Re: [PATCH 1/3] x86, random: Enable the RDSEED instruction

[Ingo Molnar <mingo@kernel.org>]

* H. Peter Anvin <hpa@linux.intel.com> wrote:

> From: "H. Peter Anvin" <hpa@linux.intel.com>
> 
> Upcoming Intel silicon adds a new RDSEED instruction.  Whereas RDRAND
> returns output from a PRNG, the RDSEED instruction returns fully
> conditioned entropy that is suitable for use as seeds to a PRNG.
> 
> The RDSEED instruction takes the same time to execute as RDRAND, but
> RDSEED unlike RDRAND can legitimately return failure (CF=0) due to
> entropy exhaustion if too many threads on too many cores are hammering
> the RDSEED instruction at the same time.  Therefore, we have to be
> more conservative and only use it in places where we can tolerate
> failures.
> 
> This patch introduces the primitives arch_get_random_seed_{int,long}()
> but does not use it yet.
> 
> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
> ---
>  arch/x86/include/asm/archrandom.h | 34 +++++++++++++++++++++++++++++++++-
>  include/linux/random.h            | 16 ++++++++++++++++
>  2 files changed, 49 insertions(+), 1 deletion(-)

Reviewed-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo