sfc: Implement hardware acceleration of RFS

Use the existing filter management functions to insert TCP/IPv4 and
UDP/IPv4 4-tuple filters for Receive Flow Steering.

For each channel, track how many RFS filters are being added during
processing of received packets and scan the corresponding number of
table entries for filters that may be reclaimed.  Do this in batches
to reduce lock overhead.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/drivers/net/sfc/filter.c b/drivers/net/sfc/filter.c
index 47a1b79..95a980f 100644
--- a/drivers/net/sfc/filter.c
+++ b/drivers/net/sfc/filter.c
@@ -8,6 +8,7 @@
  */
 
 #include <linux/in.h>
+#include <net/ip.h>
 #include "efx.h"
 #include "filter.h"
 #include "io.h"
@@ -51,6 +52,10 @@ struct efx_filter_table {
 struct efx_filter_state {
 	spinlock_t	lock;
 	struct efx_filter_table table[EFX_FILTER_TABLE_COUNT];
+#ifdef CONFIG_RFS_ACCEL
+	u32		*rps_flow_id;
+	unsigned	rps_expire_index;
+#endif
 };
 
 /* The filter hash function is LFSR polynomial x^16 + x^3 + 1 of a 32-bit
@@ -567,6 +572,13 @@ int efx_probe_filters(struct efx_nic *efx)
 	spin_lock_init(&state->lock);
 
 	if (efx_nic_rev(efx) >= EFX_REV_FALCON_B0) {
+#ifdef CONFIG_RFS_ACCEL
+		state->rps_flow_id = kcalloc(FR_BZ_RX_FILTER_TBL0_ROWS,
+					     sizeof(*state->rps_flow_id),
+					     GFP_KERNEL);
+		if (!state->rps_flow_id)
+			goto fail;
+#endif
 		table = &state->table[EFX_FILTER_TABLE_RX_IP];
 		table->id = EFX_FILTER_TABLE_RX_IP;
 		table->offset = FR_BZ_RX_FILTER_TBL0;
@@ -612,5 +624,97 @@ void efx_remove_filters(struct efx_nic *efx)
 		kfree(state->table[table_id].used_bitmap);
 		vfree(state->table[table_id].spec);
 	}
+#ifdef CONFIG_RFS_ACCEL
+	kfree(state->rps_flow_id);
+#endif
 	kfree(state);
 }
+
+#ifdef CONFIG_RFS_ACCEL
+
+int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb,
+		   u16 rxq_index, u32 flow_id)
+{
+	struct efx_nic *efx = netdev_priv(net_dev);
+	struct efx_channel *channel;
+	struct efx_filter_state *state = efx->filter_state;
+	struct efx_filter_spec spec;
+	const struct iphdr *ip;
+	const __be16 *ports;
+	int nhoff;
+	int rc;
+
+	nhoff = skb_network_offset(skb);
+
+	if (skb->protocol != htons(ETH_P_IP))
+		return -EPROTONOSUPPORT;
+
+	/* RFS must validate the IP header length before calling us */
+	EFX_BUG_ON_PARANOID(!pskb_may_pull(skb, nhoff + sizeof(*ip)));
+	ip = (const struct iphdr *)(skb->data + nhoff);
+	if (ip->frag_off & htons(IP_MF | IP_OFFSET))
+		return -EPROTONOSUPPORT;
+	EFX_BUG_ON_PARANOID(!pskb_may_pull(skb, nhoff + 4 * ip->ihl + 4));
+	ports = (const __be16 *)(skb->data + nhoff + 4 * ip->ihl);
+
+	efx_filter_init_rx(&spec, EFX_FILTER_PRI_HINT, 0, rxq_index);
+	rc = efx_filter_set_ipv4_full(&spec, ip->protocol,
+				      ip->daddr, ports[1], ip->saddr, ports[0]);
+	if (rc)
+		return rc;
+
+	rc = efx_filter_insert_filter(efx, &spec, true);
+	if (rc < 0)
+		return rc;
+
+	/* Remember this so we can check whether to expire the filter later */
+	state->rps_flow_id[rc] = flow_id;
+	channel = efx_get_channel(efx, skb_get_rx_queue(skb));
+	++channel->rfs_filters_added;
+
+	netif_info(efx, rx_status, efx->net_dev,
+		   "steering %s %pI4:%u:%pI4:%u to queue %u [flow %u filter %d]\n",
+		   (ip->protocol == IPPROTO_TCP) ? "TCP" : "UDP",
+		   &ip->saddr, ntohs(ports[0]), &ip->daddr, ntohs(ports[1]),
+		   rxq_index, flow_id, rc);
+
+	return rc;
+}
+
+bool __efx_filter_rfs_expire(struct efx_nic *efx, unsigned quota)
+{
+	struct efx_filter_state *state = efx->filter_state;
+	struct efx_filter_table *table = &state->table[EFX_FILTER_TABLE_RX_IP];
+	unsigned mask = table->size - 1;
+	unsigned index;
+	unsigned stop;
+
+	if (!spin_trylock_bh(&state->lock))
+		return false;
+
+	index = state->rps_expire_index;
+	stop = (index + quota) & mask;
+
+	while (index != stop) {
+		if (test_bit(index, table->used_bitmap) &&
+		    table->spec[index].priority == EFX_FILTER_PRI_HINT &&
+		    rps_may_expire_flow(efx->net_dev,
+					table->spec[index].dmaq_id,
+					state->rps_flow_id[index], index)) {
+			netif_info(efx, rx_status, efx->net_dev,
+				   "expiring filter %d [flow %u]\n",
+				   index, state->rps_flow_id[index]);
+			efx_filter_table_clear_entry(efx, table, index);
+		}
+		index = (index + 1) & mask;
+	}
+
+	state->rps_expire_index = stop;
+	if (table->used == 0)
+		efx_filter_table_reset_search_depth(table);
+
+	spin_unlock_bh(&state->lock);
+	return true;
+}
+
+#endif /* CONFIG_RFS_ACCEL */