mac80211: minstrel_ht: add basic support for VHT rates <= 3SS@80MHz

When the new CONFIG_MAC80211_RC_MINSTREL_VHT is not set (default 'N'),
there is no behavioral change including in sampling and MCS_GROUP_RATES
remains 8.
Otherwise MCS_GROUP_RATES is 10, and a module parameter *vht_only*
(default 'true'), restricts the rates selection to VHT when VHT is
supported.

Regarding the debugfs stats buffer:
It is explicitly increased from 8k to 32k to fit every rates incl. when
both HT and VHT rates are enabled, as for the format, before:
type           rate     tpt eprob *prob ret  *ok(*cum)        ok(      cum)
HT20/LGI ABCDP MCS0     0.0   0.0   0.0   1    0(   0)         0(        0)
after:
 type           rate      tpt eprob *prob ret  *ok(*cum)        ok(      cum)
 HT20/LGI ABCDP MCS0      0.0   0.0   0.0   1    0(   0)         0(        0)
VHT40/LGI       MCS5/2    0.0   0.0   0.0   0    0(   0)         0(        0)
Signed-off-by: Karl Beldan <karl.beldan@rivierawaves.com>
Cc: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/Kconfig

@@ -33,6 +33,13 @@ config MAC80211_RC_MINSTREL_HT
 	---help---
 	  This option enables the 'minstrel_ht' TX rate control algorithm
 
+config MAC80211_RC_MINSTREL_VHT
+	bool "Minstrel 802.11ac support" if EXPERT
+	depends on MAC80211_RC_MINSTREL_HT
+	default n
+	---help---
+	  This option enables VHT in the 'minstrel_ht' TX rate control algorithm
+
 choice
 	prompt "Default rate control algorithm"
 	depends on MAC80211_HAS_RC

net/mac80211/rc80211_minstrel_ht.c

@@ -10,6 +10,7 @@
 #include <linux/skbuff.h>
 #include <linux/debugfs.h>
 #include <linux/random.h>
+#include <linux/moduleparam.h>
 #include <linux/ieee80211.h>
 #include <net/mac80211.h>
 #include "rate.h"
@@ -36,6 +37,7 @@
 
 #define BW_20			0
 #define BW_40			1
+#define BW_80			2
 
 /*
  * Define group sort order: HT40 -> SGI -> #streams
@@ -66,6 +68,47 @@
 	}								\
 }
 
+#define VHT_GROUP_IDX(_streams, _sgi, _bw)				\
+	(MINSTREL_VHT_GROUP_0 +						\
+	 MINSTREL_MAX_STREAMS * 2 * (_bw) +				\
+	 MINSTREL_MAX_STREAMS * (_sgi) +				\
+	 (_streams) - 1)
+
+#define BW2VBPS(_bw, r3, r2, r1)					\
+	(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)
+
+#define VHT_GROUP(_streams, _sgi, _bw)					\
+	[VHT_GROUP_IDX(_streams, _sgi, _bw)] = {			\
+	.streams = _streams,						\
+	.flags =							\
+		IEEE80211_TX_RC_VHT_MCS |				\
+		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
+		(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH :		\
+		 _bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),	\
+	.duration = {							\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw,  117,  54,  26)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw,  234, 108,  52)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw,  351, 162,  78)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw,  468, 216, 104)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw,  702, 324, 156)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw,  936, 432, 208)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw, 1053, 486, 234)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw, 1170, 540, 260)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw, 1404, 648, 312)),		\
+		MCS_DURATION(_streams, _sgi,				\
+			     BW2VBPS(_bw, 1560, 720, 346))		\
+	}								\
+}
+
 #define CCK_DURATION(_bitrate, _short, _len)		\
 	(1000 * (10 /* SIFS */ +			\
 	 (_short ? 72 + 24 : 144 + 48) +		\
@@ -91,6 +134,13 @@
 		}					\
 	}
 
+#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
+static bool minstrel_vht_only = true;
+module_param(minstrel_vht_only, bool, 0644);
+MODULE_PARM_DESC(minstrel_vht_only,
+		 "Use only VHT rates when VHT is supported by sta.");
+#endif
+
 /*
  * To enable sufficiently targeted rate sampling, MCS rates are divided into
  * groups, based on the number of streams and flags (HT40, SGI) that they
@@ -124,15 +174,91 @@ const struct mcs_group minstrel_mcs_groups[] = {
 	MCS_GROUP(3, 1, BW_40),
 #endif
 
