From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752109AbbIQLki (ORCPT ); Thu, 17 Sep 2015 07:40:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48052 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751104AbbIQLkf (ORCPT ); Thu, 17 Sep 2015 07:40:35 -0400 Subject: Re: [PATCH 0/3] x86/paravirt: Fix baremetal paravirt MSR ops To: Peter Zijlstra , Andy Lutomirski References: <20150917085807.GH3816@twins.programming.kicks-ass.net> Cc: x86@kernel.org, KVM list , Arjan van de Ven , xen-devel , linux-kernel@vger.kernel.org From: Paolo Bonzini Message-ID: <55FAA6AE.9050503@redhat.com> Date: Thu, 17 Sep 2015 13:40:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20150917085807.GH3816@twins.programming.kicks-ass.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/09/2015 10:58, Peter Zijlstra wrote: > But the far greater problem I have with the whole virt thing is that > you cannot use rdmsr_safe() to probe if an MSR exists at all because, as > you told me, these virt thingies return 0 for all 'unknown' MSRs instead > of faulting. At least for KVM, that behavior is opt-in (the ignore_msrs parameter) and no distro that I know enables it by default. Paolo