ch_ktls/cxgb4: handle partial tag alone SKBs

If TCP congestion caused a very small packets which only has some
part fo the TAG, and that too is not till the end. HW can't handle
such case, so falling back to sw crypto in such cases.

v1->v2:
- Marked chcr_ktls_sw_fallback() static.

Fixes: dc05f3df ("chcr: Handle first or middle part of record")
Signed-off-by: Rohit Maheshwari <rohitm@chelsio.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c

@@ -3573,6 +3573,8 @@ static int chcr_stats_show(struct seq_file *seq, void *v)
 		   atomic64_read(&adap->ch_ktls_stats.ktls_tx_complete_pkts));
 	seq_printf(seq, "TX trim pkts :                    %20llu\n",
 		   atomic64_read(&adap->ch_ktls_stats.ktls_tx_trimmed_pkts));
+	seq_printf(seq, "TX sw fallback :                  %20llu\n",
+		   atomic64_read(&adap->ch_ktls_stats.ktls_tx_fallback));
 	while (i < MAX_NPORTS) {
 		ktls_port = &adap->ch_ktls_stats.ktls_port[i];
 		seq_printf(seq, "Port %d\n", i);

drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h

@@ -388,6 +388,7 @@ struct ch_ktls_stats_debug {
 	atomic64_t ktls_tx_retransmit_pkts;
 	atomic64_t ktls_tx_complete_pkts;
 	atomic64_t ktls_tx_trimmed_pkts;
+	atomic64_t ktls_tx_fallback;
 };
 #endif
 

drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c

@@ -1545,6 +1545,88 @@ static int chcr_ktls_tx_plaintxt(struct chcr_ktls_info *tx_info,
 	return 0;
 }
 
+static int chcr_ktls_tunnel_pkt(struct chcr_ktls_info *tx_info,
+				struct sk_buff *skb,
+				struct sge_eth_txq *q)
+{
+	u32 ctrl, iplen, maclen, wr_mid = 0, len16;
+	struct tx_sw_desc *sgl_sdesc;
+	struct fw_eth_tx_pkt_wr *wr;
+	struct cpl_tx_pkt_core *cpl;
+	unsigned int flits, ndesc;
+	int credits, last_desc;
+	u64 cntrl1, *end;
+	void *pos;
+
+	ctrl = sizeof(*cpl);
+	flits = DIV_ROUND_UP(sizeof(*wr) + ctrl, 8);
+
+	flits += chcr_sgl_len(skb_shinfo(skb)->nr_frags + 1);
+	len16 = DIV_ROUND_UP(flits, 2);
+	/* check how many descriptors needed */
+	ndesc = DIV_ROUND_UP(flits, 8);
+
+	credits = chcr_txq_avail(&q->q) - ndesc;
+	if (unlikely(credits < 0)) {
+		chcr_eth_txq_stop(q);
+		return -ENOMEM;
+	}
+
+	if (unlikely(credits < ETHTXQ_STOP_THRES)) {
+		chcr_eth_txq_stop(q);
+		wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F;
+	}
+
+	last_desc = q->q.pidx + ndesc - 1;
+	if (last_desc >= q->q.size)
+		last_desc -= q->q.size;
+	sgl_sdesc = &q->q.sdesc[last_desc];
+
+	if (unlikely(cxgb4_map_skb(tx_info->adap->pdev_dev, skb,
+				   sgl_sdesc->addr) < 0)) {
+		memset(sgl_sdesc->addr, 0, sizeof(sgl_sdesc->addr));
+		q->mapping_err++;
+		return -ENOMEM;
+	}
+
+	iplen = skb_network_header_len(skb);
+	maclen = skb_mac_header_len(skb);
+
+	pos = &q->q.desc[q->q.pidx];
+	end = (u64 *)pos + flits;
+	wr = pos;
+
+	/* Firmware work request header */
+	wr->op_immdlen = htonl(FW_WR_OP_V(FW_ETH_TX_PKT_WR) |
+			       FW_WR_IMMDLEN_V(ctrl));
+
+	wr->equiq_to_len16 = htonl(wr_mid | FW_WR_LEN16_V(len16));
+	wr->r3 = 0;
+
+	cpl = (void *)(wr + 1);
+
+	/* CPL header */
+	cpl->ctrl0 = htonl(TXPKT_OPCODE_V(CPL_TX_PKT) |
+			   TXPKT_INTF_V(tx_info->tx_chan) |
+			   TXPKT_PF_V(tx_info->adap->pf));
+	cpl->pack = 0;
+	cntrl1 = TXPKT_CSUM_TYPE_V(tx_info->ip_family == AF_INET ?
+				   TX_CSUM_TCPIP : TX_CSUM_TCPIP6);
+	cntrl1 |= T6_TXPKT_ETHHDR_LEN_V(maclen - ETH_HLEN) |
+		  TXPKT_IPHDR_LEN_V(iplen);
+	/* checksum offload */
+	cpl->ctrl1 = cpu_to_be64(cntrl1);
+	cpl->len = htons(skb->len);
+
+	pos = cpl + 1;
+
+	cxgb4_write_sgl(skb, &q->q, pos, end, 0, sgl_sdesc->addr);
+	sgl_sdesc->skb = skb;
+	chcr_txq_advance(&q->q, ndesc);
+	cxgb4_ring_tx_db(tx_info->adap, &q->q, ndesc);
+	return 0;
+}
+
 /*
  * chcr_ktls_copy_record_in_skb
  * @nskb - new skb where the frags to be added.
@@ -1733,7 +1815,7 @@ static int chcr_short_record_handler(struct chcr_ktls_info *tx_info,
 				      (TLS_CIPHER_AES_GCM_128_TAG_SIZE -
 				       remaining_record);
 		if (!trimmed_len)
-			goto out;
+			return FALLBACK;
 
