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, 22 insertions, 0 deletions

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 32ea4fdd3e2b..458e5eaa92e5 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -3874,6 +3874,22 @@ static void igc_del_flex_filter(struct igc_adapter *adapter,
 	wr32(IGC_WUFC, wufc);
 }
 
+static void igc_set_default_queue_filter(struct igc_adapter *adapter, u32 queue)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 mrqc = rd32(IGC_MRQC);
+
+	mrqc &= ~IGC_MRQC_DEFAULT_QUEUE_MASK;
+	mrqc |= FIELD_PREP(IGC_MRQC_DEFAULT_QUEUE_MASK, queue);
+	wr32(IGC_MRQC, mrqc);
+}
+
+static void igc_reset_default_queue_filter(struct igc_adapter *adapter)
+{
+	/* Reset the default queue to its default value which is Queue 0 */
+	igc_set_default_queue_filter(adapter, 0);
+}
+
 static int igc_enable_nfc_rule(struct igc_adapter *adapter,
 			       struct igc_nfc_rule *rule)
 {
@@ -3912,6 +3928,9 @@ static int igc_enable_nfc_rule(struct igc_adapter *adapter,
 			return err;
 	}
 
+	if (rule->filter.match_flags & IGC_FILTER_FLAG_DEFAULT_QUEUE)
+		igc_set_default_queue_filter(adapter, rule->action);
+
 	return 0;
 }
 
@@ -3939,6 +3958,9 @@ static void igc_disable_nfc_rule(struct igc_adapter *adapter,
 	if (rule->filter.match_flags & IGC_FILTER_FLAG_DST_MAC_ADDR)
 		igc_del_mac_filter(adapter, IGC_MAC_FILTER_TYPE_DST,
 				   rule->filter.dst_addr);
+
+	if (rule->filter.match_flags & IGC_FILTER_FLAG_DEFAULT_QUEUE)
+		igc_reset_default_queue_filter(adapter);
 }
 
 /**