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>

1 files changed, 30 insertions, 12 deletions

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index c1a2d60dfb82..653dc9c4ebac 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -59,6 +59,26 @@ enum ethtool_phys_id_state {
         ETHTOOL_ID_OFF
 };
 
+enum {
+        ETH_RSS_HASH_TOP_BIT, /* Configurable RSS hash function - Toeplitz */
+        ETH_RSS_HASH_XOR_BIT, /* Configurable RSS hash function - Xor */
+
+        /*
+         * Add your fresh new hash function bits above and remember to update
+         * rss_hash_func_strings[] in ethtool.c
+         */
+        ETH_RSS_HASH_FUNCS_COUNT
+};
+
+#define __ETH_RSS_HASH_BIT(bit) ((u32)1 << (bit))
+#define __ETH_RSS_HASH(name)    __ETH_RSS_HASH_BIT(ETH_RSS_HASH_##name##_BIT)
+
+#define ETH_RSS_HASH_TOP        __ETH_RSS_HASH(TOP)
+#define ETH_RSS_HASH_XOR        __ETH_RSS_HASH(XOR)
+
+#define ETH_RSS_HASH_UNKNOWN    0
+#define ETH_RSS_HASH_NO_CHANGE  0
+
 struct net_device;
 
 /* Some generic methods drivers may use in their ethtool_ops */
@@ -158,17 +178,14 @@ static inline u32 ethtool_rxfh_indir_default(u32 index, u32 n_rx_rings)
  *      Returns zero if not supported for this specific device.
  * @get_rxfh_indir_size: Get the size of the RX flow hash indirection table.
  *      Returns zero if not supported for this specific device.
- * @get_rxfh: Get the contents of the RX flow hash indirection table and hash
- *      key.
- *      Will only be called if one or both of @get_rxfh_indir_size and
- *      @get_rxfh_key_size are implemented and return non-zero.
- *      Returns a negative error code or zero.
- * @set_rxfh: Set the contents of the RX flow hash indirection table and/or
- *      hash key.  In case only the indirection table or hash key is to be
- *      changed, the other argument will be %NULL.
- *      Will only be called if one or both of @get_rxfh_indir_size and
- *      @get_rxfh_key_size are implemented and return non-zero.
+ * @get_rxfh: Get the contents of the RX flow hash indirection table, hash key
+ *      and/or hash function.
  *      Returns a negative error code or zero.
+ * @set_rxfh: Set the contents of the RX flow hash indirection table, hash
+ *      key, and/or hash function.  Arguments which are set to %NULL or zero
+ *      will remain unchanged.
+ *      Returns a negative error code or zero. An error code must be returned
+ *      if at least one unsupported change was requested.
  * @get_channels: Get number of channels.
  * @set_channels: Set number of channels.  Returns a negative error code or
  *      zero.
@@ -241,9 +258,10 @@ struct ethtool_ops {
         int     (*reset)(struct net_device *, u32 *);
         u32     (*get_rxfh_key_size)(struct net_device *);
         u32     (*get_rxfh_indir_size)(struct net_device *);
-        int     (*get_rxfh)(struct net_device *, u32 *indir, u8 *key);
+        int     (*get_rxfh)(struct net_device *, u32 *indir, u8 *key,
+                            u8 *hfunc);
         int     (*set_rxfh)(struct net_device *, const u32 *indir,
-                            const u8 *key);
+                            const u8 *key, const u8 hfunc);
         void    (*get_channels)(struct net_device *, struct ethtool_channels *);
         int     (*set_channels)(struct net_device *, struct ethtool_channels *);
         int     (*get_dump_flag)(struct net_device *, struct ethtool_dump *);