From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752520AbaEAUjS (ORCPT ); Thu, 1 May 2014 16:39:18 -0400 Received: from imap.thunk.org ([74.207.234.97]:44471 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752134AbaEAUjN (ORCPT ); Thu, 1 May 2014 16:39:13 -0400 Date: Thu, 1 May 2014 20:39:10 +0000 From: tytso@mit.edu To: Andy Lutomirski Cc: "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , kvm list , Florian Weimer , Kees Cook Subject: Re: random: Providing a seed value to VM guests Message-ID: <20140501203910.GB25829@thunk.org> Mail-Followup-To: tytso@mit.edu, Andy Lutomirski , "H. Peter Anvin" , "linux-kernel@vger.kernel.org" , kvm list , Florian Weimer , Kees Cook References: <20140501192618.GA25829@thunk.org> <900441a0-24e8-4976-ad35-3971805b9f34@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: tytso@thunk.org X-SA-Exim-Scanned: No (on imap.thunk.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 01, 2014 at 01:32:55PM -0700, Andy Lutomirski wrote: > On Thu, May 1, 2014 at 1:30 PM, H. Peter Anvin wrote: > > RDSEED is not synchronous. It is, however, nonblocking. > > What I mean is: IIUC it's reasonable to call RDSEED a few times in a > loop and hope it works. It makes no sense to do that with > /dev/random. RDSEED is allowed to return an error if there is insufficient entropy. So long as the caller understands that this is an emulated instruction, I don't see a problem. - Ted