r8169: support IPv6

Support the IPv6 hw checksum for RTL8111C and later chips. Note
that the hw has the limitation for the transport offset. The
checksum must be calculated by sw, when the transport offset is
out of the range which the hw accepts.
Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -27,6 +27,8 @@
 #include <linux/firmware.h>
 #include <linux/pci-aspm.h>
 #include <linux/prefetch.h>
+#include <linux/ipv6.h>
+#include <net/ip6_checksum.h>
 
 #include <asm/io.h>
 #include <asm/irq.h>
@@ -628,11 +630,16 @@ enum rtl_tx_desc_bit_0 {
 enum rtl_tx_desc_bit_1 {
 	/* First doubleword. */
 	TD1_GTSENV4	= (1 << 26),		/* Giant Send for IPv4 */
+	TD1_GTSENV6	= (1 << 25),		/* Giant Send for IPv6 */
 #define GTTCPHO_SHIFT			18
+#define GTTCPHO_MAX			0x7fU
 
 	/* Second doubleword. */
+#define TCPHO_SHIFT			18
+#define TCPHO_MAX			0x3ffU
 #define TD1_MSS_SHIFT			18	/* MSS position (11 bits) */
-	TD1_IP_CS	= (1 << 29),		/* Calculate IP checksum */
+	TD1_IPv6_CS	= (1 << 28),		/* Calculate IPv6 checksum */
+	TD1_IPv4_CS	= (1 << 29),		/* Calculate IPv4 checksum */
 	TD1_TCP_CS	= (1 << 30),		/* Calculate TCP/IP checksum */
 	TD1_UDP_CS	= (1 << 31),		/* Calculate UDP/IP checksum */
 };
@@ -5920,6 +5927,82 @@ static bool rtl_test_hw_pad_bug(struct rtl8169_private *tp, struct sk_buff *skb)
 	return skb->len < ETH_ZLEN && tp->mac_version == RTL_GIGA_MAC_VER_34;
 }
 
+static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
+				      struct net_device *dev);
+/* r8169_csum_workaround()
+ * The hw limites the value the transport offset. When the offset is out of the
+ * range, calculate the checksum by sw.
+ */
+static void r8169_csum_workaround(struct rtl8169_private *tp,
+				  struct sk_buff *skb)
+{
+	if (skb_shinfo(skb)->gso_size) {
+		netdev_features_t features = tp->dev->features;
+		struct sk_buff *segs, *nskb;
+
+		features &= ~(NETIF_F_SG | NETIF_F_IPV6_CSUM | NETIF_F_TSO6);
+		segs = skb_gso_segment(skb, features);
+		if (IS_ERR(segs) || !segs)
+			goto drop;
+
+		do {
+			nskb = segs;
+			segs = segs->next;
+			nskb->next = NULL;
+			rtl8169_start_xmit(nskb, tp->dev);
+		} while (segs);
+
+		dev_kfree_skb(skb);
+	} else if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		if (skb_checksum_help(skb) < 0)
+			goto drop;
+
+		rtl8169_start_xmit(skb, tp->dev);
+	} else {
+		struct net_device_stats *stats;
+
+drop:
+		stats = &tp->dev->stats;
+		stats->tx_dropped++;
+		dev_kfree_skb(skb);
+	}
+}
+
+/* msdn_giant_send_check()
+ * According to the document of microsoft, the TCP Pseudo Header excludes the
+ * packet length for IPv6 TCP large packets.
+ */
+static int msdn_giant_send_check(struct sk_buff *skb)
+{
+	const struct ipv6hdr *ipv6h;
+	struct tcphdr *th;
+	int ret;
+
+	ret = skb_cow_head(skb, 0);
+	if (ret)
+		return ret;
+
+	ipv6h = ipv6_hdr(skb);
+	th = tcp_hdr(skb);
+
+	th->check = 0;
+	th->check = ~tcp_v6_check(0, &ipv6h->saddr, &ipv6h->daddr, 0);
+
+	return ret;
+}
+
+static inline __be16 get_protocol(struct sk_buff *skb)
+{
+	__be16 protocol;
+
+	if (skb->protocol == htons(ETH_P_8021Q))
+		protocol = vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
+	else
+		protocol = skb->protocol;
+
+	return protocol;
+}
+
 static bool rtl8169_tso_csum_v1(struct rtl8169_private *tp,
 				struct sk_buff *skb, u32 *opts)
 {
@@ -5949,21 +6032,69 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private *tp,
 	u32 mss = skb_shinfo(skb)->gso_size;
 
