Re: [PATCH 3/3] KVM: PPC: Book3S: Add support for hwrng found on some powernv systems

Paul Mackerras
2013-10-01T09:23:28Z

On Tue, Oct 01, 2013 at 11:39:08AM +0300, Gleb Natapov wrote:
> On Tue, Oct 01, 2013 at 06:34:26PM +1000, Michael Ellerman wrote:
> > On Thu, Sep 26, 2013 at 11:06:59AM +0200, Paolo Bonzini wrote:
> > > Il 26/09/2013 08:31, Michael Ellerman ha scritto:
> > > > Some powernv systems include a hwrng. Guests can access it via the
> > > > H_RANDOM hcall.
> > >
> > > Is there any reason to do this in the kernel?
> >
> > It's less code, and it's faster :)
> >
> > > It does not have to be a particularly fast path;
> >
> > Sure, but do we have to make it slow on purpose?
> >
> We do not put non performance critical devices into the kernel.

It's not a device, it's a single hypercall, specified by PAPR, which
is the moral equivalent of x86's RDRAND.

Paul.