same-radio intra-BSS forwarding), correct?
> >>
> >> No. As written in the patch message, this specifically addresses
> >> bridge-visible WLAN egress, such as:
> >>
> >> 1. wired-to-WLAN forwarding
> >> 2. WLAN peer forwarding across another BSS, radio, or MLO link
> >>
> >> Same-link or same-radio intra-BSS forwarding can stay inside the WLAN
> >> datapath and is not covered by this patch, although it did show poor
> >> performance, whether that is due to shared airtime or not. That case
> >> appears to belong to the Wi-Fi stack/driver datapath, such as the
> >> mac80211/mt76/mt7996 path, rather than to this Airoha PPE fallback path.
> >
> > according to my understanding the l2 nft-based offloading solution should
> > add the missing info to PPE flow-table. As I pointed out, it should be
> > in-sync with hw flow-table. It seems a bug in the nft code to me.
> >
> >>
> >>> Using this approach, we are breaking the assumption PPE flow-table and hw
> >>> flow-table are in sync. If the issue is the one described above, why not
> >>> fixing the problem directly in the bridger package?
> >>
> >> Again, this problem exists in an environment without bridger.
> >
> > In order to offload L2 traffic bridger is mandatory. Do you mean the issue
> > occurs even on L3 scenario?
> >
> >>
> >>> Moreover, I see you developed the patch using Codex:gpt-5.5. Have you tested it
> >>> on a real hw?
> >>
> >> Yes. This has been tested on my Lumen W1700K2 with the environment
> >> described above. MLO Wi-Fi P2P communication and some wired-to-WLAN
> >> cases were indeed left unbound by PPE. CPU usage was high, and the
> >> unbound throughput was close to 50% of what this patch achieves now.
> >
> > ack
> >
> > Regards,
> > Lorenzo
> >
> >>
> >>>
> >>> Some comments inline.
> >>>
> >>> Regards,
> >>> Lorenzo
> >>>>>
> >>>> Before touching the PPE table, resolve the destination MAC through the
> >>>> bridge device above the ingress netdev. If the PPE driver's L2 offload
> >>>> cache lookup misses, bind the hardware flow to the resolved CDM4/WDMA
> >>>> path.
> >>>>
> >>>> Assisted-by: Codex:gpt-5.5
> >>>> Signed-off-by: Jihong Min <hurryman2212 at gmail.com>
> >>>> ---
> >>>> drivers/net/ethernet/airoha/airoha_ppe.c | 138 +++++++++++++++++++----
> >>>> 1 file changed, 119 insertions(+), 19 deletions(-)
> >>>>
> >>>> diff --git a/drivers/net/ethernet/airoha/airoha_ppe.c b/drivers/net/ethernet/airoha/airoha_ppe.c
> >>>> index 26da519236bf..ea932e6d87f6 100644
> >>>> --- a/drivers/net/ethernet/airoha/airoha_ppe.c
> >>>> +++ b/drivers/net/ethernet/airoha/airoha_ppe.c
> >>>> @@ -803,65 +803,163 @@ static void airoha_ppe_foe_flow_remove_entry(struct airoha_ppe *ppe,
> >>>> }
> >>>>
> >>>> static int
> >>>> -airoha_ppe_foe_commit_subflow_entry(struct airoha_ppe *ppe,
> >>>> - struct airoha_flow_table_entry *e,
> >>>> - u32 hash, bool rx_wlan)
> >>>> +airoha_ppe_foe_commit_subflow(struct airoha_ppe *ppe,
> >>>> + const struct airoha_foe_entry *bridge,
> >>>
> >>> maybe l2_hwe instead of bridge?
