net: thunderx: HW TSO support for pass-2 hardware

This adds support for offloading TCP segmentation to HW in pass-2
revision of hardware. Both driver level SW TSO for pass1.x chips
and HW TSO for pass-2 chip will co-exist. Modified SQ descriptor
structures to reflect pass-2 hw implementation.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/thunder/nic.h

@@ -265,6 +265,7 @@ struct nicvf {
 	u8			tns_mode:1;
 	u8			sqs_mode:1;
 	u8			loopback_supported:1;
+	bool			hw_tso;
 	u16			mtu;
 	struct queue_set	*qs;
 #define	MAX_SQS_PER_VF_SINGLE_NODE		5
@@ -489,6 +490,11 @@ static inline int nic_get_node_id(struct pci_dev *pdev)
 	return ((addr >> NIC_NODE_ID_SHIFT) & NIC_NODE_ID_MASK);
 }
 
+static inline bool pass1_silicon(struct pci_dev *pdev)
+{
+	return pdev->revision < 8;
+}
+
 int nicvf_set_real_num_queues(struct net_device *netdev,
 			      int tx_queues, int rx_queues);
 int nicvf_open(struct net_device *netdev);

drivers/net/ethernet/cavium/thunder/nic_main.c

@@ -55,11 +55,6 @@ struct nicpf {
 	bool			irq_allocated[NIC_PF_MSIX_VECTORS];
 };
 
-static inline bool pass1_silicon(struct nicpf *nic)
-{
-	return nic->pdev->revision < 8;
-}
-
 /* Supported devices */
 static const struct pci_device_id nic_id_table[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, PCI_DEVICE_ID_THUNDER_NIC_PF) },
@@ -123,7 +118,7 @@ static void nic_send_msg_to_vf(struct nicpf *nic, int vf, union nic_mbx *mbx)
 	 * when PF writes to MBOX(1), in next revisions when
 	 * PF writes to MBOX(0)
 	 */
-	if (pass1_silicon(nic)) {
+	if (pass1_silicon(nic->pdev)) {
 		/* see the comment for nic_reg_write()/nic_reg_read()
 		 * functions above
 		 */
@@ -400,7 +395,7 @@ static void nic_config_cpi(struct nicpf *nic, struct cpi_cfg_msg *cfg)
 			padd = cpi % 8; /* 3 bits CS out of 6bits DSCP */
 
 		/* Leave RSS_SIZE as '0' to disable RSS */
-		if (pass1_silicon(nic)) {
+		if (pass1_silicon(nic->pdev)) {
 			nic_reg_write(nic, NIC_PF_CPI_0_2047_CFG | (cpi << 3),
 				      (vnic << 24) | (padd << 16) |
 				      (rssi_base + rssi));
@@ -470,7 +465,7 @@ static void nic_config_rss(struct nicpf *nic, struct rss_cfg_msg *cfg)
 	}
 
 	cpi_base = nic->cpi_base[cfg->vf_id];
-	if (pass1_silicon(nic))
+	if (pass1_silicon(nic->pdev))
 		idx_addr = NIC_PF_CPI_0_2047_CFG;
 	else
 		idx_addr = NIC_PF_MPI_0_2047_CFG;

drivers/net/ethernet/cavium/thunder/nicvf_main.c

@@ -525,14 +525,22 @@ static void nicvf_snd_pkt_handler(struct net_device *netdev,
 		   __func__, cqe_tx->sq_qs, cqe_tx->sq_idx,
 		   cqe_tx->sqe_ptr, hdr->subdesc_cnt);
 
-	nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
 	nicvf_check_cqe_tx_errs(nic, cq, cqe_tx);
 	skb = (struct sk_buff *)sq->skbuff[cqe_tx->sqe_ptr];
-	/* For TSO offloaded packets only one head SKB needs to be freed */
+	/* For TSO offloaded packets only one SQE will have a valid SKB */
 	if (skb) {
+		nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
 		prefetch(skb);
 		dev_consume_skb_any(skb);
 		sq->skbuff[cqe_tx->sqe_ptr] = (u64)NULL;
+	} else {
+		/* In case of HW TSO, HW sends a CQE for each segment of a TSO
+		 * packet instead of a single CQE for the whole TSO packet
+		 * transmitted. Each of this CQE points to the same SQE, so
+		 * avoid freeing same SQE multiple times.
+		 */
+		if (!nic->hw_tso)
+			nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
 	}
 }
 
@@ -1549,6 +1557,9 @@ static int nicvf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	netdev->vlan_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
 
+	if (!pass1_silicon(nic->pdev))
+		nic->hw_tso = true;
+
 	netdev->netdev_ops = &nicvf_netdev_ops;
 	netdev->watchdog_timeo = NICVF_TX_TIMEOUT;
 

drivers/net/ethernet/cavium/thunder/nicvf_queues.c

@@ -925,7 +925,7 @@ static int nicvf_sq_subdesc_required(struct nicvf *nic, struct sk_buff *skb)
 {
 	int subdesc_cnt = MIN_SQ_DESC_PER_PKT_XMIT;
 
