netdev - [RFC PATCH net-next 1/6] net: ethtool: attach an IDR of custom RSS contexts to a netdevice

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Date:   Mon, 3 Apr 2023 17:32:58 +0100
From:   <edward.cree@....com>
To:     <linux-net-drivers@....com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>
CC:     Edward Cree <ecree.xilinx@...il.com>, <netdev@...r.kernel.org>,
        <habetsm.xilinx@...il.com>, <sudheer.mogilappagari@...el.com>
Subject: [RFC PATCH net-next 1/6] net: ethtool: attach an IDR of custom RSS contexts to a netdevice

From: Edward Cree <ecree.xilinx@...il.com>

Each context stores the RXFH settings (indir, key, and hfunc) as well
 as optionally some driver private data.
Delete any still-existing contexts at netdev unregister time.

Signed-off-by: Edward Cree <ecree.xilinx@...il.com>
---
 include/linux/ethtool.h   | 33 +++++++++++++++++++++++++++++++++
 include/linux/netdevice.h |  5 +++++
 net/core/dev.c            | 23 +++++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 798d35890118..1898f4446666 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -157,6 +157,39 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
 	return index % 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
+ * @hfunc: RSS hash function identifier.  One of the %ETH_RSS_HASH_*
+ * @priv_size: Size of driver private data, in bytes
+ */
+struct ethtool_rxfh_context {
+	u32 indir_size;
+	u32 key_size;
+	u8 hfunc;
+	u16 priv_size;
+	/* private: indirection table, hash key, and driver private data are
+	 * stored sequentially in @data area.  Use below helpers to access
+	 */
+	u8 data[];
+};
+
+static inline u32 *ethtool_rxfh_context_indir(struct ethtool_rxfh_context *ctx)
+{
+	return (u32 *)&ctx->data;
+}
+
+static inline u8 *ethtool_rxfh_context_key(struct ethtool_rxfh_context *ctx)
+{
+	return (u8 *)(ethtool_rxfh_context_indir(ctx) + ctx->indir_size);
+}
+
+static inline void *ethtool_rxfh_context_priv(struct ethtool_rxfh_context *ctx)
+{
+	return ethtool_rxfh_context_key(ctx) + ctx->key_size;
+}
+
 /* declare a link mode bitmap */
 #define __ETHTOOL_DECLARE_LINK_MODE_MASK(name)		\
 	DECLARE_BITMAP(name, __ETHTOOL_LINK_MODE_MASK_NBITS)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a740be3bb911..91f7dad070bd 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2028,6 +2028,8 @@ enum netdev_ml_priv_type {
  *	@udp_tunnel_nic_info:	static structure describing the UDP tunnel
  *				offload capabilities of the device
  *	@udp_tunnel_nic:	UDP tunnel offload state
+ *	@rss_ctx_max_id:	maximum (exclusive) supported RSS context ID
+ *	@rss_ctx:	IDR storing custom RSS context state
  *	@xdp_state:		stores info on attached XDP BPF programs
  *
  *	@nested_level:	Used as a parameter of spin_lock_nested() of
@@ -2397,6 +2399,9 @@ struct net_device {
 	const struct udp_tunnel_nic_info	*udp_tunnel_nic_info;
 	struct udp_tunnel_nic	*udp_tunnel_nic;
 
+	u32			rss_ctx_max_id;
+	struct idr		rss_ctx;
+
 	/* protected by rtnl_lock */
 	struct bpf_xdp_entity	xdp_state[__MAX_XDP_MODE];
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 7ce5985be84b..d0a936d4e532 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9983,6 +9983,9 @@ int register_netdevice(struct net_device *dev)
 	if (ret)
 		return ret;
 
+	/* rss ctx ID 0 is reserved for the default context, start from 1 */
+	idr_init_base(&dev->rss_ctx, 1);
+
 	spin_lock_init(&dev->addr_list_lock);
 	netdev_set_addr_lockdep_class(dev);
 
@@ -10777,6 +10780,24 @@ void synchronize_net(void)
 }
 EXPORT_SYMBOL(synchronize_net);
 
+static void netdev_rss_contexts_free(struct net_device *dev)
+{
+	struct ethtool_rxfh_context *ctx;
+	u32 context;
+
+	if (!dev->ethtool_ops->set_rxfh_context)
+		return;
+	idr_for_each_entry(&dev->rss_ctx, ctx, context) {
+		u32 *indir = ethtool_rxfh_context_indir(ctx);
+		u8 *key = ethtool_rxfh_context_key(ctx);
+
+		idr_remove(&dev->rss_ctx, context);
+		dev->ethtool_ops->set_rxfh_context(dev, indir, key, ctx->hfunc,
+						   &context, true);
+		kfree(ctx);
+	}
+}
+
 /**
  *	unregister_netdevice_queue - remove device from the kernel
  *	@dev: device
@@ -10881,6 +10902,8 @@ void unregister_netdevice_many_notify(struct list_head *head,
 		netdev_name_node_alt_flush(dev);
 		netdev_name_node_free(dev->name_node);
 
+		netdev_rss_contexts_free(dev);
+
 		call_netdevice_notifiers(NETDEV_PRE_UNINIT, dev);
 
 		if (dev->netdev_ops->ndo_uninit)