From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ABFA5C433E0 for ; Tue, 2 Feb 2021 23:04:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6837364F72 for ; Tue, 2 Feb 2021 23:04:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236030AbhBBXES (ORCPT ); Tue, 2 Feb 2021 18:04:18 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:32896 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233464AbhBBXEJ (ORCPT ); Tue, 2 Feb 2021 18:04:09 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612306962; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LDg4iKymZ53hNxtNIr/W8exxkDX1y1fBofy+s8scyQM=; b=Iy/yIy0C5jC7Aa87QUL1rbg0jR5Kf3jTXS3Z8DBVWIH1w7ZW+hK2tu9Ys1Ja9/DAXtJrcL npbDJ1PoL7ZNdIK1wMI0Ih8b2UrK1+NbeMnuqDOpF04uaGknfNntif5TMJAEVn5nAu+B9P jMkU7HmWiC8a8ek1D2Kj/OrbBvAPPqY= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-494-nMHFUV9hNRmme8ON7ZQAIw-1; Tue, 02 Feb 2021 18:02:40 -0500 X-MC-Unique: nMHFUV9hNRmme8ON7ZQAIw-1 Received: by mail-wr1-f70.google.com with SMTP id l13so13317593wrq.7 for ; Tue, 02 Feb 2021 15:02:40 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=LDg4iKymZ53hNxtNIr/W8exxkDX1y1fBofy+s8scyQM=; b=bMqz+Jk3TTbSudhEWtkr7vI+1l8xgHkwjKc2NcQArXgt4vbE+M/L6A7DeVDkZaMIiy u/fmTIXjOvX6I20prEvZi0M3zbZLyBypWTSYhy+Y49rys73eU+JazDx6T0fUE9VTy7BA lVUQxwEJ2wTL+GFTJK8Dyz+AqIiLOWQxGAxQN6HQNvjxefKpNkLl+8K7Wse9/GD1tIGA cUlnQuydEZCQHkWlN0cM+ww99up1bUId+YgQJMhAn5HOmiQGoWwVx+15c1S3MFySpYAA O16Pic7Cw9SEKB57UPHdg11OK5U5Inqa9qymgsfvM5dhXlj3yRq0ATt0vlhAqcnI7/QC +vJQ== X-Gm-Message-State: AOAM532Yub+piLnR08ajQc8PnZf8OmN6iScK5pLYFJLI+84E0G1n8cyQ 4Rp8b4mDYjQIMCKlwmaBNVoFcn0/W/fIP9REksT8HVBDt9XNkf1Ul11oFCFr6tuBrF/5cQL0A0o TvtcpxgnTqWY7/E6d X-Received: by 2002:adf:cd83:: with SMTP id q3mr317042wrj.225.1612306958847; Tue, 02 Feb 2021 15:02:38 -0800 (PST) X-Google-Smtp-Source: ABdhPJy7ozq2UgBjdAGg7+Fmg2ziWMUdJw6kuyXQQMlyA3fQ392T9ZIlR5Tv21sW6hC+KMtJGHELFg== X-Received: by 2002:adf:cd83:: with SMTP id q3mr317029wrj.225.1612306958663; Tue, 02 Feb 2021 15:02:38 -0800 (PST) Received: from redhat.com (bzq-79-177-39-148.red.bezeqint.net. [79.177.39.148]) by smtp.gmail.com with ESMTPSA id s4sm89994wrt.85.2021.02.02.15.02.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Feb 2021 15:02:37 -0800 (PST) Date: Tue, 2 Feb 2021 18:02:35 -0500 From: "Michael S. Tsirkin" To: Willem de Bruijn Cc: virtualization@lists.linux-foundation.org, Network Development , Jason Wang Subject: Re: [PATCH rfc 2/3] virtio-net: support receive timestamp Message-ID: <20210202175934-mutt-send-email-mst@kernel.org> References: <20201228162233.2032571-1-willemdebruijn.kernel@gmail.com> <20201228162233.2032571-3-willemdebruijn.kernel@gmail.com> <20210202090724-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Feb 02, 2021 at 05:17:13PM -0500, Willem de Bruijn wrote: > On Tue, Feb 2, 2021 at 9:08 AM Michael S. Tsirkin wrote: > > > > On Mon, Dec 28, 2020 at 11:22:32AM -0500, Willem de Bruijn wrote: > > > From: Willem de Bruijn > > > > > > Add optional PTP hardware timestamp offload for virtio-net. > > > > > > Accurate RTT measurement requires timestamps close to the wire. > > > Introduce virtio feature VIRTIO_NET_F_RX_TSTAMP. If negotiated, the > > > virtio-net header is expanded with room for a timestamp. A host may > > > pass receive timestamps for all or some packets. A timestamp is valid > > > if non-zero. > > > > > > The timestamp straddles (virtual) hardware domains. Like PTP, use > > > international atomic time (CLOCK_TAI) as global clock base. It is > > > guest responsibility to sync with host, e.g., through kvm-clock. > > > > > > Signed-off-by: Willem de Bruijn > > > --- > > > drivers/net/virtio_net.c | 20 +++++++++++++++++++- > > > include/uapi/linux/virtio_net.h | 12 ++++++++++++ > > > 2 files changed, 31 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > > index b917b7333928..57744bb6a141 100644 > > > --- a/drivers/net/virtio_net.c > > > +++ b/drivers/net/virtio_net.c > > > @@ -204,6 +204,9 @@ struct virtnet_info { > > > /* Guest will pass tx path info to the host */ > > > bool has_tx_hash; > > > > > > + /* Host will pass CLOCK_TAI receive time to the guest */ > > > + bool has_rx_tstamp; > > > + > > > /* Has control virtqueue */ > > > bool has_cvq; > > > > > > @@ -292,6 +295,13 @@ static inline struct virtio_net_hdr_mrg_rxbuf *skb_vnet_hdr(struct sk_buff *skb) > > > return (struct virtio_net_hdr_mrg_rxbuf *)skb->cb; > > > } > > > > > > +static inline struct virtio_net_hdr_v12 *skb_vnet_hdr_12(struct sk_buff *skb) > > > +{ > > > + BUILD_BUG_ON(sizeof(struct virtio_net_hdr_v12) > sizeof(skb->cb)); > > > + > > > + return (void *)skb->cb; > > > +} > > > + > > > /* > > > * private is used to chain pages for big packets, put the whole > > > * most recent used list in the beginning for reuse > > > @@ -1082,6 +1092,9 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq, > > > goto frame_err; > > > } > > > > > > + if (vi->has_rx_tstamp) > > > + skb_hwtstamps(skb)->hwtstamp = ns_to_ktime(skb_vnet_hdr_12(skb)->tstamp); > > > + > > > skb_record_rx_queue(skb, vq2rxq(rq->vq)); > > > skb->protocol = eth_type_trans(skb, dev); > > > pr_debug("Receiving skb proto 0x%04x len %i type %i\n", > > > @@ -3071,6 +3084,11 @@ static int virtnet_probe(struct virtio_device *vdev) > > > vi->hdr_len = sizeof(struct virtio_net_hdr_v1_hash); > > > } > > > > > > + if (virtio_has_feature(vdev, VIRTIO_NET_F_RX_TSTAMP)) { > > > + vi->has_rx_tstamp = true; > > > + vi->hdr_len = sizeof(struct virtio_net_hdr_v12); > > > + } > > > + > > > if (virtio_has_feature(vdev, VIRTIO_F_ANY_LAYOUT) || > > > virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) > > > vi->any_header_sg = true; > > > @@ -3261,7 +3279,7 @@ static struct virtio_device_id id_table[] = { > > > VIRTIO_NET_F_CTRL_MAC_ADDR, \ > > > VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \ > > > VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \ > > > - VIRTIO_NET_F_TX_HASH > > > + VIRTIO_NET_F_TX_HASH, VIRTIO_NET_F_RX_TSTAMP > > > > > > static unsigned int features[] = { > > > VIRTNET_FEATURES, > > > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > > > index f6881b5b77ee..0ffe2eeebd4a 100644 > > > --- a/include/uapi/linux/virtio_net.h > > > +++ b/include/uapi/linux/virtio_net.h > > > @@ -57,6 +57,7 @@ > > > * Steering */ > > > #define VIRTIO_NET_F_CTRL_MAC_ADDR 23 /* Set MAC address */ > > > > > > +#define VIRTIO_NET_F_RX_TSTAMP 55 /* Host sends TAI receive time */ > > > #define VIRTIO_NET_F_TX_HASH 56 /* Guest sends hash report */ > > > #define VIRTIO_NET_F_HASH_REPORT 57 /* Supports hash report */ > > > #define VIRTIO_NET_F_RSS 60 /* Supports RSS RX steering */ > > > @@ -182,6 +183,17 @@ struct virtio_net_hdr_v1_hash { > > > }; > > > }; > > > > > > +struct virtio_net_hdr_v12 { > > > + struct virtio_net_hdr_v1 hdr; > > > + struct { > > > + __le32 value; > > > + __le16 report; > > > + __le16 flow_state; > > > + } hash; > > > + __virtio32 reserved; > > > > > > Does endian-ness matter? If not - just u32? > > I suppose it does not matter as long as this is reserved. Should it be > __le32, at least? One can safely assign 0 to any value. > > > + __virtio64 tstamp; > > > +}; > > > + > > > > Given it's only available in modern devices, I think we > > can make this __le64 tstamp. > > Actually, would it be possible to make new features available on > legacy devices? There is nothing in the features bits precluding it. I think it won't be possible: you are using feature bit 55, legacy devices have up to 32 feature bits. And of course the header looks a bit differently for legacy, you would have to add special code to handle that when mergeable buffers are off. > > I have a revised patchset almost ready. I suppose I should send it as > RFC again, and simultaneously file an OASIS ballot for each feature? that would be great. -- MST