Re: [PATCH 0/4] random,x86,kvm: Add and use MSR_KVM_GET_RNG_SEED

Daniel Borkmann
2014-07-16T07:10:42Z

On 07/16/2014 08:41 AM, Gleb Natapov wrote:
> On Tue, Jul 15, 2014 at 07:48:06PM -0700, Andy Lutomirski wrote:
>> virtio-rng is both too complicated and insufficient for initial rng
>> seeding. It's far too complicated to use for KASLR or any other
>> early boot random number needs. It also provides /dev/random-style
>> bits, which means that making guest boot wait for virtio-rng is
>> unacceptably slow, and doing it asynchronously means that
>> /dev/urandom might be predictable when userspace starts.
>>
>> This introduces a very simple synchronous mechanism to get
>> /dev/urandom-style bits.
>
> Why can't you use RDRAND instruction for that?

You mean using it directly? I think simply for the very same reasons
as in c2557a303a ...