-	CCK_GROUP
-};
+	CCK_GROUP,
 
+#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
+	VHT_GROUP(1, 0, BW_20),
+	VHT_GROUP(2, 0, BW_20),
+#if MINSTREL_MAX_STREAMS >= 3
+	VHT_GROUP(3, 0, BW_20),
+#endif
+
+	VHT_GROUP(1, 1, BW_20),
+	VHT_GROUP(2, 1, BW_20),
+#if MINSTREL_MAX_STREAMS >= 3
+	VHT_GROUP(3, 1, BW_20),
+#endif
+
+	VHT_GROUP(1, 0, BW_40),
+	VHT_GROUP(2, 0, BW_40),
+#if MINSTREL_MAX_STREAMS >= 3
+	VHT_GROUP(3, 0, BW_40),
+#endif
+
+	VHT_GROUP(1, 1, BW_40),
+	VHT_GROUP(2, 1, BW_40),
+#if MINSTREL_MAX_STREAMS >= 3
+	VHT_GROUP(3, 1, BW_40),
+#endif
+
+	VHT_GROUP(1, 0, BW_80),
+	VHT_GROUP(2, 0, BW_80),
+#if MINSTREL_MAX_STREAMS >= 3
+	VHT_GROUP(3, 0, BW_80),
+#endif
+
+	VHT_GROUP(1, 1, BW_80),
+	VHT_GROUP(2, 1, BW_80),
+#if MINSTREL_MAX_STREAMS >= 3
+	VHT_GROUP(3, 1, BW_80),
+#endif
+#endif
+};
 
 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
 
 static void
 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
 
+/*
+ * Some VHT MCSes are invalid (when Ndbps / Nes is not an integer)
+ * e.g for MCS9@20MHzx1Nss: Ndbps=8x52*(5/6) Nes=1
+ *
+ * Returns the valid mcs map for struct minstrel_mcs_group_data.supported
+ */
+static u16
+minstrel_get_valid_vht_rates(int bw, int nss, __le16 mcs_map)
+{
+	u16 mask = 0;
+
+	if (bw == BW_20) {
+		if (nss != 3 && nss != 6)
+			mask = BIT(9);
+	} else if (bw == BW_80) {
+		if (nss == 3 || nss == 7)
+			mask = BIT(6);
+		else if (nss == 6)
+			mask = BIT(9);
+	} else {
+		WARN_ON(bw != BW_40);
+	}
+
+	switch ((le16_to_cpu(mcs_map) >> (2 * (nss - 1))) & 3) {
+	case IEEE80211_VHT_MCS_SUPPORT_0_7:
+		mask |= 0x300;
+		break;
+	case IEEE80211_VHT_MCS_SUPPORT_0_8:
+		mask |= 0x200;
+		break;
+	case IEEE80211_VHT_MCS_SUPPORT_0_9:
+		break;
+	default:
+		mask = 0x3ff;
+	}
+
+	return 0x3ff & ~mask;
+}
+
 /*
  * Look up an MCS group index based on mac80211 rate information
  */
@@ -144,6 +270,15 @@ minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
 			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
 }
 
+static int
+minstrel_vht_get_group_idx(struct ieee80211_tx_rate *rate)
+{
+	return VHT_GROUP_IDX(ieee80211_rate_get_vht_nss(rate),
+			     !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
+			     !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) +
+			     2*!!(rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH));
+}
+
 static struct minstrel_rate_stats *
 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 		      struct ieee80211_tx_rate *rate)
@@ -153,6 +288,9 @@ minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 	if (rate->flags & IEEE80211_TX_RC_MCS) {
 		group = minstrel_ht_get_group_idx(rate);
 		idx = rate->idx % 8;
+	} else if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
+		group = minstrel_vht_get_group_idx(rate);
+		idx = ieee80211_rate_get_vht_mcs(rate);
 	} else {
 		group = MINSTREL_CCK_GROUP;
 
@@ -489,7 +627,8 @@ minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rat
 	if (!rate->count)
 		return false;
 
-	if (rate->flags & IEEE80211_TX_RC_MCS)
+	if (rate->flags & IEEE80211_TX_RC_MCS ||
+	    rate->flags & IEEE80211_TX_RC_VHT_MCS)
 		return true;
 
 	return rate->idx == mp->cck_rates[0] ||
@@ -736,6 +875,9 @@ minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
 
 	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP)
 		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
+	else if (flags & IEEE80211_TX_RC_VHT_MCS)
+		idx = ((group->streams - 1) << 4) |
+		      ((index % MCS_GROUP_RATES) & 0xF);
 	else
 		idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8;
 
