datapath-windows: Refactor sofware offloads and mss

The purpose of this patch is to refactor the software offloads found in
the VXLAN and GRE code and also to refactor how the maximmum segment
size for a given NBL is obtained.

This patch introduces two functions OvsApplySWChecksumOnNB and OVSGetTcpMSS.

OVSGetTcpMSS - will return the mss found in a given NBL.

OvsApplySWChecksumOnNB - will compute and set software offloads for a given
                         NBL.

Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Acked-by: Sorin Vinturis <svinturis at cloudbasesolutions.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

11 files changed, 189 insertions, 214 deletions

diff --git a/datapath-windows/automake.mk b/datapath-windows/automake.mk
index fd2221850..f29f548a2 100644
--- a/datapath-windows/automake.mk
+++ b/datapath-windows/automake.mk
@@ -12,8 +12,6 @@ EXTRA_DIST += \
 	datapath-windows/ovsext/Atomic.h \
 	datapath-windows/ovsext/BufferMgmt.c \
 	datapath-windows/ovsext/BufferMgmt.h \
-	datapath-windows/ovsext/Checksum.c \
-	datapath-windows/ovsext/Checksum.h \
 	datapath-windows/ovsext/Datapath.c \
 	datapath-windows/ovsext/Datapath.h \
 	datapath-windows/ovsext/Debug.c \
@@ -39,6 +37,8 @@ EXTRA_DIST += \
 	datapath-windows/ovsext/Netlink/NetlinkBuf.h \
 	datapath-windows/ovsext/Netlink/NetlinkError.h \
 	datapath-windows/ovsext/Netlink/NetlinkProto.h \
+	datapath-windows/ovsext/Offload.c \
+	datapath-windows/ovsext/Offload.h \
 	datapath-windows/ovsext/Oid.c \
 	datapath-windows/ovsext/Oid.h \
 	datapath-windows/ovsext/PacketIO.c \
diff --git a/datapath-windows/ovsext/Actions.c b/datapath-windows/ovsext/Actions.c
index 8e41b7455..5a045419d 100644
--- a/datapath-windows/ovsext/Actions.c
+++ b/datapath-windows/ovsext/Actions.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,12 +16,13 @@
 
 #include "precomp.h"
 
-#include "Checksum.h"
+#include "Debug.h"
 #include "Event.h"
 #include "Flow.h"
 #include "Gre.h"
 #include "Mpls.h"
 #include "NetProto.h"
+#include "Offload.h"
 #include "PacketIO.h"
 #include "Stt.h"
 #include "Switch.h"
@@ -33,7 +34,6 @@
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_ACTION
-#include "Debug.h"
 
 typedef struct _OVS_ACTION_STATS {
     UINT64 rxGre;
diff --git a/datapath-windows/ovsext/BufferMgmt.c b/datapath-windows/ovsext/BufferMgmt.c
index 7ec073b70..3189e9b61 100644
--- a/datapath-windows/ovsext/BufferMgmt.c
+++ b/datapath-windows/ovsext/BufferMgmt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -77,18 +77,19 @@
  */
 
 #include "precomp.h"
+#include "Debug.h"
+#include "Flow.h"
+#include "Offload.h"
+#include "NetProto.h"
+#include "PacketParser.h"
 #include "Switch.h"
+#include "Vport.h"
 
 #ifdef OVS_DBG_MOD
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_BUFMGMT
-#include "Debug.h"
-#include "NetProto.h"
-#include "Flow.h"
-#include "Checksum.h"
-#include "PacketParser.h"
-#include "Vport.h"
+
 
