Merge branch 'thunderx-fixes'

Sunil Goutham says:

====================
net: thunderx: Fixes for TSO offload issues

This patch series fixes couple of issues w.r.t HW TSO offload
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -279,6 +279,7 @@ struct nicvf {
 	u8			sqs_id;
 	bool                    sqs_mode;
 	bool			hw_tso;
+	bool			t88;
 
 	/* Receive buffer alloc */
 	u32			rb_page_offset;

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

@@ -251,9 +251,14 @@ static void nic_set_tx_pkt_pad(struct nicpf *nic, int size)
 	int lmac;
 	u64 lmac_cfg;
 
-	/* Max value that can be set is 60 */
-	if (size > 60)
-		size = 60;
+	/* There is a issue in HW where-in while sending GSO sized
+	 * pkts as part of TSO, if pkt len falls below this size
+	 * NIC will zero PAD packet and also updates IP total length.
+	 * Hence set this value to lessthan min pkt size of MAC+IP+TCP
+	 * headers, BGX will do the padding to transmit 64 byte pkt.
+	 */
+	if (size > 52)
+		size = 52;
 
 	for (lmac = 0; lmac < (MAX_BGX_PER_CN88XX * MAX_LMAC_PER_BGX); lmac++) {
 		lmac_cfg = nic_reg_read(nic, NIC_PF_LMAC_0_7_CFG | (lmac << 3));

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

@@ -513,6 +513,7 @@ static void nicvf_snd_pkt_handler(struct net_device *netdev,
 	struct nicvf *nic = netdev_priv(netdev);
 	struct snd_queue *sq;
 	struct sq_hdr_subdesc *hdr;
+	struct sq_hdr_subdesc *tso_sqe;
 
 	sq = &nic->qs->sq[cqe_tx->sq_idx];
 
@@ -527,17 +528,21 @@ static void nicvf_snd_pkt_handler(struct net_device *netdev,
 
 	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 SQE will have a valid SKB */
 	if (skb) {
+		/* Check for dummy descriptor used for HW TSO offload on 88xx */
+		if (hdr->dont_send) {
+			/* Get actual TSO descriptors and free them */
+			tso_sqe =
+			 (struct sq_hdr_subdesc *)GET_SQ_DESC(sq, hdr->rsvd2);
+			nicvf_put_sq_desc(sq, tso_sqe->subdesc_cnt + 1);
+		}
 		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.
+		/* In case of SW TSO on 88xx, only last segment will have
+		 * a SKB attached, so just free SQEs here.
 		 */
 		if (!nic->hw_tso)
 			nicvf_put_sq_desc(sq, hdr->subdesc_cnt + 1);
@@ -1502,6 +1507,7 @@ static int nicvf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	struct net_device *netdev;
 	struct nicvf *nic;
 	int    err, qcount;
+	u16    sdevid;
 
 	err = pci_enable_device(pdev);
 	if (err) {
@@ -1575,6 +1581,10 @@ static int nicvf_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!pass1_silicon(nic->pdev))
 		nic->hw_tso = true;
 
+	pci_read_config_word(nic->pdev, PCI_SUBSYSTEM_ID, &sdevid);
+	if (sdevid == 0xA134)
+		nic->t88 = true;
+
 	/* Check if this VF is in QS only mode */
 	if (nic->sqs_mode)
 		return 0;

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

@@ -938,6 +938,8 @@ static int nicvf_tso_count_subdescs(struct sk_buff *skb)
 	return num_edescs + sh->gso_segs;
 }
 
+#define POST_CQE_DESC_COUNT 2
+
 /* Get the number of SQ descriptors needed to xmit this skb */
 static int nicvf_sq_subdesc_required(struct nicvf *nic, struct sk_buff *skb)
 {
@@ -948,6 +950,10 @@ static int nicvf_sq_subdesc_required(struct nicvf *nic, struct sk_buff *skb)
 		return subdesc_cnt;
 	}
 
+	/* Dummy descriptors to get TSO pkt completion notification */
+	if (nic->t88 && nic->hw_tso && skb_shinfo(skb)->gso_size)
+		subdesc_cnt += POST_CQE_DESC_COUNT;
+
 	if (skb_shinfo(skb)->nr_frags)
 		subdesc_cnt += skb_shinfo(skb)->nr_frags;
 
