From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753519AbdKJPjf (ORCPT ); Fri, 10 Nov 2017 10:39:35 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:55386 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752417AbdKJPjc (ORCPT ); Fri, 10 Nov 2017 10:39:32 -0500 X-Google-Smtp-Source: AGs4zMYBT5r8ns23BcIUuvKQ83s+CbrzWqfuwifulwW01uiZaUwIUnBvAl7DJn1MVQLzWw1XHoU1QA== Subject: Re: [PATCH RFC 00/10] Intel EPT-Based Sub-page Write Protection Support. From: Paolo Bonzini To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, rkrcmar@redhat.com, ravi.sahita@intel.com References: <20171104001243.GA81548@dazhang1-ssd.sh.intel.com> Message-ID: Date: Fri, 10 Nov 2017 16:39:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/11/2017 17:54, Paolo Bonzini wrote: > On 04/11/2017 01:12, Yi Zhang wrote: >>> >> Adding Ravi, >> >> Does anyone have further comments on current implementation, it is a >> important feature in our next generation chip-set. > > What matters is not the feature, but the use case; without a use case, > there is no point in including code for SPP in KVM. KVM doesn't use > VMFUNC or #VE for example, because they are not necessary. > > SPP may become useful once we have the introspection interface. Or, if > another hypervisor uses it, support for nested SPP may be useful (for > example we support nested VMFUNC and should get nested #VE sooner or > later, even though the features are not used on bare metal). > > Right now, however, supporting SPP does not seem to be particularly > important honestly. Hi Yi Zhang, are you going to work on nested SPP? I guess that would be most useful way to add SPP support to KVM (and you could also test it with kvm-unit-tests). Thanks, Paolo