 /*
  * --------------------------------------------------------------------------
diff --git a/datapath-windows/ovsext/BufferMgmt.h b/datapath-windows/ovsext/BufferMgmt.h
index 79abc3d9d..11a05b2c5 100644
--- a/datapath-windows/ovsext/BufferMgmt.h
+++ b/datapath-windows/ovsext/BufferMgmt.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,7 +63,6 @@ typedef union _OVS_BUFFER_CONTEXT {
     UINT64 value[MEM_ALIGN_SIZE(16) >> 3];
 } OVS_BUFFER_CONTEXT, *POVS_BUFFER_CONTEXT;
 
-
 typedef struct _OVS_NBL_POOL {
     NDIS_SWITCH_CONTEXT ndisContext;
     NDIS_HANDLE   ndisHandle;
@@ -83,11 +82,13 @@ typedef struct _OVS_NBL_POOL {
 
 
 NDIS_STATUS OvsInitBufferPool(PVOID context);
+
 VOID OvsCleanupBufferPool(PVOID context);
 
 PNET_BUFFER_LIST OvsAllocateFixSizeNBL(PVOID context,
                                        UINT32 size,
                                        UINT32 headRoom);
+
 PNET_BUFFER_LIST OvsAllocateVariableSizeNBL(PVOID context,
                                             UINT32 size,
                                             UINT32 headRoom);
@@ -106,20 +107,27 @@ PNET_BUFFER_LIST OvsPartialCopyToMultipleNBLs(PVOID context,
                                               UINT32 copySize,
                                               UINT32 headRoom,
                                               BOOLEAN copyNblInfo);
+
 PNET_BUFFER_LIST OvsFullCopyNBL(PVOID context, PNET_BUFFER_LIST nbl,
                                 UINT32 headRoom, BOOLEAN copyNblInfo);
+
 PNET_BUFFER_LIST OvsTcpSegmentNBL(PVOID context,
                                   PNET_BUFFER_LIST nbl,
                                   POVS_PACKET_HDR_INFO hdrInfo,
                                   UINT32 MSS,
                                   UINT32 headRoom);
+
 PNET_BUFFER_LIST OvsAllocateNBLFromBuffer(PVOID context,
                                           PVOID buffer,
                                           ULONG length);
-PNET_BUFFER_LIST OvsFullCopyToMultipleNBLs(PVOID context,
-    PNET_BUFFER_LIST nbl, UINT32 headRoom, BOOLEAN copyNblInfo);
+
+PNET_BUFFER_LIST OvsFullCopyToMultipleNBLs(PVOID context, PNET_BUFFER_LIST nbl,
+                                           UINT32 headRoom,
+                                           BOOLEAN copyNblInfo);
+
 PNET_BUFFER_LIST OvsCompleteNBL(PVOID context, PNET_BUFFER_LIST nbl,
                                 BOOLEAN updateRef);
+
 NDIS_STATUS OvsSetCtxSourcePortNo(PNET_BUFFER_LIST nbl, UINT32 portNo);
 
 NDIS_STATUS OvsGetCtxSourcePortNo(PNET_BUFFER_LIST nbl, UINT32 *portNo);
diff --git a/datapath-windows/ovsext/Gre.c b/datapath-windows/ovsext/Gre.c
index 5abd4a43e..cb4159379 100644
--- a/datapath-windows/ovsext/Gre.c
+++ b/datapath-windows/ovsext/Gre.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Cloudbase Solutions Srl
+ * Copyright (c) 2015, 2016 Cloudbase Solutions Srl
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,11 +17,12 @@
 #include "precomp.h"
 
 #include "Atomic.h"
-#include "Checksum.h"
+#include "Debug.h"
 #include "Flow.h"
 #include "Gre.h"
 #include "IpHelper.h"
 #include "NetProto.h"
+#include "Offload.h"
 #include "PacketIO.h"
 #include "PacketParser.h"
 #include "Switch.h"
@@ -33,7 +34,6 @@
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_GRE
-#include "Debug.h"
 
 static NDIS_STATUS
 OvsDoEncapGre(POVS_VPORT_ENTRY vport, PNET_BUFFER_LIST curNbl,
@@ -147,21 +147,8 @@ OvsDoEncapGre(POVS_VPORT_ENTRY vport,
     packetLength = NET_BUFFER_DATA_LENGTH(curNb);
 
