Merge branch 'ethtool-dynamic-rss-context-indirection-table-resizing'

Björn Töpel says:

====================
ethtool: Dynamic RSS context indirection table resizing

Some NICs (e.g. bnxt) change their RSS indirection table size based on
the queue count, because the hardware table is a shared resource. The
ethtool core locks ctx->indir_size at context creation, so drivers
have to reject channel changes when RSS contexts exist.

This series adds resize helpers and wires them up in bnxt. It also
adds tracking of the user provided indirection table size to the
ethtool core.

Patch 1 tracks the user-provided indirection table size (user_size)
in ctx->indir_user_size for non-default RSS contexts and in
dev->ethtool->rss_indir_user_size for context 0. It is set when the
indirection table is configured via netlink or ioctl, and cleared to
zero on reset-to-default.

IFF_RXFH_CONFIGURED is removed, and replaced with rss_indir_user_size.
The flag is redundant now that user_size captures the same
information.

Patch 2 adds core resize helpers:
  ethtool_rxfh_indir_can_resize() - read-only validation for context 0
  ethtool_rxfh_indir_resize() - fold/unfold context 0 table in place
  ethtool_rxfh_ctxs_can_resize() - validate all non-default contexts
  ethtool_rxfh_ctxs_resize() - resize all non-default contexts,
    with locking and RSS_NTF notifications

Patch 3 uses the resize helpers in bnxt_set_channels().

Patch 4 adds HW tests in rss_drv.py (devices without dynamic table
sizing are skipped):
  resize_periodic - fold/unfold with a non-default [3,2,1,0]
    sub-table (user_size=4), verifying exact content preservation
    (main + ctx)
  resize_below_user_size_reject - periodic sub-table with user_size
    between big and small device table sizes; verifies that shrinking
    below user_size is rejected even when the table is periodic
    (main + ctx)
  resize_nonperiodic_reject - non-periodic table blocks channel
    reduction, with an extra periodic context to exercise
    multi-context validation (main + ctx)
  resize_nonperiodic_no_corruption - failed resize leaves table
    contents and channel count unchanged (main + ctx)

Running the tests:

  # On real hardware
  sudo NETIF=eth0 ./rss_drv.py
====================

Link: https://patch.msgid.link/20260320085826.1957255-1-bjorn@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 14 insertions, 6 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 656d465bcd06..1cb0740ba331 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -176,6 +176,8 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
  * struct ethtool_rxfh_context - a custom RSS context configuration
  * @indir_size: Number of u32 entries in indirection table
  * @key_size: Size of hash key, in bytes
+ * @indir_user_size: number of user provided entries for the
+ *	indirection table
  * @priv_size: Size of driver private data, in bytes
  * @hfunc: RSS hash function identifier.  One of the %ETH_RSS_HASH_*
  * @input_xfrm: Defines how the input data is transformed. Valid values are one
@@ -186,6 +188,7 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
 struct ethtool_rxfh_context {
 	u32 indir_size;
 	u32 key_size;
+	u32 indir_user_size;
 	u16 priv_size;
 	u8 hfunc;
 	u8 input_xfrm;
@@ -214,6 +217,13 @@ static inline u8 *ethtool_rxfh_context_key(struct ethtool_rxfh_context *ctx)
 }
 
 void ethtool_rxfh_context_lost(struct net_device *dev, u32 context_id);
+void ethtool_rxfh_indir_lost(struct net_device *dev);
+bool ethtool_rxfh_indir_can_resize(struct net_device *dev, const u32 *tbl,
+				   u32 old_size, u32 new_size);
+void ethtool_rxfh_indir_resize(struct net_device *dev, u32 *tbl,
+			       u32 old_size, u32 new_size);
+int ethtool_rxfh_ctxs_can_resize(struct net_device *dev, u32 new_indir_size);
+void ethtool_rxfh_ctxs_resize(struct net_device *dev, u32 new_indir_size);
 
 struct link_mode_info {
 	int	speed;
@@ -1337,12 +1347,15 @@ int ethtool_virtdev_set_link_ksettings(struct net_device *dev,
  * @rss_ctx:		XArray of custom RSS contexts
  * @rss_lock:		Protects entries in @rss_ctx.  May be taken from
  *			within RTNL.
+ * @rss_indir_user_size: Number of user provided entries for the default
+ *			 (context 0) indirection table.
  * @wol_enabled:	Wake-on-LAN is enabled
  * @module_fw_flash_in_progress: Module firmware flashing is in progress.
  */
 struct ethtool_netdev_state {
 	struct xarray		rss_ctx;
 	struct mutex		rss_lock;
+	u32			rss_indir_user_size;
 	unsigned		wol_enabled:1;
 	unsigned		module_fw_flash_in_progress:1;
 };
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6882b41bb3e8..e15367373f7c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1716,7 +1716,6 @@ struct net_device_ops {
  * @IFF_OPENVSWITCH: device is a Open vSwitch master
  * @IFF_L3MDEV_SLAVE: device is enslaved to an L3 master device
  * @IFF_TEAM: device is a team device
- * @IFF_RXFH_CONFIGURED: device has had Rx Flow indirection table configured
  * @IFF_PHONY_HEADROOM: the headroom value is controlled by an external
  *	entity (i.e. the master device for bridged veth)
  * @IFF_MACSEC: device is a MACsec device
@@ -1752,7 +1751,6 @@ enum netdev_priv_flags {
 	IFF_OPENVSWITCH			= 1<<20,
 	IFF_L3MDEV_SLAVE		= 1<<21,
 	IFF_TEAM			= 1<<22,
-	IFF_RXFH_CONFIGURED		= 1<<23,
 	IFF_PHONY_HEADROOM		= 1<<24,
 	IFF_MACSEC			= 1<<25,
 	IFF_NO_RX_HANDLER		= 1<<26,
@@ -5580,10 +5578,7 @@ static inline bool netif_is_lag_port(const struct net_device *dev)
 	return netif_is_bond_slave(dev) || netif_is_team_port(dev);
 }
 
-static inline bool netif_is_rxfh_configured(const struct net_device *dev)
-{
-	return dev->priv_flags & IFF_RXFH_CONFIGURED;
-}
+bool netif_is_rxfh_configured(const struct net_device *dev);
 
 static inline bool netif_is_failover(const struct net_device *dev)
 {