From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933967AbcIEN7f (ORCPT ); Mon, 5 Sep 2016 09:59:35 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:34239 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932192AbcIEN7b (ORCPT ); Mon, 5 Sep 2016 09:59:31 -0400 Subject: Re: [PATCH 3/4] KVM: x86: introduce get_kvmclock_ns To: Roman Kagan , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, peterhornyack@google.com, rkrcmar@redhat.com, den@openvz.org References: <1472743575-123756-1-git-send-email-pbonzini@redhat.com> <1472743575-123756-4-git-send-email-pbonzini@redhat.com> <20160902152439.xraq7pmtryd2nkta@rkaganb.sw.ru> From: Paolo Bonzini Message-ID: <8db8781a-a6d7-7e70-f8ef-221078a34770@redhat.com> Date: Mon, 5 Sep 2016 15:59:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160902152439.xraq7pmtryd2nkta@rkaganb.sw.ru> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/09/2016 17:24, Roman Kagan wrote: > On Thu, Sep 01, 2016 at 05:26:14PM +0200, Paolo Bonzini wrote: >> Introduce a function that reads the exact nanoseconds value that is >> provided to the guest in kvmclock. This crystallizes the notion of >> kvmclock as a thin veneer over a stable TSC, that the guest will >> (hopefully) convert with NTP. In other words, kvmclock is *not* a >> paravirtualized host-to-guest NTP. > > It might also be worth documenting this approach in a comment somewhere > around pvclock_gtod_notify / update_pvclock_gtod or friends. And, if > those could be simplified due to this change, it would be great, too. Yes, Radim or I are going to look at it next... Paolo