From: Michael Chan <michael.chan@broadcom.com>
Date: Sat, 16 Dec 2017 03:09:40 -0500
Subject: net: Introduce NETIF_F_GRO_HW.
Patch-mainline: v4.16-rc1
Git-commit: fb1f5f79ae96331a0201b4080d34f3bc3b5c0b1d
References: bsc#1050242 FATE#322914
Introduce NETIF_F_GRO_HW feature flag for NICs that support hardware
GRO. With this flag, we can now independently turn on or off hardware
GRO when GRO is on. Previously, drivers were using NETIF_F_GRO to
control hardware GRO and so it cannot be independently turned on or
off without affecting GRO.
Hardware GRO (just like GRO) guarantees that packets can be re-segmented
by TSO/GSO to reconstruct the original packet stream. Logically,
GRO_HW should depend on GRO since it a subset, but we will let
individual drivers enforce this dependency as they see fit.
Since NETIF_F_GRO is not propagated between upper and lower devices,
NETIF_F_GRO_HW should follow suit since it is a subset of GRO. In other
words, a lower device can independent have GRO/GRO_HW enabled or disabled
and no feature propagation is required. This will preserve the current
GRO behavior. This can be changed later if we decide to propagate GRO/
GRO_HW/RXCSUM from upper to lower devices.
Cc: Ariel Elior <Ariel.Elior@cavium.com>
Cc: everest-linux-l2@cavium.com
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
Documentation/networking/netdev-features.txt | 9 +++++++++
include/linux/netdev_features.h | 3 +++
net/core/dev.c | 12 ++++++++++++
net/core/ethtool.c | 1 +
4 files changed, 25 insertions(+)
--- a/Documentation/networking/netdev-features.txt
+++ b/Documentation/networking/netdev-features.txt
@@ -163,3 +163,12 @@ This requests that the NIC receive all p
frames (such as bad FCS, etc). This can be helpful when sniffing a link with
bad packets on it. Some NICs may receive more packets if also put into normal
PROMISC mode.
+
+* rx-gro-hw
+
+This requests that the NIC enables Hardware GRO (generic receive offload).
+Hardware GRO is basically the exact reverse of TSO, and is generally
+stricter than Hardware LRO. A packet stream merged by Hardware GRO must
+be re-segmentable by GSO or TSO back to the exact original packet stream.
+Hardware GRO is dependent on RXCSUM since every packet successfully merged
+by hardware must also have the checksum verified by hardware.
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -78,6 +78,8 @@ enum {
NETIF_F_HW_ESP_TX_CSUM_BIT, /* ESP with TX checksum offload */
NETIF_F_RX_UDP_TUNNEL_PORT_BIT, /* Offload of RX port for UDP tunnels */
+ NETIF_F_GRO_HW_BIT, /* Hardware Generic receive offload */
+
/*
* Add your fresh new feature above and remember to update
* netdev_features_strings[] in net/core/ethtool.c and maybe
@@ -97,6 +99,7 @@ enum {
#define NETIF_F_FRAGLIST __NETIF_F(FRAGLIST)
#define NETIF_F_FSO __NETIF_F(FSO)
#define NETIF_F_GRO __NETIF_F(GRO)
+#define NETIF_F_GRO_HW __NETIF_F(GRO_HW)
#define NETIF_F_GSO __NETIF_F(GSO)
#define NETIF_F_GSO_ROBUST __NETIF_F(GSO_ROBUST)
#define NETIF_F_HIGHDMA __NETIF_F(HIGHDMA)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7244,6 +7244,18 @@ static netdev_features_t netdev_fix_feat
features &= ~dev->gso_partial_features;
}
+ if (!(features & NETIF_F_RXCSUM)) {
+ /* NETIF_F_GRO_HW implies doing RXCSUM since every packet
+ * successfully merged by hardware must also have the
+ * checksum verified by hardware. If the user does not
+ * want to enable RXCSUM, logically, we should disable GRO_HW.
+ */
+ if (features & NETIF_F_GRO_HW) {
+ netdev_dbg(dev, "Dropping NETIF_F_GRO_HW since no RXCSUM feature.\n");
+ features &= ~NETIF_F_GRO_HW;
+ }
+ }
+
return features;
}
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -73,6 +73,7 @@ static const char netdev_features_string
[NETIF_F_LLTX_BIT] = "tx-lockless",
[NETIF_F_NETNS_LOCAL_BIT] = "netns-local",
[NETIF_F_GRO_BIT] = "rx-gro",
+ [NETIF_F_GRO_HW_BIT] = "rx-gro-hw",
[NETIF_F_LRO_BIT] = "rx-lro",
[NETIF_F_TSO_BIT] = "tx-tcp-segmentation",