> >>>
> >>>> + u32 hash, bool rx_wlan)
> >>>> {
> >>>> u32 mask = AIROHA_FOE_IB1_BIND_PACKET_TYPE | AIROHA_FOE_IB1_BIND_UDP;
> >>>> struct airoha_foe_entry *hwe_p, hwe;
> >>>> - struct airoha_flow_table_entry *f;
> >>>> int type;
> >>>>
> >>>> hwe_p = airoha_ppe_foe_get_entry_locked(ppe, hash);
> >>>> if (!hwe_p)
> >>>> return -EINVAL;
> >>>>
> >>>> - f = kzalloc_obj(*f, GFP_ATOMIC);
> >>>> - if (!f)
> >>>> - return -ENOMEM;
> >>>> -
> >>>> - hlist_add_head(&f->l2_subflow_node, &e->l2_flows);
> >>>> - f->type = FLOW_TYPE_L2_SUBFLOW;
> >>>> - f->hash = hash;
> >>>> -
> >>>> memcpy(&hwe, hwe_p, sizeof(*hwe_p));
> >>>> - hwe.ib1 = (hwe.ib1 & mask) | (e->data.ib1 & ~mask);
> >>>> + hwe.ib1 = (hwe.ib1 & mask) | (bridge->ib1 & ~mask);
> >>>>
> >>>> type = FIELD_GET(AIROHA_FOE_IB1_BIND_PACKET_TYPE, hwe.ib1);
> >>>> if (type >= PPE_PKT_TYPE_IPV6_ROUTE_3T) {
> >>>> - memcpy(&hwe.ipv6.l2, &e->data.bridge.l2, sizeof(hwe.ipv6.l2));
> >>>> - hwe.ipv6.ib2 = e->data.bridge.ib2;
> >>>> + memcpy(&hwe.ipv6.l2, &bridge->bridge.l2,
> >>>> + sizeof(hwe.ipv6.l2));
> >>>> + hwe.ipv6.ib2 = bridge->bridge.ib2;
> >>>> /* setting smac_id to 0xf instruct the hw to keep original
> >>>> * source mac address
> >>>> */
> >>>> hwe.ipv6.l2.src_mac_hi = FIELD_PREP(AIROHA_FOE_MAC_SMAC_ID,
> >>>> 0xf);
> >>>> } else {
> >>>> - memcpy(&hwe.bridge.l2, &e->data.bridge.l2,
> >>>> + memcpy(&hwe.bridge.l2, &bridge->bridge.l2,
> >>>> sizeof(hwe.bridge.l2));
> >>>> - hwe.bridge.ib2 = e->data.bridge.ib2;
> >>>> + hwe.bridge.ib2 = bridge->bridge.ib2;
> >>>> if (type == PPE_PKT_TYPE_IPV4_HNAPT)
> >>>> memcpy(&hwe.ipv4.new_tuple, &hwe.ipv4.orig_tuple,
> >>>> sizeof(hwe.ipv4.new_tuple));
> >>>> }
> >>>>
> >>>> - hwe.bridge.data = e->data.bridge.data;
> >>>> - airoha_ppe_foe_commit_entry(ppe, &hwe, hash, rx_wlan);
> >>>> + hwe.bridge.data = bridge->bridge.data;
> >>>> +
> >>>> + return airoha_ppe_foe_commit_entry(ppe, &hwe, hash, rx_wlan);
> >>>> +}
> >>>> +
> >>>> +static int
> >>>> +airoha_ppe_foe_commit_subflow_entry(struct airoha_ppe *ppe,
> >>>> + struct airoha_flow_table_entry *e,
> >>>> + u32 hash, bool rx_wlan)
> >>>> +{
> >>>> + struct airoha_flow_table_entry *f;
> >>>> + int err;
> >>>> +
> >>>> + f = kzalloc_obj(*f, GFP_ATOMIC);
> >>>> + if (!f)
> >>>> + return -ENOMEM;
> >>>> +
> >>>> + err = airoha_ppe_foe_commit_subflow(ppe, &e->data, hash, rx_wlan);
> >>>> + if (err) {
> >>>> + kfree(f);
> >>>> + return err;
> >>>> + }
> >>>> +
> >>>> + hlist_add_head(&f->l2_subflow_node, &e->l2_flows);
> >>>> + f->type = FLOW_TYPE_L2_SUBFLOW;
> >>>> + f->hash = hash;
> >>>>
> >>>> return 0;
> >>>> }
> >>>>
> >>>> +static bool
> >>>> +airoha_ppe_foe_prepare_wdma_subflow_dev(struct airoha_ppe *ppe,
> >>>> + struct net_device *dev,
> >>>> + struct airoha_flow_data *data,
> >>>> + struct airoha_foe_entry *hwe)
> >>>> +{
> >>>> + u32 pse_port;
> >>>> + int err;
> >>>> +
> >>>> + err = airoha_ppe_foe_entry_prepare(ppe->eth, hwe, dev,
> >>>> + PPE_PKT_TYPE_BRIDGE, data, 0);
> >>>> + if (err)
> >>>> + return false;
> >>>> +
> >>>> + pse_port = FIELD_GET(AIROHA_FOE_IB2_PSE_PORT, hwe->bridge.ib2);
> >>>> + if (pse_port != FE_PSE_PORT_CDM4)
> >>>> + return false;
> >>>> +
> >>>> + return true;
> >>>
> >>> return pse_port == FE_PSE_PORT_CDM4;
> >>>
> >>>> +}
> >>>> +
