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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 095FFC4361B for ; Thu, 10 Dec 2020 13:02:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF1B723D50 for ; Thu, 10 Dec 2020 13:02:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388894AbgLJNCu (ORCPT ); Thu, 10 Dec 2020 08:02:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387506AbgLJNCt (ORCPT ); Thu, 10 Dec 2020 08:02:49 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E94BFC0613CF; Thu, 10 Dec 2020 05:02:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=8DNWVeAUd7OvyCVtE5PeUeZEuJerl3ZR6gz0ZKvmpyo=; b=QoPx6KFRU+xS+RaJr2y1Qphzjb s+yXByA3V4D2JJjPNrqJEj1y++RZMQ2QrVSvDnGQqtmx8Lo3LdXjBPtz6vEngpYhMZ98DjG9GIJ9N vXErudo8loKA59o3aKxKOwrOiETZnptD4jkclkS27O9+TI1oA9mUX0LhghbGIG1XS6WdyaqIC019R eJRa7Pn/tHHTPljQtMtEZc+TQJWcFm0Ef/WN0X2mlbE2Ut6pZQmyaSKeiAdBskXfwa2uDiHcEnJuN GdkBDPHqdcZlK7QNdKtrpU1zccUIpK/CQWvIM06IHs+Ak9gYHhzEXczcug14IEm8h+EtHPNMYGynU jDQ0bHzQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1knLZd-0004f1-BZ; Thu, 10 Dec 2020 13:01:33 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id A3D693007CD; Thu, 10 Dec 2020 14:01:31 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8C5B7209B20CB; Thu, 10 Dec 2020 14:01:31 +0100 (CET) Date: Thu, 10 Dec 2020 14:01:31 +0100 From: Peter Zijlstra To: Paolo Bonzini Cc: Thomas Gleixner , Vitaly Kuznetsov , Maxim Levitsky , "H. Peter Anvin" , Jonathan Corbet , Jim Mattson , Wanpeng Li , "open list:KERNEL SELFTEST FRAMEWORK" , Marcelo Tosatti , Sean Christopherson , open list , Ingo Molnar , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Joerg Roedel , Borislav Petkov , Shuah Khan , Andrew Jones , Oliver Upton , "open list:DOCUMENTATION" , kvm@vger.kernel.org Subject: Re: [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE Message-ID: <20201210130131.GP2414@hirez.programming.kicks-ass.net> References: <20201203171118.372391-1-mlevitsk@redhat.com> <20201203171118.372391-2-mlevitsk@redhat.com> <87a6uq9abf.fsf@nanos.tec.linutronix.de> <1dbbeefc7c76c259b55582468ccd3aab35a6de60.camel@redhat.com> <87im9dlpsw.fsf@vitty.brq.redhat.com> <875z5d5x9m.fsf@nanos.tec.linutronix.de> <20201210121417.GN2414@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 10, 2020 at 01:22:02PM +0100, Paolo Bonzini wrote: > On 10/12/20 13:14, Peter Zijlstra wrote: > > On Thu, Dec 10, 2020 at 12:42:36PM +0100, Paolo Bonzini wrote: > > > On 07/12/20 18:41, Thomas Gleixner wrote: > > > > Right this happens still occasionally, but for quite some time this is > > > > 100% firmware sillyness and not a fundamental property of the hardware > > > > anymore. > > > > > > It's still a fundamental property of old hardware. Last time I tried to > > > kill support for processors earlier than Core 2, I had to revert it. That's > > > older than Nehalem. > > > > Core2 doesn't use TSC for timekeeping anyway. KVM shouldn't either. > > On Core2, KVM guests pass TSC through kvmclock in order to get something > usable and not incredibly slow. Which is incredibly wrong.