netdevsim: add HDS feature

HDS options(tcp-data-split, hds-thresh) have dependencies between other
features like XDP. Basic dependencies are checked in the core API.
netdevsim is very useful to check basic dependencies.

The default tcp-data-split mode is UNKNOWN but netdevsim driver
returns ENABLED when ethtool dumps tcp-data-split mode.
The default value of HDS threshold is 0 and the maximum value is 1024.

ethtool shows like this.

ethtool -g eni1np1
Ring parameters for eni1np1:
Pre-set maximums:
...
HDS thresh:             1024
Current hardware settings:
...
TCP data split:         on
HDS thresh:             0

ethtool -G eni1np1 tcp-data-split on hds-thresh 1024
ethtool -g eni1np1
Ring parameters for eni1np1:
Pre-set maximums:
...
HDS thresh:             1024
Current hardware settings:
...
TCP data split:         on
HDS thresh:             1024

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://patch.msgid.link/20250114142852.3364986-10-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index a70f62af4c88..dcf073bc4802 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -16,6 +16,7 @@
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/ethtool.h>
+#include <linux/ethtool_netlink.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/netdevice.h>
@@ -36,6 +37,8 @@
 #define NSIM_IPSEC_VALID		BIT(31)
 #define NSIM_UDP_TUNNEL_N_PORTS		4
 
+#define NSIM_HDS_THRESHOLD_MAX		1024
+
 struct nsim_sa {
 	struct xfrm_state *xs;
 	__be32 ipaddr[4];