From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753291AbcFORHt (ORCPT ); Wed, 15 Jun 2016 13:07:49 -0400 Received: from mail.skyhub.de ([78.46.96.112]:35643 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752096AbcFORHq (ORCPT ); Wed, 15 Jun 2016 13:07:46 -0400 Date: Wed, 15 Jun 2016 19:07:43 +0200 From: Borislav Petkov To: Eduardo Habkost Cc: kernel test robot , Andy Lutomirski , Paolo Bonzini , LKP , wfg@linux.intel.com, lkml Subject: Re: [x86] 5ac0c41bf3: WARNING: CPU: 0 PID: 0 at arch/x86/mm/extable.c:50 ex_handler_rdmsr_unsafe Message-ID: <20160615170743.GB30309@pd.tnic> References: <57614955.l3IQMtSfaGPEBdCy%fengguang.wu@intel.com> <20160615142532.GE32588@pd.tnic> <20160615145150.GH18662@thinpad.lan.raisama.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160615145150.GH18662@thinpad.lan.raisama.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 15, 2016 at 11:51:50AM -0300, Eduardo Habkost wrote: > We have that: it is "-feature" (or "feature=off"). Features that > can't be configured in the command-line should never appear to > the guest unless you use "-cpu host,migratable=off". > > Something that allows disabling feature flags that still don't > have a name in QEMU would be useful for "-cpu > host,migratable=off" only (and that's an interesting suggestion). > But that's not the case here, I guess. Right, and I'm wondering whether something like that would be useful for testing purposes. For example, I want to enable a CPUID feature on the command line and see how the kernel I'm booting in the guest reacts. And that feature bit is not necessarily known to qemu/kvm. Can we, say, pass whole CPUID leafs to qemu to report to the guest? I.e., something like: ... -cpuid=0x5,eax=0x40,ebx=0xdeadbeef,ecx=0xcaffee ... and so on. Would that be interesting to add to qemu? I'd find something like that very useful for testing kernels... Thanks. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.