Willem de Bruijn
2017-Oct-05 16:18 UTC
[PATCH RFC 1/2] virtio_net: implement VIRTIO_CONFIG_S_NEEDS_RESET
On Tue, Aug 29, 2017 at 4:20 PM, Michael S. Tsirkin <mst at redhat.com> wrote:> On Tue, Aug 29, 2017 at 04:07:58PM -0400, Willem de Bruijn wrote: >> From: Willem de Bruijn <willemb at google.com> >> >> Implement the reset communication request defined in the VIRTIO 1.0 >> specification and introduces in Linux in commit c00bbcf862896 ("virtio: >> add VIRTIO_CONFIG_S_NEEDS_RESET device status bit"). >> >> Since that patch, the virtio-net driver has added a virtnet_reset >> function that implements the requested behavior through calls to the >> power management freeze and restore functions. >> >> That function has recently been reverted when its sole caller was >> updated. Bring it back and listen for the request from the host on >> the config channel. >> >> Implement the feature analogous to other config requests. In >> particular, acknowledge the request in the same manner as the >> NET_S_ANNOUNCE link announce request, by responding with a new >> VIRTIO_NET_CTRL_${TYPE} command. On reception, the host must check >> the config status register for success or failure. > > > Pls make it clearer why do you need these interface extensions. > >> The existing freeze handler verifies that no config changes are >> running concurrently. Elide this check for reset. The request is >> always handled from the config workqueue. No other config requests >> can be active or scheduled concurrently on vi->config. > > You need to prevent packet TX from being in progress.I had another look at this. As of commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") virtnet_freeze_down calls synchronize_net() after stopping the queues to quiesce the device before any further actions. This should suffice for virtnet_reset, too. The control path can indeed be much simpler than my initial patchset. The host can read vdev->status to observe when the reset went through. It adds flag VIRTIO_CONFIG_S_NEEDS_RESET to request the reset. This flag is cleared by the operation itself.> >> >> Signed-off-by: Willem de Bruijn <willemb at google.com> >> --- >> drivers/net/virtio_net.c | 69 +++++++++++++++++++++++++++++++++++------ >> include/uapi/linux/virtio_net.h | 4 +++ > > virtio dev or another virtio TC list must be Cc'd on any proposed API changes. > > >> 2 files changed, 64 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index 52ae78ca3d38..5e349226f7c1 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -1458,12 +1458,11 @@ static void virtnet_netpoll(struct net_device *dev) >> } >> #endif >> >> -static void virtnet_ack_link_announce(struct virtnet_info *vi) >> +static void virtnet_ack(struct virtnet_info *vi, u8 class, u8 cmd) >> { >> rtnl_lock(); >> - if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_ANNOUNCE, >> - VIRTIO_NET_CTRL_ANNOUNCE_ACK, NULL)) >> - dev_warn(&vi->dev->dev, "Failed to ack link announce.\n"); >> + if (!virtnet_send_command(vi, class, cmd, NULL)) >> + dev_warn(&vi->dev->dev, "Failed to ack %u.%u\n", class, cmd); >> rtnl_unlock(); >> } >> >> @@ -1857,13 +1856,16 @@ static const struct ethtool_ops virtnet_ethtool_ops = { >> .set_link_ksettings = virtnet_set_link_ksettings, >> }; >> >> -static void virtnet_freeze_down(struct virtio_device *vdev) >> +static void virtnet_freeze_down(struct virtio_device *vdev, bool in_reset) >> { >> struct virtnet_info *vi = vdev->priv; >> int i; >> >> - /* Make sure no work handler is accessing the device */ >> - flush_work(&vi->config_work); >> + /* Make sure no work handler is accessing the device, >> + * unless this call is made from the reset work handler itself. >> + */ >> + if (!in_reset) >> + flush_work(&vi->config_work); >> >> netif_device_detach(vi->dev); >> netif_tx_disable(vi->dev); >> @@ -1878,6 +1880,7 @@ static void virtnet_freeze_down(struct virtio_device *vdev) >> } >> >> static int init_vqs(struct virtnet_info *vi); >> +static void remove_vq_common(struct virtnet_info *vi); >> >> static int virtnet_restore_up(struct virtio_device *vdev) >> { >> @@ -1906,6 +1909,45 @@ static int virtnet_restore_up(struct virtio_device *vdev) >> return err; >> } >> >> +static int virtnet_reset(struct virtnet_info *vi) >> +{ >> + struct virtio_device *dev = vi->vdev; >> + bool failed; >> + int ret; >> + >> + virtio_config_disable(dev); >> + failed = dev->config->get_status(dev) & VIRTIO_CONFIG_S_FAILED; >> + virtnet_freeze_down(dev, true); >> + remove_vq_common(vi); >> + >> + virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); >> + virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); >> + >> + /* Restore the failed status (see virtio_device_restore). */ >> + if (failed) >> + virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); >> + >> + ret = virtio_finalize_features(dev); >> + if (ret) >> + goto err; >> + >> + ret = virtnet_restore_up(dev); >> + if (ret) >> + goto err; >> + >> + ret = virtnet_set_queues(vi, vi->curr_queue_pairs); >> + if (ret) >> + goto err; >> + >> + virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); >> + virtio_config_enable(dev); >> + return 0; >> + >> +err: >> + virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED); >> + return ret; >> +} >> + >> static int virtnet_set_guest_offloads(struct virtnet_info *vi, u64 offloads) >> { >> struct scatterlist sg; >> @@ -2085,7 +2127,16 @@ static void virtnet_config_changed_work(struct work_struct *work) >> >> if (v & VIRTIO_NET_S_ANNOUNCE) { >> netdev_notify_peers(vi->dev); >> - virtnet_ack_link_announce(vi); >> + virtnet_ack(vi, VIRTIO_NET_CTRL_ANNOUNCE, >> + VIRTIO_NET_CTRL_ANNOUNCE_ACK); >> + } >> + >> + if (vi->vdev->config->get_status(vi->vdev) & >> + VIRTIO_CONFIG_S_NEEDS_RESET) { >> + virtnet_reset(vi); >> + virtnet_ack(vi, VIRTIO_NET_CTRL_RESET, >> + VIRTIO_NET_CTRL_RESET_ACK); >> + >> } >> >> /* Ignore unknown (future) status bits */ >> @@ -2708,7 +2759,7 @@ static __maybe_unused int virtnet_freeze(struct virtio_device *vdev) >> struct virtnet_info *vi = vdev->priv; >> >> virtnet_cpu_notif_remove(vi); >> - virtnet_freeze_down(vdev); >> + virtnet_freeze_down(vdev, false); >> remove_vq_common(vi); >> >> return 0; >> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h >> index fc353b518288..188fdc528f13 100644 >> --- a/include/uapi/linux/virtio_net.h >> +++ b/include/uapi/linux/virtio_net.h >> @@ -245,4 +245,8 @@ struct virtio_net_ctrl_mq { >> #define VIRTIO_NET_CTRL_GUEST_OFFLOADS 5 >> #define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET 0 >> >> +/* Signal that the driver received and executed the reset command. */ >> +#define VIRTIO_NET_CTRL_RESET 6 >> +#define VIRTIO_NET_CTRL_RESET_ACK 0 >> + >> #endif /* _UAPI_LINUX_VIRTIO_NET_H */ >> -- >> 2.14.1.342.g6490525c54-goog
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