From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753297AbbJTO2B (ORCPT ); Tue, 20 Oct 2015 10:28:01 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:24970 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752725AbbJTO2A (ORCPT ); Tue, 20 Oct 2015 10:28:00 -0400 Subject: Re: [Xen-devel] PROBLEM: kernel panic xsave_init To: Jan Beulich , John Doe References: <562430E6.6010205@gmail.com> <20151019075618.GA22488@gmail.com> <5624C2FB.6080605@gmail.com> <56251973.9010603@oracle.com> <56262AD802000078000ACAA1@prv-mh.provo.novell.com> <56262F81.804@gmail.com> <56264008.8090800@oracle.com> <5626613002000078000ACE3B@prv-mh.provo.novell.com> Cc: Ingo Molnar , x86@kernel.org, xen-devel@lists.xen.org, linux-kernel@vger.kernel.org From: Boris Ostrovsky Message-ID: <56264F5D.9000104@oracle.com> Date: Tue, 20 Oct 2015 10:27:41 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <5626613002000078000ACE3B@prv-mh.provo.novell.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/20/2015 09:43 AM, Jan Beulich wrote: >>>> On 20.10.15 at 15:22, wrote: >> The reason I think its this commit is that RAX, RDX and RCX look very >> much like arguments to xsetbv (which xstate_enable_boot_cpu() executes) >> and RAX value is 0x1f, which has two new bits that this commit defined. > That would be the two MPX related bits, yet us (luckily) white listing > leaf 7 in pv_cpuid(), it is quite easy to validate that we don't expose > this feature to PV(H) guests. Oh, so something like cpuid=['0x7:ebx=xxxxxxxxxxxxxxxxx0xxxxxxxxxxxxxx'] (bit 14 as zero) for John to try then. -boris > Sadly the story is different for HVM > guests (where the leaf handling uses black listing), but the register > dump here clearly points to a PV guest (or Dom0). > > Jan >