     if (layers->isTcp) {
-        NDIS_TCP_LARGE_SEND_OFFLOAD_NET_BUFFER_LIST_INFO tsoInfo;
-
-        tsoInfo.Value = NET_BUFFER_LIST_INFO(curNbl,
-                                             TcpLargeSendNetBufferListInfo);
-        switch (tsoInfo.Transmit.Type) {
-            case NDIS_TCP_LARGE_SEND_OFFLOAD_V1_TYPE:
-                mss = tsoInfo.LsoV1Transmit.MSS;
-                break;
-            case NDIS_TCP_LARGE_SEND_OFFLOAD_V2_TYPE:
-                mss = tsoInfo.LsoV2Transmit.MSS;
-                break;
-            default:
-                OVS_LOG_ERROR("Unknown LSO transmit type:%d",
-                              tsoInfo.Transmit.Type);
-        }
+        mss = OVSGetTcpMSS(curNbl);
+
         OVS_LOG_TRACE("MSS %u packet len %u", mss,
                       packetLength);
         if (mss) {
@@ -188,71 +175,15 @@ OvsDoEncapGre(POVS_VPORT_ENTRY vport,
             OVS_LOG_ERROR("Unable to copy NBL");
             return NDIS_STATUS_FAILURE;
         }
-        /*
-         * To this point we do not have GRE hardware offloading.
-         * Apply defined checksums
-         */
-        curNb = NET_BUFFER_LIST_FIRST_NB(*newNbl);
-        curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
-                                                           LowPagePriority);
-        if (!bufferStart) {
-            status = NDIS_STATUS_RESOURCES;
-            goto ret_error;
-        }
 
         NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO csumInfo;
         csumInfo.Value = NET_BUFFER_LIST_INFO(curNbl,
                                               TcpIpChecksumNetBufferListInfo);
 
-        bufferStart += NET_BUFFER_CURRENT_MDL_OFFSET(curNb);
-
-        if (layers->isIPv4) {
-            IPHdr *ip = (IPHdr *)(bufferStart + layers->l3Offset);
-
-            if (csumInfo.Transmit.IpHeaderChecksum) {
-                ip->check = 0;
-                ip->check = IPChecksum((UINT8 *)ip, 4 * ip->ihl, 0);
-            }
-
-            if (layers->isTcp && csumInfo.Transmit.TcpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                TCPHdr *tcp = (TCPHdr *)(bufferStart + layers->l4Offset);
-                tcp->check = IPPseudoChecksum(&ip->saddr, &ip->daddr,
-                                              IPPROTO_TCP, csumLength);
-                tcp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            } else if (layers->isUdp && csumInfo.Transmit.UdpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                UDPHdr *udp = (UDPHdr *)((PCHAR)ip + sizeof *ip);
-                udp->check = IPPseudoChecksum(&ip->saddr, &ip->daddr,
-                                              IPPROTO_UDP, csumLength);
-                udp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            }
-        } else if (layers->isIPv6) {
-            IPv6Hdr *ip = (IPv6Hdr *)(bufferStart + layers->l3Offset);
-
-            if (layers->isTcp && csumInfo.Transmit.TcpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                TCPHdr *tcp = (TCPHdr *)(bufferStart + layers->l4Offset);
-                tcp->check = IPv6PseudoChecksum((UINT32 *) &ip->saddr,
-                                                (UINT32 *) &ip->daddr,
-                                                IPPROTO_TCP, csumLength);
-                tcp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            } else if (layers->isUdp && csumInfo.Transmit.UdpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                UDPHdr *udp = (UDPHdr *)((PCHAR)ip + sizeof *ip);
-                udp->check = IPv6PseudoChecksum((UINT32 *) &ip->saddr,
-                                                (UINT32 *) &ip->daddr,
-                                                IPPROTO_UDP, csumLength);
-                udp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            }
+        status = OvsApplySWChecksumOnNB(layers, *newNbl, &csumInfo);
+        if (status != NDIS_STATUS_SUCCESS) {
+            goto ret_error;
         }
-        /* Clear out TcpIpChecksumNetBufferListInfo flag */
-        NET_BUFFER_LIST_INFO(*newNbl, TcpIpChecksumNetBufferListInfo) = 0;
     }
 
