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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 DA02EC43144 for ; Fri, 29 Jun 2018 07:30:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 91BFF24240 for ; Fri, 29 Jun 2018 07:30:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 91BFF24240 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933502AbeF2Hau (ORCPT ); Fri, 29 Jun 2018 03:30:50 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:57836 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753259AbeF2Has (ORCPT ); Fri, 29 Jun 2018 03:30:48 -0400 Received: from hsi-kbw-5-158-153-55.hsi19.kabel-badenwuerttemberg.de ([5.158.153.55] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1fYnrD-0002HP-VV; Fri, 29 Jun 2018 09:30:16 +0200 Date: Fri, 29 Jun 2018 09:30:10 +0200 (CEST) From: Thomas Gleixner To: Pavel Tatashin cc: Steven Sistare , Daniel Jordan , linux@armlinux.org.uk, Martin Schwidefsky , Heiko Carstens , John Stultz , sboyd@codeaurora.org, x86@kernel.org, LKML , mingo@redhat.com, "H. Peter Anvin" , douly.fnst@cn.fujitsu.com, Peter Zijlstra , Prarit Bhargava , feng.tang@intel.com, Petr Mladek , gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org, andriy.shevchenko@linux.intel.com, boris.ostrovsky@oracle.com, pbonzini@redhat.com Subject: Re: [PATCH v12 09/11] x86/tsc: prepare for early sched_clock In-Reply-To: Message-ID: References: <20180621212518.19914-1-pasha.tatashin@oracle.com> <20180621212518.19914-10-pasha.tatashin@oracle.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 28 Jun 2018, Pavel Tatashin wrote: > On Thu, Jun 28, 2018 at 11:23 AM Thomas Gleixner wrote: > Hi Thomas, > > In addition to above, we have xen hvm: > > setup_arch() > ... > init_hypervisor_platform(); > x86_init.hyper.init_platform(); > xen_hvm_guest_init() > xen_hvm_init_time_ops(); Duh. Missed that completely. > ... > tsc_early_delay_calibrate(); > tsc_khz = x86_platform.calibrate_tsc(); == xen_tsc_khz() > ... > > Which works early. > > So, what should we do with xen, which seems to be the only platform > that would provide different tsc frequency early and late, because of > different calibration method? Fix it? I have no idea why XEN has two variants of the scheme and I neither have a clue why the KVM clock stuff is late. Thanks, tglx