Re: [PATCH net-next v6 3/4] virtio-net: Map NAPIs to queues

[Jason Wang <jasowang@redhat.com>]

On Fri, Mar 7, 2025 at 9:12 AM Joe Damato <jdamato@fastly.com> wrote:
>
> Use netif_queue_set_napi to map NAPIs to queue IDs so that the mapping
> can be accessed by user apps. Note that the netif_queue_set_napi
> currently requires RTNL, so care must be taken to ensure RTNL is held on
> paths where this API might be reached.
>
> The paths in the driver where this API can be reached appear to be:
>
>   - ndo_open, ndo_close, which hold RTNL so no driver change is needed.
>   - rx_pause, rx_resume, tx_pause, tx_resume are reached either via
>     an ethtool ioctl or via XSK - neither path requires a driver change.
>   - power management paths (which call open and close), which have been
>     updated to hold/release RTNL.
>
> $ ethtool -i ens4 | grep driver
> driver: virtio_net
>
> $ sudo ethtool -L ens4 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': 8289, 'type': 'rx'},
>  {'id': 1, 'ifindex': 2, 'napi-id': 8290, 'type': 'rx'},
>  {'id': 2, 'ifindex': 2, 'napi-id': 8291, 'type': 'rx'},
>  {'id': 3, 'ifindex': 2, 'napi-id': 8292, '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'}]
>
> Note that virtio_net has TX-only NAPIs which do not have NAPI IDs, so
> the lack of 'napi-id' in the above output is expected.
>
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks