Octeontx2-vf: Fix max packet length errors

Once driver submits the packets to the hardware, each packet
traverse through multiple transmit levels in the following
order:
	SMQ -> TL4 -> TL3 -> TL2 -> TL1

The SMQ supports configurable minimum and maximum packet sizes.
It enters to a hang state, if driver submits packets with
out of bound lengths.

To avoid the same, implement packet length validation before
submitting packets to the hardware. Increment tx_dropped counter
on failure.

Fixes: 3184fb5 ("octeontx2-vf: Virtual function driver support")
Fixes: 22f8587 ("octeontx2-pf: Add basic net_device_ops")
Fixes: 3ca6c4c ("octeontx2-pf: Add packet transmission support")
Signed-off-by: Hariprasad Kelam <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Hariprasad Kelam

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c

@@ -124,7 +124,9 @@ void otx2_get_dev_stats(struct otx2_nic *pfvf)
 			       dev_stats->rx_ucast_frames;
 
 	dev_stats->tx_bytes = OTX2_GET_TX_STATS(TX_OCTS);
-	dev_stats->tx_drops = OTX2_GET_TX_STATS(TX_DROP);
+	dev_stats->tx_drops = OTX2_GET_TX_STATS(TX_DROP) +
+			       (unsigned long)atomic_long_read(&dev_stats->tx_discards);
+
 	dev_stats->tx_bcast_frames = OTX2_GET_TX_STATS(TX_BCAST);
 	dev_stats->tx_mcast_frames = OTX2_GET_TX_STATS(TX_MCAST);
 	dev_stats->tx_ucast_frames = OTX2_GET_TX_STATS(TX_UCAST);

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h

@@ -153,6 +153,7 @@ struct otx2_dev_stats {
 	u64 tx_bcast_frames;
 	u64 tx_mcast_frames;
 	u64 tx_drops;
+	atomic_long_t tx_discards;
 };
 
 /* Driver counted stats */

drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c

@@ -2220,6 +2220,7 @@ static netdev_tx_t otx2_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct otx2_nic *pf = netdev_priv(netdev);
 	int qidx = skb_get_queue_mapping(skb);
+	struct otx2_dev_stats *dev_stats;
 	struct otx2_snd_queue *sq;
 	struct netdev_queue *txq;
 	int sq_idx;
@@ -2232,6 +2233,8 @@ static netdev_tx_t otx2_xmit(struct sk_buff *skb, struct net_device *netdev)
 	/* Check for minimum and maximum packet length */
 	if (skb->len <= ETH_HLEN ||
 	    (!skb_shinfo(skb)->gso_size && skb->len > pf->tx_max_pktlen)) {
+		dev_stats = &pf->hw.dev_stats;
+		atomic_long_inc(&dev_stats->tx_discards);
 		dev_kfree_skb(skb);
 		return NETDEV_TX_OK;
 	}

drivers/net/ethernet/marvell/octeontx2/nic/otx2_vf.c

@@ -417,9 +417,19 @@ static netdev_tx_t otx2vf_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct otx2_nic *vf = netdev_priv(netdev);
 	int qidx = skb_get_queue_mapping(skb);
+	struct otx2_dev_stats *dev_stats;
 	struct otx2_snd_queue *sq;
 	struct netdev_queue *txq;
 
+	/* Check for minimum and maximum packet length */
+	if (skb->len <= ETH_HLEN ||
+	    (!skb_shinfo(skb)->gso_size && skb->len > vf->tx_max_pktlen)) {
+		dev_stats = &vf->hw.dev_stats;
+		atomic_long_inc(&dev_stats->tx_discards);
+		dev_kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+
 	sq = &vf->qset.sq[qidx];
 	txq = netdev_get_tx_queue(netdev, qidx);
 

drivers/net/ethernet/marvell/octeontx2/nic/rep.c

@@ -371,7 +371,8 @@ static void rvu_rep_get_stats(struct work_struct *work)
 	stats->rx_mcast_frames = rsp->rx.mcast;
 	stats->tx_bytes = rsp->tx.octs;
 	stats->tx_frames = rsp->tx.ucast + rsp->tx.bcast + rsp->tx.mcast;
-	stats->tx_drops = rsp->tx.drop;
+	stats->tx_drops = rsp->tx.drop +
+			  (unsigned long)atomic_long_read(&stats->tx_discards);
 exit:
 	mutex_unlock(&priv->mbox.lock);
 }
@@ -418,6 +419,16 @@ static netdev_tx_t rvu_rep_xmit(struct sk_buff *skb, struct net_device *dev)
 	struct otx2_nic *pf = rep->mdev;
 	struct otx2_snd_queue *sq;
 	struct netdev_queue *txq;
+	struct rep_stats *stats;
+
+	/* Check for minimum and maximum packet length */
+	if (skb->len <= ETH_HLEN ||
+	    (!skb_shinfo(skb)->gso_size && skb->len > pf->tx_max_pktlen)) {
+		stats = &rep->stats;
+		atomic_long_inc(&stats->tx_discards);
+		dev_kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
 
 	sq = &pf->qset.sq[rep->rep_id];
 	txq = netdev_get_tx_queue(dev, 0);

drivers/net/ethernet/marvell/octeontx2/nic/rep.h

@@ -27,6 +27,7 @@ struct rep_stats {
 	u64 tx_bytes;
 	u64 tx_frames;
 	u64 tx_drops;
+	atomic_long_t tx_discards;
 };
 
 struct rep_dev {