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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 BAA13C433E0 for ; Thu, 18 Mar 2021 18:06:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88F2264F10 for ; Thu, 18 Mar 2021 18:06:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232469AbhCRSGE (ORCPT ); Thu, 18 Mar 2021 14:06:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30434 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232465AbhCRSFz (ORCPT ); Thu, 18 Mar 2021 14:05:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616090754; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ll1bQe/UBT3VroUgF4BnknfLZ8l/4NCV9c8uHrwM20E=; b=RryRHP/EIMvWXwce0uixse+3hGjzoqDZxry5gOT0QyaS2mSRtLAUfcZFTHMv/MSmzYg76H cw2YRVV5LIrJ8ET34EsAz79SNYf3rtn4KhVKYBzYdOPYGLXH+NbCM8/oSd9Y7+/NOAl38h 0mHwIye4pa8rdL43YYvgYM3svSnuM8k= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-463-77VoZfaPOyCD72D0yIILjA-1; Thu, 18 Mar 2021 14:05:53 -0400 X-MC-Unique: 77VoZfaPOyCD72D0yIILjA-1 Received: by mail-ed1-f72.google.com with SMTP id q25so6892042eds.16 for ; Thu, 18 Mar 2021 11:05:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=ll1bQe/UBT3VroUgF4BnknfLZ8l/4NCV9c8uHrwM20E=; b=anMinDbGh9aYDW/2qnfSMIFvDI5xuzUzLXkaWs9ACkwy7eda28G+bHYBbgmGstucrV vQRfUgZmwDFBef9KelbkGw1oDDkBHeHIymX8Qg1UfZiOnChRDMDpsHM1SPL+fXjuzYGv M0njvUA/OLG8tu42JUmPCCloWgkuNURGVktkg2Ue1HvA9l3xEDTyhd6V8WGaDFnTmHem /rlmWGTgh8nla5fcS3zTbeWz3pROUv/k5oesQz2ZsZ0g8q0jz2N6qvI3X2bsb1UThZnM xBLbLqnoZGh6/1QIetqAD3N8+IlfzPAm8iY8rstrS2M5aCntQNL/zIZMyelFuOV0oDF6 7p1w== X-Gm-Message-State: AOAM531mXHcyKMSw7mU4xFLEDQEnYNIlta04q/PWqm96PQWagKr7o+k9 SKN3lNQ6On7mCnc4DuO7sdCngFAT9n5ZvbTj/VMuNUAZiYUMSCrf6rUC1WVA4JfmL/Qjcu6e5le 7wqmfZINXtjvs X-Received: by 2002:aa7:cf95:: with SMTP id z21mr5178746edx.76.1616090751811; Thu, 18 Mar 2021 11:05:51 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzqqSjbYGjJWtUB2B2KJKUh//doS8F2HuRxswNQ5R59+pULlSEFiMiIKjm8fFkQY7ir6bK24g== X-Received: by 2002:aa7:cf95:: with SMTP id z21mr5178729edx.76.1616090751630; Thu, 18 Mar 2021 11:05:51 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id k9sm2788266edn.68.2021.03.18.11.05.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 18 Mar 2021 11:05:51 -0700 (PDT) Subject: Re: [PATCH v2 2/4] KVM: x86: hyper-v: Prevent using not-yet-updated TSC page by secondary CPUs To: Marcelo Tosatti , Vitaly Kuznetsov Cc: kvm@vger.kernel.org, Sean Christopherson , Wanpeng Li , Jim Mattson References: <20210316143736.964151-1-vkuznets@redhat.com> <20210316143736.964151-3-vkuznets@redhat.com> <20210318170208.GB36190@fuller.cnet> <20210318180446.GA41953@fuller.cnet> From: Paolo Bonzini Message-ID: <5634f6c9-bee9-ae07-c8ce-8e79bd2bd1a7@redhat.com> Date: Thu, 18 Mar 2021 19:05:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210318180446.GA41953@fuller.cnet> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 18/03/21 19:04, Marcelo Tosatti wrote: >> >> Not clear why this is necessary, if the choice was to not touch TSC page >> at all, when invariant TSC is supported on the host... > > s/invariant TSC/TSC scaling/ > >> Ah, OK, this is not for the migration with iTSC on destination case, >> but any call to kvm_gen_update_masterclock, correct? Yes, any update can be racy. Paolo