From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 1/4] KVM: MMU: fix permission_fault() Date: Tue, 29 Mar 2016 22:09:23 +0200 Message-ID: <56FAE0F3.9090809@redhat.com> References: <1458911978-19430-1-git-send-email-guangrong.xiao@linux.intel.com> <56F54983.4010508@redhat.com> <56FABECE.40601@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: gleb@kernel.org, mtosatti@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Xiao Guangrong Return-path: In-Reply-To: <56FABECE.40601@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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? Paolo