From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: tainted Linux kernel in default SMP QEMU/KVM guests Date: Fri, 19 Mar 2010 08:12:04 -0500 Message-ID: <4BA37824.6000504@codemonkey.ws> References: <4BA36B06.5060002@amd.com> <4BA374F9.9040008@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andre Przywara , QEMU devel , KVM list To: Paolo Bonzini Return-path: Received: from qw-out-2122.google.com ([74.125.92.25]:38576 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998Ab0CSNMJ (ORCPT ); Fri, 19 Mar 2010 09:12:09 -0400 Received: by qw-out-2122.google.com with SMTP id 8so565139qwh.37 for ; Fri, 19 Mar 2010 06:12:08 -0700 (PDT) In-Reply-To: <4BA374F9.9040008@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/19/2010 07:58 AM, Paolo Bonzini wrote: > >> 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. Let's switch to -cpu host for kvm. Regards, Anthony Liguori > Paolo > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html