Re: [Qemu-devel] [PATCH 1/3] virtio: Introduce VirtIODevice.broken

[Michael S. Tsirkin]

On Tue, Apr 22, 2014 at 04:55:15PM +0800, Fam Zheng wrote:
> If guest driver behaves abnormally, emulation code could mark the device
> as "broken".
> 
> Once "broken" is set, device emulation will typically wait for a reset
> command and ignore any other operations, but it could also return error
> responds. In other words, whether and how does guest know about this
> error status is device specific.
> 
> Signed-off-by: Fam Zheng <address@hidden>

We really need a flag to notify guest about this state though.
We should add this in virtio 1.0.
For now, how about clearing DRIVER_OK?
This way we don't need to touch so much code.

> ---
>  hw/virtio/virtio.c         | 12 ++++++++++++
>  include/hw/virtio/virtio.h |  3 +++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index aeabf3a..222bb73 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -538,6 +538,16 @@ void virtio_set_status(VirtIODevice *vdev, uint8_t val)
>      vdev->status = val;
>  }
>  
> +bool virtio_broken(VirtIODevice *vdev)
> +{
> +    return vdev->broken;
> +}
> +
> +void virtio_set_broken(VirtIODevice *vdev)
> +{
> +    vdev->broken = true;
> +}
> +
>  void virtio_reset(void *opaque)
>  {
>      VirtIODevice *vdev = opaque;
> @@ -554,6 +564,7 @@ void virtio_reset(void *opaque)
>      vdev->queue_sel = 0;
>      vdev->status = 0;
>      vdev->isr = 0;
> +    vdev->broken = false;
>      vdev->config_vector = VIRTIO_NO_VECTOR;
>      virtio_notify_vector(vdev, vdev->config_vector);
>  
> @@ -995,6 +1006,7 @@ void virtio_init(VirtIODevice *vdev, const char *name,
>      vdev->status = 0;
>      vdev->isr = 0;
>      vdev->queue_sel = 0;
> +    vdev->broken = 0;
>      vdev->config_vector = VIRTIO_NO_VECTOR;
>      vdev->vq = g_malloc0(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX);
>      vdev->vm_running = runstate_is_running();
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 3e54e90..5b16faa 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -121,6 +121,7 @@ struct VirtIODevice
>      bool vm_running;
>      VMChangeStateEntry *vmstate;
>      char *bus_name;
> +    bool broken;
>  };
>  
>  typedef struct VirtioDeviceClass {
> @@ -211,6 +212,8 @@ void virtio_queue_notify(VirtIODevice *vdev, int n);
>  uint16_t virtio_queue_vector(VirtIODevice *vdev, int n);
>  void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector);
>  void virtio_set_status(VirtIODevice *vdev, uint8_t val);
> +void virtio_set_broken(VirtIODevice *vdev);
> +bool virtio_broken(VirtIODevice *vdev);
>  void virtio_reset(void *opaque);
>  void virtio_update_irq(VirtIODevice *vdev);
>  int virtio_set_features(VirtIODevice *vdev, uint32_t val);
> -- 
> 1.9.2