Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753083AbcC3GgW (ORCPT ); Wed, 30 Mar 2016 02:36:22 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:32894 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751926AbcC3GgV (ORCPT ); Wed, 30 Mar 2016 02:36:21 -0400 Subject: Re: [PATCH 1/4] KVM: MMU: fix permission_fault() To: Xiao Guangrong References: <1458911978-19430-1-git-send-email-guangrong.xiao@linux.intel.com> <56F54983.4010508@redhat.com> <56FABECE.40601@linux.intel.com> <56FAE0F3.9090809@redhat.com> <56FB3254.5070403@linux.intel.com> Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org From: Paolo Bonzini Message-ID: <56FB73E0.7060601@redhat.com> Date: Wed, 30 Mar 2016 08:36:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <56FB3254.5070403@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 600 Lines: 19 On 30/03/2016 03:56, Xiao Guangrong wrote: >> x86/access.flat is currently using the "other" definition, i.e., PFEC.PK >> is only set if W=1 or CR0.WP=0 && PFEC.U=0 or PFEC.W=0. Can you use it >> (with ept=1 of course) to check what the processor is doing? > > Sure. > > And ept=1 is hard to trigger MMU issue, i am enabling PKEY on shadow > MMU, let's see what will happen. ;) No, don't do that! ept=1 lets you test what the processor does. It means you cannot test permission_fault(), but what we want here is just reverse engineering the microcode. ept=1 lets you do exactly that. Paolo