Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756716AbcLOXEi (ORCPT ); Thu, 15 Dec 2016 18:04:38 -0500 Received: from mx2.suse.de ([195.135.220.15]:54852 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752929AbcLOXEh (ORCPT ); Thu, 15 Dec 2016 18:04:37 -0500 Date: Fri, 16 Dec 2016 00:04:33 +0100 From: Borislav Petkov To: Boris Ostrovsky Cc: Juergen Gross , Linux Kernel Mailing List , xen-devel Subject: Re: Can't boot as Xen dom0 due to commit fe055896 Message-ID: <20161215230433.m52cs2gef662c2s7@pd.tnic> References: <20161215164635.thm7ruio2ddnxszw@pd.tnic> <20161215171755.xpfuax7a6q3jofet@pd.tnic> <20161215173609.ornfok6lk5oro2pj@pd.tnic> <385ac3cd-7a3f-4c4d-69bb-8feee235fb7e@oracle.com> <20161215192305.dlgyrmteirgzop4y@pd.tnic> <399c758a-a94b-8aa1-efbb-79a0161b8020@oracle.com> <20161215200324.6ju7o5e3aiirrycf@pd.tnic> <51f0a58d-a5bc-aae4-22b2-f45bf7164088@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <51f0a58d-a5bc-aae4-22b2-f45bf7164088@oracle.com> User-Agent: NeoMutt/20161014 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 963 Lines: 26 On Thu, Dec 15, 2016 at 05:56:44PM -0500, Boris Ostrovsky wrote: > With CONFIG_PARAVIRT (which I suspect you don't have on) cpuid() is a > call via a pointer, you can see it, for example, if you disassemble > load_ucode_amd_bsp(). And we don't have paging on yet when we call > load_ucode_amd_bsp (at least in 32-bit mode). That's a good catch, you can send me that one as a proper patch with a commit message and so on... > Since this happens during AP bringup PV cpuid is available and can be > checked to see whether we are a guest. What exactly do I need to check there? CPUID(4), leaf which, reg which? How do I identify a xen hypervisor properly? > But I think it may be worthwhile trying to understand why we are > dying, it hasn't happened until now. What for? We don't want to run the microcode loader on xen at all. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --