Re: [Qemu-devel] [PATCH 1/1] virtio-serial-bus: fix guest_connected init before driver init

[Michael S. Tsirkin]

On Tue, Apr 24, 2012 at 02:55:26PM +0530, Amit Shah wrote:
> From: Alon Levy <address@hidden>
> 
> guest_connected should be false before guest driver initialization, and
> true after, both for multiport aware and non multiport aware drivers.
> 
> Don't set it before the guest_features are available; instead use
> set_status which is called by io to VIRTIO_PCI_STATUS with
> VIRTIO_CONFIG_S_DRIVER_OK by even older non multiport drivers.
> 
> [Amit: Add comment, tweak summary]

Logic also changed fron Alon's patch. Why?

> 
> Signed-off-by: Alon Levy <address@hidden>
> Acked-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Amit Shah <address@hidden>
> ---
>  hw/virtio-serial-bus.c |   29 +++++++++++++++++++++--------
>  1 files changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
> index e22940e..796224b 100644
> --- a/hw/virtio-serial-bus.c
> +++ b/hw/virtio-serial-bus.c
> @@ -528,6 +528,26 @@ static void set_config(VirtIODevice *vdev, const uint8_t 
> *config_data)
>      memcpy(&config, config_data, sizeof(config));
>  }
>  
> +static void set_status(VirtIODevice *vdev, uint8_t status)
> +{
> +    VirtIOSerial *vser;
> +    VirtIOSerialPort *port;
> +
> +    vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
> +    port = find_port_by_id(vser, 0);
> +
> +    if (port && !use_multiport(port->vser)
> +        && (status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> +        /*
> +         * Non-multiport guests won't be able to tell us guest
> +         * open/close status.  Such guests can only have a port at id
> +         * 0, so set guest_connected for such ports as soon as guest
> +         * is up.
> +         */
> +        port->guest_connected = true;
> +    }
> +}
> +

Weird.  Don't you want to set guest_connected = false when driver
is unloaded?
This is what Alon's patch did:
        port->guest_connected = status & VIRTIO_CONFIG_S_DRIVER_OK;

>  static void virtio_serial_save(QEMUFile *f, void *opaque)
>  {
>      VirtIOSerial *s = opaque;
> @@ -798,14 +818,6 @@ static int virtser_port_qdev_init(DeviceState *qdev)
>          return ret;
>      }
>  
> -    if (!use_multiport(port->vser)) {
> -        /*
> -         * Allow writes to guest in this case; we have no way of
> -         * knowing if a guest port is connected.
> -         */
> -        port->guest_connected = true;
> -    }
> -
>      port->elem.out_num = 0;
>  
>      QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
> @@ -905,6 +917,7 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, 
> virtio_serial_conf *conf)
>      vser->vdev.get_features = get_features;
>      vser->vdev.get_config = get_config;
>      vser->vdev.set_config = set_config;
> +    vser->vdev.set_status = set_status;
>  
>      vser->qdev = dev;
>  
> -- 
> 1.7.7.6