From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756045Ab0IBQeT (ORCPT ); Thu, 2 Sep 2010 12:34:19 -0400 Received: from va3ehsobe006.messaging.microsoft.com ([216.32.180.16]:51236 "EHLO VA3EHSOBE008.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755997Ab0IBQeR (ORCPT ); Thu, 2 Sep 2010 12:34:17 -0400 X-SpamScore: -32 X-BigFish: VS-32(zzbb2dK1432N98dN9371Pzz1202hzz15d4Rz32i2a8h87h43h61h) X-Spam-TCS-SCL: 0:0 X-FB-DOMAIN-IP-MATCH: fail X-WSS-ID: 0L84OH1-01-BW2-02 X-M-MSG: Date: Thu, 2 Sep 2010 18:29:34 +0200 From: "Roedel, Joerg" To: Avi Kivity CC: Marcelo Tosatti , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "stable@kernel.org" Subject: Re: [PATCH 2/3] KVM: SVM: Restore correct registers after sel_cr0 intercept emulation Message-ID: <20100902162934.GD1964@amd.com> References: <1283441387-7378-1-git-send-email-joerg.roedel@amd.com> <1283441387-7378-3-git-send-email-joerg.roedel@amd.com> <4C7FCA7A.1020809@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <4C7FCA7A.1020809@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-Reverse-DNS: unknown Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 02, 2010 at 12:02:02PM -0400, Avi Kivity wrote: > On 09/02/2010 06:29 PM, Joerg Roedel wrote: > > This patch implements restoring of the correct rip, rsp, and > > rax after the svm emulation in KVM injected a selective_cr0 > > write intercept into the guest hypervisor. The problem was > > that the vmexit is emulated in the instruction emulation > > which later commits the registers right after the write-cr0 > > instruction. So the l1 guest will continue to run with the > > l2 rip, rsp and rax resulting in unpredictable behavior. > > Please post a unit test for this. Will do. Should be an easy test. > > This patch is not the final word, it is just an easy patch > > to fix the issue. The real fix will be done when the > > instruction emulator is made aware of nested virtualization. > > Until this is done this patch fixes the issue and provides > > an easy way to fix this in -stable too. > > I agree. We can probably use X86EMUL_PROPAGATE_FAULT to abort > emulation, but looking at the code, it will take some refactoring. I thought of an X86EMUL_INTERCEPTED. An architecture specific function is called after instruction decoding which checks if an intercept is necessary. If it returns X86EMUL_INTERCEPTED then the instruction emulation is discarded and kvm goes straight back into the guest. 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