Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934132AbdGKTiZ convert rfc822-to-8bit (ORCPT ); Tue, 11 Jul 2017 15:38:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42372 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933601AbdGKTiW (ORCPT ); Tue, 11 Jul 2017 15:38:22 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com C18977C847 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=bsd@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com C18977C847 From: Bandan Das To: Radim =?utf-8?B?S3LEjW3DocWZ?= Cc: Jim Mattson , David Hildenbrand , kvm list , Paolo Bonzini , LKML Subject: Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor References: <20170710204936.4001-1-bsd@redhat.com> <20170710204936.4001-4-bsd@redhat.com> <2d50ebc4-9328-ce08-b55b-6a331ee13cc3@redhat.com> <20170711191334.GB3442@potion> Date: Tue, 11 Jul 2017 15:38:14 -0400 In-Reply-To: <20170711191334.GB3442@potion> ("Radim \=\?utf-8\?B\?S3LEjW3DocWZ\?\= \=\?utf-8\?B\?Iidz\?\= message of "Tue, 11 Jul 2017 21:13:34 +0200") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 11 Jul 2017 19:38:21 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1085 Lines: 26 Radim Krčmář writes: > 2017-07-11 14:35-0400, Bandan Das: >> Jim Mattson writes: >> ... >> >>> I can find the definition for an vmexit in case of index >= >> >>> VMFUNC_EPTP_ENTRIES, but not for !vmcs12->eptp_list_address in the SDM. >> >>> >> >>> Can you give me a hint? >> >> >> >> I don't think there is. Since, we are basically emulating eptp switching >> >> for L2, this is a good check to have. >> > >> > There is nothing wrong with a hypervisor using physical page 0 for >> > whatever purpose it likes, including an EPTP list. >> >> Right, but of all the things, a l1 hypervisor wanting page 0 for a eptp list >> address most likely means it forgot to initialize it. Whatever damage it does will >> still end up with vmfunc vmexit anyway. > > Most likely, but not certainly. I also don't see a to diverge from the > spec here. Actually, this is a specific case where I would like to diverge from the spec. But then again, it's L1 shooting itself in the foot and this would be a rarely used code path, so, I am fine removing it.