 		WARN_ON(trimmed_len > data_len);
 
@@ -1837,6 +1919,34 @@ static int chcr_short_record_handler(struct chcr_ktls_info *tx_info,
 	return NETDEV_TX_BUSY;
 }
 
+static int chcr_ktls_sw_fallback(struct sk_buff *skb,
+				 struct chcr_ktls_info *tx_info,
+				 struct sge_eth_txq *q)
+{
+	u32 data_len, skb_offset;
+	struct sk_buff *nskb;
+	struct tcphdr *th;
+
+	nskb = tls_encrypt_skb(skb);
+
+	if (!nskb)
+		return 0;
+
+	th = tcp_hdr(nskb);
+	skb_offset =  skb_transport_offset(nskb) + tcp_hdrlen(nskb);
+	data_len = nskb->len - skb_offset;
+	skb_tx_timestamp(nskb);
+
+	if (chcr_ktls_tunnel_pkt(tx_info, nskb, q))
+		goto out;
+
+	tx_info->prev_seq = ntohl(th->seq) + data_len;
+	atomic64_inc(&tx_info->adap->ch_ktls_stats.ktls_tx_fallback);
+	return 0;
+out:
+	dev_kfree_skb_any(nskb);
+	return 0;
+}
 /* nic tls TX handler */
 static int chcr_ktls_xmit(struct sk_buff *skb, struct net_device *dev)
 {
@@ -2012,6 +2122,10 @@ static int chcr_ktls_xmit(struct sk_buff *skb, struct net_device *dev)
 		if (ret) {
 			if (th->fin)
 				dev_kfree_skb_any(skb);
+
+			if (ret == FALLBACK)
+				return chcr_ktls_sw_fallback(skb, tx_info, q);
+
 			return NETDEV_TX_OK;
 		}
 

drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.h

@@ -26,6 +26,7 @@
 
 #define CHCR_KTLS_WR_SIZE	(CHCR_PLAIN_TX_DATA_LEN +\
 				 sizeof(struct cpl_tx_sec_pdu))
+#define FALLBACK		35
 
 enum ch_ktls_open_state {
 	CH_KTLS_OPEN_SUCCESS = 0,