[RFC net-next 09/10] net: bnxt: Add SW GSO completion and teardown support

[Joe Damato <joe@dama.to>]

Update __bnxt_tx_int and bnxt_free_one_tx_ring_skbs to handle SW GSO
segments:

- MID segments: adjust tx_pkts/tx_bytes accounting and skip skb free
  (the skb is shared across all segments and freed only once)

- LAST segments: no special cleanup needed -- payload DMA unmapping is
  handled by the existing per-BD dma_unmap_len walk, and the header
  inline buffer is pre-allocated per-ring (freed at ring teardown)

sw_gso is initialized to zero, so the new code paths are not run.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Joe Damato <joe@dama.to>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     | 63 ++++++++++++++++---
 .../net/ethernet/broadcom/bnxt/bnxt_ethtool.c | 19 +++++-
 2 files changed, 72 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 906e842d9c53..47dc98479066 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -74,6 +74,8 @@
 #include "bnxt_debugfs.h"
 #include "bnxt_coredump.h"
 #include "bnxt_hwmon.h"
+#include "bnxt_gso.h"
+#include <net/tso.h>
 
 #define BNXT_TX_TIMEOUT		(5 * HZ)
 #define BNXT_DEF_MSG_ENABLE	(NETIF_MSG_DRV | NETIF_MSG_HW | \
@@ -818,12 +820,13 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
 	bool rc = false;
 
 	while (RING_TX(bp, cons) != hw_cons) {
-		struct bnxt_sw_tx_bd *tx_buf;
+		struct bnxt_sw_tx_bd *tx_buf, *head_buf;
 		struct sk_buff *skb;
 		bool is_ts_pkt;
 		int j, last;
 
 		tx_buf = &txr->tx_buf_ring[RING_TX(bp, cons)];
+		head_buf = tx_buf;
 		skb = tx_buf->skb;
 
 		if (unlikely(!skb)) {
@@ -870,6 +873,14 @@ static bool __bnxt_tx_int(struct bnxt *bp, struct bnxt_tx_ring_info *txr,
 							    DMA_TO_DEVICE, 0);
 			}
 		}
+		if (unlikely(head_buf->is_sw_gso)) {
+			if (head_buf->is_sw_gso == BNXT_SW_GSO_MID) {
+				tx_pkts--;
+				tx_bytes -= skb->len;
+				skb = NULL;
+			}
+			head_buf->is_sw_gso = 0;
+		}
 		if (unlikely(is_ts_pkt)) {
 			if (BNXT_CHIP_P5(bp)) {
 				/* PTP worker takes ownership of the skb */
@@ -3417,6 +3428,7 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
 
 	for (i = 0; i < max_idx;) {
 		struct bnxt_sw_tx_bd *tx_buf = &txr->tx_buf_ring[i];
+		struct bnxt_sw_tx_bd *head_buf = tx_buf;
 		struct sk_buff *skb;
 		int j, last;
 
@@ -3467,7 +3479,10 @@ static void bnxt_free_one_tx_ring_skbs(struct bnxt *bp,
 									  len),
 							    DMA_TO_DEVICE, 0);
 		}
-		dev_kfree_skb(skb);
+		if (head_buf->is_sw_gso == BNXT_SW_GSO_MID)
+			skb = NULL;
+		if (skb)
+			dev_kfree_skb(skb);
 	}
 	netdev_tx_reset_queue(netdev_get_tx_queue(bp->dev, idx));
 }
@@ -3975,9 +3990,9 @@ static void bnxt_free_tx_inline_buf(struct bnxt_tx_ring_info *txr,
 	txr->tx_inline_size = 0;
 }
 
-static int __maybe_unused bnxt_alloc_tx_inline_buf(struct bnxt_tx_ring_info *txr,
-						   struct pci_dev *pdev,
-						   unsigned int size)
+static int bnxt_alloc_tx_inline_buf(struct bnxt_tx_ring_info *txr,
+				    struct pci_dev *pdev,
+				    unsigned int size)
 {
 	txr->tx_inline_buf = kmalloc(size, GFP_KERNEL);
 	if (!txr->tx_inline_buf)
@@ -4080,6 +4095,14 @@ static int bnxt_alloc_tx_rings(struct bnxt *bp)
 				sizeof(struct tx_push_bd);
 			txr->data_mapping = cpu_to_le64(mapping);
 		}
+		if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+		    (bp->dev->features & NETIF_F_GSO_UDP_L4)) {
+			rc = bnxt_alloc_tx_inline_buf(txr, pdev,
+						      BNXT_SW_USO_MAX_SEGS *
+						      TSO_HEADER_SIZE);
+			if (rc)
+				return rc;
+		}
 		qidx = bp->tc_to_qidx[j];
 		ring->queue_id = bp->q_info[qidx].queue_id;
 		spin_lock_init(&txr->xdp_tx_lock);
@@ -4611,6 +4634,10 @@ static int bnxt_init_tx_rings(struct bnxt *bp)
 
 	bp->tx_wake_thresh = max_t(int, bp->tx_ring_size / 2,
 				   BNXT_MIN_TX_DESC_CNT);
+	if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+	    (bp->dev->features & NETIF_F_GSO_UDP_L4))
+		bp->tx_wake_thresh = max_t(int, bp->tx_wake_thresh,
+					   BNXT_SW_USO_MAX_DESCS);
 
 	for (i = 0; i < bp->tx_nr_rings; i++) {
 		struct bnxt_tx_ring_info *txr = &bp->tx_ring[i];
@@ -13778,6 +13805,11 @@ static netdev_features_t bnxt_fix_features(struct net_device *dev,
 	if ((features & NETIF_F_NTUPLE) && !bnxt_rfs_capable(bp, false))
 		features &= ~NETIF_F_NTUPLE;
 
+	if ((features & NETIF_F_GSO_UDP_L4) &&
+	    !(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+	    bp->tx_ring_size < 2 * BNXT_SW_USO_MAX_DESCS)
+		features &= ~NETIF_F_GSO_UDP_L4;
+
 	if ((bp->flags & BNXT_FLAG_NO_AGG_RINGS) || bp->xdp_prog)
 		features &= ~(NETIF_F_LRO | NETIF_F_GRO_HW);
 
@@ -13823,6 +13855,15 @@ static int bnxt_set_features(struct net_device *dev, netdev_features_t features)
 	int rc = 0;
 	bool re_init = false;
 
+	if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP)) {
+		if (features & NETIF_F_GSO_UDP_L4)
+			bp->tx_wake_thresh = max_t(int, bp->tx_wake_thresh,
+						   BNXT_SW_USO_MAX_DESCS);
+		else
+			bp->tx_wake_thresh = max_t(int, bp->tx_ring_size / 2,
+						   BNXT_MIN_TX_DESC_CNT);
+	}
+
 	flags &= ~BNXT_FLAG_ALL_CONFIG_FEATS;
 	if (features & NETIF_F_GRO_HW)
 		flags |= BNXT_FLAG_GRO;
@@ -16803,8 +16844,7 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 			   NETIF_F_GSO_UDP_TUNNEL_CSUM | NETIF_F_GSO_GRE_CSUM |
 			   NETIF_F_GSO_PARTIAL | NETIF_F_RXHASH |
 			   NETIF_F_RXCSUM | NETIF_F_GRO;
-	if (bp->flags & BNXT_FLAG_UDP_GSO_CAP)
-		dev->hw_features |= NETIF_F_GSO_UDP_L4;
+	dev->hw_features |= NETIF_F_GSO_UDP_L4;
 
 	if (BNXT_SUPPORTS_TPA(bp))
 		dev->hw_features |= NETIF_F_LRO;
@@ -16837,8 +16877,15 @@ static int bnxt_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	dev->priv_flags |= IFF_UNICAST_FLT;
 
 	netif_set_tso_max_size(dev, GSO_MAX_SIZE);
-	if (bp->tso_max_segs)
+	if (!(bp->flags & BNXT_FLAG_UDP_GSO_CAP)) {
+		u16 max_segs = BNXT_SW_USO_MAX_SEGS;
+
+		if (bp->tso_max_segs)
+			max_segs = min_t(u16, max_segs, bp->tso_max_segs);
+		netif_set_tso_max_segs(dev, max_segs);
+	} else if (bp->tso_max_segs) {
 		netif_set_tso_max_segs(dev, bp->tso_max_segs);
+	}
 
 	dev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
 			    NETDEV_XDP_ACT_RX_SG;
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 3ce092bc8bba..50a4736f512a 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -33,6 +33,7 @@
 #include "bnxt_xdp.h"
 #include "bnxt_ptp.h"
 #include "bnxt_ethtool.h"
+#include "bnxt_gso.h"
 #include "bnxt_nvm_defs.h"	/* NVRAM content constant and structure defs */
 #include "bnxt_fw_hdr.h"	/* Firmware hdr constant and structure defs */
 #include "bnxt_coredump.h"
@@ -846,12 +847,18 @@ static int bnxt_set_ringparam(struct net_device *dev,
 	u8 tcp_data_split = kernel_ering->tcp_data_split;
 	struct bnxt *bp = netdev_priv(dev);
 	u8 hds_config_mod;
+	int rc;
 
 	if ((ering->rx_pending > BNXT_MAX_RX_DESC_CNT) ||
 	    (ering->tx_pending > BNXT_MAX_TX_DESC_CNT) ||
 	    (ering->tx_pending < BNXT_MIN_TX_DESC_CNT))
 		return -EINVAL;
 
+	if ((dev->features & NETIF_F_GSO_UDP_L4) &&
+	    !(bp->flags & BNXT_FLAG_UDP_GSO_CAP) &&
+	    ering->tx_pending < 2 * BNXT_SW_USO_MAX_DESCS)
+		return -EINVAL;
+
 	hds_config_mod = tcp_data_split != dev->cfg->hds_config;
 	if (tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_DISABLED && hds_config_mod)
 		return -EINVAL;
@@ -876,9 +883,17 @@ static int bnxt_set_ringparam(struct net_device *dev,
 	bp->tx_ring_size = ering->tx_pending;
 	bnxt_set_ring_params(bp);
 
-	if (netif_running(dev))
-		return bnxt_open_nic(bp, false, false);
+	if (netif_running(dev)) {
+		rc = bnxt_open_nic(bp, false, false);
+		if (rc)
+			return rc;
+	}
 
+	/* ring size changes may affect features (SW USO requires a minimum
+	 * ring size), so recalculate features to ensure the correct features
+	 * are blocked/available.
+	 */
+	netdev_update_features(dev);
 	return 0;
 }
 
-- 
2.52.0