     curNbl = *newNbl;
diff --git a/datapath-windows/ovsext/Checksum.c b/datapath-windows/ovsext/Offload.c
index 5d9b035e2..1e43a9e71 100644
--- a/datapath-windows/ovsext/Checksum.c
+++ b/datapath-windows/ovsext/Offload.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,15 +15,15 @@
  */
 
 #include "precomp.h"
-#include "Checksum.h"
+#include "Debug.h"
 #include "Flow.h"
+#include "Offload.h"
+#include "PacketParser.h"
 
 #ifdef OVS_DBG_MOD
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_CHECKSUM
-#include "Debug.h"
-#include "PacketParser.h"
 
 #ifndef htons
 #define htons(_x) (((UINT16)(_x) >> 8) + (((UINT16)(_x) << 8) & 0xff00))
@@ -594,3 +594,110 @@ OvsValidateUDPChecksum(PNET_BUFFER_LIST curNbl, BOOLEAN udpCsumZero)
 
     return NDIS_STATUS_SUCCESS;
 }
+
+
+/*
+ * OvsApplySWChecksumOnNB --
+ *
+ * This function calculates and sets the required sofware offloads given by
+ * csumInfo for a given NBL(nbl) with a single NB.
+ *
+ */
+NDIS_STATUS
+OvsApplySWChecksumOnNB(POVS_PACKET_HDR_INFO layers,
+                       PNET_BUFFER_LIST nbl,
+                       PNDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO csumInfo)
+{
+    PNET_BUFFER curNb;
+    PMDL curMdl;
+    PUINT8 bufferStart;
+    UINT32 packetLength = 0;
+    ASSERT(nbl != NULL);
+
+    curNb = NET_BUFFER_LIST_FIRST_NB(nbl);
+    ASSERT(curNb->Next == NULL);
+    packetLength = NET_BUFFER_DATA_LENGTH(curNb);
+    curMdl = NET_BUFFER_CURRENT_MDL(curNb);
+    bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl,
+                                                       LowPagePriority);
+    if (!bufferStart) {
+        return NDIS_STATUS_RESOURCES;
+    }
+
+    bufferStart += NET_BUFFER_CURRENT_MDL_OFFSET(curNb);
+
+    if (layers->isIPv4) {
+        IPHdr *ip = (IPHdr *)(bufferStart + layers->l3Offset);
+
+        if (csumInfo->Transmit.IpHeaderChecksum) {
+            ip->check = 0;
+            ip->check = IPChecksum((UINT8 *)ip, 4 * ip->ihl, 0);
+        }
+
+        if (layers->isTcp && csumInfo->Transmit.TcpChecksum) {
+            UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
+            TCPHdr *tcp = (TCPHdr *)(bufferStart + layers->l4Offset);
+            tcp->check = IPPseudoChecksum(&ip->saddr, &ip->daddr,
+                                          IPPROTO_TCP, csumLength);
+            tcp->check = CalculateChecksumNB(curNb, csumLength,
+                                             (UINT32)(layers->l4Offset));
+        } else if (layers->isUdp && csumInfo->Transmit.UdpChecksum) {
+            UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
+            UDPHdr *udp = (UDPHdr *)((PCHAR)ip + sizeof *ip);
+            udp->check = IPPseudoChecksum(&ip->saddr, &ip->daddr,
+                                          IPPROTO_UDP, csumLength);
