Re: [net-next v4 07/16] i40e: Rx checksum offload for VXLAN

From: Joseph Gasparakis <redacted>

This implements receive offload for VXLAN for i40e.  The hardware
supports checksum offload/verification of the inner/outer header.

Change-Id: I450db300af6713f2044fef1191a0d1d294c13369
Signed-off-by: Joseph Gasparakis <redacted>
Signed-off-by: Jesse Brandeburg <redacted>
Signed-off-by: Jeff Kirsher <redacted>
---
 drivers/net/ethernet/intel/i40e/i40e.h      |  1 +
 drivers/net/ethernet/intel/i40e/i40e_txrx.c | 57 ++++++++++++++++++++++++++---
 drivers/net/ethernet/intel/i40e/i40e_type.h | 51 ++++++++++++++------------
 3 files changed, 81 insertions(+), 28 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 6f1edc1..34a54e7 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h

@@ -29,6 +29,7 @@
 #define _I40E_H_

 #include <net/tcp.h>
+#include <net/udp.h>
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/errno.h>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 01d0334..a978451 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -860,12 +860,25 @@ static void i40e_receive_skb(struct i40e_ring *rx_ring,
  * @skb: skb currently being received and modified
  * @rx_status: status value of last descriptor in packet
  * @rx_error: error value of last descriptor in packet
+ * @rx_ptype: ptype value of last descriptor in packet
  **/
 static inline void i40e_rx_checksum(struct i40e_vsi *vsi,
                                    struct sk_buff *skb,
                                    u32 rx_status,
-                                   u32 rx_error)
+                                   u32 rx_error,
+                                   u16 rx_ptype)
 {
+       bool ipv4_tunnel, ipv6_tunnel;
+       __wsum rx_udp_csum;
+       __sum16 csum;
+       struct iphdr *iph;
+
+       ipv4_tunnel = (rx_ptype > I40E_RX_PTYPE_GRENAT4_MAC_PAY3) &&
+                     (rx_ptype < I40E_RX_PTYPE_GRENAT4_MACVLAN_IPV6_ICMP_PAY4);
+       ipv6_tunnel = (rx_ptype > I40E_RX_PTYPE_GRENAT6_MAC_PAY3) &&
+                     (rx_ptype < I40E_RX_PTYPE_GRENAT6_MACVLAN_IPV6_ICMP_PAY4);
+
+       skb->encapsulation = ipv4_tunnel || ipv6_tunnel;
        skb->ip_summed = CHECKSUM_NONE;

        /* Rx csum enabled and ip headers found? */

@@ -873,13 +886,43 @@ static inline void i40e_rx_checksum(struct i40e_vsi *vsi,
              rx_status & (1 << I40E_RX_DESC_STATUS_L3L4P_SHIFT)))
                return;

-       /* IP or L4 checksum error */
+       /* IP or L4 or outmost IP checksum error */
        if (rx_error & ((1 << I40E_RX_DESC_ERROR_IPE_SHIFT) |
-                       (1 << I40E_RX_DESC_ERROR_L4E_SHIFT))) {
+                       (1 << I40E_RX_DESC_ERROR_L4E_SHIFT) |
+                       (1 << I40E_RX_DESC_ERROR_EIPE_SHIFT))) {
                vsi->back->hw_csum_rx_error++;
                return;
        }

+       if (ipv4_tunnel &&
+           !(rx_status & (1 << I40E_RX_DESC_STATUS_UDP_0_SHIFT))) {
+               /* If VXLAN traffic has an outer UDPv4 checksum we need to check
+                * it in the driver, hardware does not do it for us.
+                * Since L3L4P bit was set we assume a valid IHL value (>=5)
+                * so the total length of IPv4 header is IHL*4 bytes
+                */

+               skb->transport_header = skb->mac_header +
+                                       sizeof(struct ethhdr) +
+                                       (ip_hdr(skb)->ihl * 4);
+
+               /* Add 4 bytes for VLAN tagged packets */
+               skb->transport_header += (skb->protocol == htons(ETH_P_8021Q) ||
+                                         skb->protocol == htons(ETH_P_8021AD))
+                                         ? VLAN_HLEN : 0;
+
+               rx_udp_csum = udp_csum(skb);
+               iph = ip_hdr(skb);
+               csum = csum_tcpudp_magic(
+                               iph->saddr, iph->daddr,
+                               (skb->len - skb_transport_offset(skb)),
+                               IPPROTO_UDP, rx_udp_csum);
+
+               if (udp_hdr(skb)->check != csum) {
+                       vsi->back->hw_csum_rx_error++;
+                       return;
+               }
+       }
+
        skb->ip_summed = CHECKSUM_UNNECESSARY;
 }