On Thu, Apr 12, 2012 at 02:43:52PM +0800, Jason Wang wrote: > As hypervior does not have the knowledge of guest network configuration, it's > better to ask guest to send gratuitous packets when needed. > > This patch implements VIRTIO_NET_F_GUEST_ANNOUNCE feature: hypervisor would > notice the guest when it thinks it's time for guest to announce the link > presnece. Guest tests VIRTIO_NET_S_ANNOUNCE bit during config change interrupt > and woule send gratuitous packets through netif_notify_peers() and ack the > notification through ctrl vq. > > We need to make sure the atomicy of read and ack in guest otherwise we may ack > more times than being notified. This is done through handling the whole config > change interrupt in an non-reentrant workqueue. > > Signed-off-by: Jason Wang <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]> > > --- > > Changes from v6: > - move the whole event processing to system_nrt_wq > - introduce the config_enable and config_lock to synchronize with dev removing > and pm > - protect the ack with rtnl_lock > > Changes from v5: > - notify the chain before acking the link annoucement > - ack the link announcement notification through control vq > > Changes from v4: > - typos > - handle workqueue unconditionally > - move VIRTIO_NET_S_ANNOUNCE to bit 8 to separate rw bits from ro bits > > Changes from v3: > - cancel the workqueue during freeze > > Changes from v2: > - fix the race between unregister_dev() and workqueue > --- > drivers/net/virtio_net.c | 64 > +++++++++++++++++++++++++++++++++++++++++--- > include/linux/virtio_net.h | 14 ++++++++++ > 2 files changed, 73 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 4de2760..23403b6 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -66,12 +66,21 @@ struct virtnet_info { > /* Host will merge rx buffers for big packets (shake it! shake it!) */ > bool mergeable_rx_bufs; > > + /* enable config space updates */ > + bool config_enable; > + > /* Active statistics */ > struct virtnet_stats __percpu *stats; > > /* Work struct for refilling if we run low on memory. */ > struct delayed_work refill; > > + /* Work struct for config space updates */ > + struct work_struct config_work; > + > + /* Lock for config space updates */ > + struct mutex config_lock; > + > /* Chain pages by the private ptr. */ > struct page *pages; > > @@ -781,6 +790,16 @@ static bool virtnet_send_command(struct virtnet_info > *vi, u8 class, u8 cmd, > return status == VIRTIO_NET_OK; > } > > +static void virtnet_ack_link_announce(struct virtnet_info *vi) > +{ > + rtnl_lock(); > + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE, > + VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL, > + 0, 0)) > + dev_warn(&vi->dev->dev, "Failed to ack link announce.\n"); > + rtnl_unlock(); > +} > + > static int virtnet_close(struct net_device *dev) > { > struct virtnet_info *vi = netdev_priv(dev); > @@ -952,20 +971,31 @@ static const struct net_device_ops virtnet_netdev = { > #endif > }; > > -static void virtnet_update_status(struct virtnet_info *vi) > +static void virtnet_config_changed_work(struct work_struct *work) > { > + struct virtnet_info *vi = > + container_of(work, struct virtnet_info, config_work); > u16 v; > > + mutex_lock(&vi->config_lock); > + if (!vi->config_enable) > + goto done; > + > if (virtio_config_val(vi->vdev, VIRTIO_NET_F_STATUS, > offsetof(struct virtio_net_config, status), > &v) < 0) > - return; > + goto done; > + > + if (v & VIRTIO_NET_S_ANNOUNCE) { > + netif_notify_peers(vi->dev); > + virtnet_ack_link_announce(vi); > + } > > /* Ignore unknown (future) status bits */ > v &= VIRTIO_NET_S_LINK_UP; > > if (vi->status == v) > - return; > + goto done; > > vi->status = v; > > @@ -976,13 +1006,15 @@ static void virtnet_update_status(struct virtnet_info > *vi) > netif_carrier_off(vi->dev); > netif_stop_queue(vi->dev); > } > +done: > + mutex_unlock(&vi->config_lock); > } > > static void virtnet_config_changed(struct