Re: Commit d9e7972619334656 breaks KVM's virtio-rng-pci

[Kees Cook]

On Sun, Jul 20, 2014 at 9:18 AM, Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
> Hello,
>
> the commit d9e7972619334656 ends up being responsible that using "-device virtio-rng-pci" in KVM no longer works.
>
>         From: Kees Cook <keescook@xxxxxxxxxxxx>
>         Date: Mon, 3 Mar 2014 15:51:48 -0800
>         Subject: [PATCH] hwrng: add randomness to system from rng sources
>
>         When bringing a new RNG source online, it seems like it would make sense
>         to use some of its bytes to make the system entropy pool more random,
>         as done with all sorts of other devices that contain per-device or
>         per-boot differences.
>
> When providing "-device virtio-rng-pci" to a kernel with the above commit, the kernel never finishes booting. It just stops. My guess it is waiting for some magic entropy to appear.
>
> Maybe this is something that should be fixed in virtio-rng driver instead of reverting this patch, but I leave this to the experts in this area.

Yup, this has already been handled. See various threads around:
https://lkml.org/lkml/2014/7/5/14

-Kees

-- 
Kees Cook
Chrome OS Security
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