[PATCH V2 net-next 1/6] ethtool: add support to set/get tx copybreak buf size via ethtool

[Guangbin Huang <huangguangbin2@huawei.com>]

From: Hao Chen <chenhao288@hisilicon.com>

Add support for ethtool to set/get tx copybreak buf size.

Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
---
 Documentation/networking/ethtool-netlink.rst | 24 ++++++++++++++++++++
 include/uapi/linux/ethtool.h                 |  1 +
 net/ethtool/common.c                         |  1 +
 net/ethtool/ioctl.c                          |  1 +
 4 files changed, 27 insertions(+)

diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index d9b55b7a1a4d..a47b0255aaf9 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -1521,6 +1521,30 @@ Kernel response contents:
   ``ETHTOOL_A_PHC_VCLOCKS_INDEX``       s32     PHC index array
   ====================================  ======  ==========================
 
+TUNABLE_SET
+===========
+
+Request contents:
+
+  =====================================  ======  ==========================
+  ``ETHTOOL_TX_COPYBREAK_BUF_SIZE``      u32     buf size for tx copybreak
+  =====================================  ======  ==========================
+
+Tx copybreak buf size is used for tx copybreak feature, the feature is used
+for small size packet or frag. It adds a queue based tx shared bounce buffer
+to memcpy the small packet when the len of xmitted skb is below tx_copybreak
+(value to distinguish small size and normal size), and reduce the overhead
+of dma map and unmap when IOMMU is on.
+
+TUNABLE_GET
+===========
+
+Kernel response contents:
+
+  ====================================  ======  ==========================
+  ``ETHTOOL_TX_COPYBREAK_BUF_SIZE``     u32     buf size for tx copybreak
+  ====================================  ======  ==========================
+
 Request translation
 ===================
 
diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index b6db6590baf0..266e95e4fb33 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -231,6 +231,7 @@ enum tunable_id {
 	ETHTOOL_RX_COPYBREAK,
 	ETHTOOL_TX_COPYBREAK,
 	ETHTOOL_PFC_PREVENTION_TOUT, /* timeout in msecs */
+	ETHTOOL_TX_COPYBREAK_BUF_SIZE,
 	/*
 	 * Add your fresh new tunable attribute above and remember to update
 	 * tunable_strings[] in net/ethtool/common.c
diff --git a/net/ethtool/common.c b/net/ethtool/common.c
index c63e0739dc6a..0c5210015911 100644
--- a/net/ethtool/common.c
+++ b/net/ethtool/common.c
@@ -89,6 +89,7 @@ tunable_strings[__ETHTOOL_TUNABLE_COUNT][ETH_GSTRING_LEN] = {
 	[ETHTOOL_RX_COPYBREAK]	= "rx-copybreak",
 	[ETHTOOL_TX_COPYBREAK]	= "tx-copybreak",
 	[ETHTOOL_PFC_PREVENTION_TOUT] = "pfc-prevention-tout",
+	[ETHTOOL_TX_COPYBREAK_BUF_SIZE] = "tx-copybreak-buf-size",
 };
 
 const char
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index 999e2a6bed13..a6600e361c34 100644
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -2381,6 +2381,7 @@ static int ethtool_tunable_valid(const struct ethtool_tunable *tuna)
 	switch (tuna->id) {
 	case ETHTOOL_RX_COPYBREAK:
 	case ETHTOOL_TX_COPYBREAK:
+	case ETHTOOL_TX_COPYBREAK_BUF_SIZE:
 		if (tuna->len != sizeof(u32) ||
 		    tuna->type_id != ETHTOOL_TUNABLE_U32)
 			return -EINVAL;
-- 
2.33.0