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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 EC700C43142 for ; Thu, 28 Jun 2018 11:47:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3375272DF for ; Thu, 28 Jun 2018 11:47:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dKoAnec0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A3375272DF Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S965645AbeF1LrH (ORCPT ); Thu, 28 Jun 2018 07:47:07 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:58750 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933933AbeF1LrE (ORCPT ); Thu, 28 Jun 2018 07:47:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=TcAM7vpWeW9JbkdbBEj1QaU68boBMzAQSJAhI1EDWOU=; b=dKoAnec0CaNRMfEK51clWgjMd NKxr6cR5C4quKtH0bxmTsW1AfkIT/CsNCK97v4gRxZFLbWDTYNt43DmAAiLv4KBwPoFOclrlNNzW4 fv7Is1Gxq0TcgAlNUikLASOj07ticyMEPXvU37N7maQnPmUHq9IF/W8ORU93WkIFOd8AC2CwpCcWU kMnVoBJmUNnznlDuO+TKy4ZRSpiJOVR727nAwL9OzXTxIQLst/+vcImw3oJovP6GlPFdbz4wbbKWY mY/eCt0TIs7AVvyidElMrc83CegCyiy72aK/SHfNGAdgETBHrk90kLjJbfJ/f/OcwImzmWdDn1NPm zqva22NUg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fYVNT-0002jb-93; Thu, 28 Jun 2018 11:46:19 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E4D2220289CE5; Thu, 28 Jun 2018 13:46:15 +0200 (CEST) Date: Thu, 28 Jun 2018 13:46:15 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: Pavel Tatashin , 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, Prarit Bhargava , feng.tang@intel.com, Petr Mladek , gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org, Andy Shevchenko , Boris Ostrovsky Subject: Re: [PATCH v12 09/11] x86/tsc: prepare for early sched_clock Message-ID: <20180628114615.GF2494@hirez.programming.kicks-ass.net> References: <20180621212518.19914-1-pasha.tatashin@oracle.com> <20180621212518.19914-10-pasha.tatashin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 28, 2018 at 12:43:59PM +0200, Thomas Gleixner wrote: > init_hypervisor_platform() > vmware: > Retrieves frequency and store it for the > calibration function > > khz = vmware_get_khz_magic() > vmware_tsc_khz = khz > calibrate_cpu = vmware_get_tsc_khz > calibrate_tsc = vmware_get_tsc_khz > preset_lpj(khz) > > hyperv: > if special hyperv MSRs are available: > > calibrate_cpu = hv_get_tsc_khz > calibrate_tsc = hv_get_tsc_khz > > MSR is readable already in this function > > jailhouse: > > Frequency is available in this function and store > in a variable for the calibration function > > calibrate_cpu = jailhouse_get_tsc > calibrate_tsc = jailhouse_get_tsc > > ... > > kvmclock_init() > > if (magic_conditions) > calibrate_tsc = kvm_get_tsc_khz > calibrate_cpu = kvm_get_tsc_khz > > kvm_get_preset_lpj() > khz = kvm_get_tsc_khz() > preset_lpj(khz); Note that all these which get TSC values from a HV _should_ set X86_FEATURE_TSC_KNOWN_FREQ to avoid the late recalibrate. Calibrating against a virtual PIT/HPET/PMTIMER is utterly pointless. > The generic initilizaiton does everything twice, which makes no sense, > except for the unlikely case were no fast functions are available and the > quick PIT calibration fails (PMTIMER/HPET) are not available in early > calibration. HPET Incomplete; but I suspect you want to talk about how we can make HPET available early by putting it in a fixmap. And only if we fail, do we at a later stage try again using PMTIMER. Currently it all works by accident, since !hpet and acpi_pm_read_early() returns 0, but really we should not be running the fallback crap at all that early.