From 9690ae60429020f38e4aa2540c306f27eb021bc0 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 27 Jan 2022 10:42:59 -0800 Subject: [PATCH] ethtool: add header/data split indication 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 Signed-off-by: David S. Miller --- 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(-) diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst index 9d98e0511249..cae28af7a476 100644 --- a/Documentation/networking/ethtool-netlink.rst +++ b/Documentation/networking/ethtool-netlink.rst @@ -860,8 +860,16 @@ 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 ========= diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h index 11efc45de66a..e0853f48b75e 100644 --- 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; }; /** diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h index cca6e474a085..417d4280d7b5 100644 --- a/include/uapi/linux/ethtool_netlink.h +++ b/include/uapi/linux/ethtool_netlink.h @@ -318,6 +318,12 @@ 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_* */ @@ -330,6 +336,7 @@ 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, diff --git a/net/ethtool/rings.c b/net/ethtool/rings.c index c1d5f5e0fdc9..18a5035d3bee 100644 --- a/net/ethtool/rings.c +++ b/net/ethtool/rings.c @@ -53,7 +53,8 @@ static int rings_reply_size(const struct ethnl_req_info *req_base, 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_buff *skb, 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_buff *skb, 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;