vmxnet3: add geneve and vxlan tunnel offload support

Vmxnet3 version 3 device supports checksum/TSO offload. Thus, vNIC to
pNIC traffic can leverage hardware checksum/TSO offloads. However,
vmxnet3 does not support checksum/TSO offload for Geneve/VXLAN
encapsulated packets. Thus, for a vNIC configured with an overlay, the
guest stack must first segment the inner packet, compute the inner
checksum for each segment and encapsulate each segment before
transmitting the packet via the vNIC. This results in significant
performance penalty.

This patch will enhance vmxnet3 to support Geneve/VXLAN TSO as well as
checksum offload.

Signed-off-by: Ronak Doshi <doshir@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vmxnet3/vmxnet3_int.h

@@ -219,10 +219,16 @@ struct vmxnet3_tx_ctx {
 	bool   ipv4;
 	bool   ipv6;
 	u16 mss;
-	u32 eth_ip_hdr_size; /* only valid for pkts requesting tso or csum
-				 * offloading
+	u32    l4_offset;	/* only valid for pkts requesting tso or csum
+				 * offloading. For encap offload, it refers to
+				 * inner L4 offset i.e. it includes outer header
+				 * encap header and inner eth and ip header size
+				 */
+
+	u32	l4_hdr_size;	/* only valid if mss != 0
+				 * Refers to inner L4 hdr size for encap
+				 * offload
 				 */
-	u32 l4_hdr_size;     /* only valid if mss != 0 */
 	u32 copy_size;       /* # of bytes copied into the data ring */
 	union Vmxnet3_GenericDesc *sop_txd;
 	union Vmxnet3_GenericDesc *eop_txd;