net: ethtool: extend ringparam set/get APIs for tx_push

Currently tx push is a standard driver feature which controls use of a fast
path descriptor push. So this patch extends the ringparam APIs and data
structures to support set/get tx push by ethtool -G/g.

Signed-off-by: Jie Wang <wangjie125@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
index 24d9be69065d3ce774f3f5945d0640814f85cf14..dbca3e9ec782f677e3699c888ec51877d5bbff33 100644 (file)
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -862,6 +862,7 @@ Kernel response contents:
   ``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_CQE_SIZE``          u32     Size of TX/RX CQE
+  ``ETHTOOL_A_RINGS_TX_PUSH``           u8      flag of TX Push mode
   ====================================  ======  ===========================
 
 ``ETHTOOL_A_RINGS_TCP_DATA_SPLIT`` indicates whether the device is usable with
@@ -871,6 +872,12 @@ 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.
 
+``ETHTOOL_A_RINGS_TX_PUSH`` flag is used to enable descriptor fast
+path to send packets. In ordinary path, driver fills descriptors in DRAM and
+notifies NIC hardware. In fast path, driver pushes descriptors to the device
+through MMIO writes, thus reducing the latency. However, enabling this feature
+may increase the CPU cost. Drivers may enforce additional per-packet
+eligibility checks (e.g. on packet size).
 
 RINGS_SET
 =========
@@ -887,6 +894,7 @@ Request contents:
   ``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_CQE_SIZE``          u32     Size of TX/RX CQE
+  ``ETHTOOL_A_RINGS_TX_PUSH``           u8      flag of TX Push mode
   ====================================  ======  ===========================
 
 Kernel checks that requested ring sizes do not exceed limits reported by

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 4af58459a1e79cbdb8984aa6ca9e228e3bc32805..99dc7bfbcd3c3241b9796a509a0d74e348834fc8 100644 (file)
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -71,11 +71,13 @@ 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
+ * @tx_push: The flag of tx push mode
  * @cqe_size: Size of TX/RX completion queue event
  */
 struct kernel_ethtool_ringparam {
        u32     rx_buf_len;
        u8      tcp_data_split;
+       u8      tx_push;
        u32     cqe_size;
 };
 
@@ -83,10 +85,12 @@ struct kernel_ethtool_ringparam {
  * enum ethtool_supported_ring_param - indicator caps for setting ring params
  * @ETHTOOL_RING_USE_RX_BUF_LEN: capture for setting rx_buf_len
  * @ETHTOOL_RING_USE_CQE_SIZE: capture for setting cqe_size
+ * @ETHTOOL_RING_USE_TX_PUSH: capture for setting tx_push
  */
 enum ethtool_supported_ring_param {
        ETHTOOL_RING_USE_RX_BUF_LEN = BIT(0),
        ETHTOOL_RING_USE_CQE_SIZE   = BIT(1),
+       ETHTOOL_RING_USE_TX_PUSH    = BIT(2),
 };
 
 #define __ETH_RSS_HASH_BIT(bit)        ((u32)1 << (bit))

diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 979850221b8dd841f540d2af6ec05cd7d170940c..d2fb4f7be61b2ab312f7a9e2c8117b5187a8146c 100644 (file)
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -338,6 +338,7 @@ enum {
        ETHTOOL_A_RINGS_RX_BUF_LEN,                     /* u32 */
        ETHTOOL_A_RINGS_TCP_DATA_SPLIT,                 /* u8 */
        ETHTOOL_A_RINGS_CQE_SIZE,                       /* u32 */
+       ETHTOOL_A_RINGS_TX_PUSH,                        /* u8 */
 
