From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH v1 2/2] KVM: VMX: always require WB memory type for EPT Date: Thu, 10 Aug 2017 21:54:53 +0200 Message-ID: References: <20170810133512.13442-1-david@redhat.com> <20170810133512.13442-3-david@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= To: Bandan Das Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59446 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752807AbdHJTy6 (ORCPT ); Thu, 10 Aug 2017 15:54:58 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8E3DC7F3FB for ; Thu, 10 Aug 2017 19:54:58 +0000 (UTC) In-Reply-To: Content-Language: en-US Sender: kvm-owner@vger.kernel.org List-ID: On 10.08.2017 21:40, Bandan Das wrote: > David Hildenbrand writes: > >> We already always set that type but don't check if it is supported. Also >> for nVMX, we only support WB for now. Let's just require it. > > Out of curiosity, is there old hardware that supports ept but not WB ? > I guess no. KVM always sets up WB for all eptps. KVM would in the current state simply not work on these machines (vm entry failure). I guess the same is also true for 4level page-walk length. This should also be part of any EPT implementation but still we have to check for it. -- Thanks, David