From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Brook Subject: Re: [Qemu-devel] Re: [PATCH 1/2] allow hypervisor CPUID bit to be overriden Date: Tue, 23 Jun 2009 12:31:12 +0100 Message-ID: <200906231231.15206.paul@codesourcery.com> References: <1245707244-743-1-git-send-email-andre.przywara@amd.com> <4A40A7EC.8070100@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Andre Przywara , aliguori@us.ibm.com, kvm@vger.kernel.org To: qemu-devel@nongnu.org Return-path: Received: from mail.codesourcery.com ([65.74.133.4]:54923 "EHLO mail.codesourcery.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752995AbZFWLbP (ORCPT ); Tue, 23 Jun 2009 07:31:15 -0400 In-Reply-To: <4A40A7EC.8070100@redhat.com> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Tuesday 23 June 2009, Avi Kivity wrote: > On 06/23/2009 12:47 AM, Andre Przywara wrote: > > KVM defaults to the hypervisor CPUID bit to be set, whereas pure QEMU > > clears it. On some occasions one want to set or clear it the other way > > round (for instance to get HyperV running inside a guest). > > Allow the default to be overridden on the command line and fix some > > whitespace damage on the way. > > It makes sense for qemu to set the hypervisor bit unconditionally. A > guest running under qemu is not bare metal. I see no reason why a guest has to be told that it's running inside a VM. In principle an appropriately configured qemu should be indistinguishable from real hardware. In practice it's technically infeasible to cover absolutely everything, but if we set this bit we're not even trying. I have no objection to the bit being set by default for the QEMU CPU types. Paul