From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [RFC 0/2] GET_EMULATED_CPUID support with "allow-emulation" option Date: Thu, 05 Jun 2014 18:26:41 +0200 Message-ID: <53909A41.1060800@redhat.com> References: <1401984741-26882-1-git-send-email-ehabkost@redhat.com> <539099B6.2090000@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Borislav Petkov , "Gabriel L. Somlo" , kvm@vger.kernel.org, "Michael S. Tsirkin" , Michael Mueller , Christian Borntraeger , "Jason J. Herne" , =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= To: Alexander Graf , Eduardo Habkost , qemu-devel@nongnu.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:46686 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750907AbaFEQ1O (ORCPT ); Thu, 5 Jun 2014 12:27:14 -0400 In-Reply-To: <539099B6.2090000@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: Il 05/06/2014 18:24, Alexander Graf ha scritto: > > On 05.06.14 18:12, Eduardo Habkost wrote: >> This implements GET_SUPPORTED_CPUID support using an explicit option >> for it: >> "allow-emulation". We don't want any emulated feature to be enabled by >> accident, >> so they will be enabled only if the user explicitly wants to allow them. > > So is this an all-or-nothing approach? I would really prefer to override > individual bits. You can still disable them with "cpu foo,-movbe,allow-emulation". > Also, I don't think the line "emulated" is the right one to draw. We > "emulate" SVM or VMX too, but still enable them by default as soon as we > think they're ready enough. Well, I disagreed with the whole KVM_GET_EMULATED_CPUID concept for MOVBE too for example. It seemed overengineered to me, sooner or later we might graduate MOVBE out of KVM_GET_EMULATED_CPUID as well. However, for MONITOR/MWAIT it makes some sense. Paolo