From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755143Ab0LGJej (ORCPT ); Tue, 7 Dec 2010 04:34:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60020 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755118Ab0LGJei (ORCPT ); Tue, 7 Dec 2010 04:34:38 -0500 Message-ID: <4CFDFFA9.5050804@redhat.com> Date: Tue, 07 Dec 2010 11:34:33 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.12) Gecko/20101103 Fedora/1.0-0.33.b2pre.fc14 Lightning/1.0b3pre Thunderbird/3.1.6 MIME-Version: 1.0 To: "Roedel, Joerg" CC: Marcelo Tosatti , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] KVM: SVM: Add xsetbv intercept References: <1291394523-7689-1-git-send-email-joerg.roedel@amd.com> <4CFD0B06.9010308@redhat.com> <20101206174852.GG4936@amd.com> In-Reply-To: <20101206174852.GG4936@amd.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/06/2010 07:48 PM, Roedel, Joerg wrote: > On Mon, Dec 06, 2010 at 11:10:46AM -0500, Avi Kivity wrote: > > On 12/03/2010 06:42 PM, Joerg Roedel wrote: > > > This patch implements the xsetbv intercept to the AMD part > > > of KVM. This makes AVX usable in a save way for the guest on > > > AVX capable AMD hardware. > > > The patch is tested by using AVX in the guest and host in > > > parallel and checking for data corruption. I also used the > > > KVM xsave unit-tests and they all pass. > > > > > > > That is really strange. You didn't need to do anything to get cpuid.avx > > recognized. So running an older kvm on newer hardware will happily > > expose avx even though it's not supported. > > > > We screwed up - we should have made cpuid.avx dependent on vendor support. > > Hmm, right. The set_supported_cpuid arch-callback should basically > disable xsave on AMD for all KVM versions which do not handle the xsetbv > intercept. > Please post a patch to do that, and update this patch to undo the change. We'll backport the first patch to -stable so that people running older kernels don't get a nasty surprise when they upgrade their hardware (and use -cpu host). One more thing to watch out for. We also need to see if there aren't more mistakes like that out there. -- error compiling committee.c: too many arguments to function