From: Felix Fietkau <nbd@nbd.name>
Date: Sun, 30 Aug 2026 02:30:20 +0200
Subject: [PATCH] wifi: mac80211_hwsim: support SCS and MSCS

Advertise both services, so that the stack can be tested without
hardware. mac80211 implements them in software, so the two extended
feature flags are all a simulated device needs for classification.

Also implement sta_set_scs, since mac80211 declines every descriptor
with a traffic description when no driver answers it. Nothing here
schedules a stream, so the answer comes from debugfs: the scs_status
file holds the status code for such descriptors, and zero accepts them.
This lets a test cover both outcomes.

Set the SCS Traffic Description Support subfield of the EHT MAC
Capabilities for AP interfaces on every band. Without it, a non-AP EHT
STA never sends a QoS Characteristics element to a simulated AP
(IEEE Std 802.11be-2024, 35.17: "A non-AP EHT STA shall not transmit an
SCS Request frame with SCS Descriptor element(s) containing a QoS
Characteristics element to an AP from which it has not received an EHT
Capabilities element with the SCS Traffic Description Support field
equal to 1.").

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/drivers/net/wireless/virtual/mac80211_hwsim_i.h
+++ b/drivers/net/wireless/virtual/mac80211_hwsim_i.h
@@ -149,6 +149,9 @@ struct mac80211_hwsim_data {
 	/* RSSI in rx status of the receiver */
 	int rx_rssi;
 
+	/* Status code for a traffic description, 0 accepts */
+	u16 scs_status;
+
 	/* only used when pmsr capability is supplied */
 	struct cfg80211_pmsr_capabilities pmsr_capa;
 	struct cfg80211_pmsr_request *pmsr_request;
--- a/drivers/net/wireless/virtual/mac80211_hwsim_main.c
+++ b/drivers/net/wireless/virtual/mac80211_hwsim_main.c
@@ -4519,6 +4519,24 @@ static int mac80211_hwsim_set_radar_back
 	return 0;
 }
 
+/* The status code for a traffic description is set via debugfs for testing */
+static int mac80211_hwsim_sta_set_scs(struct ieee80211_hw *hw,
+				      struct ieee80211_vif *vif,
+				      struct ieee80211_sta *sta,
+				      struct cfg80211_scs_desc * const *desc,
+				      struct cfg80211_scs_result *res,
+				      u8 n_desc)
+{
+	struct mac80211_hwsim_data *data = hw->priv;
+	u8 i;
+
+	for (i = 0; i < n_desc; i++)
+		if (desc[i]->qos_char)
+			res[i].status = data->scs_status;
+
+	return 0;
+}
+
 #ifdef CPTCFG_MAC80211_DEBUGFS
 #define HWSIM_DEBUGFS_OPS					\
 	.link_add_debugfs = mac80211_hwsim_link_add_debugfs,
@@ -4543,6 +4561,7 @@ static int mac80211_hwsim_set_radar_back
 	.link_sta_rc_update = mac80211_hwsim_sta_rc_update,	\
 	.conf_tx = mac80211_hwsim_conf_tx,			\
 	.get_survey = mac80211_hwsim_get_survey,		\
+	.sta_set_scs = mac80211_hwsim_sta_set_scs,		\
 	CFG80211_TESTMODE_CMD(mac80211_hwsim_testmode_cmd)	\
 	.ampdu_action = mac80211_hwsim_ampdu_action,		\
 	.flush = mac80211_hwsim_flush,				\
@@ -4916,7 +4935,8 @@ static const struct ieee80211_sband_ifty
 				.mac_cap_info[0] =
 					IEEE80211_EHT_MAC_CAP0_EPCS_PRIO_ACCESS |
 					IEEE80211_EHT_MAC_CAP0_OM_CONTROL |
-					IEEE80211_EHT_MAC_CAP0_TRIG_TXOP_SHARING_MODE1,
+					IEEE80211_EHT_MAC_CAP0_TRIG_TXOP_SHARING_MODE1 |
+					IEEE80211_EHT_MAC_CAP0_SCS_TRAFFIC_DESC,
 				.phy_cap_info[0] =
 					IEEE80211_EHT_PHY_CAP0_242_TONE_RU_GT20MHZ |
 					IEEE80211_EHT_PHY_CAP0_NDP_4_EHT_LFT_32_GI |
@@ -5212,7 +5232,8 @@ static const struct ieee80211_sband_ifty
 				.mac_cap_info[0] =
 					IEEE80211_EHT_MAC_CAP0_EPCS_PRIO_ACCESS |
 					IEEE80211_EHT_MAC_CAP0_OM_CONTROL |
-					IEEE80211_EHT_MAC_CAP0_TRIG_TXOP_SHARING_MODE1,
+					IEEE80211_EHT_MAC_CAP0_TRIG_TXOP_SHARING_MODE1 |
+					IEEE80211_EHT_MAC_CAP0_SCS_TRAFFIC_DESC,
 				.phy_cap_info[0] =
 					IEEE80211_EHT_PHY_CAP0_242_TONE_RU_GT20MHZ |
 					IEEE80211_EHT_PHY_CAP0_NDP_4_EHT_LFT_32_GI |
@@ -5555,7 +5576,8 @@ static const struct ieee80211_sband_ifty
 				.mac_cap_info[0] =
 					IEEE80211_EHT_MAC_CAP0_EPCS_PRIO_ACCESS |
 					IEEE80211_EHT_MAC_CAP0_OM_CONTROL |
-					IEEE80211_EHT_MAC_CAP0_TRIG_TXOP_SHARING_MODE1,
+					IEEE80211_EHT_MAC_CAP0_TRIG_TXOP_SHARING_MODE1 |
+					IEEE80211_EHT_MAC_CAP0_SCS_TRAFFIC_DESC,
 				.phy_cap_info[0] =
 					IEEE80211_EHT_PHY_CAP0_320MHZ_IN_6GHZ |
 					IEEE80211_EHT_PHY_CAP0_242_TONE_RU_GT20MHZ |
@@ -6214,6 +6236,8 @@ static int mac80211_hwsim_new_radio(stru
 			      NL80211_EXT_FEATURE_EXT_KEY_ID);
 	wiphy_ext_feature_set(hw->wiphy,
 			      NL80211_EXT_FEATURE_ASSOC_FRAME_ENCRYPTION);
+	wiphy_ext_feature_set(hw->wiphy, NL80211_EXT_FEATURE_SCS);
+	wiphy_ext_feature_set(hw->wiphy, NL80211_EXT_FEATURE_MSCS);
 
 	hw->wiphy->interface_modes = param->iftypes;
 
@@ -6408,6 +6432,8 @@ static int mac80211_hwsim_new_radio(stru
 			    &hwsim_fops_group);
 	debugfs_create_file("rx_rssi", 0666, data->debugfs, data,
 			    &hwsim_fops_rx_rssi);
+	debugfs_create_u16("scs_status", 0600, data->debugfs,
+			   &data->scs_status);
 	if (!data->use_chanctx)
 		debugfs_create_file("dfs_simulate_radar", 0222,
 				    data->debugfs,