 	if (mss) {
-		opts[0] |= TD1_GTSENV4;
+		if (transport_offset > GTTCPHO_MAX) {
+			netif_warn(tp, tx_err, tp->dev,
+				   "Invalid transport offset 0x%x for TSO\n",
+				   transport_offset);
+			return false;
+		}
+
+		switch (get_protocol(skb)) {
+		case htons(ETH_P_IP):
+			opts[0] |= TD1_GTSENV4;
+			break;
+
+		case htons(ETH_P_IPV6):
+			if (msdn_giant_send_check(skb))
+				return false;
+
+			opts[0] |= TD1_GTSENV6;
+			break;
+
+		default:
+			WARN_ON_ONCE(1);
+			break;
+		}
+
 		opts[0] |= transport_offset << GTTCPHO_SHIFT;
 		opts[1] |= min(mss, TD_MSS_MAX) << TD1_MSS_SHIFT;
 	} else if (skb->ip_summed == CHECKSUM_PARTIAL) {
-		const struct iphdr *ip = ip_hdr(skb);
+		u8 ip_protocol;
 
 		if (unlikely(rtl_test_hw_pad_bug(tp, skb)))
 			return skb_checksum_help(skb) == 0 && rtl_skb_pad(skb);
 
-		if (ip->protocol == IPPROTO_TCP)
-			opts[1] |= TD1_IP_CS | TD1_TCP_CS;
-		else if (ip->protocol == IPPROTO_UDP)
-			opts[1] |= TD1_IP_CS | TD1_UDP_CS;
+		if (transport_offset > TCPHO_MAX) {
+			netif_warn(tp, tx_err, tp->dev,
+				   "Invalid transport offset 0x%x\n",
+				   transport_offset);
+			return false;
+		}
+
+		switch (get_protocol(skb)) {
+		case htons(ETH_P_IP):
+			opts[1] |= TD1_IPv4_CS;
+			ip_protocol = ip_hdr(skb)->protocol;
+			break;
+
+		case htons(ETH_P_IPV6):
+			opts[1] |= TD1_IPv6_CS;
+			ip_protocol = ipv6_hdr(skb)->nexthdr;
+			break;
+
+		default:
+			ip_protocol = IPPROTO_RAW;
+			break;
+		}
+
+		if (ip_protocol == IPPROTO_TCP)
+			opts[1] |= TD1_TCP_CS;
+		else if (ip_protocol == IPPROTO_UDP)
+			opts[1] |= TD1_UDP_CS;
 		else
 			WARN_ON_ONCE(1);
+
+		opts[1] |= transport_offset << TCPHO_SHIFT;
 	} else {
 		if (unlikely(rtl_test_hw_pad_bug(tp, skb)))
 			return rtl_skb_pad(skb);
@@ -5996,8 +6127,10 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 	opts[1] = cpu_to_le32(rtl8169_tx_vlan_tag(skb));
 	opts[0] = DescOwn;
 
-	if (!tp->tso_csum(tp, skb, opts))
-		goto err_update_stats;
+	if (!tp->tso_csum(tp, skb, opts)) {
+		r8169_csum_workaround(tp, skb);
+		return NETDEV_TX_OK;
+	}
 
 	len = skb_headlen(skb);
 	mapping = dma_map_single(d, skb->data, len, DMA_TO_DEVICE);
@@ -6062,7 +6195,6 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 	rtl8169_unmap_tx_skb(d, tp->tx_skb + entry, txd);
 err_dma_0:
 	dev_kfree_skb_any(skb);
-err_update_stats:
 	dev->stats.tx_dropped++;
 	return NETDEV_TX_OK;
 
@@ -7149,9 +7281,10 @@ rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	if (tp->txd_version == RTL_TD_0)
 		tp->tso_csum = rtl8169_tso_csum_v1;
-	else if (tp->txd_version == RTL_TD_1)
+	else if (tp->txd_version == RTL_TD_1) {
 		tp->tso_csum = rtl8169_tso_csum_v2;
-	else
+		dev->hw_features |= NETIF_F_IPV6_CSUM | NETIF_F_TSO6;
+	} else
 		WARN_ON_ONCE(1);
 
 	dev->hw_features |= NETIF_F_RXALL;