-	if (skb_shinfo(skb)->gso_size) {
+	if (skb_shinfo(skb)->gso_size && !nic->hw_tso) {
 		subdesc_cnt = nicvf_tso_count_subdescs(skb);
 		return subdesc_cnt;
 	}
@@ -940,7 +940,7 @@ static int nicvf_sq_subdesc_required(struct nicvf *nic, struct sk_buff *skb)
  * First subdescriptor for every send descriptor.
  */
 static inline void
-nicvf_sq_add_hdr_subdesc(struct snd_queue *sq, int qentry,
+nicvf_sq_add_hdr_subdesc(struct nicvf *nic, struct snd_queue *sq, int qentry,
 			 int subdesc_cnt, struct sk_buff *skb, int len)
 {
 	int proto;
@@ -976,6 +976,15 @@ nicvf_sq_add_hdr_subdesc(struct snd_queue *sq, int qentry,
 			break;
 		}
 	}
+
+	if (nic->hw_tso && skb_shinfo(skb)->gso_size) {
+		hdr->tso = 1;
+		hdr->tso_start = skb_transport_offset(skb) + tcp_hdrlen(skb);
+		hdr->tso_max_paysize = skb_shinfo(skb)->gso_size;
+		/* For non-tunneled pkts, point this to L2 ethertype */
+		hdr->inner_l3_offset = skb_network_offset(skb) - 2;
+		nic->drv_stats.tx_tso++;
+	}
 }
 
 /* SQ GATHER subdescriptor
@@ -1045,7 +1054,7 @@ static int nicvf_sq_append_tso(struct nicvf *nic, struct snd_queue *sq,
 			data_left -= size;
 			tso_build_data(skb, &tso, size);
 		}
-		nicvf_sq_add_hdr_subdesc(sq, hdr_qentry,
+		nicvf_sq_add_hdr_subdesc(nic, sq, hdr_qentry,
 					 seg_subdescs - 1, skb, seg_len);
 		sq->skbuff[hdr_qentry] = (u64)NULL;
 		qentry = nicvf_get_nxt_sqentry(sq, qentry);
@@ -1098,11 +1107,12 @@ int nicvf_sq_append_skb(struct nicvf *nic, struct sk_buff *skb)
 	qentry = nicvf_get_sq_desc(sq, subdesc_cnt);
 
 	/* Check if its a TSO packet */
-	if (skb_shinfo(skb)->gso_size)
+	if (skb_shinfo(skb)->gso_size && !nic->hw_tso)
 		return nicvf_sq_append_tso(nic, sq, sq_num, qentry, skb);
 
 	/* Add SQ header subdesc */
-	nicvf_sq_add_hdr_subdesc(sq, qentry, subdesc_cnt - 1, skb, skb->len);
+	nicvf_sq_add_hdr_subdesc(nic, sq, qentry, subdesc_cnt - 1,
+				 skb, skb->len);
 
 	/* Add SQ gather subdescs */
 	qentry = nicvf_get_nxt_sqentry(sq, qentry);

drivers/net/ethernet/cavium/thunder/q_struct.h

@@ -545,25 +545,28 @@ struct sq_hdr_subdesc {
 	u64    subdesc_cnt:8;
 	u64    csum_l4:2;
 	u64    csum_l3:1;
-	u64    rsvd0:5;
+	u64    csum_inner_l4:2;
+	u64    csum_inner_l3:1;
+	u64    rsvd0:2;
 	u64    l4_offset:8;
 	u64    l3_offset:8;
 	u64    rsvd1:4;
 	u64    tot_len:20; /* W0 */
 
-	u64    tso_sdc_cont:8;
-	u64    tso_sdc_first:8;
-	u64    tso_l4_offset:8;
-	u64    tso_flags_last:12;
-	u64    tso_flags_first:12;
-	u64    rsvd2:2;
+	u64    rsvd2:24;
+	u64    inner_l4_offset:8;
+	u64    inner_l3_offset:8;
+	u64    tso_start:8;
+	u64    rsvd3:2;
 	u64    tso_max_paysize:14; /* W1 */
 #elif defined(__LITTLE_ENDIAN_BITFIELD)
 	u64    tot_len:20;
 	u64    rsvd1:4;
 	u64    l3_offset:8;
 	u64    l4_offset:8;
-	u64    rsvd0:5;
+	u64    rsvd0:2;
+	u64    csum_inner_l3:1;
+	u64    csum_inner_l4:2;
 	u64    csum_l3:1;
 	u64    csum_l4:2;
 	u64    subdesc_cnt:8;
@@ -574,12 +577,11 @@ struct sq_hdr_subdesc {
 	u64    subdesc_type:4; /* W0 */
 
 	u64    tso_max_paysize:14;
-	u64    rsvd2:2;
-	u64    tso_flags_first:12;
-	u64    tso_flags_last:12;
-	u64    tso_l4_offset:8;
-	u64    tso_sdc_first:8;
-	u64    tso_sdc_cont:8; /* W1 */
+	u64    rsvd3:2;
+	u64    tso_start:8;
+	u64    inner_l3_offset:8;
+	u64    inner_l4_offset:8;
+	u64    rsvd2:24; /* W1 */
 #endif
 };