From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: tainted Linux kernel in default SMP QEMU/KVM guests Date: Fri, 19 Mar 2010 13:58:33 +0100 Message-ID: <4BA374F9.9040008@redhat.com> References: <4BA36B06.5060002@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: QEMU devel , KVM list To: Andre Przywara Return-path: Received: from mail-pw0-f46.google.com ([209.85.160.46]:59126 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751838Ab0CSM6k (ORCPT ); Fri, 19 Mar 2010 08:58:40 -0400 Received: by pwi5 with SMTP id 5so1203224pwi.19 for ; Fri, 19 Mar 2010 05:58:39 -0700 (PDT) In-Reply-To: <4BA36B06.5060002@amd.com> Sender: kvm-owner@vger.kernel.org List-ID: > 1) Change the default CPUID bits from 6/2/3 to 6/6/1, this passes the > Linux kernel check. But I am not sure if that would introduce > regressions, since some OSes apply quirks if they detect certain models > (like we had with the sysenter issue in the past) > > 2) Only change the CPUID bits to 6/6/1 if we use SMP. Still has the > above drawback, but would be limited to SMP guests only. > > 3) Set kvm64/kvm32 as the default CPU model if KVM is enabled. This > would limit the report and taint to TCG, where SMP is rarely used. > Additionally less people (if any) use it for production systems. > > 4) Make the Linux' kernel quirk dependent on the missing hypervisor bit. > I don't think this will be accepted easily upstream (and I don't want to > support Ingo's recent ideas ;-), also this would not fix older kernels. > > I can easily provide patches for all solutions, but I'd like to get > advice from people on which one to pursue. Doing (3) seems the most sensible thing to do, and it does not prevent doing (1) later on for TCG only. Paolo