igc: Link IRQs to NAPI instances

Link IRQs to NAPI instances via netdev-genl API so that users can query
this information with netlink.

Compare the output of /proc/interrupts (noting that IRQ 128 is the
"other" IRQ which does not appear to have a NAPI instance):

$ cat /proc/interrupts | grep enp86s0 | cut --delimiter=":" -f1
 128
 129
 130
 131
 132

The output from netlink shows the mapping of NAPI IDs to IRQs (again
noting that 128 is absent as it is the "other" IRQ):

$ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
                         --dump napi-get --json='{"ifindex": 2}'

[{'defer-hard-irqs': 0,
  'gro-flush-timeout': 0,
  'id': 8196,
  'ifindex': 2,
  'irq': 132},
 {'defer-hard-irqs': 0,
  'gro-flush-timeout': 0,
  'id': 8195,
  'ifindex': 2,
  'irq': 131},
 {'defer-hard-irqs': 0,
  'gro-flush-timeout': 0,
  'id': 8194,
  'ifindex': 2,
  'irq': 130},
 {'defer-hard-irqs': 0,
  'gro-flush-timeout': 0,
  'id': 8193,
  'ifindex': 2,
  'irq': 129}]

Signed-off-by: Joe Damato <[email protected]>
Reviewed-by: Vitaly Lifshits <[email protected]>
Tested-by: Avigail Dahan <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: jdamato-fsly

drivers/net/ethernet/intel/igc/igc_main.c

@@ -5570,6 +5570,9 @@ static int igc_request_msix(struct igc_adapter *adapter)
 				  q_vector);
 		if (err)
 			goto err_free;
+
+		netif_napi_set_irq(&q_vector->napi,
+				   adapter->msix_entries[vector].vector);
 	}
 
 	igc_configure_msix(adapter);