@@ -917,6 +1059,9 @@ minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
 	if (sample_idx / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
 		int idx = sample_idx % ARRAY_SIZE(mp->cck_rates);
 		rate->idx = mp->cck_rates[idx];
+	} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
+		ieee80211_rate_set_vht(rate, sample_idx % MCS_GROUP_RATES,
+				       sample_group->streams);
 	} else {
 		rate->idx = sample_idx % MCS_GROUP_RATES +
 			    (sample_group->streams - 1) * 8;
@@ -962,6 +1107,8 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 	struct minstrel_ht_sta *mi = &msp->ht;
 	struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
 	u16 sta_cap = sta->ht_cap.cap;
+	struct ieee80211_sta_vht_cap *vht_cap = &sta->vht_cap;
+	int use_vht;
 	int n_supported = 0;
 	int ack_dur;
 	int stbc;
@@ -973,6 +1120,13 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 
 	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != MINSTREL_GROUPS_NB);
 
+#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
+	if (vht_cap->vht_supported)
+		use_vht = vht_cap->vht_mcs.tx_mcs_map != cpu_to_le16(~0);
+	else
+#endif
+	use_vht = 0;
+
 	msp->is_ht = true;
 	memset(mi, 0, sizeof(*mi));
 
@@ -996,15 +1150,19 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 	}
 	mi->sample_tries = 4;
 
+	/* TODO tx_flags for vht - ATM the RC API is not fine-grained enough */
+	if (!use_vht) {
 		stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
 			IEEE80211_HT_CAP_RX_STBC_SHIFT;
 		mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
 
 		if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
 			mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
+	}
 
 	for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
 		u32 gflags = minstrel_mcs_groups[i].flags;
+		int bw, nss;
 
 		mi->groups[i].supported = 0;
 		if (i == MINSTREL_CCK_GROUP) {
@@ -1026,13 +1184,47 @@ minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
 		    sta->bandwidth < IEEE80211_STA_RX_BW_40)
 			continue;
 
+		nss = minstrel_mcs_groups[i].streams;
+
 		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
-		if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
-		    minstrel_mcs_groups[i].streams > 1)
+		if (sta->smps_mode == IEEE80211_SMPS_STATIC && nss > 1)
 			continue;
 
-		mi->groups[i].supported =
-			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
+		/* HT rate */
+		if (gflags & IEEE80211_TX_RC_MCS) {
+#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
+			if (minstrel_vht_only)
+				continue;
+#endif
+			mi->groups[i].supported = mcs->rx_mask[nss - 1];
+			if (mi->groups[i].supported)
+				n_supported++;
+			continue;
+		}
+
+		/* VHT rate */
+		if (!vht_cap->vht_supported ||
+		    WARN_ON(!(gflags & IEEE80211_TX_RC_VHT_MCS)) ||
+		    WARN_ON(gflags & IEEE80211_TX_RC_160_MHZ_WIDTH))
+			continue;
+
+		if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH) {
+			if (sta->bandwidth < IEEE80211_STA_RX_BW_80 ||
+			    ((gflags & IEEE80211_TX_RC_SHORT_GI) &&
+			     !(vht_cap->cap & IEEE80211_VHT_CAP_SHORT_GI_80))) {
+				continue;
+			}
+		}
+
+		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH)
+			bw = BW_40;
+		else if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH)
+			bw = BW_80;
+		else
+			bw = BW_20;
+
+		mi->groups[i].supported = minstrel_get_valid_vht_rates(bw, nss,
+				vht_cap->vht_mcs.tx_mcs_map);
 
 		if (mi->groups[i].supported)
 			n_supported++;

net/mac80211/rc80211_minstrel_ht.h

@@ -15,17 +15,30 @@
  */
 #define MINSTREL_MAX_STREAMS		3
 #define MINSTREL_HT_STREAM_GROUPS	4 /* BW(=2) * SGI(=2) */
+#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
+#define MINSTREL_VHT_STREAM_GROUPS	6 /* BW(=3) * SGI(=2) */
+#else
+#define MINSTREL_VHT_STREAM_GROUPS	0
+#endif
 
 #define MINSTREL_HT_GROUPS_NB	(MINSTREL_MAX_STREAMS *		\
 				 MINSTREL_HT_STREAM_GROUPS)
+#define MINSTREL_VHT_GROUPS_NB	(MINSTREL_MAX_STREAMS *		\
+				 MINSTREL_VHT_STREAM_GROUPS)
 #define MINSTREL_CCK_GROUPS_NB	1
 #define MINSTREL_GROUPS_NB	(MINSTREL_HT_GROUPS_NB +	\
+				 MINSTREL_VHT_GROUPS_NB +	\
 				 MINSTREL_CCK_GROUPS_NB)
 
