[PATCH v4 net-next 02/21] net: Introduce crc offload for tcp ddp ulp

Boris Pismenny
2021-02-11T21:11:32Z

This commit introduces support for CRC offload to direct data placement
ULP on the receive side. Both DDP and CRC share a common API to
initialize the offload for a TCP socket. But otherwise, both can
be executed independently.

On the receive side, CRC offload relies on a new SKB bit that
indicates that no CRC error was encountered while processing this packet.
If all packets of a ULP message have this bit set, then the CRC
verification for the message can be skipped, as hardware already checked
it.

The following patches will set and use this bit to perform NVME-TCP
CRC offload.

A subsequent series, will add NVMe-TCP transmit side CRC support.

Signed-off-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: Ben Ben-Ishay <benishay@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Yoray Zack <yorayz@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
---
include/linux/netdev_features.h | 2 ++
include/linux/netdevice.h | 2 +-
include/linux/skbuff.h | 2 +-
net/Kconfig | 8 ++++++++
net/ethtool/common.c | 1 +
net/ipv4/tcp_input.c | 4 ++--
net/ipv4/tcp_ipv4.c | 2 +-
net/ipv4/tcp_offload.c | 2 +-
8 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index 7977371d2dd1..77fb2cb99b78 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -86,6 +86,7 @@ enum {
NETIF_F_HW_MACSEC_BIT, /* Offload MACsec operations */
NETIF_F_GRO_UDP_FWD_BIT, /* Allow UDP GRO for forwarding */
NETIF_F_HW_TCP_DDP_BIT, /* TCP direct data placement offload */
+ NETIF_F_HW_TCP_DDP_CRC_RX_BIT, /* TCP DDP CRC RX offload */

/*
* Add your fresh new feature above and remember to update
@@ -161,6 +162,7 @@ enum {
#define NETIF_F_HW_MACSEC __NETIF_F(HW_MACSEC)
#define NETIF_F_GRO_UDP_FWD __NETIF_F(GRO_UDP_FWD)
#define NETIF_F_HW_TCP_DDP __NETIF_F(HW_TCP_DDP)
+#define NETIF_F_HW_TCP_DDP_CRC_RX __NETIF_F(HW_TCP_DDP_CRC_RX)

/* Finds the next feature with the highest number of the range of start till 0.
*/
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index bd28520e30f2..1065ddaa8e6b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1943,7 +1943,7 @@ struct net_device {
const struct tlsdev_ops *tlsdev_ops;
#endif

-#ifdef CONFIG_TCP_DDP
+#if IS_ENABLED(CONFIG_TCP_DDP) || IS_ENABLED(CONFIG_TCP_DDP_CRC)
const struct tcp_ddp_dev_ops *tcp_ddp_ops;
#endif

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c7c88b2d0d47..0d1be25574cc 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -861,7 +861,7 @@ struct sk_buff {
#ifdef CONFIG_TLS_DEVICE
__u8 decrypted:1;
#endif
-#ifdef CONFIG_TCP_DDP
+#if defined(CONFIG_TCP_DDP) || defined(CONFIG_TCP_DDP_CRC)
__u8 ddp_crc:1;
#endif

diff --git a/net/Kconfig b/net/Kconfig
index 3876861cdc90..80ed9f038968 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -465,6 +465,14 @@ config TCP_DDP
NVMe-TCP/iSCSI, to request the NIC to place TCP payload data
of a command response directly into kernel pages.

+config TCP_DDP_CRC
+ bool "TCP direct data placement CRC offload"
+ default n
+ help
+ Direct Data Placement (DDP) CRC32C offload for TCP enables ULP, such as
+ NVMe-TCP/iSCSI, to request the NIC to calculate/verify the data digest
+ of commands as they go through the NIC. Thus avoiding the costly
+ per-byte overhead.

endif # if NET

diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 2878a5613e72..7ac78b0a90b0 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -70,6 +70,7 @@ const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] = {
[NETIF_F_HW_MACSEC_BIT] = "macsec-hw-offload",
[NETIF_F_GRO_UDP_FWD_BIT] = "rx-udp-gro-forwarding",
[NETIF_F_HW_TCP_DDP_BIT] = "tcp-ddp-offload",
+ [NETIF_F_HW_TCP_DDP_CRC_RX_BIT] = "tcp-ddp-crc-rx-offload",
};

const char
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0ae1ffca090d..cd490bd548a3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5150,7 +5150,7 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root,
#ifdef CONFIG_TLS_DEVICE
nskb->decrypted = skb->decrypted;
#endif
-#ifdef CONFIG_TCP_DDP
+#if defined(CONFIG_TCP_DDP) || defined(CONFIG_TCP_DDP_CRC)
nskb->ddp_crc = skb->ddp_crc;
#endif
TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(nskb)->end_seq = start;
@@ -5186,7 +5186,7 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list, struct rb_root *root,
if (skb->decrypted != nskb->decrypted)
goto end;
#endif
-#ifdef CONFIG_TCP_DDP
+#if defined(CONFIG_TCP_DDP) || defined(CONFIG_TCP_DDP_CRC)

if (skb->ddp_crc != nskb->ddp_crc)
goto end;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 676bc1584356..8750646f8621 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1814,7 +1814,7 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb)
#ifdef CONFIG_TLS_DEVICE
tail->decrypted != skb->decrypted ||
#endif
-#ifdef CONFIG_TCP_DDP
+#if defined(CONFIG_TCP_DDP) || defined(CONFIG_TCP_DDP_CRC)
tail->ddp_crc != skb->ddp_crc ||
#endif
thtail->doff != th->doff ||
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index 3ce196375d94..9e43a044e730 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -262,7 +262,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
#ifdef CONFIG_TLS_DEVICE
flush |= p->decrypted ^ skb->decrypted;
#endif
-#ifdef CONFIG_TCP_DDP
+#if defined(CONFIG_TCP_DDP) || defined(CONFIG_TCP_DDP_CRC)
flush |= p->ddp_crc ^ skb->ddp_crc;
#endif