ethtool: Support for configurable RSS hash function

This patch extends the set/get_rxfh ethtool-options for getting or
setting the RSS hash function.

It modifies drivers implementation of set/get_rxfh accordingly.

This change also delegates the responsibility of checking whether a
modification to a certain RX flow hash parameter is supported to the
driver implementation of set_rxfh.

User-kernel API is done through the new hfunc bitmask field in the
ethtool_rxfh struct. A bit set in the hfunc field is corresponding to an
index in the new string-set ETH_SS_RSS_HASH_FUNCS.

Got approval from most of the relevant driver maintainers that their
driver is using Toeplitz, and for the few that didn't answered, also
assumed it is Toeplitz.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Ariel Elior <ariel.elior@qlogic.com>
Cc: Prashant Sreedharan <prashant@broadcom.com>
Cc: Michael Chan <mchan@broadcom.com>
Cc: Hariprasad S <hariprasad@chelsio.com>
Cc: Sathya Perla <sathya.perla@emulex.com>
Cc: Subbu Seetharaman <subbu.seetharaman@emulex.com>
Cc: Ajit Khaparde <ajit.khaparde@emulex.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Bruce Allan <bruce.w.allan@intel.com>
Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
Cc: Don Skidmore <donald.c.skidmore@intel.com>
Cc: Greg Rose <gregory.v.rose@intel.com>
Cc: Matthew Vick <matthew.vick@intel.com>
Cc: John Ronciak <john.ronciak@intel.com>
Cc: Mitch Williams <mitch.a.williams@intel.com>
Cc: Amir Vadai <amirv@mellanox.com>
Cc: Solarflare linux maintainers <linux-net-drivers@solarflare.com>
Cc: Shradha Shah <sshah@solarflare.com>
Cc: Shreyas Bhatewara <sbhatewara@vmware.com>
Cc: "VMware, Inc." <pv-drivers@vmware.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Eyal Perry <eyalpe@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c

@@ -3358,12 +3358,18 @@ static u32 bnx2x_get_rxfh_indir_size(struct net_device *dev)
 	return T_ETH_INDIRECTION_TABLE_SIZE;
 }
 
-static int bnx2x_get_rxfh(struct net_device *dev, u32 *indir, u8 *key)
+static int bnx2x_get_rxfh(struct net_device *dev, u32 *indir, u8 *key,
+			  u8 *hfunc)
 {
 	struct bnx2x *bp = netdev_priv(dev);
 	u8 ind_table[T_ETH_INDIRECTION_TABLE_SIZE] = {0};
 	size_t i;
 
+	if (hfunc)
+		*hfunc = ETH_RSS_HASH_TOP;
+	if (!indir)
+		return 0;
+
 	/* Get the current configuration of the RSS indirection table */
 	bnx2x_get_rss_ind_table(&bp->rss_conf_obj, ind_table);
 
@@ -3383,11 +3389,21 @@ static int bnx2x_get_rxfh(struct net_device *dev, u32 *indir, u8 *key)
 }
 
 static int bnx2x_set_rxfh(struct net_device *dev, const u32 *indir,
-			  const u8 *key)
+			  const u8 *key, const u8 hfunc)
 {
 	struct bnx2x *bp = netdev_priv(dev);
 	size_t i;
 
+	/* We require at least one supported parameter to be changed and no
+	 * change in any of the unsupported parameters
+	 */
+	if (key ||
+	    (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP))
+		return -EOPNOTSUPP;
+
+	if (!indir)
+		return 0;
+
 	for (i = 0; i < T_ETH_INDIRECTION_TABLE_SIZE; i++) {
 		/*
 		 * The same as in bnx2x_get_rxfh: we can't use a memcpy()

drivers/net/ethernet/broadcom/tg3.c

@@ -12561,22 +12561,38 @@ static u32 tg3_get_rxfh_indir_size(struct net_device *dev)
 	return size;
 }
 
-static int tg3_get_rxfh(struct net_device *dev, u32 *indir, u8 *key)
+static int tg3_get_rxfh(struct net_device *dev, u32 *indir, u8 *key, u8 *hfunc)
 {
 	struct tg3 *tp = netdev_priv(dev);
 	int i;
 
+	if (hfunc)
+		*hfunc = ETH_RSS_HASH_TOP;
+	if (!indir)
+		return 0;
+
 	for (i = 0; i < TG3_RSS_INDIR_TBL_SIZE; i++)
 		indir[i] = tp->rss_ind_tbl[i];
 
 	return 0;
 }
 
-static int tg3_set_rxfh(struct net_device *dev, const u32 *indir, const u8 *key)
+static int tg3_set_rxfh(struct net_device *dev, const u32 *indir, const u8 *key,
+			const u8 hfunc)
 {
 	struct tg3 *tp = netdev_priv(dev);
 	size_t i;
 
+	/* We require at least one supported parameter to be changed and no
+	 * change in any of the unsupported parameters
+	 */
+	if (key ||
+	    (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP))
+		return -EOPNOTSUPP;
+
+	if (!indir)
+		return 0;
+
 	for (i = 0; i < TG3_RSS_INDIR_TBL_SIZE; i++)
 		tp->rss_ind_tbl[i] = indir[i];