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Date: Wed, 30 Sep 2020 19:20:02 +0300
From: Boris Pismenny <borisp@...lanox.com>
To: kuba@...nel.org, davem@...emloft.net, saeedm@...dia.com,
hch@....de, sagi@...mberg.me, axboe@...com, kbusch@...nel.org,
viro@...iv.linux.org.uk, edumazet@...gle.com
Cc: boris.pismenny@...il.com, linux-nvme@...ts.infradead.org,
netdev@...r.kernel.org, Ben Ben-Ishay <benishay@...lanox.com>,
Or Gerlitz <ogerlitz@...lanox.com>,
Yoray Zack <yorayz@...lanox.com>
Subject: [PATCH net-next RFC v1 02/10] net: Introduce direct data placement tcp offload
This commit introduces direct data placement offload for TCP.
This capability is accompanied by new net_device operations that
configure
hardware contexts. There is a context per socket, and a context per DDP
opreation. Additionally, a resynchronization routine is used to assist
hardware handle TCP OOO, and continue the offload.
Furthermore, we let the offloading driver advertise what is the max hw
sectors/segments.
Using this interface, the NIC hardware will scatter TCP payload directly
to the BIO pages according to the command_id.
To maintain the correctness of the network stack, the driver is expected
to construct SKBs that point to the BIO pages.
This, the SKB represents the data on the wire, while it is pointing
to data that is already placed in the destination buffer.
As a result, data from page frags should not be copied out to
the linear part.
As SKBs that use DDP are already very memory efficient, we modify
skb_condence to avoid copying data from fragments to the linear
part of SKBs that belong to a socket that uses DDP offload.
A follow-up patch will use this interface for DDP in NVMe-TCP.
Signed-off-by: Boris Pismenny <borisp@...lanox.com>
Signed-off-by: Ben Ben-Ishay <benishay@...lanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@...lanox.com>
Signed-off-by: Yoray Zack <yorayz@...lanox.com>
---
include/linux/netdev_features.h | 2 +
include/linux/netdevice.h | 5 ++
include/net/inet_connection_sock.h | 4 ++
include/net/tcp_ddp.h | 90 ++++++++++++++++++++++++++++++
net/Kconfig | 9 +++
net/core/skbuff.c | 9 ++-
net/ethtool/common.c | 1 +
7 files changed, 119 insertions(+), 1 deletion(-)
create mode 100644 include/net/tcp_ddp.h
diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index 0b17c4322b09..a0074b244372 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -84,6 +84,7 @@ enum {
NETIF_F_GRO_FRAGLIST_BIT, /* Fraglist GRO */
NETIF_F_HW_MACSEC_BIT, /* Offload MACsec operations */
+ NETIF_F_HW_TCP_DDP_BIT, /* TCP direct data placement offload */
/*
* Add your fresh new feature above and remember to update
@@ -157,6 +158,7 @@ enum {
#define NETIF_F_GRO_FRAGLIST __NETIF_F(GRO_FRAGLIST)
#define NETIF_F_GSO_FRAGLIST __NETIF_F(GSO_FRAGLIST)
#define NETIF_F_HW_MACSEC __NETIF_F(HW_MACSEC)
+#define NETIF_F_HW_TCP_DDP __NETIF_F(HW_TCP_DDP)
/* 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 a431c3229cbf..b00e1663724b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -935,6 +935,7 @@ struct dev_ifalias {
struct devlink;
struct tlsdev_ops;
+struct tcp_ddp_dev_ops;
struct netdev_name_node {
struct hlist_node hlist;
@@ -1922,6 +1923,10 @@ struct net_device {
const struct tlsdev_ops *tlsdev_ops;
#endif
+#ifdef CONFIG_TCP_DDP
+ const struct tcp_ddp_dev_ops *tcp_ddp_ops;
+#endif
+
const struct header_ops *header_ops;
unsigned int flags;
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index dc763ca9413c..503092d8860d 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -66,6 +66,8 @@ struct inet_connection_sock_af_ops {
* @icsk_ulp_ops Pluggable ULP control hook
* @icsk_ulp_data ULP private data
* @icsk_clean_acked Clean acked data hook
+ * @icsk_ulp_ddp_ops Pluggable ULP direct data placement control hook
+ * @icsk_ulp_ddp_data ULP direct data placement private data
* @icsk_listen_portaddr_node hash to the portaddr listener hashtable
* @icsk_ca_state: Congestion control state
* @icsk_retransmits: Number of unrecovered [RTO] timeouts
@@ -94,6 +96,8 @@ struct inet_connection_sock {
const struct tcp_ulp_ops *icsk_ulp_ops;
void __rcu *icsk_ulp_data;
void (*icsk_clean_acked)(struct sock *sk, u32 acked_seq);
+ const struct tcp_ddp_ulp_ops *icsk_ulp_ddp_ops;
+ void __rcu *icsk_ulp_ddp_data;
struct hlist_node icsk_listen_portaddr_node;
unsigned int (*icsk_sync_mss)(struct sock *sk, u32 pmtu);
__u8 icsk_ca_state:5,
diff --git a/include/net/tcp_ddp.h b/include/net/tcp_ddp.h
new file mode 100644
index 000000000000..4c0d9660b039
--- /dev/null
+++ b/include/net/tcp_ddp.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * tcp_ddp.h
+ * Author: Boris Pismenny <borisp@...lanox.com>
+ * Copyright (C) 2020 Mellanox Technologies.
