ibmveth: Enable IPv6 checksum offload

This patch enables TCP checksum offload support for IPv6 on ibmveth.
This completely eliminates the generation and checking of the checksum
for IPv6 packets that are completely virtual and never touch a physical
network.  A basic TCPIPV6_STREAM netperf run showed a ~30% throughput
improvement when an MTU of 64000 was used.

This featured is enabled by default, as is the case for IPv4 checksum
offload.  When checksum offload is enabled the driver will negotiate
IPv4 and IPv6 offload with the firmware separately and enable what
is available.  As long as either IPv4 or IPv6 offload is supported
and enabled the device will report that checksum offload is enabled.
The device stats, available through ethtool, will display which
checksum offload features are supported/enabled by firmware.

Performance testing against a stock kernel shows no regression for IPv4
or IPv6 in terms of throughput or processor utilization with checksum
disabled or enabled.

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Santiago Leon <santil@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/ibmveth.h b/drivers/net/ibmveth.h
index d5651c79e199..84e4ab224124 100644
--- a/drivers/net/ibmveth.h
+++ b/drivers/net/ibmveth.h
@@ -149,6 +149,8 @@ struct ibmveth_adapter {
     void *bounce_buffer;
     dma_addr_t bounce_buffer_dma;
 
+    u64 fw_ipv6_csum_support;
+    u64 fw_ipv4_csum_support;
     /* adapter specific stats */
     u64 replenish_task_cycles;
     u64 replenish_no_mem;