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 <[e-mail]>
Reviewed-by: Harshitha Ramamurthy <[e-mail]>
Reviewed-by: Willem de Bruijn <[e-mail]>
Signed-off-by: Praveen Kaligineedi <[e-mail]>
Signed-off-by: Jeroen de Borst <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/google/gve/gve.h

···
 #define GVE_FLOW_RULE_IDS_CACHE_SIZE \
 	(GVE_ADMINQ_BUFFER_SIZE / sizeof(((struct gve_adminq_queried_flow_rule *)0)->location))
 
+#define GVE_RSS_KEY_SIZE	40
+#define GVE_RSS_INDIR_SIZE	128
+
 #define GVE_XDP_ACTIONS 5
 
 #define GVE_GQ_TX_MIN_PKT_DESC_BYTES 182
···
 	u16 packet_buffer_size;
 	bool raw_addressing;
 	bool enable_header_split;
+	bool reset_rss;
 
 	/* Allocated resources are returned here */
 	struct gve_rx_ring *rx;
···
 	/* The total number of queried rules that stored in the caches */
 	u32 rules_cache_num;
 	u32 rule_ids_cache_num;
+};
+
+struct gve_rss_config {
+	u8 *hash_key;
+	u32 *hash_lut;
 };
 
 struct gve_priv {
···
 
 	u16 rss_key_size;
 	u16 rss_lut_size;
+	bool cache_rss_config;
+	struct gve_rss_config rss_config;
 };
 
 enum gve_service_task_flags_bit {
···
 		      struct gve_rx_alloc_rings_cfg *rx_alloc_cfg);
 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);
 /* flow steering rule */
 int gve_get_flow_rule_entry(struct gve_priv *priv, struct ethtool_rxnfc *cmd);
 int gve_get_flow_rule_ids(struct gve_priv *priv, struct ethtool_rxnfc *cmd, u32 *rule_locs);
 int gve_add_flow_rule(struct gve_priv *priv, struct ethtool_rxnfc *cmd);
 int gve_del_flow_rule(struct gve_priv *priv, struct ethtool_rxnfc *cmd);
 int gve_flow_rules_reset(struct gve_priv *priv);
+/* RSS config */
+int gve_init_rss_config(struct gve_priv *priv, u16 num_queues);
 /* report stats handling */
 void gve_handle_report_stats(struct gve_priv *priv);
 /* exported by ethtool.c */

drivers/net/ethernet/google/gve/gve_adminq.c

···
 	priv->min_rx_desc_cnt = priv->rx_desc_cnt;
 }
 
+static void gve_set_default_rss_sizes(struct gve_priv *priv)
+{
+	if (!gve_is_gqi(priv)) {
+		priv->rss_key_size = GVE_RSS_KEY_SIZE;
+		priv->rss_lut_size = GVE_RSS_INDIR_SIZE;
+		priv->cache_rss_config = true;
+	}
+}
+
 static void gve_enable_supported_features(struct gve_priv *priv,
 					  u32 supported_features_mask,
 					  const struct gve_device_option_jumbo_frames
···
 			be16_to_cpu(dev_op_rss_config->hash_key_size);
 		priv->rss_lut_size =
 			be16_to_cpu(dev_op_rss_config->hash_lut_size);
+		priv->cache_rss_config = false;
+		dev_dbg(&priv->pdev->dev,
+			"RSS device option enabled with key size of %u, lut size of %u.\n",
+			priv->rss_key_size, priv->rss_lut_size);
 	}
 }
 
···
 
 	/* set default descriptor counts */
 	gve_set_default_desc_cnt(priv, descriptor);
+
+	gve_set_default_rss_sizes(priv);
 
