From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 40E9928DA4; Mon, 15 Apr 2024 07:36:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713166590; cv=none; b=eJN3Qt5iOgeDhPR0PUb49PI+BkaUw7seR+Mze4abKk7MMFponb1/qLc2kyopzU6DZnAeLkhw6WtsExSxlX+/Y36E4GrKh01YuNl11vdgpmjMCm2+lk9WrywlKpsPVXP9WEr1AVqGWswMcpMp/fuSlgxUbNSkPfkLXPgz1Z5YQC8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713166590; c=relaxed/simple; bh=QEw7la3k+1B4uCDc5JgoVTPpyYgSenrHp3AkQ1ZVoJU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bSyCdcw0LAnGgSFuwhA5FBXrLBvQTRXIJYwAVi8hgpthfYuaeTyAkQuFzfsdSok8p48/taJVyPle90Eqjapww5cmyObmimlrasBBqOatlsZ1JtXhos0DnHuVZOaoZZWhZc0a36V+NuK1ZHBnR8VITt+V4zn53ujZxB4z+08woYk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YyRLmHiy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YyRLmHiy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CBFF7C113CC; Mon, 15 Apr 2024 07:36:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713166589; bh=QEw7la3k+1B4uCDc5JgoVTPpyYgSenrHp3AkQ1ZVoJU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=YyRLmHiyug+86g4mlvEV92WKvQWj+LlNyCyjYn5muAT8/zLjDAb59Hv0bmqyWxrS4 rV+0tP4dKrzcp6qN9fwibJ0+Ol/j+n8lSLPYtdKvjBvAoxm4gqX/5agtxIPm95FGhx QQXBXMCKyVsJy5GF1jz6fLxB4af0/yZ2DRukpSd1JvHd2RhC0pK4ZKfvyuZ17mbfdf XooX7dDXA7p/RONR4G6I1x/dQ6aDeUGFiNC6Ep3IZ9yuVRYjGpk7xzJ530pcsW3Yha ZhNOT1v5UnD5NZOLhQBySfy4NPVr7HJ/Q/nadoj+zG03v+C69+zLxrBB3KVQ+asp2j bRIvoNGTRXjrg== Message-ID: <01c82cfb-e215-4929-9540-484378275ec3@kernel.org> Date: Mon, 15 Apr 2024 09:36:25 +0200 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v7] virtio_net: Support RX hash XDP hint To: Liang Chen , mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, hengqi@linux.alibaba.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: netdev@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, john.fastabend@gmail.com, daniel@iogearbox.net, ast@kernel.org References: <20240413041035.7344-1-liangchen.linux@gmail.com> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <20240413041035.7344-1-liangchen.linux@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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.odaki@daynix.com/#r > > Signed-off-by: Liang Chen > --- > 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? 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)