+ */
+#ifndef _TCP_DDP_H
+#define _TCP_DDP_H
+
+#include <linux/blkdev.h>
+#include <linux/netdevice.h>
+#include <net/inet_connection_sock.h>
+#include <net/sock.h>
+
+/* limits returned by the offload driver, zero means don't care */
+struct tcp_ddp_limits {
+ int max_ddp_sgl_len;
+};
+
+enum tcp_ddp_type {
+ TCP_DDP_NVME = 1,
+};
+
+struct tcp_ddp_config {
+ enum tcp_ddp_type type;
+ unsigned char buf[];
+};
+
+struct nvme_tcp_config {
+ struct tcp_ddp_config cfg;
+
+ u16 pfv;
+ u8 cpda;
+ u8 dgst;
+ int queue_size;
+ int queue_id;
+ int io_cpu;
+};
+
+struct tcp_ddp_io {
+ u32 command_id;
+ int nents;
+ struct sg_table sg_table;
+ struct scatterlist first_sgl[SG_CHUNK_SIZE];
+};
+
+struct tcp_ddp_dev_ops {
+ int (*tcp_ddp_limits)(struct net_device *netdev,
+ struct tcp_ddp_limits *limits);
+ int (*tcp_ddp_sk_add)(struct net_device *netdev,
+ struct sock *sk,
+ struct tcp_ddp_config *config);
+ void (*tcp_ddp_sk_del)(struct net_device *netdev,
+ struct sock *sk);
+ int (*tcp_ddp_setup)(struct net_device *netdev,
+ struct sock *sk,
+ struct tcp_ddp_io *io);
+ int (*tcp_ddp_teardown)(struct net_device *netdev,
+ struct sock *sk,
+ struct tcp_ddp_io *io,
+ void *ddp_ctx);
+ void (*tcp_ddp_resync)(struct net_device *netdev,
+ struct sock *sk, u32 seq);
+};
+
+#define TCP_DDP_RESYNC_REQ (1 << 0)
+
+/*
+ * Interface to register uppper layer Direct Data Placement (DDP) TCP offload
+ */
+struct tcp_ddp_ulp_ops {
+ /* NIC requests ulp to indicate if @seq is the start of a message */
+ bool (*resync_request)(struct sock *sk, u32 seq, u32 flags);
+ /* NIC driver informs the ulp that ddp teardown is done */
+ void (*ddp_teardown_done)(void *ddp_ctx);
+};
+
+struct tcp_ddp_ctx {
+ enum tcp_ddp_type type;
+ unsigned char buf[];
+};
+
+static inline struct tcp_ddp_ctx *tcp_ddp_get_ctx(const struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ return (__force struct tcp_ddp_ctx *)icsk->icsk_ulp_ddp_data;
+}
+
+#endif //_TCP_DDP_H
diff --git a/net/Kconfig b/net/Kconfig
index 3831206977a1..346e9fa7a6ec 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -460,6 +460,15 @@ config ETHTOOL_NETLINK
netlink. It provides better extensibility and some new features,
e.g. notification messages.
+config TCP_DDP
+ bool "TCP direct data placement offload"
+ default n
+ help
+ Direct Data Placement (DDP) offload for TCP enables ULP, such as
+ NVMe-TCP/iSCSI, to request the NIC to place TCP payload data
+ of a command response directly into kernel pages.
+
+
endif # if NET
# Used by archs to tell that they support BPF JIT compiler plus which flavour.
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e0774471f56d..ad32985876da 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -69,6 +69,7 @@
#include <net/xfrm.h>
#include <net/mpls.h>
#include <net/mptcp.h>
+#include <net/tcp_ddp.h>
#include <linux/uaccess.h>
#include <trace/events/skb.h>
@@ -6059,9 +6060,15 @@ EXPORT_SYMBOL(pskb_extract);
*/
void skb_condense(struct sk_buff *skb)
{
+ bool is_ddp = false;
+
+#ifdef CONFIG_TCP_DDP
+ is_ddp = skb->sk && inet_csk(skb->sk) &&
+ inet_csk(skb->sk)->icsk_ulp_ddp_data;
+#endif
if (skb->data_len) {
if (skb->data_len > skb->end - skb->tail ||
- skb_cloned(skb))
+ skb_cloned(skb) || is_ddp)
return;
/* Nice, we can free page frag(s) right now */
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index 24036e3055a1..a2ff7a4a6bbf 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -68,6 +68,7 @@ const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] = {
[NETIF_F_HW_TLS_RX_BIT] = "tls-hw-rx-offload",
[NETIF_F_GRO_FRAGLIST_BIT] = "rx-gro-list",
[NETIF_F_HW_MACSEC_BIT] = "macsec-hw-offload",
+ [NETIF_F_HW_TCP_DDP_BIT] = "tcp-ddp-offload",
};
const char
--
2.24.1
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