mac80211: add rx decapsulation offload support

This allows drivers to pass 802.3 frames to mac80211, with some restrictions:

- the skb must be passed with a valid sta
- fast-rx needs to be active for the sta
- monitor mode needs to be disabled

mac80211 will tell the driver when it is safe to enable rx decap offload for
a particular station.

In order to implement support, a driver must:

- call ieee80211_hw_set(hw, SUPPORTS_RX_DECAP_OFFLOAD)
- implement ops->sta_set_decap_offload
- mark 802.3 frames with RX_FLAG_8023

If it doesn't want to enable offload for some vif types, it can mask out
IEEE80211_OFFLOAD_DECAP_ENABLED in vif->offload_flags from within the
.add_interface or .update_vif_offload driver ops

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20201218184718.93650-6-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 3b9ec4ef81c3..1b44690823aa 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -765,7 +765,7 @@ static const struct net_device_ops ieee80211_dataif_8023_ops = {
 	.ndo_get_stats64	= ieee80211_get_stats64,
 };
 
-static bool ieee80211_iftype_supports_encap_offload(enum nl80211_iftype iftype)
+static bool ieee80211_iftype_supports_hdr_offload(enum nl80211_iftype iftype)
 {
 	switch (iftype) {
 	/* P2P GO and client are mapped to AP/STATION types */
@@ -785,7 +785,7 @@ static bool ieee80211_set_sdata_offload_flags(struct ieee80211_sub_if_data *sdat
 	flags = sdata->vif.offload_flags;
 
 	if (ieee80211_hw_check(&local->hw, SUPPORTS_TX_ENCAP_OFFLOAD) &&
-	    ieee80211_iftype_supports_encap_offload(sdata->vif.type)) {
+	    ieee80211_iftype_supports_hdr_offload(sdata->vif.type)) {
 		flags |= IEEE80211_OFFLOAD_ENCAP_ENABLED;
 
 		if (!ieee80211_hw_check(&local->hw, SUPPORTS_TX_FRAG) &&
@@ -798,10 +798,21 @@ static bool ieee80211_set_sdata_offload_flags(struct ieee80211_sub_if_data *sdat
 		flags &= ~IEEE80211_OFFLOAD_ENCAP_ENABLED;
 	}
 
+	if (ieee80211_hw_check(&local->hw, SUPPORTS_RX_DECAP_OFFLOAD) &&
+	    ieee80211_iftype_supports_hdr_offload(sdata->vif.type)) {
+		flags |= IEEE80211_OFFLOAD_DECAP_ENABLED;
+
+		if (local->monitors)
+			flags &= ~IEEE80211_OFFLOAD_DECAP_ENABLED;
+	} else {
+		flags &= ~IEEE80211_OFFLOAD_DECAP_ENABLED;
+	}
+
 	if (sdata->vif.offload_flags == flags)
 		return false;
 
 	sdata->vif.offload_flags = flags;
+	ieee80211_check_fast_rx_iface(sdata);
 	return true;
 }
 
@@ -819,7 +830,7 @@ static void ieee80211_set_vif_encap_ops(struct ieee80211_sub_if_data *sdata)
 	}
 
 	if (!ieee80211_hw_check(&local->hw, SUPPORTS_TX_ENCAP_OFFLOAD) ||
-	    !ieee80211_iftype_supports_encap_offload(bss->vif.type))
+	    !ieee80211_iftype_supports_hdr_offload(bss->vif.type))
 		return;
 
 	enabled = bss->vif.offload_flags & IEEE80211_OFFLOAD_ENCAP_ENABLED;