virtio_net: Use persistent NAPI config

virtio_net: Use persistent NAPI config

Use persistent NAPI config so that NAPI IDs are not renumbered as queue
counts change.

$ sudo ethtool -l ens4  | tail -5 | egrep -i '(current|combined)'
Current hardware settings:
Combined:       4

$ ./tools/net/ynl/pyynl/cli.py \
    --spec Documentation/netlink/specs/netdev.yaml \
    --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'rx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'type': 'tx'},
 {'id': 1, 'ifindex': 2, 'type': 'tx'},
 {'id': 2, 'ifindex': 2, 'type': 'tx'},
 {'id': 3, 'ifindex': 2, 'type': 'tx'}]

Now adjust the queue count, note that the NAPI IDs are not renumbered:

$ sudo ethtool -L ens4 combined 1
$ ./tools/net/ynl/pyynl/cli.py \
    --spec Documentation/netlink/specs/netdev.yaml \
    --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 0, 'ifindex': 2, 'type': 'tx'}]

$ sudo ethtool -L ens4 combined 8
$ ./tools/net/ynl/pyynl/cli.py \
    --spec Documentation/netlink/specs/netdev.yaml \
    --dump queue-get --json='{"ifindex": 2}'
[{'id': 0, 'ifindex': 2, 'napi-id': 8193, 'type': 'rx'},
 {'id': 1, 'ifindex': 2, 'napi-id': 8194, 'type': 'rx'},
 {'id': 2, 'ifindex': 2, 'napi-id': 8195, 'type': 'rx'},
 {'id': 3, 'ifindex': 2, 'napi-id': 8196, 'type': 'rx'},
 {'id': 4, 'ifindex': 2, 'napi-id': 8197, 'type': 'rx'},
 {'id': 5, 'ifindex': 2, 'napi-id': 8198, 'type': 'rx'},
 {'id': 6, 'ifindex': 2, 'napi-id': 8199, 'type': 'rx'},
 {'id': 7, 'ifindex': 2, 'napi-id': 8200, 'type': 'rx'},
 [...]

Signed-off-by: Joe Damato <jdamato@fastly.com>
Reviewed-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Link: https://patch.msgid.link/20250307011215.266806-5-jdamato@fastly.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>