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=-5.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 035C5C2BB84 for ; Wed, 16 Sep 2020 11:32:12 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7C6DE21D7D for ; Wed, 16 Sep 2020 11:32:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LFdoltyQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C6DE21D7D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:48730 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kIVfW-0007wJ-Gq for qemu-devel@archiver.kernel.org; Wed, 16 Sep 2020 07:32:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49332) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kIVdj-0007Ew-2u for qemu-devel@nongnu.org; Wed, 16 Sep 2020 07:30:19 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:41723) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kIVdg-0005Zz-79 for qemu-devel@nongnu.org; Wed, 16 Sep 2020 07:30:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600255815; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=CLMDr0I82qDNenqvpoxtIAcZBgkokDUzKrJ+7RU7h6E=; b=LFdoltyQ4Xb/bLvR1Auk+/tJjT/20M0P/4IhhGhfYtSNFoyB6e/E9A7x8d7Q1Ei+yHU1I8 tqmB8D1OWRFzeN/fYgTu0la/Yoa3itKJHKfntyNxd20ijd56imXyVFIMbRIXmX/1BJoU4l RoHhqrvhCFmR5PSmEbnK0WzTVHsrMJU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-540-ddu9Z7AZMWGz9GlQGWIPbw-1; Wed, 16 Sep 2020 07:30:13 -0400 X-MC-Unique: ddu9Z7AZMWGz9GlQGWIPbw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4C3CF890E7A; Wed, 16 Sep 2020 11:30:12 +0000 (UTC) Received: from work-vm (ovpn-114-237.ams2.redhat.com [10.36.114.237]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B7DFC5DE8D; Wed, 16 Sep 2020 11:29:58 +0000 (UTC) Date: Wed, 16 Sep 2020 12:29:56 +0100 From: "Dr. David Alan Gilbert" To: Antoine Damhet , vkuznets@redhat.com Subject: Re: [BUG] Migration hv_time rollback Message-ID: <20200916112956.GE2833@work-vm> References: <20200916090602.blkm7eym6g5bnvvk@tartarus> MIME-Version: 1.0 In-Reply-To: <20200916090602.blkm7eym6g5bnvvk@tartarus> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/16 02:35:56 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.999, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , Juan Quintela , qemu-devel@nongnu.org, "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" cc'ing in Vitaly who knows about the hv stuff. * Antoine Damhet (antoine.damhet@blade-group.com) wrote: > Hi, > > We are experiencing timestamp rollbacks during live-migration of > Windows 10 guests with the following qemu configuration (linux 5.4.46 > and qemu master): > ``` > $ qemu-system-x86_64 -enable-kvm -cpu host,kvm=off,hv_time [...] > ``` How big a jump are you seeing, and how did you notice it in the guest? Dave > I have tracked the bug to the fact that `kvmclock` is not exposed and > disabled from qemu PoV but is in fact used by `hv-time` (in KVM). > > I think we should enable the `kvmclock` (qemu device) if `hv-time` is > present and add Hyper-V support for the `kvmclock_current_nsec` > function. > > I'm asking for advice because I am unsure this is the _right_ approach > and how to keep migration compatibility between qemu versions. > > Thank you all, > > -- > Antoine 'xdbob' Damhet -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK