On Mon, Apr 15, 2024 at 3:36 PM Jesper Dangaard Brouer <h...@kernel.org> wrote: > > > > On 13/04/2024 06.10, Liang Chen wrote: > > The RSS hash report is a feature that's part of the virtio specification. > > Currently, virtio backends like qemu, vdpa (mlx5), and potentially vhost > > (still a work in progress as per [1]) support this feature. While the > > capability to obtain the RSS hash has been enabled in the normal path, > > it's currently missing in the XDP path. Therefore, we are introducing > > XDP hints through kfuncs to allow XDP programs to access the RSS hash. > > > > 1. > > https://lore.kernel.org/all/20231015141644.260646-1-akihiko.od...@daynix.com/#r > > > > Signed-off-by: Liang Chen <liangchen.li...@gmail.com> > > --- > > Changes from v6: > > - fix a coding style issue > > Changes from v5: > > - Preservation of the hash value has been dropped, following the conclusion > > from discussions in V3 reviews. The virtio_net driver doesn't > > accessing/using the virtio_net_hdr after the XDP program execution, so > > nothing tragic should happen. As to the xdp program, if it smashes the > > entry in virtio header, it is likely buggy anyways. Additionally, looking > > up the Intel IGC driver, it also does not bother with this particular > > aspect. > > --- > > drivers/net/virtio_net.c | 55 ++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 55 insertions(+) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index c22d1118a133..2a1892b7b8d3 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -4621,6 +4621,60 @@ static void virtnet_set_big_packets(struct > > virtnet_info *vi, const int mtu) > > } > > } > > > > +static int virtnet_xdp_rx_hash(const struct xdp_md *_ctx, u32 *hash, > > + enum xdp_rss_hash_type *rss_type) > > +{ > > + const struct xdp_buff *xdp = (void *)_ctx; > > + struct virtio_net_hdr_v1_hash *hdr_hash; > > + struct virtnet_info *vi; > > + > > + if (!(xdp->rxq->dev->features & NETIF_F_RXHASH)) > > + return -ENODATA; > > + > > + vi = netdev_priv(xdp->rxq->dev); > > + hdr_hash = (struct virtio_net_hdr_v1_hash *)(xdp->data - vi->hdr_len); > > + > > + switch (__le16_to_cpu(hdr_hash->hash_report)) { > > + case VIRTIO_NET_HASH_REPORT_TCPv4: > > + *rss_type = XDP_RSS_TYPE_L4_IPV4_TCP; > > + break; > > + case VIRTIO_NET_HASH_REPORT_UDPv4: > > + *rss_type = XDP_RSS_TYPE_L4_IPV4_UDP; > > + break; > > + case VIRTIO_NET_HASH_REPORT_TCPv6: > > + *rss_type = XDP_RSS_TYPE_L4_IPV6_TCP; > > + break; > > + case VIRTIO_NET_HASH_REPORT_UDPv6: > > + *rss_type = XDP_RSS_TYPE_L4_IPV6_UDP; > > + break; > > + case VIRTIO_NET_HASH_REPORT_TCPv6_EX: > > + *rss_type = XDP_RSS_TYPE_L4_IPV6_TCP_EX; > > + break; > > + case VIRTIO_NET_HASH_REPORT_UDPv6_EX: > > + *rss_type = XDP_RSS_TYPE_L4_IPV6_UDP_EX; > > + break; > > + case VIRTIO_NET_HASH_REPORT_IPv4: > > + *rss_type = XDP_RSS_TYPE_L3_IPV4; > > + break; > > + case VIRTIO_NET_HASH_REPORT_IPv6: > > + *rss_type = XDP_RSS_TYPE_L3_IPV6; > > + break; > > + case VIRTIO_NET_HASH_REPORT_IPv6_EX: > > + *rss_type = XDP_RSS_TYPE_L3_IPV6_EX; > > + break; > > + case VIRTIO_NET_HASH_REPORT_NONE: > > + default: > > + *rss_type = XDP_RSS_TYPE_NONE; > > + } > > Why is this not implemented as a table lookup? >
Sure. Thanks for the suggestion! > Like: > > https://elixir.bootlin.com/linux/v6.9-rc4/source/drivers/net/ethernet/intel/igc/igc_main.c#L6652 > https://elixir.bootlin.com/linux/latest/A/ident/xdp_rss_hash_type > > --Jesper > > > + > > + *hash = __le32_to_cpu(hdr_hash->hash_value); > > + return 0; > > +} > > + > > +static const struct xdp_metadata_ops virtnet_xdp_metadata_ops = { > > + .xmo_rx_hash = virtnet_xdp_rx_hash, > > +}; > > + > > static int virtnet_probe(struct virtio_device *vdev) > > { > > int i, err = -ENOMEM; > > @@ -4747,6 +4801,7 @@ static int virtnet_probe(struct virtio_device *vdev) > > VIRTIO_NET_RSS_HASH_TYPE_UDP_EX); > > > > dev->hw_features |= NETIF_F_RXHASH; > > + dev->xdp_metadata_ops = &virtnet_xdp_metadata_ops; > > } > > > > if (vi->has_rss_hash_report)