virtio_device *vdev) > { > struct virtnet_info *vi = vdev->priv; > > - virtnet_update_status(vi); > + queue_work(system_nrt_wq, &vi->config_work); > } > > static int init_vqs(struct virtnet_info *vi) > @@ -1076,6 +1108,9 @@ static int virtnet_probe(struct virtio_device *vdev) > goto free; > > INIT_DELAYED_WORK(&vi->refill, refill_work); > + mutex_init(&vi->config_lock); > + vi->config_enable = true; > + INIT_WORK(&vi->config_work, virtnet_config_changed_work); > sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg)); > sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg)); > > @@ -1111,7 +1146,7 @@ static int virtnet_probe(struct virtio_device *vdev) > otherwise get link status from config. */ > if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) { > netif_carrier_off(dev); > - virtnet_update_status(vi); > + queue_work(system_nrt_wq, &vi->config_work); > } else { > vi->status = VIRTIO_NET_S_LINK_UP; > netif_carrier_on(dev); > @@ -1170,10 +1205,17 @@ static void __devexit virtnet_remove(struct > virtio_device *vdev) > { > struct virtnet_info *vi = vdev->priv; > > + /* Prevent config work handler from accessing the device. */ > + mutex_lock(&vi->config_lock); > + vi->config_enable = false; > + mutex_unlock(&vi->config_lock); > + > unregister_netdev(vi->dev); > > remove_vq_common(vi); > > + flush_work(&vi->config_work); > + > free_percpu(vi->stats); > free_netdev(vi->dev); > } > @@ -1183,6 +1225,11 @@ static int virtnet_freeze(struct virtio_device *vdev) > { > struct virtnet_info *vi = vdev->priv; > > + /* Prevent config work handler from accessing the device */ > + mutex_lock(&vi->config_lock); > + vi->config_enable = false; > + mutex_unlock(&vi->config_lock); > + > virtqueue_disable_cb(vi->rvq); > virtqueue_disable_cb(vi->svq); > if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) > @@ -1196,6 +1243,8 @@ static int virtnet_freeze(struct virtio_device *vdev) > > remove_vq_common(vi); > > + flush_work(&vi->config_work); > + > return 0; > } > > @@ -1216,6 +1265,10 @@ static int virtnet_restore(struct virtio_device *vdev) > if (!try_fill_recv(vi, GFP_KERNEL)) > queue_delayed_work(system_nrt_wq, &vi->refill, 0); > > + mutex_lock(&vi->config_lock); > + vi->config_enable = true; > + mutex_unlock(&vi->config_lock); > + > return 0; > } > #endif > @@ -1233,6 +1286,7 @@ static unsigned int features[] = { > VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO, > VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ, > VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, > + VIRTIO_NET_F_GUEST_ANNOUNCE, > }; > > static struct virtio_driver virtio_net_driver = { > diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h > index 970d5a2..2470f54 100644 > --- a/include/linux/virtio_net.h > +++ b/include/linux/virtio_net.h > @@ -49,8 +49,11 @@ > #define VIRTIO_NET_F_CTRL_RX 18 /* Control channel RX mode support */ > #define VIRTIO_NET_F_CTRL_VLAN 19 /* Control channel VLAN > filtering */ > #define VIRTIO_NET_F_CTRL_RX_EXTRA 20 /* Extra RX mode control > support */ > +#define VIRTIO_NET_F_GUEST_ANNOUNCE 21 /* Guest can announce device on > the > + * network */ > > #define VIRTIO_NET_S_LINK_UP 1 /* Link is up */ > +#define VIRTIO_NET_S_ANNOUNCE 2 /* Announcement is needed */ > > struct virtio_net_config { > /* The config defining mac address (if VIRTIO_NET_F_MAC) */ > @@ -152,4 +155,15 @@ struct virtio_net_ctrl_mac { > #define VIRTIO_NET_CTRL_VLAN_ADD 0 > #define VIRTIO_NET_CTRL_VLAN_DEL 1 > > +/* > + * Control link announce acknowledgement > + * > + * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that > + * driver has recevied received :) > the notification; device would clear the > + * VIRTIO_NET_S_ANNOUNCE bit in the status field after it receives > + * this command. > + */ > +#define VIRTIO_NET_CTRL_ANNOUNCE 3 > + #define VIRTIO_NET_CTRL_ANNOUNCE_ACK 0 > + > #endif /* _LINUX_VIRTIO_NET_H */ _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
