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Re: [Qemu-devel] [PATCH v2] virtio-rng: process pending requests when dr
From: |
Daniel P . Berrangé |
Subject: |
Re: [Qemu-devel] [PATCH v2] virtio-rng: process pending requests when driver is ready |
Date: |
Wed, 27 Jun 2018 12:27:41 +0100 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
On Wed, Jun 27, 2018 at 04:55:20PM +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.
Presumably this all worked previously at some point, so do you know what
change in QEMU has caused a regression in this regard.
>
> 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 <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> Signed-off-by: Pankaj Gupta <address@hidden>
> ---
> v1->v2: Update new status value early only for virtio-rng (Stefan)
>
> hw/virtio/virtio-rng.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
> index 289bbcac03..855f1b41d1 100644
> --- a/hw/virtio/virtio-rng.c
> +++ b/hw/virtio/virtio-rng.c
> @@ -156,6 +156,19 @@ 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;
> + }
> + vdev->status = status;
> +
> + /* Something changed, try to process buffers */
> + virtio_rng_process(vrng);
> +}
> +
> static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
> {
> VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> @@ -261,6 +274,7 @@ static void virtio_rng_class_init(ObjectClass *klass,
> void *data)
> vdc->realize = virtio_rng_device_realize;
> vdc->unrealize = virtio_rng_device_unrealize;
> vdc->get_features = get_features;
> + vdc->set_status = virtio_rng_set_status;
> }
>
> static const TypeInfo virtio_rng_info = {
> --
> 2.14.3
>
>
Regards,
Daniel
--
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