[dpdk-stable] patch 'net/virtio: do not falsely claim to do IP checksum' has been queued to LTS release 16.11.3

[Yuanhan Liu]

Hi,

FYI, your patch has been queued to LTS release 16.11.3

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 07/19/17. So please
shout if anyone has objections.

Thanks.

	--yliu

---
>From 8a20d34f959d56f8a83867fe70fd8941a912d20a Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <stephen at networkplumber.org>
Date: Fri, 7 Jul 2017 12:52:49 -0700
Subject: [PATCH] net/virtio: do not falsely claim to do IP checksum

[ upstream commit 4dab342b752222c6e248dae5ec9de2302aacd746 ]

The virtio driver is confused about the meaning of the ip_checksum
flag.  In DPDK, ip_checksum means the hardware is capable of checking
the Layer 3 IP checksum.  But KVM/QEMU does not do that. The flag
VIRTIO_NET_F_GUEST_CSUM controls whether the receive side does
Layer 4 (TCP/UDP) checksum offload.

Fix by erroring out any requests to do IP checksum.

Fixes: 96cb6711939e ("net/virtio: support Rx checksum offload")

Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
Acked-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
---
 drivers/net/virtio/virtio_ethdev.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 1d2b8e4..e86d12e 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1482,8 +1482,13 @@ virtio_dev_configure(struct rte_eth_dev *dev)
 
 	PMD_INIT_LOG(DEBUG, "configure");
 	req_features = VIRTIO_PMD_DEFAULT_GUEST_FEATURES;
-	if (rxmode->hw_ip_checksum)
-		req_features |= (1ULL << VIRTIO_NET_F_GUEST_CSUM);
+
+	/* Virtio does L4 checksum but not L3! */
+	if (rxmode->hw_ip_checksum) {
+		PMD_DRV_LOG(NOTICE,
+			    "virtio does not support IP checksum");
+		return -ENOTSUP;
+	}
 	if (rxmode->enable_lro)
 		req_features |=
 			(1ULL << VIRTIO_NET_F_GUEST_TSO4) |
@@ -1496,13 +1501,6 @@ virtio_dev_configure(struct rte_eth_dev *dev)
 			return ret;
 	}
 
-	if (rxmode->hw_ip_checksum &&
-		!vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_CSUM)) {
-		PMD_DRV_LOG(NOTICE,
-			"rx ip checksum not available on this host");
-		return -ENOTSUP;
-	}
-
 	if (rxmode->enable_lro &&
 		(!vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO4) ||
 			!vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO4))) {
-- 
2.7.4