+            udp->check = CalculateChecksumNB(curNb, csumLength,
+                                             (UINT32)(layers->l4Offset));
+        }
+    } else if (layers->isIPv6) {
+        IPv6Hdr *ip = (IPv6Hdr *)(bufferStart + layers->l3Offset);
+
+        if (layers->isTcp && csumInfo->Transmit.TcpChecksum) {
+            UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
+            TCPHdr *tcp = (TCPHdr *)(bufferStart + layers->l4Offset);
+            tcp->check = IPv6PseudoChecksum((UINT32 *) &ip->saddr,
+                                            (UINT32 *) &ip->daddr,
+                                            IPPROTO_TCP, csumLength);
+            tcp->check = CalculateChecksumNB(curNb, csumLength,
+                                             (UINT32)(layers->l4Offset));
+        } else if (layers->isUdp && csumInfo->Transmit.UdpChecksum) {
+            UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
+            UDPHdr *udp = (UDPHdr *)((PCHAR)ip + sizeof *ip);
+            udp->check = IPv6PseudoChecksum((UINT32 *) &ip->saddr,
+                                            (UINT32 *) &ip->daddr,
+                                            IPPROTO_UDP, csumLength);
+            udp->check = CalculateChecksumNB(curNb, csumLength,
+                                             (UINT32)(layers->l4Offset));
+        }
+    }
+
+    return NDIS_STATUS_SUCCESS;
+}
+
+/*
+ * OVSGetTcpMSS --
+ *
+ * This function returns the maximum segment size of the given NBL. It takes
+ * into consideration both LSO v1 and v2.
+ */
+ULONG
+OVSGetTcpMSS(PNET_BUFFER_LIST nbl)
+{
+    NDIS_TCP_LARGE_SEND_OFFLOAD_NET_BUFFER_LIST_INFO lsoInfo;
+    ASSERT(nbl != NULL);
+
+    lsoInfo.Value = NET_BUFFER_LIST_INFO(nbl,
+                                         TcpLargeSendNetBufferListInfo);
+    switch (lsoInfo.Transmit.Type) {
+        case NDIS_TCP_LARGE_SEND_OFFLOAD_V1_TYPE:
+            return lsoInfo.LsoV1Transmit.MSS;
+            break;
+        case NDIS_TCP_LARGE_SEND_OFFLOAD_V2_TYPE:
+            return lsoInfo.LsoV2Transmit.MSS;
+            break;
+        default:
+            OVS_LOG_ERROR("Unknown LSO transmit type:%d",
+                          lsoInfo.Transmit.Type);
+            return 0;
+    }
+}
diff --git a/datapath-windows/ovsext/Checksum.h b/datapath-windows/ovsext/Offload.h
index 2378a324a..b5cae2f2c 100644
--- a/datapath-windows/ovsext/Checksum.h
+++ b/datapath-windows/ovsext/Offload.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef __CHECKSUM_H_
-#define __CHECKSUM_H_ 1
+#ifndef __OFFLOAD_H_
+#define __OFFLOAD_H_ 1
 
 typedef union _OVS_PACKET_HDR_INFO *POVS_PACKET_HDR_INFO;
 
@@ -36,4 +36,12 @@ NDIS_STATUS OvsValidateIPChecksum(PNET_BUFFER_LIST curNbl,
 NDIS_STATUS OvsValidateUDPChecksum(PNET_BUFFER_LIST curNbl,
                                    BOOLEAN udpCsumZero);
 
