From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753452Ab0LFRtz (ORCPT ); Mon, 6 Dec 2010 12:49:55 -0500 Received: from tx2ehsobe001.messaging.microsoft.com ([65.55.88.11]:29989 "EHLO TX2EHSOBE001.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752806Ab0LFRtx (ORCPT ); Mon, 6 Dec 2010 12:49:53 -0500 X-SpamScore: -46 X-BigFish: VPS-46(zzbb2dK1432N98dN14ffO179dN9371P10d1Izz1202hzz15d4Rz32i637h668h61h) X-Spam-TCS-SCL: 0:0 X-Forefront-Antispam-Report: KIP:(null);UIP:(null);IPVD:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-WSS-ID: 0LD0PHY-01-RST-02 X-M-MSG: Date: Mon, 6 Dec 2010 18:48:52 +0100 From: "Roedel, Joerg" To: Avi Kivity CC: Marcelo Tosatti , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] KVM: SVM: Add xsetbv intercept Message-ID: <20101206174852.GG4936@amd.com> References: <1291394523-7689-1-git-send-email-joerg.roedel@amd.com> <4CFD0B06.9010308@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <4CFD0B06.9010308@redhat.com> Organization: Advanced Micro Devices =?iso-8859-1?Q?GmbH?= =?iso-8859-1?Q?=2C_Karl-Hammerschmidt-Str=2E_34=2C_85609_Dornach_bei_M=FC?= =?iso-8859-1?Q?nchen=2C_Gesch=E4ftsf=FChrer=3A_Thomas_M=2E_McCoy=2C_Giuli?= =?iso-8859-1?Q?ano_Meroni=2C_Andrew_Bowd=2C_Sitz=3A_Dornach=2C_Gemeinde_A?= =?iso-8859-1?Q?schheim=2C_Landkreis_M=FCnchen=2C_Registergericht_M=FCnche?= =?iso-8859-1?Q?n=2C?= HRB Nr. 43632 User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632