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Message-ID: <20170829231739-mutt-send-email-mst@kernel.org>
Date: Tue, 29 Aug 2017 23:20:33 +0300
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: netdev@...r.kernel.org, jasowang@...hat.com,
virtualization@...ts.linux-foundation.org,
Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH RFC 1/2] virtio_net: implement VIRTIO_CONFIG_S_NEEDS_RESET
On Tue, Aug 29, 2017 at 04:07:58PM -0400, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.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.
>
> Signed-off-by: Willem de Bruijn <willemb@...gle.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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