Re: [PATCH] virtio: rng: add derating factor for use by hwrng core

[Amos Kong]

On Thu, Aug 14, 2014 at 04:39:07AM +0930, Rusty Russell wrote:
> The khwrngd thread is started when a hwrng device of sufficient
> quality is registered.  The virtio-rng device is backed by the
> hypervisor, and we trust the hypervisor to provide real entropy.
> 
> A malicious hypervisor is a scenario that's irrelevant -- such a setup
> is bound to cause all sorts of badness, and a compromised hwrng is not
> the biggest threat.
> 
> Given this, we are certain the quality of randomness we receive is
> perfectly trustworthy.  Hence, we use 100% for the factor, indicating
> maximum confidence in the source.
> 
> Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>


Reviewed-by: Amos Kong <akong@xxxxxxxxxx>

> ---
> Pretty small and contained patch; would be great if it is picked up for
> 3.17.
> 
> v2: re-word commit msg
> 
> [Agreed, re-sending to Linus with SOB before jumping on plane]
> ---
>  drivers/char/hw_random/virtio-rng.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/char/hw_random/virtio-rng.c
> b/drivers/char/hw_random/virtio-rng.c
> index 0027137..2e3139e 100644
> --- a/drivers/char/hw_random/virtio-rng.c
> +++ b/drivers/char/hw_random/virtio-rng.c
> @@ -116,6 +116,7 @@ static int probe_common(struct virtio_device *vdev)
> 		.cleanup = virtio_cleanup,
> 		.priv = (unsigned long)vi,
> 		.name = vi->name,
> +		.quality = 1000,
> 	};
> 	vdev->priv = vi;
> 
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-- 
			Amos.
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