> >>>> +static struct net_device *
> >>>> +airoha_ppe_foe_get_bridge_master(struct net_device *dev)
> >>>> +{
> >>>> + struct net_device *master = NULL;
> >>>> +
> >>>> + rcu_read_lock();
> >>>> + master = netdev_master_upper_dev_get_rcu(dev);
> >>>> + if (master && netif_is_bridge_master(master))
> >>>> + dev_hold(master);
> >>>> + else
> >>>> + master = NULL;
> >>>> + rcu_read_unlock();
> >>>> +
> >>>> + return master;
> >>>> +}
> >>>> +
> >>>> +static bool
> >>>> +airoha_ppe_foe_prepare_wdma_subflow(struct airoha_ppe *ppe,
> >>>> + struct sk_buff *skb,
> >>>> + struct airoha_foe_entry *hwe)
> >>>> +{
> >>>> + struct ethhdr *eh = eth_hdr(skb);
> >>>> + struct airoha_flow_data data = {};
> >>>> + struct net_device *master;
> >>>> +
> >>>> + if (!is_valid_ether_addr(eh->h_source) ||
> >>>> + !is_valid_ether_addr(eh->h_dest))
> >>>> + return false;
> >>>> +
> >>>> + ether_addr_copy(data.eth.h_dest, eh->h_dest);
> >>>> + ether_addr_copy(data.eth.h_source, eh->h_source);
> >>>> +
> >>>> + if (!skb->dev)
> >>>> + return false;
> >>>> +
> >>>> + /* WLAN egress unbound hits can arrive before flowtable creates the
> >>>> + * L2 master flow normally used for subflow binding. Resolve only
> >>>> + * through the bridge master so dev_fill_forward_path() must use the
> >>>> + * bridge FDB for the destination MAC. Calling the ingress AP netdev
> >>>> + * directly can describe the source station's WDMA path and would
> >>>> + * corrupt Wi-Fi-to-wired flows whose real egress is not WDMA.
> >>>> + */
> >>>> + master = airoha_ppe_foe_get_bridge_master(skb->dev);
> >>>> + if (!master)
> >>>> + return false;
> >>>> +
> >>>> + if (airoha_ppe_foe_prepare_wdma_subflow_dev(ppe, master, &data,
> >>>> + hwe)) {
> >>>> + dev_put(master);
> >>>> + return true;
> >>>> + }
> >>>> +
> >>>> + dev_put(master);
> >>>> + return false;
> >>>
> >>> maybe something like:
> >>>
> >>> ret = airoha_ppe_foe_prepare_wdma_subflow_dev();
> >>> dev_put(master);
> >>>
> >>> return ret;
> >>>
> >>>> +}
> >>>> +
> >>>> static void airoha_ppe_foe_insert_entry(struct airoha_ppe *ppe,
> >>>> struct sk_buff *skb,
> >>>> u32 hash, bool rx_wlan)
> >>>> {
> >>>> + struct airoha_foe_entry wdma_hwe = {};
> >>>> struct airoha_flow_table_entry *e;
> >>>> struct airoha_foe_bridge br = {};
> >>>> struct airoha_foe_entry *hwe;
> >>>> bool commit_done = false;
> >>>> + bool wdma_ready = false;
> >>>> struct hlist_node *n;
> >>>> u32 index, state;
> >>>>
> >>>> + wdma_ready = airoha_ppe_foe_prepare_wdma_subflow(ppe, skb,
> >>>> + &wdma_hwe);
> >>>> +
> >>>> spin_lock_bh(&ppe_lock);
> >>>>
> >>>> hwe = airoha_ppe_foe_get_entry_locked(ppe, hash);
> >>>> @@ -899,6 +997,8 @@ static void airoha_ppe_foe_insert_entry(struct airoha_ppe *ppe,
> >>>> airoha_l2_flow_table_params);
> >>>> if (e)
> >>>> airoha_ppe_foe_commit_subflow_entry(ppe, e, hash, rx_wlan);
> >>>> + else if (wdma_ready)
> >>>> + airoha_ppe_foe_commit_subflow(ppe, &wdma_hwe, hash, rx_wlan);
> >>>> unlock:
> >>>> spin_unlock_bh(&ppe_lock);
> >>>> }
> >>>> --
> >>>> 2.53.0
> >>>>
> >>
> >> All inline code-style review comments will be addressed in the next
> >> submission of the patch set, together with the responses to Sashiko's
> >> review, if any.
>
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