@@ -965,14 +971,21 @@ nicvf_sq_add_hdr_subdesc(struct nicvf *nic, struct snd_queue *sq, int qentry,
 	struct sq_hdr_subdesc *hdr;
 
 	hdr = (struct sq_hdr_subdesc *)GET_SQ_DESC(sq, qentry);
-	sq->skbuff[qentry] = (u64)skb;
-
 	memset(hdr, 0, SND_QUEUE_DESC_SIZE);
 	hdr->subdesc_type = SQ_DESC_TYPE_HEADER;
-	/* Enable notification via CQE after processing SQE */
-	hdr->post_cqe = 1;
-	/* No of subdescriptors following this */
-	hdr->subdesc_cnt = subdesc_cnt;
+
+	if (nic->t88 && nic->hw_tso && skb_shinfo(skb)->gso_size) {
+		/* post_cqe = 0, to avoid HW posting a CQE for every TSO
+		 * segment transmitted on 88xx.
+		 */
+		hdr->subdesc_cnt = subdesc_cnt - POST_CQE_DESC_COUNT;
+	} else {
+		sq->skbuff[qentry] = (u64)skb;
+		/* Enable notification via CQE after processing SQE */
+		hdr->post_cqe = 1;
+		/* No of subdescriptors following this */
+		hdr->subdesc_cnt = subdesc_cnt;
+	}
 	hdr->tot_len = len;
 
 	/* Offload checksum calculation to HW */
@@ -1023,6 +1036,37 @@ static inline void nicvf_sq_add_gather_subdesc(struct snd_queue *sq, int qentry,
 	gather->addr = data;
 }
 
+/* Add HDR + IMMEDIATE subdescriptors right after descriptors of a TSO
+ * packet so that a CQE is posted as a notifation for transmission of
+ * TSO packet.
+ */
+static inline void nicvf_sq_add_cqe_subdesc(struct snd_queue *sq, int qentry,
+					    int tso_sqe, struct sk_buff *skb)
+{
+	struct sq_imm_subdesc *imm;
+	struct sq_hdr_subdesc *hdr;
+
+	sq->skbuff[qentry] = (u64)skb;
+
+	hdr = (struct sq_hdr_subdesc *)GET_SQ_DESC(sq, qentry);
+	memset(hdr, 0, SND_QUEUE_DESC_SIZE);
+	hdr->subdesc_type = SQ_DESC_TYPE_HEADER;
+	/* Enable notification via CQE after processing SQE */
+	hdr->post_cqe = 1;
+	/* There is no packet to transmit here */
+	hdr->dont_send = 1;
+	hdr->subdesc_cnt = POST_CQE_DESC_COUNT - 1;
+	hdr->tot_len = 1;
+	/* Actual TSO header SQE index, needed for cleanup */
+	hdr->rsvd2 = tso_sqe;
+
+	qentry = nicvf_get_nxt_sqentry(sq, qentry);
+	imm = (struct sq_imm_subdesc *)GET_SQ_DESC(sq, qentry);
+	memset(imm, 0, SND_QUEUE_DESC_SIZE);
+	imm->subdesc_type = SQ_DESC_TYPE_IMMEDIATE;
+	imm->len = 1;
+}
+
 /* Segment a TSO packet into 'gso_size' segments and append
  * them to SQ for transfer
  */
@@ -1096,7 +1140,7 @@ static int nicvf_sq_append_tso(struct nicvf *nic, struct snd_queue *sq,
 int nicvf_sq_append_skb(struct nicvf *nic, struct sk_buff *skb)
 {
 	int i, size;
-	int subdesc_cnt;
+	int subdesc_cnt, tso_sqe = 0;
 	int sq_num, qentry;
 	struct queue_set *qs;
 	struct snd_queue *sq;
@@ -1131,6 +1175,7 @@ int nicvf_sq_append_skb(struct nicvf *nic, struct sk_buff *skb)
 	/* Add SQ header subdesc */
 	nicvf_sq_add_hdr_subdesc(nic, sq, qentry, subdesc_cnt - 1,
 				 skb, skb->len);
+	tso_sqe = qentry;
 
 	/* Add SQ gather subdescs */
 	qentry = nicvf_get_nxt_sqentry(sq, qentry);
@@ -1154,6 +1199,11 @@ int nicvf_sq_append_skb(struct nicvf *nic, struct sk_buff *skb)
 	}
 
 doorbell:
+	if (nic->t88 && skb_shinfo(skb)->gso_size) {
+		qentry = nicvf_get_nxt_sqentry(sq, qentry);
+		nicvf_sq_add_cqe_subdesc(sq, qentry, tso_sqe, skb);
+	}
+
 	/* make sure all memory stores are done before ringing doorbell */
 	smp_wmb();