From: Jakub Kicinski <kuba@kernel.org>
Date: Thu, 27 Jan 2022 10:42:59 -0800
Subject: ethtool: add header/data split indication
Patch-mainline: v5.18-rc1
Git-commit: 9690ae60429020f38e4aa2540c306f27eb021bc0
References: jsc#PED-1495
For applications running on a mix of platforms it's useful
to have a clear indication whether host's NIC supports the
geometry requirements of TCP zero-copy. TCP zero-copy Rx
requires data to be neatly placed into memory pages.
Most NICs can't do that.
This patch is adding GET support only, since the NICs
I work with either always have the feature enabled or
enable it whenever MTU is set to jumbo. In other words
I don't need SET. But adding set should be trivial.
(The only note on SET is that we will likely want
the setting to be "sticky" and use 0 / `unknown`
to reset it back to driver default.)
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
Documentation/networking/ethtool-netlink.rst | 8 ++++++++
include/linux/ethtool.h | 2 ++
include/uapi/linux/ethtool_netlink.h | 7 +++++++
net/ethtool/rings.c | 15 ++++++++++-----
4 files changed, 27 insertions(+), 5 deletions(-)
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -834,8 +834,16 @@ Kernel response contents:
``ETHTOOL_A_RINGS_RX_JUMBO`` u32 size of RX jumbo ring
``ETHTOOL_A_RINGS_TX`` u32 size of TX ring
``ETHTOOL_A_RINGS_RX_BUF_LEN`` u32 size of buffers on the ring
+ ``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` u8 TCP header / data split
==================================== ====== ===========================
+``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` indicates whether the device is usable with
+page-flipping TCP zero-copy receive (``getsockopt(TCP_ZEROCOPY_RECEIVE)``).
+If enabled the device is configured to place frame headers and data into
+separate buffers. The device configuration must make it possible to receive
+full memory pages of data, for example because MTU is high enough or through
+HW-GRO.
+
RINGS_SET
=========
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -70,9 +70,11 @@ enum {
/**
* struct kernel_ethtool_ringparam - RX/TX ring configuration
* @rx_buf_len: Current length of buffers on the rx ring.
+ * @tcp_data_split: Scatter packet headers and data to separate buffers
*/
struct kernel_ethtool_ringparam {
u32 rx_buf_len;
+ u8 tcp_data_split;
};
/**
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -315,6 +315,12 @@ enum {
/* RINGS */
enum {
+ ETHTOOL_TCP_DATA_SPLIT_UNKNOWN = 0,
+ ETHTOOL_TCP_DATA_SPLIT_DISABLED,
+ ETHTOOL_TCP_DATA_SPLIT_ENABLED,
+};
+
+enum {
ETHTOOL_A_RINGS_UNSPEC,
ETHTOOL_A_RINGS_HEADER, /* nest - _A_HEADER_* */
ETHTOOL_A_RINGS_RX_MAX, /* u32 */
@@ -326,6 +332,7 @@ enum {
ETHTOOL_A_RINGS_RX_JUMBO, /* u32 */
ETHTOOL_A_RINGS_TX, /* u32 */
ETHTOOL_A_RINGS_RX_BUF_LEN, /* u32 */
+ ETHTOOL_A_RINGS_TCP_DATA_SPLIT, /* u8 */
/* add new constants above here */
__ETHTOOL_A_RINGS_CNT,
--- a/net/ethtool/rings.c
+++ b/net/ethtool/rings.c
@@ -53,7 +53,8 @@ static int rings_reply_size(const struct
nla_total_size(sizeof(u32)) + /* _RINGS_RX_MINI */
nla_total_size(sizeof(u32)) + /* _RINGS_RX_JUMBO */
nla_total_size(sizeof(u32)) + /* _RINGS_TX */
- nla_total_size(sizeof(u32)); /* _RINGS_RX_BUF_LEN */
+ nla_total_size(sizeof(u32)) + /* _RINGS_RX_BUF_LEN */
+ nla_total_size(sizeof(u8)); /* _RINGS_TCP_DATA_SPLIT */
}
static int rings_fill_reply(struct sk_buff *skb,
@@ -61,9 +62,11 @@ static int rings_fill_reply(struct sk_bu
const struct ethnl_reply_data *reply_base)
{
const struct rings_reply_data *data = RINGS_REPDATA(reply_base);
- const struct kernel_ethtool_ringparam *kernel_ringparam = &data->kernel_ringparam;
+ const struct kernel_ethtool_ringparam *kr = &data->kernel_ringparam;
const struct ethtool_ringparam *ringparam = &data->ringparam;
+ WARN_ON(kr->tcp_data_split > ETHTOOL_TCP_DATA_SPLIT_ENABLED);
+
if ((ringparam->rx_max_pending &&
(nla_put_u32(skb, ETHTOOL_A_RINGS_RX_MAX,
ringparam->rx_max_pending) ||
@@ -84,9 +87,11 @@ static int rings_fill_reply(struct sk_bu
ringparam->tx_max_pending) ||
nla_put_u32(skb, ETHTOOL_A_RINGS_TX,
ringparam->tx_pending))) ||
- (kernel_ringparam->rx_buf_len &&
- (nla_put_u32(skb, ETHTOOL_A_RINGS_RX_BUF_LEN,
- kernel_ringparam->rx_buf_len))))
+ (kr->rx_buf_len &&
+ (nla_put_u32(skb, ETHTOOL_A_RINGS_RX_BUF_LEN, kr->rx_buf_len))) ||
+ (kr->tcp_data_split &&
+ (nla_put_u8(skb, ETHTOOL_A_RINGS_TCP_DATA_SPLIT,
+ kr->tcp_data_split))))
return -EMSGSIZE;
return 0;