Re: [PATCH V4 net-next 3/3] virtio-net: synchronize operstate with admin state on up/down

From: Jason Wang
Date: Wed Jul 31 2024 - 22:25:32 EST

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In reply to: Michael S. Tsirkin: "Re: [PATCH V4 net-next 3/3] virtio-net: synchronize operstate with admin state on up/down"
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On Thu, Aug 1, 2024 at 5:26 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> On Wed, Jul 31, 2024 at 10:59:47AM +0800, Jason Wang wrote:
> > This patch synchronize operstate with admin state per RFC2863.
> >
> > This is done by trying to toggle the carrier upon open/close and
> > synchronize with the config change work. This allows propagate status
> > correctly to stacked devices like:
> >
> > ip link add link enp0s3 macvlan0 type macvlan
> > ip link set link enp0s3 down
> > ip link show
> >
> > Before this patch:
> >
> > 3: enp0s3: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
> > link/ether 00:00:05:00:00:09 brd ff:ff:ff:ff:ff:ff
> > ......
> > 5: macvlan0@enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
> > link/ether b2:a9:c5:04:da:53 brd ff:ff:ff:ff:ff:ff
> >
> > After this patch:
> >
> > 3: enp0s3: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
> > link/ether 00:00:05:00:00:09 brd ff:ff:ff:ff:ff:ff
> > ...
> > 5: macvlan0@enp0s3: <NO-CARRIER,BROADCAST,MULTICAST,UP,M-DOWN> mtu 1500 qdisc noqueue state LOWERLAYERDOWN mode DEFAULT group default qlen 1000
> > link/ether b2:a9:c5:04:da:53 brd ff:ff:ff:ff:ff:ff
> >
> > Cc: Venkat Venkatsubra <venkat.x.venkatsubra@xxxxxxxxxx>
> > Cc: Gia-Khanh Nguyen <gia-khanh.nguyen@xxxxxxxxxx>
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> Changelog?

In the cover letter actually.

>
> > ---
> > drivers/net/virtio_net.c | 84 ++++++++++++++++++++++++++--------------
> > 1 file changed, 54 insertions(+), 30 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 0383a3e136d6..0cb93261eba1 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2878,6 +2878,7 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
> > return err;
> > }
> >
> > +
> > static void virtnet_cancel_dim(struct virtnet_info *vi, struct dim *dim)
> > {
> > if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
>
> hmm
>
> > @@ -2885,6 +2886,25 @@ static void virtnet_cancel_dim(struct virtnet_info *vi, struct dim *dim)
> > net_dim_work_cancel(dim);
> > }
> >
> > +static void virtnet_update_settings(struct virtnet_info *vi)
> > +{
> > + u32 speed;
> > + u8 duplex;
> > +
> > + if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
> > + return;
> > +
> > + virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
> > +
> > + if (ethtool_validate_speed(speed))
> > + vi->speed = speed;
> > +
> > + virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
> > +
> > + if (ethtool_validate_duplex(duplex))
> > + vi->duplex = duplex;
> > +}
> > +
>
> I already commented on this approach. This is now invoked on each open,
> lots of extra VM exits. No bueno, people are working hard to keep setup
> overhead under control. Handle this in the config change interrupt -
> your new infrastructure is perfect for this.

No, in this version it doesn't. Config space read only happens if
there's a pending config interrupt during ndo_open:

+ if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
+ if (vi->status & VIRTIO_NET_S_LINK_UP)
+ netif_carrier_on(vi->dev);
+ virtio_config_driver_enable(vi->vdev);
+ } else {
+ vi->status = VIRTIO_NET_S_LINK_UP;
+ netif_carrier_on(dev);
+ virtnet_update_settings(vi);
+ }

>
>
> > static int virtnet_open(struct net_device *dev)
> > {
> > struct virtnet_info *vi = netdev_priv(dev);
> > @@ -2903,6 +2923,16 @@ static int virtnet_open(struct net_device *dev)
> > goto err_enable_qp;
> > }
> >
> > + if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> > + if (vi->status & VIRTIO_NET_S_LINK_UP)
> > + netif_carrier_on(vi->dev);
> > + virtio_config_driver_enable(vi->vdev);
> > + } else {
> > + vi->status = VIRTIO_NET_S_LINK_UP;
> > + netif_carrier_on(dev);
> > + virtnet_update_settings(vi);
> > + }
> > +
> > return 0;
> >
> > err_enable_qp:
> > @@ -3381,12 +3411,18 @@ static int virtnet_close(struct net_device *dev)
> > disable_delayed_refill(vi);
> > /* Make sure refill_work doesn't re-enable napi! */
> > cancel_delayed_work_sync(&vi->refill);
> > + /* Make sure config notification doesn't schedule config work */
>
> it's clear what this does even without a comment.
> what you should comment on, and do not, is *why*.

Well, it just follows the existing style, for example the above said

"/* Make sure refill_work doesn't re-enable napi! */"

>
> > + virtio_config_driver_disable(vi->vdev);
> > + /* Make sure status updating is cancelled */
>
> same
>
> also what "status updating"? confuses more than this clarifies.

Does "Make sure the config changed work is cancelled" sounds better?

>
> > + cancel_work_sync(&vi->config_work);
> >
> > for (i = 0; i < vi->max_queue_pairs; i++) {
> > virtnet_disable_queue_pair(vi, i);
> > virtnet_cancel_dim(vi, &vi->rq[i].dim);
> > }
> >
> > + netif_carrier_off(dev);
> > +
> > return 0;
> > }
> >
> > @@ -5085,25 +5121,6 @@ static void virtnet_init_settings(struct net_device *dev)
> > vi->duplex = DUPLEX_UNKNOWN;
> > }
> >
> > -static void virtnet_update_settings(struct virtnet_info *vi)
> > -{
> > - u32 speed;
> > - u8 duplex;
> > -
> > - if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
> > - return;
> > -
> > - virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
> > -
> > - if (ethtool_validate_speed(speed))
> > - vi->speed = speed;
> > -
> > - virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
> > -
> > - if (ethtool_validate_duplex(duplex))
> > - vi->duplex = duplex;
> > -}
> > -
> > static u32 virtnet_get_rxfh_key_size(struct net_device *dev)
> > {
> > return ((struct virtnet_info *)netdev_priv(dev))->rss_key_size;
> > @@ -6514,6 +6531,11 @@ static int virtnet_probe(struct virtio_device *vdev)
> > goto free_failover;
> > }
> >
> > + /* Forbid config change notification until ndo_open. */
>
> notifications
>
> Disable, not forbid.

Ok.

>
> > + virtio_config_driver_disable(vi->vdev);
> > + /* Make sure status updating work is done */
>
>
>
> > + cancel_work_sync(&vi->config_work);
> > +
> > virtio_device_ready(vdev);
> >
> > virtnet_set_queues(vi, vi->curr_queue_pairs);
> > @@ -6563,6 +6585,19 @@ static int virtnet_probe(struct virtio_device *vdev)
> > vi->device_stats_cap = le64_to_cpu(v);
> > }
> >
> > + /* Assume link up if device can't report link status,
> > + otherwise get link status from config. */
> > + netif_carrier_off(dev);
> > + if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> > + /* This is safe as config notification change has been
>
> config change notification
>
> > + disabled. */
> > + virtnet_config_changed_work(&vi->config_work);
> > + } else {
> > + vi->status = VIRTIO_NET_S_LINK_UP;
> > + virtnet_update_settings(vi);
> > + netif_carrier_on(dev);
> > + }
> > +
> > rtnl_unlock();
> >
> > err = virtnet_cpu_notif_add(vi);
> > @@ -6571,17 +6606,6 @@ static int virtnet_probe(struct virtio_device *vdev)
> > goto free_unregister_netdev;
> > }
> >
> > - /* Assume link up if device can't report link status,
> > - otherwise get link status from config. */
> > - netif_carrier_off(dev);
> > - if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> > - schedule_work(&vi->config_work);
> > - } else {
> > - vi->status = VIRTIO_NET_S_LINK_UP;
> > - virtnet_update_settings(vi);
> > - netif_carrier_on(dev);
> > - }
> > -
> > for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
> > if (virtio_has_feature(vi->vdev, guest_offloads[i]))
> > set_bit(guest_offloads[i], &vi->guest_offloads);
> > --
> > 2.31.1
>

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Previous message: Cristian Ciocaltea: "[PATCH 2/2] drm/bridge: synopsys: Add DW HDMI QP TX Controller driver"
In reply to: Michael S. Tsirkin: "Re: [PATCH V4 net-next 3/3] virtio-net: synchronize operstate with admin state on up/down"
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