From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xiao Guangrong Subject: Re: [PATCH 1/4] KVM: MMU: fix permission_fault() Date: Wed, 30 Mar 2016 09:56:36 +0800 Message-ID: <56FB3254.5070403@linux.intel.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Paolo Bonzini Return-path: Received: from mga03.intel.com ([134.134.136.65]:3358 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752940AbcC3B5f (ORCPT ); Tue, 29 Mar 2016 21:57:35 -0400 In-Reply-To: <56FAE0F3.9090809@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/30/2016 04:09 AM, Paolo Bonzini wrote: > > > On 29/03/2016 19:43, Xiao Guangrong wrote: >> Based on the SDM: >> PK flag (bit 5). >> This flag is 1 if (1) IA32_EFER.LMA = CR4.PKE = 1; (2) the access >> causing the page-fault exception was a data access; (3) the linear >> address was a user-mode address with protection key i; and (5) the PKRU >> register (see Section 4.6.2) is such that either (a) ADi = 1; or (b) the >> following all hold: (i) WDi = 1; (ii) the access is a write access; and >> (iii) either CR0.WP = 1 or the access causing the page-fault exception >> was a user-mode access. >> >> So I think PKEY check and ordinary check are independent, i.e, PFEC.PKEY >> may be set even if the on permission on the page table is not adequate. > > 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. ;)