-#endif /* __CHECKSUM_H_ */
+
+ULONG OVSGetTcpMSS(PNET_BUFFER_LIST nbl);
+
+NDIS_STATUS OvsApplySWChecksumOnNB(POVS_PACKET_HDR_INFO layers,
+                                   PNET_BUFFER_LIST nbl,
+                                   PNDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO
+                                                                     csumInfo);
+
+#endif /* __OFFLOAD_H_ */
diff --git a/datapath-windows/ovsext/Stt.c b/datapath-windows/ovsext/Stt.c
index 0ae263391..dd7bf9279 100644
--- a/datapath-windows/ovsext/Stt.c
+++ b/datapath-windows/ovsext/Stt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 VMware, Inc.
+ * Copyright (c) 2015, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,10 +17,12 @@
 #include "precomp.h"
 
 #include "Atomic.h"
-#include "Checksum.h"
+#include "Debug.h"
 #include "Flow.h"
 #include "IpHelper.h"
+#include "Jhash.h"
 #include "NetProto.h"
+#include "Offload.h"
 #include "PacketIO.h"
 #include "PacketParser.h"
 #include "Stt.h"
@@ -33,8 +35,7 @@
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_STT
-#include "Debug.h"
-#include "Jhash.h"
+
 
 KSTART_ROUTINE OvsSttDefragCleaner;
 static PLIST_ENTRY OvsSttPktFragHash;
@@ -163,20 +164,7 @@ OvsDoEncapStt(POVS_VPORT_ENTRY vport,
     BOOLEAN innerPartialChecksum = FALSE;
 
     if (layers->isTcp) {
-        lsoInfo.Value = NET_BUFFER_LIST_INFO(curNbl,
-                TcpLargeSendNetBufferListInfo);
-
-        switch (lsoInfo.Transmit.Type) {
-            case NDIS_TCP_LARGE_SEND_OFFLOAD_V1_TYPE:
-                mss = lsoInfo.LsoV1Transmit.MSS;
-                break;
-            case NDIS_TCP_LARGE_SEND_OFFLOAD_V2_TYPE:
-                mss = lsoInfo.LsoV2Transmit.MSS;
-                break;
-            default:
-                OVS_LOG_ERROR("Unknown LSO transmit type:%d",
-                              lsoInfo.Transmit.Type);
-        }
+        mss = OVSGetTcpMSS(curNbl);
     }
 
     vportStt = (POVS_STT_VPORT) GetOvsVportPriv(vport);
diff --git a/datapath-windows/ovsext/User.c b/datapath-windows/ovsext/User.c
index 04d22949e..e97f2b2b6 100644
--- a/datapath-windows/ovsext/User.c
+++ b/datapath-windows/ovsext/User.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,23 +22,23 @@
 
 #include "precomp.h"
 
-#include "Switch.h"
-#include "Vport.h"
-#include "Event.h"
-#include "User.h"
 #include "Datapath.h"
-#include "PacketIO.h"
-#include "Checksum.h"
-#include "NetProto.h"
+#include "Debug.h"
+#include "Event.h"
 #include "Flow.h"
-#include "TunnelIntf.h"
 #include "Jhash.h"
+#include "NetProto.h"
+#include "Offload.h"
+#include "PacketIO.h"
+#include "Switch.h"
+#include "TunnelIntf.h"
+#include "User.h"
+#include "Vport.h"
 
 #ifdef OVS_DBG_MOD
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_USER
-#include "Debug.h"
 
 POVS_PACKET_QUEUE_ELEM OvsGetNextPacket(POVS_OPEN_INSTANCE instance);
 extern PNDIS_SPIN_LOCK gOvsCtrlLock;
diff --git a/datapath-windows/ovsext/Vxlan.c b/datapath-windows/ovsext/Vxlan.c
index 2516ece35..b89c03209 100644
--- a/datapath-windows/ovsext/Vxlan.c
+++ b/datapath-windows/ovsext/Vxlan.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 VMware, Inc.
+ * Copyright (c) 2014, 2016 VMware, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,18 +15,20 @@
  */
 
