gve: Add RSS cache for non RSS device option scenario

Not all the devices have the capability for the driver to query for the
registered RSS configuration. The driver can discover this by checking
the relevant device option during setup. If it cannot, the driver needs
to store the RSS config cache and directly return such cache when
queried by the ethtool. RSS config is inited when driver probes. Also the
default RSS config will be adjusted when there is RX queue count change.

At this point, only keys of GVE_RSS_KEY_SIZE and indirection tables of
GVE_RSS_INDIR_SIZE are supported.

Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Praveen Kaligineedi <pkaligineedi@google.com>
Signed-off-by: Jeroen de Borst <jeroendb@google.com>
Link: https://patch.msgid.link/20250219200451.3348166-1-jeroendb@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 84 insertions, 2 deletions

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 92237fb0b60c..029be8342b7b 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -184,6 +184,43 @@ static void gve_free_flow_rule_caches(struct gve_priv *priv)
 	flow_rules_cache->rules_cache = NULL;
 }
 
+static int gve_alloc_rss_config_cache(struct gve_priv *priv)
+{
+	struct gve_rss_config *rss_config = &priv->rss_config;
+
+	if (!priv->cache_rss_config)
+		return 0;
+
+	rss_config->hash_key = kcalloc(priv->rss_key_size,
+				       sizeof(rss_config->hash_key[0]),
+				       GFP_KERNEL);
+	if (!rss_config->hash_key)
+		return -ENOMEM;
+
+	rss_config->hash_lut = kcalloc(priv->rss_lut_size,
+				       sizeof(rss_config->hash_lut[0]),
+				       GFP_KERNEL);
+	if (!rss_config->hash_lut)
+		goto free_rss_key_cache;
+
+	return 0;
+
+free_rss_key_cache:
+	kfree(rss_config->hash_key);
+	rss_config->hash_key = NULL;
+	return -ENOMEM;
+}
+
+static void gve_free_rss_config_cache(struct gve_priv *priv)
+{
+	struct gve_rss_config *rss_config = &priv->rss_config;
+
+	kfree(rss_config->hash_key);
+	kfree(rss_config->hash_lut);
+
+	memset(rss_config, 0, sizeof(*rss_config));
+}
+
 static int gve_alloc_counter_array(struct gve_priv *priv)
 {
 	priv->counter_array =
@@ -575,9 +612,12 @@ static int gve_setup_device_resources(struct gve_priv *priv)
 	err = gve_alloc_flow_rule_caches(priv);
 	if (err)
 		return err;
-	err = gve_alloc_counter_array(priv);
+	err = gve_alloc_rss_config_cache(priv);
 	if (err)
 		goto abort_with_flow_rule_caches;
+	err = gve_alloc_counter_array(priv);
+	if (err)
+		goto abort_with_rss_config_cache;
 	err = gve_alloc_notify_blocks(priv);
 	if (err)
 		goto abort_with_counter;
@@ -611,6 +651,12 @@ static int gve_setup_device_resources(struct gve_priv *priv)
 		}
 	}
 
+	err = gve_init_rss_config(priv, priv->rx_cfg.num_queues);
+	if (err) {
+		dev_err(&priv->pdev->dev, "Failed to init RSS config");
+		goto abort_with_ptype_lut;
+	}
+
 	err = gve_adminq_report_stats(priv, priv->stats_report_len,
 				      priv->stats_report_bus,
 				      GVE_STATS_REPORT_TIMER_PERIOD);
@@ -629,6 +675,8 @@ abort_with_ntfy_blocks:
 	gve_free_notify_blocks(priv);
 abort_with_counter:
 	gve_free_counter_array(priv);
+abort_with_rss_config_cache:
+	gve_free_rss_config_cache(priv);
 abort_with_flow_rule_caches:
 	gve_free_flow_rule_caches(priv);
 
@@ -669,6 +717,7 @@ static void gve_teardown_device_resources(struct gve_priv *priv)
 	priv->ptype_lut_dqo = NULL;
 
 	gve_free_flow_rule_caches(priv);
+	gve_free_rss_config_cache(priv);
 	gve_free_counter_array(priv);
 	gve_free_notify_blocks(priv);
 	gve_free_stats_report(priv);
@@ -1390,6 +1439,12 @@ static int gve_queues_start(struct gve_priv *priv,
 	if (err)
 		goto stop_and_free_rings;
 
+	if (rx_alloc_cfg->reset_rss) {
+		err = gve_init_rss_config(priv, priv->rx_cfg.num_queues);
+		if (err)
+			goto reset;
+	}
+
 	err = gve_register_qpls(priv);
 	if (err)
 		goto reset;
@@ -1786,6 +1841,26 @@ static int gve_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 	}
 }
 
+int gve_init_rss_config(struct gve_priv *priv, u16 num_queues)
+{
+	struct gve_rss_config *rss_config = &priv->rss_config;
+	struct ethtool_rxfh_param rxfh = {0};
+	u16 i;
+
+	if (!priv->cache_rss_config)
+		return 0;
+
+	for (i = 0; i < priv->rss_lut_size; i++)
+		rss_config->hash_lut[i] =
+			ethtool_rxfh_indir_default(i, num_queues);
+
+	netdev_rss_key_fill(rss_config->hash_key, priv->rss_key_size);
+
+	rxfh.hfunc = ETH_RSS_HASH_TOP;
+
+	return gve_adminq_configure_rss(priv, &rxfh);
+}
+
 int gve_flow_rules_reset(struct gve_priv *priv)
 {
 	if (!priv->max_flow_rules)
@@ -1834,7 +1909,8 @@ int gve_adjust_config(struct gve_priv *priv,
 
 int gve_adjust_queues(struct gve_priv *priv,
 		      struct gve_queue_config new_rx_config,
-		      struct gve_queue_config new_tx_config)
+		      struct gve_queue_config new_tx_config,
+		      bool reset_rss)
 {
 	struct gve_tx_alloc_rings_cfg tx_alloc_cfg = {0};
 	struct gve_rx_alloc_rings_cfg rx_alloc_cfg = {0};
@@ -1847,6 +1923,7 @@ int gve_adjust_queues(struct gve_priv *priv,
 	tx_alloc_cfg.qcfg = &new_tx_config;
 	rx_alloc_cfg.qcfg_tx = &new_tx_config;
 	rx_alloc_cfg.qcfg = &new_rx_config;
+	rx_alloc_cfg.reset_rss = reset_rss;
 	tx_alloc_cfg.num_rings = new_tx_config.num_queues;
 
 	/* Add dedicated XDP TX queues if enabled. */
@@ -1858,6 +1935,11 @@ int gve_adjust_queues(struct gve_priv *priv,
 		return err;
 	}
 	/* Set the config for the next up. */
+	if (reset_rss) {
+		err = gve_init_rss_config(priv, new_rx_config.num_queues);
+		if (err)
+			return err;
+	}
 	priv->tx_cfg = new_tx_config;
 	priv->rx_cfg = new_rx_config;