From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 1/2] KVM: x86 emulator: don't update vcpu state if instruction is restarted. Date: Mon, 02 Aug 2010 11:54:58 +0300 Message-ID: <4C5687E2.8040508@redhat.com> References: <20100801105337.GF24773@redhat.com> <4C5565C6.1090004@redhat.com> <20100801122316.GG24773@redhat.com> <4C556A1D.2050105@redhat.com> <20100801132714.GH24773@redhat.com> <4C5651D4.7060905@redhat.com> <20100802075838.GL24773@redhat.com> <4C567BCE.50106@redhat.com> <20100802081729.GM24773@redhat.com> <4C5680AE.4050907@redhat.com> <20100802083449.GN24773@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: mtosatti@redhat.com, kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from mx1.redhat.com ([209.132.183.28]:25274 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752388Ab0HBIy7 (ORCPT ); Mon, 2 Aug 2010 04:54:59 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o728sxq1003483 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 2 Aug 2010 04:54:59 -0400 Received: from cleopatra.tlv.redhat.com (cleopatra.tlv.redhat.com [10.35.255.11]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o728swuM003974 for ; Mon, 2 Aug 2010 04:54:59 -0400 In-Reply-To: <20100802083449.GN24773@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/02/2010 11:34 AM, Gleb Natapov wrote: > On Mon, Aug 02, 2010 at 11:24:14AM +0300, Avi Kivity wrote: >> On 08/02/2010 11:17 AM, Gleb Natapov wrote: >>>> We don't know what they'll do. API stability means we only change >>>> things to fix bugs. >>> Is this API documented? Do we guaranty somewhere anywhere that rip during io >>> point past the instruction? I think it should be documented that cpu >>> state cannot be accessed during io emulation. >> The user code was written before the documentation. >> > We did it with unmapped pages in the middles of the slot recently. What guests did we break? >> IIRC it leaves fs and gs pointing to large segments, but it never >> accesses them. Since we can't tell whether the guest will use those >> segments, we can't avoid emulating big real mode. Right now most >> things work, but that's because we hacked around everything. >> > We have logic in TPR patching code that tries to detect WindowsXP guest > and if XP is detected it enables vapic. We can disable e_i_g_s if vapic > is enabled. That code is in userspace. If we can change userspace, the whole problem is gone. -- error compiling committee.c: too many arguments to function