igc: Add wildcard rule support to ethtool NFC using Default Queue

Introduce support for a lowest priority wildcard (catch-all) rule in
ethtool's Network Flow Classification (NFC) for the igc driver. The
wildcard rule directs all unmatched network traffic, including traffic not
captured by Receive Side Scaling (RSS), to a specified queue. This
functionality utilizes the Default Queue feature available in I225/I226
hardware.

The implementation has been validated on Intel ADL-S systems with two
back-to-back connected I226 network interfaces.

Testing Procedure:
1. On the Device Under Test (DUT), verify the initial statistic:
   $ ethtool -S enp1s0 | grep rx_q.*packets
        rx_queue_0_packets: 0
        rx_queue_1_packets: 0
        rx_queue_2_packets: 0
        rx_queue_3_packets: 0

2. From the Link Partner, send 10 ARP packets:
   $ arping -c 10 -I enp170s0 169.254.1.2

3. On the DUT, verify the packet reception on Queue 0:
   $ ethtool -S enp1s0 | grep rx_q.*packets
        rx_queue_0_packets: 10
        rx_queue_1_packets: 0
        rx_queue_2_packets: 0
        rx_queue_3_packets: 0

4. On the DUT, add a wildcard rule to route all packets to Queue 3:
   $ sudo ethtool -N enp1s0 flow-type ether queue 3

5. From the Link Partner, send another 10 ARP packets:
   $ arping -c 10 -I enp170s0 169.254.1.2

6. Now, packets are routed to Queue 3 by the wildcard (Default Queue) rule:
   $ ethtool -S enp1s0 | grep rx_q.*packets
        rx_queue_0_packets: 10
        rx_queue_1_packets: 0
        rx_queue_2_packets: 0
        rx_queue_3_packets: 10

7. On the DUT, add a EtherType rule to route ARP packet to Queue 1:
   $ sudo ethtool -N enp1s0 flow-type ether proto 0x0806 queue 1

8. From the Link Partner, send another 10 ARP packets:
   $ arping -c 10 -I enp170s0 169.254.1.2

9. Now, packets are routed to Queue 1 by the EtherType rule because it is
   higher priority than the wildcard (Default Queue) rule:
   $ ethtool -S enp1s0 | grep rx_q.*packets
        rx_queue_0_packets: 10
        rx_queue_1_packets: 10
        rx_queue_2_packets: 0
        rx_queue_3_packets: 10

10. On the DUT, delete all the NFC rules:
    $ sudo ethtool -N enp1s0 delete 63
    $ sudo ethtool -N enp1s0 delete 64

11. From the Link Partner, send another 10 ARP packets:
    $ arping -c 10 -I enp170s0 169.254.1.2

12. Now, packets are routed to Queue 0 because the value of Default Queue
    is reset back to 0:
    $ ethtool -S enp1s0 | grep rx_q.*packets
         rx_queue_0_packets: 20
         rx_queue_1_packets: 10
         rx_queue_2_packets: 0
         rx_queue_3_packets: 10

Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Co-developed-by: Blanco Alcaine Hector <hector.blanco.alcaine@intel.com>
Signed-off-by: Blanco Alcaine Hector <hector.blanco.alcaine@intel.com>
Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index a7f397b58cd6..ecb35b693ce5 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -1283,6 +1283,24 @@ static void igc_ethtool_init_nfc_rule(struct igc_nfc_rule *rule,
 		rule->flex = true;
 	else
 		rule->flex = false;
+
+	/* The wildcard rule is only applied if:
+	 *  a) None of the other filtering rules match (match_flags is zero)
+	 *  b) The flow type is ETHER_FLOW only (no additional fields set)
+	 *  c) Mask for Source MAC address is not specified (all zeros)
+	 *  d) Mask for Destination MAC address is not specified (all zeros)
+	 *  e) Mask for L2 EtherType is not specified (zero)
+	 *
+	 * If all these conditions are met, the rule is treated as a wildcard
+	 * rule. Default queue feature will be used, so that all packets that do
+	 * not match any other rule will be routed to the default queue.
+	 */
+	if (!rule->filter.match_flags &&
+	    fsp->flow_type == ETHER_FLOW &&
+	    is_zero_ether_addr(fsp->m_u.ether_spec.h_source) &&
+	    is_zero_ether_addr(fsp->m_u.ether_spec.h_dest) &&
+	    !fsp->m_u.ether_spec.h_proto)
+		rule->filter.match_flags = IGC_FILTER_FLAG_DEFAULT_QUEUE;
 }
 
 /**