From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Network Development <netdev@vger.kernel.org>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH rfc 2/3] virtio-net: support receive timestamp
Date: Tue, 2 Feb 2021 17:17:13 -0500 [thread overview]
Message-ID: <CA+FuTSeEVvtmmQ2HioTUrA6nX9s6yLEvNXfg=fLKw6X+E9wWow@mail.gmail.com> (raw)
In-Reply-To: <20210202090724-mutt-send-email-mst@kernel.org>
On Tue, Feb 2, 2021 at 9:08 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Dec 28, 2020 at 11:22:32AM -0500, Willem de Bruijn wrote:
> > From: Willem de Bruijn <willemb@google.com>
> >
> > 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 <willemb@google.com>
> > ---
> > 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?
> > + __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 have a revised patchset almost ready. I suppose I should send it as
RFC again, and simultaneously file an OASIS ballot for each feature?
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next prev parent reply other threads:[~2021-02-02 22:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 16:22 [PATCH rfc 0/3] virtio-net: add tx-hash, rx-tstamp and tx-tstamp Willem de Bruijn
2020-12-28 16:22 ` [PATCH rfc 1/3] virtio-net: support transmit hash report Willem de Bruijn
2020-12-28 16:28 ` Michael S. Tsirkin
2020-12-28 16:47 ` Willem de Bruijn
2020-12-28 17:22 ` Michael S. Tsirkin
2020-12-29 1:19 ` Willem de Bruijn
2020-12-28 21:36 ` Michael S. Tsirkin
2020-12-29 1:23 ` Willem de Bruijn
2020-12-28 16:22 ` [PATCH rfc 2/3] virtio-net: support receive timestamp Willem de Bruijn
2020-12-28 17:28 ` Michael S. Tsirkin
2020-12-28 19:30 ` Willem de Bruijn
2020-12-28 21:32 ` Michael S. Tsirkin
2020-12-29 1:05 ` Willem de Bruijn
2020-12-29 9:17 ` Jason Wang
2020-12-29 14:20 ` Willem de Bruijn
2020-12-30 8:38 ` Jason Wang
[not found] ` <20201228145953.08673c8c@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
2020-12-29 0:57 ` Willem de Bruijn
2020-12-30 8:44 ` Jason Wang
2021-02-02 13:05 ` kernel test robot
2021-02-02 14:08 ` Michael S. Tsirkin
2021-02-02 22:17 ` Willem de Bruijn [this message]
2021-02-02 23:02 ` Michael S. Tsirkin
2021-02-02 23:43 ` Willem de Bruijn
2020-12-28 16:22 ` [PATCH rfc 3/3] virtio-net: support transmit timestamp Willem de Bruijn
[not found] ` <20201230123854.GB2034@hoboy.vegasvil.org>
2020-12-30 15:25 ` Willem de Bruijn
2021-02-02 13:47 ` kernel test robot
2020-12-28 17:29 ` [PATCH rfc 0/3] virtio-net: add tx-hash, rx-tstamp and tx-tstamp Michael S. Tsirkin
2020-12-28 19:51 ` Willem de Bruijn
2020-12-28 21:38 ` Michael S. Tsirkin
2020-12-29 1:14 ` Willem de Bruijn
2021-01-06 20:32 ` Willem de Bruijn
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