From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Roedel, Joerg" Subject: Re: [PATCH] KVM: SVM: Fix fault-rip on vmsave/vmload emulation Date: Wed, 6 Apr 2011 14:27:53 +0200 Message-ID: <20110406122753.GM23633@amd.com> References: <1302085803-25399-1-git-send-email-joerg.roedel@amd.com> <4D9C4C9C.6060401@redhat.com> <4D9C4E58.7020002@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Marcelo Tosatti , "kvm@vger.kernel.org" , "stable@kernel.org" To: Avi Kivity Return-path: Received: from va3ehsobe001.messaging.microsoft.com ([216.32.180.11]:26860 "EHLO VA3EHSOBE008.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755375Ab1DFM2d (ORCPT ); Wed, 6 Apr 2011 08:28:33 -0400 Content-Disposition: inline In-Reply-To: <4D9C4E58.7020002@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Apr 06, 2011 at 07:28:24AM -0400, Avi Kivity wrote: > On 04/06/2011 02:21 PM, Avi Kivity wrote: > > On 04/06/2011 01:30 PM, Joerg Roedel wrote: > >> When the emulation of vmload or vmsave fails because the > >> guest passed an unsupported physical address it gets an #GP > >> with rip pointing to the instruction after vmsave/vmload. > >> This is a bug and fixed by this patch. > >> > > > > Applied, thanks. > > > > btw, I think the actual address check is incorrect, need to check > MAXPHYADDR and not hardcoded 0xffff000000000000. There is a difference. MAX_PHYSADDR_BITS is the maximum Linux can support while the mask above is the current limit the hardware supports. It is the same on real hardware, when rax is >= (1<<48) there is a #GP (and no intercept if in guest-mode). Here is btw. a difference between nested-svm and hardware-svm, if rax contains a physical address which is supported but not backed by RAM the machine will just freeze on real hardware where as in nested-svm it causes a #GP (should be fine because the behavior in this case is undefined). 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