 #include "precomp.h"
+
 #include "Atomic.h"
-#include "NetProto.h"
-#include "Switch.h"
-#include "Vport.h"
+#include "Debug.h"
+#include "Flow.h"
 #include "Flow.h"
-#include "Vxlan.h"
 #include "IpHelper.h"
-#include "Checksum.h"
-#include "User.h"
+#include "NetProto.h"
+#include "Offload.h"
 #include "PacketIO.h"
-#include "Flow.h"
 #include "PacketParser.h"
+#include "Switch.h"
+#include "User.h"
+#include "Vport.h"
+#include "Vxlan.h"
 
 #pragma warning( push )
 #pragma warning( disable:4127 )
@@ -36,7 +38,6 @@
 #undef OVS_DBG_MOD
 #endif
 #define OVS_DBG_MOD OVS_DBG_VXLAN
-#include "Debug.h"
 
 /* Helper macro to check if a VXLAN ID is valid. */
 #define VXLAN_ID_IS_VALID(vxlanID) (0 < (vxlanID) && (vxlanID) <= 0xffffff)
@@ -201,21 +202,8 @@ OvsDoEncapVxlan(POVS_VPORT_ENTRY vport,
     packetLength = NET_BUFFER_DATA_LENGTH(curNb);
 
     if (layers->isTcp) {
-        NDIS_TCP_LARGE_SEND_OFFLOAD_NET_BUFFER_LIST_INFO tsoInfo;
-
-        tsoInfo.Value = NET_BUFFER_LIST_INFO(curNbl,
-                                             TcpLargeSendNetBufferListInfo);
-        switch (tsoInfo.Transmit.Type) {
-            case NDIS_TCP_LARGE_SEND_OFFLOAD_V1_TYPE:
-                mss = tsoInfo.LsoV1Transmit.MSS;
-                break;
-            case NDIS_TCP_LARGE_SEND_OFFLOAD_V2_TYPE:
-                mss = tsoInfo.LsoV2Transmit.MSS;
-                break;
-            default:
-                OVS_LOG_ERROR("Unknown LSO transmit type:%d",
-                              tsoInfo.Transmit.Type);
-        }
+        mss = OVSGetTcpMSS(curNbl);
+
         OVS_LOG_TRACE("MSS %u packet len %u", mss,
                       packetLength);
         if (mss) {
@@ -242,70 +230,14 @@ OvsDoEncapVxlan(POVS_VPORT_ENTRY vport,
             OVS_LOG_ERROR("Unable to copy NBL");
             return NDIS_STATUS_FAILURE;
         }
-        /*
-         * To this point we do not have VXLAN offloading.
-         * Apply defined checksums
-         */
-        curNb = NET_BUFFER_LIST_FIRST_NB(*newNbl);
-        curMdl = NET_BUFFER_CURRENT_MDL(curNb);
-        bufferStart = (PUINT8)MmGetSystemAddressForMdlSafe(curMdl, LowPagePriority);
-        if (!bufferStart) {
-            status = NDIS_STATUS_RESOURCES;
-            goto ret_error;
-        }
-
         NDIS_TCP_IP_CHECKSUM_NET_BUFFER_LIST_INFO csumInfo;
         csumInfo.Value = NET_BUFFER_LIST_INFO(curNbl,
                                               TcpIpChecksumNetBufferListInfo);
+        status = OvsApplySWChecksumOnNB(layers, *newNbl, &csumInfo);
 