 	/* DQO supports LRO. */
 	if (!gve_is_gqi(priv))
···
 
 int gve_adminq_configure_rss(struct gve_priv *priv, struct ethtool_rxfh_param *rxfh)
 {
+	const u32 *hash_lut_to_config = NULL;
+	const u8 *hash_key_to_config = NULL;
 	dma_addr_t lut_bus = 0, key_bus = 0;
-	u16 key_size = 0, lut_size = 0;
 	union gve_adminq_command cmd;
 	__be32 *lut = NULL;
 	u8 hash_alg = 0;
···
 
 	switch (rxfh->hfunc) {
 	case ETH_RSS_HASH_NO_CHANGE:
-		break;
+		fallthrough;
 	case ETH_RSS_HASH_TOP:
 		hash_alg = ETH_RSS_HASH_TOP;
 		break;
···
 	}
 
 	if (rxfh->indir) {
-		lut_size = priv->rss_lut_size;
+		if (rxfh->indir_size != priv->rss_lut_size)
+			return -EINVAL;
+
+		hash_lut_to_config = rxfh->indir;
+	} else if (priv->cache_rss_config) {
+		hash_lut_to_config = priv->rss_config.hash_lut;
+	}
+
+	if (hash_lut_to_config) {
 		lut = dma_alloc_coherent(&priv->pdev->dev,
-					 lut_size * sizeof(*lut),
+					 priv->rss_lut_size * sizeof(*lut),
 					 &lut_bus, GFP_KERNEL);
 		if (!lut)
 			return -ENOMEM;
 
 		for (i = 0; i < priv->rss_lut_size; i++)
-			lut[i] = cpu_to_be32(rxfh->indir[i]);
+			lut[i] = cpu_to_be32(hash_lut_to_config[i]);
 	}
 
 	if (rxfh->key) {
-		key_size = priv->rss_key_size;
+		if (rxfh->key_size != priv->rss_key_size) {
+			err = -EINVAL;
+			goto out;
+		}
+
+		hash_key_to_config = rxfh->key;
+	} else if (priv->cache_rss_config) {
+		hash_key_to_config = priv->rss_config.hash_key;
+	}
+
+	if (hash_key_to_config) {
 		key = dma_alloc_coherent(&priv->pdev->dev,
-					 key_size, &key_bus, GFP_KERNEL);
+					 priv->rss_key_size,
+					 &key_bus, GFP_KERNEL);
 		if (!key) {
 			err = -ENOMEM;
 			goto out;
 		}
 
-		memcpy(key, rxfh->key, key_size);
+		memcpy(key, hash_key_to_config, priv->rss_key_size);
 	}
 
 	/* Zero-valued fields in the cmd.configure_rss instruct the device to
···
 					  BIT(GVE_RSS_HASH_TCPV6) |
 					  BIT(GVE_RSS_HASH_UDPV6)),
 		.hash_alg = hash_alg,
-		.hash_key_size = cpu_to_be16(key_size),
-		.hash_lut_size = cpu_to_be16(lut_size),
+		.hash_key_size =
+			cpu_to_be16((key_bus) ? priv->rss_key_size : 0),
+		.hash_lut_size =
+			cpu_to_be16((lut_bus) ? priv->rss_lut_size : 0),
 		.hash_key_addr = cpu_to_be64(key_bus),
 		.hash_lut_addr = cpu_to_be64(lut_bus),
 	};
···
 out:
 	if (lut)
 		dma_free_coherent(&priv->pdev->dev,
-				  lut_size * sizeof(*lut),
+				  priv->rss_lut_size * sizeof(*lut),
 				  lut, lut_bus);
 	if (key)
 		dma_free_coherent(&priv->pdev->dev,
-				  key_size, key, key_bus);
+				  priv->rss_key_size, key, key_bus);
 	return err;
 }
 
···
 	rxfh->hfunc = descriptor->hash_alg;
 
 	rss_info_addr = (void *)(descriptor + 1);
-	if (rxfh->key)
+	if (rxfh->key) {
+		rxfh->key_size = priv->rss_key_size;
 		memcpy(rxfh->key, rss_info_addr, priv->rss_key_size);
+	}
 
 	rss_info_addr += priv->rss_key_size;
 	lut = (__be32 *)rss_info_addr;
 	if (rxfh->indir) {
+		rxfh->indir_size = priv->rss_lut_size;
 		for (i = 0; i < priv->rss_lut_size; i++)
 			rxfh->indir[i] = be32_to_cpu(lut[i]);
 	}

drivers/net/ethernet/google/gve/gve_ethtool.c

···
 	struct ethtool_channels old_settings;
 	int new_tx = cmd->tx_count;
 	int new_rx = cmd->rx_count;
+	bool reset_rss = false;
 
 	gve_get_channels(netdev, &old_settings);
 
