Merge branch 'add-tx-push-buf-len-param-to-ethtool'

Shay Agroskin says:

====================
Add tx push buf len param to ethtool

This patchset adds a new sub-configuration to ethtool get/set queue
params (ethtool -g) called 'tx-push-buf-len'.

This configuration specifies the maximum number of bytes of a
transmitted packet a driver can push directly to the underlying
device ('push' mode). The motivation for pushing some of the bytes to
the device has the advantages of

- Allowing a smart device to take fast actions based on the packet's
  header
- Reducing latency for small packets that can be copied completely into
  the device

This new param is practically similar to tx-copybreak value that can be
set using ethtool's tunable but conceptually serves a different purpose.
While tx-copybreak is used to reduce the overhead of DMA mapping and
makes no sense to use if less than the whole segment gets copied,
tx-push-buf-len allows to improve performance by analyzing the packet's
data (usually headers) before performing the DMA operation.

The configuration can be queried and set using the commands:

    $ ethtool -g [interface]

    # ethtool -G [interface] tx-push-buf-len [number of bytes]

This patchset also adds support for the new configuration in ENA driver
for which this parameter ensures efficient resources management on the
device side.
====================

Link: https://lore.kernel.org/r/20230323163610.1281468-1-shayagr@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 2792185dda22..798d35890118 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -75,6 +75,8 @@ enum {
  * @tx_push: The flag of tx push mode
  * @rx_push: The flag of rx push mode
  * @cqe_size: Size of TX/RX completion queue event
+ * @tx_push_buf_len: Size of TX push buffer
+ * @tx_push_buf_max_len: Maximum allowed size of TX push buffer
  */
 struct kernel_ethtool_ringparam {
 	u32	rx_buf_len;
@@ -82,6 +84,8 @@ struct kernel_ethtool_ringparam {
 	u8	tx_push;
 	u8	rx_push;
 	u32	cqe_size;
+	u32	tx_push_buf_len;
+	u32	tx_push_buf_max_len;
 };
 
 /**
@@ -90,12 +94,14 @@ struct kernel_ethtool_ringparam {
  * @ETHTOOL_RING_USE_CQE_SIZE: capture for setting cqe_size
  * @ETHTOOL_RING_USE_TX_PUSH: capture for setting tx_push
  * @ETHTOOL_RING_USE_RX_PUSH: capture for setting rx_push
+ * @ETHTOOL_RING_USE_TX_PUSH_BUF_LEN: capture for setting tx_push_buf_len
  */
 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),
-	ETHTOOL_RING_USE_RX_PUSH    = BIT(3),
+	ETHTOOL_RING_USE_RX_BUF_LEN		= BIT(0),
+	ETHTOOL_RING_USE_CQE_SIZE		= BIT(1),
+	ETHTOOL_RING_USE_TX_PUSH		= BIT(2),
+	ETHTOOL_RING_USE_RX_PUSH		= BIT(3),
+	ETHTOOL_RING_USE_TX_PUSH_BUF_LEN	= BIT(4),
 };
 
 #define __ETH_RSS_HASH_BIT(bit)	((u32)1 << (bit))