From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC PATCH v3 0/3] Add segment limit checks to emulator Date: Mon, 12 Jul 2010 09:26:35 +0300 Message-ID: <4C3AB59B.60705@redhat.com> References: <1278888970-2936-1-git-send-email-m.gamal005@gmail.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: Mohammed Gamal Return-path: Received: from mx1.redhat.com ([209.132.183.28]:62347 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752145Ab0GLG0l (ORCPT ); Mon, 12 Jul 2010 02:26:41 -0400 In-Reply-To: <1278888970-2936-1-git-send-email-m.gamal005@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On 07/12/2010 01:56 AM, Mohammed Gamal wrote: > fter some conversation with Avi concerning why unreal mode has been seen to work > with KVM on Intel. It clears out the scenario is caused as follows: > > - guest enters big real mode > - kvm squashes limit to 64k-1 > - guest executes instructions with offset> 64k > - cpu issues #GP due to limit violation > - kvm handle_rmode_exception() -> emulator > - emulator ignores limit, emulates instruction > > With these applied I am getting vmentry failures with SeaBIOS and > gPXE. I could still get SeaBIOS to work with emulate_invalid_guest_state=1. > So it's needless to say that these patches are not meant for merging! > Well, eventually you need to fix this. > -------- > > Changes from v2: > - Addeded generic segment limit check helpers > - Removed individual segment register segment helpers as they're no longer needed > > What about the rest of my comments? -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.