From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757189Ab2D3Ula (ORCPT ); Mon, 30 Apr 2012 16:41:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:26365 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757132Ab2D3Ul2 (ORCPT ); Mon, 30 Apr 2012 16:41:28 -0400 Date: Mon, 30 Apr 2012 23:41:27 +0300 From: "Michael S. Tsirkin" To: Anthony Liguori Cc: Avi Kivity , Marcelo Tosatti , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, davej@redhat.com Subject: Re: [PATCH] kvm: fix cpuid eax Message-ID: <20120430204126.GA14876@redhat.com> References: <20120430143902.GA10181@redhat.com> <4F9EF7FA.3060007@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F9EF7FA.3060007@codemonkey.ws> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 30, 2012 at 03:37:14PM -0500, Anthony Liguori wrote: > On 04/30/2012 09:39 AM, Michael S. Tsirkin wrote: > >cpuid eax should return the max leaf so that > >guests can find out the valid range. > >This matches Xen et al. > > What KVM does here predates Xen and Hyper-V. > > This is an ABI breaker. It is? I tested an old guest and qemu and both work fine. What breaks? > Regards, > > Anthony Liguori > > > > >Tested using -cpu host. > > > >Signed-off-by: Michael S. Tsirkin > >--- > > arch/x86/kvm/cpuid.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > >diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > >index 7d00d2d..bda4877 100644 > >--- a/arch/x86/kvm/cpuid.c > >+++ b/arch/x86/kvm/cpuid.c > >@@ -397,7 +397,7 @@ static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > > case KVM_CPUID_SIGNATURE: { > > char signature[12] = "KVMKVMKVM\0\0"; > > u32 *sigptr = (u32 *)signature; > >- entry->eax = 0; > >+ entry->eax = KVM_CPUID_FEATURES; > > entry->ebx = sigptr[0]; > > entry->ecx = sigptr[1]; > > entry->edx = sigptr[2];