···
 		return -EINVAL;
 	}
 
-	if (!netif_running(netdev)) {
-		priv->tx_cfg.num_queues = new_tx;
-		priv->rx_cfg.num_queues = new_rx;
-		return 0;
-	}
+	if (new_rx != priv->rx_cfg.num_queues &&
+	    priv->cache_rss_config && !netif_is_rxfh_configured(netdev))
+		reset_rss = true;
 
 	new_tx_cfg.num_queues = new_tx;
 	new_rx_cfg.num_queues = new_rx;
 
-	return gve_adjust_queues(priv, new_rx_cfg, new_tx_cfg);
+	return gve_adjust_queues(priv, new_rx_cfg, new_tx_cfg, reset_rss);
 }
 
 static void gve_get_ringparam(struct net_device *netdev,
···
 	return priv->rss_lut_size;
 }
 
+static void gve_get_rss_config_cache(struct gve_priv *priv,
+				     struct ethtool_rxfh_param *rxfh)
+{
+	struct gve_rss_config *rss_config = &priv->rss_config;
+
+	rxfh->hfunc = ETH_RSS_HASH_TOP;
+
+	if (rxfh->key) {
+		rxfh->key_size = priv->rss_key_size;
+		memcpy(rxfh->key, rss_config->hash_key, priv->rss_key_size);
+	}
+
+	if (rxfh->indir) {
+		rxfh->indir_size = priv->rss_lut_size;
+		memcpy(rxfh->indir, rss_config->hash_lut,
+		       priv->rss_lut_size * sizeof(*rxfh->indir));
+	}
+}
+
 static int gve_get_rxfh(struct net_device *netdev, struct ethtool_rxfh_param *rxfh)
 {
 	struct gve_priv *priv = netdev_priv(netdev);
···
 	if (!priv->rss_key_size || !priv->rss_lut_size)
 		return -EOPNOTSUPP;
 
+	if (priv->cache_rss_config) {
+		gve_get_rss_config_cache(priv, rxfh);
+		return 0;
+	}
+
 	return gve_adminq_query_rss_config(priv, rxfh);
+}
+
+static void gve_set_rss_config_cache(struct gve_priv *priv,
+				     struct ethtool_rxfh_param *rxfh)
+{
+	struct gve_rss_config *rss_config = &priv->rss_config;
+
+	if (rxfh->key)
+		memcpy(rss_config->hash_key, rxfh->key, priv->rss_key_size);
+
+	if (rxfh->indir)
+		memcpy(rss_config->hash_lut, rxfh->indir,
+		       priv->rss_lut_size * sizeof(*rxfh->indir));
 }
 
 static int gve_set_rxfh(struct net_device *netdev, struct ethtool_rxfh_param *rxfh,
 			struct netlink_ext_ack *extack)
 {
 	struct gve_priv *priv = netdev_priv(netdev);
+	int err;
 
 	if (!priv->rss_key_size || !priv->rss_lut_size)
 		return -EOPNOTSUPP;
 
-	return gve_adminq_configure_rss(priv, rxfh);
+	err = gve_adminq_configure_rss(priv, rxfh);
+	if (err) {
+		NL_SET_ERR_MSG_MOD(extack, "Fail to configure RSS config");
+		return err;
+	}
+
+	if (priv->cache_rss_config)
+		gve_set_rss_config_cache(priv, rxfh);
+
+	return 0;
 }
 
 const struct ethtool_ops gve_ethtool_ops = {

drivers/net/ethernet/google/gve/gve_main.c

···
 	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 =
···
 	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;
···
 		}
 	}
 
+	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);
···
 	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);
 
···
 	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);
···
 	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;
···
 	}
 }
 
+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)
···
 
 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};
···
 	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. */
···
 		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;