From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86452C432C1 for ; Tue, 24 Sep 2019 08:09:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4475B2146E for ; Tue, 24 Sep 2019 08:09:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="nsB7Q+qj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504087AbfIXIJH (ORCPT ); Tue, 24 Sep 2019 04:09:07 -0400 Received: from mail-yb1-f194.google.com ([209.85.219.194]:41442 "EHLO mail-yb1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2409392AbfIXIJG (ORCPT ); Tue, 24 Sep 2019 04:09:06 -0400 Received: by mail-yb1-f194.google.com with SMTP id x4so368252ybo.8 for ; Tue, 24 Sep 2019 01:09:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=oytvwTJ/h++ppV0afAZb6O2XZSdvl/Vc69K9QBOB/1I=; b=nsB7Q+qjaMYUId+8LsfJGaz0hmV70zOa+b32OgGfRwJiHbfQ/Qh3Wuq1hdAYuLsScy GCFwfdqUZj9Twgo/ZDpsOICE2FztUhXDuDGl4Rfqm7QHou3CPGBwjPRhkkAj90y1nVhf J6QiHjDnwuRo+2YP44RMBn3wXMrOR1UKgUmMagAz1sIHPfcHm/IepjBNIjJwL6OJHpL1 LKEiZAeNGqjhQ2c4EvkDWaz6sGUi5oHuyILSJHo/gWd8KP4yCYApb1ZqTucdWowT7BHn k2BpmoXk1E3/Fra3cyexYK0s5IqTkN0gD6ZLlGCo7txBa77c0j3OZMPC5V7HQFyZwpoq LuYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=oytvwTJ/h++ppV0afAZb6O2XZSdvl/Vc69K9QBOB/1I=; b=K+oz5gDRgxetBxvXN/kHzJYIvdk1cPBE+xXAkirlo9OTfsu4r3QMW5XzL373dK+kD9 SYh5rPgECnsFPasRcriNIFQpHme6QyhkUdrfaYPJvwp8Ss/eR2za0zZCuhWDtIWfdU/9 wehST49F0dB/YeUUeb5nEN0SZwQ0CT04uLG5pnnGAna8aRjp0GEErZHXBc9hNj+eLHBF jjPfEHnKpuuwL2TuA73tH80si9M6B8nVsky+jC1LnDQ6YAx2WrPLdDKaZOMZ83qO7Rho PhTA+Hjo2pCjAkIqTxbQMNNFYOkzJ0Qzd/X3EPL2WCp0P+UEFdCDkW7Fl9+w2+2HAUw9 7PuA== X-Gm-Message-State: APjAAAXjT9p0doa/X/5Ootq+a+7KyXSy6PjlAHHbpIcCk3lUy0VUY+/B T4Uk9TWLVYt0lTjCSjwpfZrmnHD8Xb+jlOeE+0pdRw== X-Google-Smtp-Source: APXvYqw27y/Qen9avOGLVC1H7Ty4V0crxs6S2bV+PW+p3P+bzFt3FmBWB9gwHx9i22bWEUc/UxHPSbS2ENiDKbUB7eA= X-Received: by 2002:a25:a421:: with SMTP id f30mr1060469ybi.287.1569312545144; Tue, 24 Sep 2019 01:09:05 -0700 (PDT) MIME-Version: 1.0 References: <20190920062713.78503-1-suleiman@google.com> <1ec0b238-61a7-8353-026e-3a2ee23e6240@redhat.com> In-Reply-To: From: Suleiman Souhlal Date: Tue, 24 Sep 2019 17:08:53 +0900 Message-ID: Subject: Re: [RFC 0/2] kvm: Use host timekeeping in guest. To: Thomas Gleixner Cc: Paolo Bonzini , rkrcmar@redhat.com, john.stultz@linaro.org, sboyd@kernel.org, Linux Kernel , kvm@vger.kernel.org, Tomasz Figa Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 20, 2019 at 7:23 PM Thomas Gleixner wrote: > > On Fri, 20 Sep 2019, Paolo Bonzini wrote: > > > On 20/09/19 08:27, Suleiman Souhlal wrote: > > > To do that, I am changing kvmclock to request to the host to copy > > > its timekeeping parameters (mult, base, cycle_last, etc), so that > > > the guest timekeeper can use the same values, so that time can > > > be synchronized between the guest and the host. > > > > > > Any suggestions or feedback would be highly appreciated. > > > > I'm not a timekeeping maintainer, but I don't think the > > kernel/time/timekeeping.c changes are acceptable. > > Indeed. #ifdef WHATEVERTHEHECK does not go anywhere. If at all this needs > to be a runtime switch, but I have yet to understand the whole picture of > this. Yeah, I will try to make this a runtime switch. As for the PTP driver, I don't think it will work for us because we need CLOCK_MONOTONIC and CLOCK_BOOTTIME to match the host, and from my understanding, PTP doesn't solve that. Thanks, -- Suleiman