On Tue, Apr 16, 2024 at 3:35 PM Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> wrote: > > > > 在 2024/4/16 下午2:19, Liang Chen 写道: > > 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.odaki@xxxxxxxxxx/#r > > > > Signed-off-by: Liang Chen <liangchen.linux@xxxxxxxxx> > > --- > > Changes from v7: > > - use table lookup for rss hash type > > 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 | 42 +++++++++++++++++++++++++++++++++ > > include/uapi/linux/virtio_net.h | 1 + > > 2 files changed, 43 insertions(+) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index c22d1118a133..1d750009f615 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -4621,6 +4621,47 @@ static void virtnet_set_big_packets(struct virtnet_info *vi, const int mtu) > > } > > } > > > > +static enum xdp_rss_hash_type > > +virtnet_xdp_rss_type[VIRTIO_NET_HASH_REPORT_MAX_TABLE] = { > > + [VIRTIO_NET_HASH_REPORT_NONE] = XDP_RSS_TYPE_NONE, > > + [VIRTIO_NET_HASH_REPORT_IPv4] = XDP_RSS_TYPE_L3_IPV4, > > + [VIRTIO_NET_HASH_REPORT_TCPv4] = XDP_RSS_TYPE_L4_IPV4_TCP, > > + [VIRTIO_NET_HASH_REPORT_UDPv4] = XDP_RSS_TYPE_L4_IPV4_UDP, > > + [VIRTIO_NET_HASH_REPORT_IPv6] = XDP_RSS_TYPE_L3_IPV6, > > + [VIRTIO_NET_HASH_REPORT_TCPv6] = XDP_RSS_TYPE_L4_IPV6_TCP, > > + [VIRTIO_NET_HASH_REPORT_UDPv6] = XDP_RSS_TYPE_L4_IPV6_UDP, > > + [VIRTIO_NET_HASH_REPORT_IPv6_EX] = XDP_RSS_TYPE_L3_IPV6_EX, > > + [VIRTIO_NET_HASH_REPORT_TCPv6_EX] = XDP_RSS_TYPE_L4_IPV6_TCP_EX, > > + [VIRTIO_NET_HASH_REPORT_UDPv6_EX] = XDP_RSS_TYPE_L4_IPV6_UDP_EX > > +}; > > + > > +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; > > + u16 hash_report; > > + > > + 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); > > + hash_report = __le16_to_cpu(hdr_hash->hash_report); > > + > > + if (hash_report >= VIRTIO_NET_HASH_REPORT_MAX_TABLE) > > + hash_report = VIRTIO_NET_HASH_REPORT_NONE; > > When this happens, it may mean an error or user modification of the > header occurred. > Should the following *hash* value be cleared to 0? > Referring to the igc and mlx5 drivers, the hash value is not cleared to 0 in such cases either. This is because if the rss type is XDP_RSS_TYPE_NONE, the hash value is considered to be not relevant. Thanks! > Thanks, > Heng > > > + > > + *rss_type = virtnet_xdp_rss_type[hash_report]; > > + *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 +4788,7 @@ 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) > > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > > index cc65ef0f3c3e..3ee695450096 100644 > > --- a/include/uapi/linux/virtio_net.h > > +++ b/include/uapi/linux/virtio_net.h > > @@ -176,6 +176,7 @@ struct virtio_net_hdr_v1_hash { > > #define VIRTIO_NET_HASH_REPORT_IPv6_EX 7 > > #define VIRTIO_NET_HASH_REPORT_TCPv6_EX 8 > > #define VIRTIO_NET_HASH_REPORT_UDPv6_EX 9 > > +#define VIRTIO_NET_HASH_REPORT_MAX_TABLE 10 > > __le16 hash_report; > > __le16 padding; > > }; >
