On Sat, Feb 3, 2024 at 12:20 AM Jesper Dangaard Brouer <h...@kernel.org> wrote: > > > > On 02/02/2024 13.11, 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> > > Reviewed-by: Xuan Zhuo <xuanz...@linux.alibaba.com> > > Acked-by: Jason Wang <jasow...@redhat.com> > > --- > > Changes from v4: > > - cc complete list of maintainers > > --- > > drivers/net/virtio_net.c | 98 +++++++++++++++++++++++++++++++++++----- > > 1 file changed, 86 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index d7ce4a1011ea..7ce666c86ee0 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -349,6 +349,12 @@ struct virtio_net_common_hdr { > > }; > > }; > > > > +struct virtnet_xdp_buff { > > + struct xdp_buff xdp; > > + __le32 hash_value; > > + __le16 hash_report; > > +}; > > + > > static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf); > > > > static bool is_xdp_frame(void *ptr) > > @@ -1033,6 +1039,16 @@ static void put_xdp_frags(struct xdp_buff *xdp) > > } > > } > > > > +static void virtnet_xdp_save_rx_hash(struct virtnet_xdp_buff *virtnet_xdp, > > + struct net_device *dev, > > + struct virtio_net_hdr_v1_hash *hdr_hash) > > +{ > > + if (dev->features & NETIF_F_RXHASH) { > > + virtnet_xdp->hash_value = hdr_hash->hash_value; > > + virtnet_xdp->hash_report = hdr_hash->hash_report; > > + } > > +} > > + > > Would it be possible to store a pointer to hdr_hash in virtnet_xdp_buff, > with the purpose of delaying extracting this, until and only if XDP > bpf_prog calls the kfunc? >
That seems to be the way v1 works, https://lore.kernel.org/all/20240122102256.261374-1-liangchen.li...@gmail.com/ . But it was pointed out that the inline header may be overwritten by the xdp prog, so the hash is copied out to maintain its integrity. Thanks, Liang > > > > static int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff > > *xdp, > > struct net_device *dev, > > unsigned int *xdp_xmit, > > @@ -1199,9 +1215,10 @@ static struct sk_buff *receive_small_xdp(struct > > net_device *dev, > > unsigned int headroom = vi->hdr_len + header_offset; > > struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset; > > struct page *page = virt_to_head_page(buf); > > + struct virtnet_xdp_buff virtnet_xdp; > > struct page *xdp_page; > > + struct xdp_buff *xdp; > > unsigned int buflen; > > - struct xdp_buff xdp; > > struct sk_buff *skb; > > unsigned int metasize = 0; > > u32 act; > > @@ -1233,17 +1250,20 @@ static struct sk_buff *receive_small_xdp(struct > > net_device *dev, > > page = xdp_page; > > } > > > > - xdp_init_buff(&xdp, buflen, &rq->xdp_rxq); > > - xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len, > > + xdp = &virtnet_xdp.xdp; > > + xdp_init_buff(xdp, buflen, &rq->xdp_rxq); > > + xdp_prepare_buff(xdp, buf + VIRTNET_RX_PAD + vi->hdr_len, > > xdp_headroom, len, true); > > > > - act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats); > > + virtnet_xdp_save_rx_hash(&virtnet_xdp, dev, (void *)hdr); > > + > > + act = virtnet_xdp_handler(xdp_prog, xdp, dev, xdp_xmit, stats); > > > > switch (act) { > > case XDP_PASS: > > /* Recalculate length in case bpf program changed it */ > > - len = xdp.data_end - xdp.data; > > - metasize = xdp.data - xdp.data_meta; > > + len = xdp->data_end - xdp->data; > > + metasize = xdp->data - xdp->data_meta; > > break; > > > > case XDP_TX: > > @@ -1254,7 +1274,7 @@ static struct sk_buff *receive_small_xdp(struct > > net_device *dev, > > goto err_xdp; > > } > > > > - skb = virtnet_build_skb(buf, buflen, xdp.data - buf, len); > > + skb = virtnet_build_skb(buf, buflen, xdp->data - buf, len); > > if (unlikely(!skb)) > > goto err; > > > > @@ -1591,10 +1611,11 @@ static struct sk_buff *receive_mergeable_xdp(struct > > net_device *dev, > > int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers); > > struct page *page = virt_to_head_page(buf); > > int offset = buf - page_address(page); > > + struct virtnet_xdp_buff virtnet_xdp; > > unsigned int xdp_frags_truesz = 0; > > struct sk_buff *head_skb; > > unsigned int frame_sz; > > - struct xdp_buff xdp; > > + struct xdp_buff *xdp; > > void *data; > > u32 act; > > int err; > > @@ -1604,16 +1625,19 @@ static struct sk_buff *receive_mergeable_xdp(struct > > net_device *dev, > > if (unlikely(!data)) > > goto err_xdp; > > > > - err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, > > frame_sz, > > + xdp = &virtnet_xdp.xdp; > > + err = virtnet_build_xdp_buff_mrg(dev, vi, rq, xdp, data, len, > > frame_sz, > > &num_buf, &xdp_frags_truesz, stats); > > if (unlikely(err)) > > goto err_xdp; > > > > - act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats); > > + virtnet_xdp_save_rx_hash(&virtnet_xdp, dev, (void *)hdr); > > + > > + act = virtnet_xdp_handler(xdp_prog, xdp, dev, xdp_xmit, stats); > > > > switch (act) { > > case XDP_PASS: > > - head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, > > xdp_frags_truesz); > > + head_skb = build_skb_from_xdp_buff(dev, vi, xdp, > > xdp_frags_truesz); > > if (unlikely(!head_skb)) > > break; > > return head_skb; > > @@ -1626,7 +1650,7 @@ static struct sk_buff *receive_mergeable_xdp(struct > > net_device *dev, > > break; > > } > > > > - put_xdp_frags(&xdp); > > + put_xdp_frags(xdp); > > > > err_xdp: > > put_page(page); > > @@ -4579,6 +4603,55 @@ 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 virtnet_xdp_buff *virtnet_xdp = (void *)_ctx; > > + > > + if (!(virtnet_xdp->xdp.rxq->dev->features & NETIF_F_RXHASH)) > > + return -ENODATA; > > + > > + switch (__le16_to_cpu(virtnet_xdp->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; > > + } > > + > > + *hash = __le32_to_cpu(virtnet_xdp->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; > > @@ -4704,6 +4777,7 @@ 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)