-        bufferStart += NET_BUFFER_CURRENT_MDL_OFFSET(curNb);
-
-        if (layers->isIPv4) {
-            IPHdr *ip = (IPHdr *)(bufferStart + layers->l3Offset);
-
-            if (csumInfo.Transmit.IpHeaderChecksum) {
-                ip->check = 0;
-                ip->check = IPChecksum((UINT8 *)ip, 4 * ip->ihl, 0);
-            }
-
-            if (layers->isTcp && csumInfo.Transmit.TcpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                TCPHdr *tcp = (TCPHdr *)(bufferStart + layers->l4Offset);
-                tcp->check = IPPseudoChecksum(&ip->saddr, &ip->daddr,
-                                              IPPROTO_TCP, csumLength);
-                tcp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            } else if (layers->isUdp && csumInfo.Transmit.UdpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                UDPHdr *udp = (UDPHdr *)((PCHAR)ip + sizeof *ip);
-                udp->check = IPPseudoChecksum(&ip->saddr, &ip->daddr,
-                                              IPPROTO_UDP, csumLength);
-                udp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            }
-        } else if (layers->isIPv6) {
-            IPv6Hdr *ip = (IPv6Hdr *)(bufferStart + layers->l3Offset);
-
-            if (layers->isTcp && csumInfo.Transmit.TcpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                TCPHdr *tcp = (TCPHdr *)(bufferStart + layers->l4Offset);
-                tcp->check = IPv6PseudoChecksum((UINT32 *) &ip->saddr,
-                                                (UINT32 *) &ip->daddr,
-                                                IPPROTO_TCP, csumLength);
-                tcp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            } else if (layers->isUdp && csumInfo.Transmit.UdpChecksum) {
-                UINT16 csumLength = (UINT16)(packetLength - layers->l4Offset);
-                UDPHdr *udp = (UDPHdr *)((PCHAR)ip + sizeof *ip);
-                udp->check = IPv6PseudoChecksum((UINT32 *) &ip->saddr,
-                                                (UINT32 *) &ip->daddr,
-                                                IPPROTO_UDP, csumLength);
-                udp->check = CalculateChecksumNB(curNb, csumLength,
-                                                 (UINT32)(layers->l4Offset));
-            }
+        if (status != NDIS_STATUS_SUCCESS) {
+            goto ret_error;
         }
-        /* Clear out TcpIpChecksumNetBufferListInfo flag */
-        NET_BUFFER_LIST_INFO(*newNbl, TcpIpChecksumNetBufferListInfo) = 0;
     }
 
     curNbl = *newNbl;
diff --git a/datapath-windows/ovsext/ovsext.vcxproj b/datapath-windows/ovsext/ovsext.vcxproj
index fd10809dd..7b0ebcfaf 100644
--- a/datapath-windows/ovsext/ovsext.vcxproj
+++ b/datapath-windows/ovsext/ovsext.vcxproj
@@ -73,7 +73,6 @@
     <ClInclude Include="..\include\OvsDpInterfaceExt.h" />
     <ClInclude Include="Atomic.h" />
     <ClInclude Include="BufferMgmt.h" />
-    <ClInclude Include="Checksum.h" />
     <ClInclude Include="Datapath.h" />
     <ClInclude Include="Debug.h" />
     <ClInclude Include="DpInternal.h" />
@@ -89,6 +88,7 @@
     <ClInclude Include="Netlink/NetlinkProto.h" />
     <ClInclude Include="Netlink\NetlinkError.h" />
     <ClInclude Include="NetProto.h" />
+    <ClInclude Include="Offload.h" />
     <ClInclude Include="Oid.h" />
     <ClInclude Include="PacketIO.h" />
     <ClInclude Include="PacketParser.h" />
@@ -169,7 +169,6 @@
   <ItemGroup>
     <ClCompile Include="Actions.c" />
     <ClCompile Include="BufferMgmt.c" />
-    <ClCompile Include="Checksum.c" />
     <ClCompile Include="Debug.c" />
     <ClCompile Include="Driver.c" />
     <ClCompile Include="Event.c" />
@@ -180,6 +179,7 @@
     <ClCompile Include="Netlink/Netlink.c" />
     <ClCompile Include="Netlink/NetlinkBuf.c" />
     <ClCompile Include="Datapath.c" />
+    <ClCompile Include="Offload.c" />
     <ClCompile Include="Oid.c" />
     <ClCompile Include="PacketIO.c" />
     <ClCompile Include="PacketParser.c" />