        /* add new constants above here */
        __ETHTOOL_A_RINGS_CNT,

diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index 29d01662a48ba1157fd1cea18c61a14450702de8..7919ddb2371ce04860019e1e28861eb055401efd 100644 (file)
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -363,7 +363,7 @@ extern const struct nla_policy ethnl_features_set_policy[ETHTOOL_A_FEATURES_WANT
 extern const struct nla_policy ethnl_privflags_get_policy[ETHTOOL_A_PRIVFLAGS_HEADER + 1];
 extern const struct nla_policy ethnl_privflags_set_policy[ETHTOOL_A_PRIVFLAGS_FLAGS + 1];
 extern const struct nla_policy ethnl_rings_get_policy[ETHTOOL_A_RINGS_HEADER + 1];
-extern const struct nla_policy ethnl_rings_set_policy[ETHTOOL_A_RINGS_CQE_SIZE + 1];
+extern const struct nla_policy ethnl_rings_set_policy[ETHTOOL_A_RINGS_TX_PUSH + 1];
 extern const struct nla_policy ethnl_channels_get_policy[ETHTOOL_A_CHANNELS_HEADER + 1];
 extern const struct nla_policy ethnl_channels_set_policy[ETHTOOL_A_CHANNELS_COMBINED_COUNT + 1];
 extern const struct nla_policy ethnl_coalesce_get_policy[ETHTOOL_A_COALESCE_HEADER + 1];

diff --git a/net/ethtool/rings.c b/net/ethtool/rings.c
index 9f33c9689b56949dc8cabe05d08a51e5fbe06df0..9ed60c507d97d673bcaec18d123c56bce6ec1997 100644 (file)
--- a/net/ethtool/rings.c
+++ b/net/ethtool/rings.c
@@ -55,7 +55,8 @@ static int rings_reply_size(const struct ethnl_req_info *req_base,
               nla_total_size(sizeof(u32)) +    /* _RINGS_TX */
               nla_total_size(sizeof(u32)) +    /* _RINGS_RX_BUF_LEN */
               nla_total_size(sizeof(u8))  +    /* _RINGS_TCP_DATA_SPLIT */
-              nla_total_size(sizeof(u32));     /* _RINGS_CQE_SIZE */
+              nla_total_size(sizeof(u32)  +    /* _RINGS_CQE_SIZE */
+              nla_total_size(sizeof(u8)));     /* _RINGS_TX_PUSH */
 }
 
 static int rings_fill_reply(struct sk_buff *skb,
@@ -94,7 +95,8 @@ static int rings_fill_reply(struct sk_buff *skb,
             (nla_put_u8(skb, ETHTOOL_A_RINGS_TCP_DATA_SPLIT,
                         kr->tcp_data_split))) ||
            (kr->cqe_size &&
-            (nla_put_u32(skb, ETHTOOL_A_RINGS_CQE_SIZE, kr->cqe_size))))
+            (nla_put_u32(skb, ETHTOOL_A_RINGS_CQE_SIZE, kr->cqe_size))) ||
+           nla_put_u8(skb, ETHTOOL_A_RINGS_TX_PUSH, !!kr->tx_push))
                return -EMSGSIZE;
 
        return 0;
@@ -123,6 +125,7 @@ const struct nla_policy ethnl_rings_set_policy[] = {
        [ETHTOOL_A_RINGS_TX]                    = { .type = NLA_U32 },
        [ETHTOOL_A_RINGS_RX_BUF_LEN]            = NLA_POLICY_MIN(NLA_U32, 1),
        [ETHTOOL_A_RINGS_CQE_SIZE]              = NLA_POLICY_MIN(NLA_U32, 1),
+       [ETHTOOL_A_RINGS_TX_PUSH]               = NLA_POLICY_MAX(NLA_U8, 1),
 };
 
 int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info)
@@ -149,6 +152,15 @@ int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info)
        if (!ops->get_ringparam || !ops->set_ringparam)
                goto out_dev;
 
+       if (tb[ETHTOOL_A_RINGS_TX_PUSH] &&
+           !(ops->supported_ring_params & ETHTOOL_RING_USE_TX_PUSH)) {
+               ret = -EOPNOTSUPP;
+               NL_SET_ERR_MSG_ATTR(info->extack,
+                                   tb[ETHTOOL_A_RINGS_TX_PUSH],
+                                   "setting tx push not supported");
+               goto out_dev;
+       }
+
        rtnl_lock();
        ret = ethnl_ops_begin(dev);
        if (ret < 0)
@@ -165,6 +177,8 @@ int ethnl_set_rings(struct sk_buff *skb, struct genl_info *info)
                         tb[ETHTOOL_A_RINGS_RX_BUF_LEN], &mod);
        ethnl_update_u32(&kernel_ringparam.cqe_size,
                         tb[ETHTOOL_A_RINGS_CQE_SIZE], &mod);
+       ethnl_update_u8(&kernel_ringparam.tx_push,
+                       tb[ETHTOOL_A_RINGS_TX_PUSH], &mod);
        ret = 0;
        if (!mod)
                goto out_ops;