 #define MINSTREL_HT_GROUP_0	0
 #define MINSTREL_CCK_GROUP	(MINSTREL_HT_GROUP_0 + MINSTREL_HT_GROUPS_NB)
+#define MINSTREL_VHT_GROUP_0	(MINSTREL_CCK_GROUP + 1)
 
+#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
+#define MCS_GROUP_RATES		10
+#else
 #define MCS_GROUP_RATES		8
+#endif
 
 struct mcs_group {
 	u32 flags;
@@ -40,7 +53,7 @@ struct minstrel_mcs_group_data {
 	u8 column;
 
 	/* bitfield of supported MCS rates of this group */
-	u8 supported;
+	u16 supported;
 
 	/* sorted rate set within a MCS group*/
 	u16 max_group_tp_rate[MAX_THR_RATES];

net/mac80211/rc80211_minstrel_ht_debugfs.c

@@ -29,6 +29,8 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 	mg = &minstrel_mcs_groups[i];
 	if (mg->flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
 		htmode = '4';
+	else if (mg->flags & IEEE80211_TX_RC_80_MHZ_WIDTH)
+		htmode = '8';
 	if (mg->flags & IEEE80211_TX_RC_SHORT_GI)
 		gimode = 'S';
 
@@ -41,9 +43,11 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 			continue;
 
 		if (i == MINSTREL_CCK_GROUP)
-			p += sprintf(p, "CCK/%cP   ", j < 4 ? 'L' : 'S');
+			p += sprintf(p, " CCK/%cP   ", j < 4 ? 'L' : 'S');
+		else if (i >= MINSTREL_VHT_GROUP_0)
+			p += sprintf(p, "VHT%c0/%cGI ", htmode, gimode);
 		else
-			p += sprintf(p, "HT%c0/%cGI ", htmode, gimode);
+			p += sprintf(p, " HT%c0/%cGI ", htmode, gimode);
 
 		*(p++) = (idx == mi->max_tp_rate[0]) ? 'A' : ' ';
 		*(p++) = (idx == mi->max_tp_rate[1]) ? 'B' : ' ';
@@ -53,9 +57,11 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 
 		if (i == MINSTREL_CCK_GROUP) {
 			int r = bitrates[j % 4];
-			p += sprintf(p, " %2u.%1uM", r / 10, r % 10);
+			p += sprintf(p, " %2u.%1uM ", r / 10, r % 10);
+		} else if (i >= MINSTREL_VHT_GROUP_0) {
+			p += sprintf(p, " MCS%-1u/%1u", j, mg->streams);
 		} else {
-			p += sprintf(p, " MCS%-2u", (mg->streams - 1) * 8 + j);
+			p += sprintf(p, " MCS%-2u ", (mg->streams - 1) * 8 + j);
 		}
 
 		tp = mr->cur_tp / 10;
@@ -94,19 +100,20 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file)
 		return ret;
 	}
 
-	ms = kmalloc(8192, GFP_KERNEL);
+	ms = kmalloc(32768, GFP_KERNEL);
 	if (!ms)
 		return -ENOMEM;
 
 	file->private_data = ms;
 	p = ms->buf;
-	p += sprintf(p, "type           rate     tpt eprob *prob "
+	p += sprintf(p, " type           rate      tpt eprob *prob "
 			"ret  *ok(*cum)        ok(      cum)\n");
 
-
 	p = minstrel_ht_stats_dump(mi, MINSTREL_CCK_GROUP, p);
 	for (i = 0; i < MINSTREL_CCK_GROUP; i++)
 		p = minstrel_ht_stats_dump(mi, i, p);
+	for (i++; i < ARRAY_SIZE(mi->groups); i++)
+		p = minstrel_ht_stats_dump(mi, i, p);
 
 	p += sprintf(p, "\nTotal packet count::    ideal %d      "
 			"lookaround %d\n",
@@ -117,7 +124,7 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file)
 		MINSTREL_TRUNC(mi->avg_ampdu_len * 10) % 10);
 	ms->len = p - ms->buf;
 
-	WARN_ON(ms->len + sizeof(*ms) > 8192);
+	WARN_ON(ms->len + sizeof(*ms) > 32768);
 
 	return nonseekable_open(inode, file);
 }