Re: [Qemu-devel] [PATCH v4] virtio-rng: process pending requests when driver is ready

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Mon, Jul 02, 2018 at 12:07:25PM +0530, Pankaj Gupta wrote:
>  virtio-rng device causing old guest kernels(2.6.32) to hang on latest qemu.
>  The driver attempts to read from the virtio-rng device too early in it's
>  initialization. Qemu detects guest is not ready and returns, resulting in
>  hang.
> 
>  Fix is to handle pending request when guest is running and driver status is
>  set to 'VIRTIO_CONFIG_S_DRIVER_OK'.
> 
> Reported-by: Sergio lopez <slopezpa@redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
> ---
> v3->v4: Added signed-off & reported-by tags again.
> v2->v3: Add comment to explain virtio-rng early status update (Stefan)
> v1->v2: Update new status value early only for virtio-rng (Stefan)
> 
>  hw/virtio/virtio-rng.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
> index 289bbcac03..0b586bd750 100644
> --- a/hw/virtio/virtio-rng.c
> +++ b/hw/virtio/virtio-rng.c
> @@ -156,6 +156,24 @@ static void check_rate_limit(void *opaque)
>      vrng->activate_timer = true;
>  }
>  
> +static void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status)
> +{
> +    VirtIORNG *vrng = VIRTIO_RNG(vdev);
> +
> +    if (!vdev->vm_running) {
> +        return;
> +    }
> +    /* Set device status in VirtIODevice object. Its used in 'is_guest_ready'

s/Its/It's/

Can be fixed when merging.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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