From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.7 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id A67F27D90D for ; Wed, 28 Aug 2019 12:09:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726400AbfH1MJj (ORCPT ); Wed, 28 Aug 2019 08:09:39 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:46996 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726259AbfH1MJj (ORCPT ); Wed, 28 Aug 2019 08:09:39 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id EB15781E70; Wed, 28 Aug 2019 14:09:22 +0200 (CEST) Date: Wed, 28 Aug 2019 14:09:36 +0200 From: Pavel Machek To: Borislav Petkov Cc: Pavel Machek , Thomas Gleixner , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Tom Lendacky , Andrew Cooper , Andrew Morton , Chen Yu , "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Josh Poimboeuf , Juergen Gross , Kees Cook , "linux-doc@vger.kernel.org" , "linux-pm@vger.kernel.org" , Nathan Chancellor , Paolo Bonzini , "Rafael J. Wysocki" , "x86@kernel.org" Subject: Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h Message-ID: <20190828120935.GD8052@amd> References: <20190827072718.142728620@linuxfoundation.org> <20190827072722.020603090@linuxfoundation.org> <20190827113604.GB18218@amd> <20190828103113.GA14677@amd> <20190828114947.GC8052@amd> <20190828120024.GF4920@zn.tnic> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Xm/fll+QQv+hsKip" Content-Disposition: inline In-Reply-To: <20190828120024.GF4920@zn.tnic> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org --Xm/fll+QQv+hsKip Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed 2019-08-28 14:00:24, Borislav Petkov wrote: > On Wed, Aug 28, 2019 at 01:49:47PM +0200, Pavel Machek wrote: > > AMD screwed this up, >=20 > Except that it wasn't AMD who screwed up but BIOS on *some* laptops. Yes, and now AMD has patch to break it on *all* machines. Hmm. "Get random data" instruction that fails to return random data, depending on BIOS... (and even indicates success, IIRC)... Sounds like CPU vendor screwup to me. And they can also fix it up. If re-initing random generator is impossible from kernel, surely CPU microcode can be either updated to do the init automatically, or at least allow kernel to do the init. Best regards, Pavel --=20 DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --Xm/fll+QQv+hsKip Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl1mbv8ACgkQMOfwapXb+vKuGQCggrpXRxPboGyVt8+wPQDzbHsk Y5AAoJH+7uzv6qf18s+wwWNFoIo3pTOc =xR92 -----END PGP SIGNATURE----- --Xm/fll+QQv+hsKip--