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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 9AB7FC35254 for ; Mon, 17 Feb 2020 11:23:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 68428207FD for ; Mon, 17 Feb 2020 11:23:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gE+G+JlB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728884AbgBQLXX (ORCPT ); Mon, 17 Feb 2020 06:23:23 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:36583 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728572AbgBQLXX (ORCPT ); Mon, 17 Feb 2020 06:23:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581938602; 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=MzSShR7Baq3pMc/kBpgCJS277t/Xu5wsk9DwxCBu5Qs=; b=gE+G+JlB0xdu6FzNBGbC4AngtKZfMEQaiTvaLR3FC0EljGIF5/r54HrS87Z2IR46QIcgaF zOL5oIwNmoCAlDICC5HZtaFpWxI8/iPRELJ6MVsZ7fRglPOo1HLgcI4mQxRzZYrbImGnxp RD4gAGse5w9waflZDwbN9cMnSTqaP4E= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-148-SXA9mesqOpafUisj1Yu9aA-1; Mon, 17 Feb 2020 06:23:20 -0500 X-MC-Unique: SXA9mesqOpafUisj1Yu9aA-1 Received: by mail-wr1-f72.google.com with SMTP id j4so8792295wrs.13 for ; Mon, 17 Feb 2020 03:23:19 -0800 (PST) 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=MzSShR7Baq3pMc/kBpgCJS277t/Xu5wsk9DwxCBu5Qs=; b=sbkbCfSlpq+wwpkLmvJq9lc50HDD0zIczMQHJDjakHSwor75NvMGs4MxOP36VXcF86 I208C5DCgqUgb74YtpLXyoOMvedMnzAwcvmw/Uk5qb/TMZF14mbsqXkLfFNhf5W8qaua AlbPGuSK3e2z1WS4l+Se9bExvAU/DYYnZSR5FA9bVR1Lx+2LTDeNWydZsXPO1CZKcTX1 V/qv7x4nqTikIOaybgb4jDrrnox20TavTxMSADLSVFG3UFINiKZlK7yeFpJ7cGXu4x+0 lWVn/7S+KRH97H5rNID4IDzR2L+jFSkCOzTGP4znw307EF/cJGVdlThtCCE5djrHVa0b PX3A== X-Gm-Message-State: APjAAAWrDI/rm9T0Dj0oNIRl9mMudjZymi64BVp2bwVgp3zCUR2oIqLl PCit1CvQgTPWUoO/OJ+ab932aM79Wg4Gbl+XBf5LUKFNm6FlpyHAs3e23aB7s7BNEqBtI0iglo1 mtVM374xgejA4W+VAlhugXMja X-Received: by 2002:a1c:e388:: with SMTP id a130mr21631729wmh.176.1581938598880; Mon, 17 Feb 2020 03:23:18 -0800 (PST) X-Google-Smtp-Source: APXvYqxRwSyzU0Sqecaad9VwaOksR0eo61oSfyaLYDxhxuBCi+8SmZweE1jjTzMmyVXDqR/8yH9N7Q== X-Received: by 2002:a1c:e388:: with SMTP id a130mr21631707wmh.176.1581938598568; Mon, 17 Feb 2020 03:23:18 -0800 (PST) Received: from ?IPv6:2001:b07:6468:f312:59c7:c3ee:2dec:d2b4? ([2001:b07:6468:f312:59c7:c3ee:2dec:d2b4]) by smtp.gmail.com with ESMTPSA id i16sm213867wmb.36.2020.02.17.03.23.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Feb 2020 03:23:18 -0800 (PST) Subject: Re: [PATCH v3 1/2] KVM: X86: Less kvmclock sync induced vmexits after VM boots To: Wanpeng Li , LKML , kvm Cc: Sean Christopherson , Wanpeng Li , Vitaly Kuznetsov , Jim Mattson , Joerg Roedel References: From: Paolo Bonzini Message-ID: <8fd7a83a-6fde-652f-0a2e-ec7b90c13616@redhat.com> Date: Mon, 17 Feb 2020 12:23:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/02/20 11:36, Wanpeng Li wrote: > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index fb5d64e..d0ba2d4 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -9390,8 +9390,9 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) > if (!kvmclock_periodic_sync) > return; > > - schedule_delayed_work(&kvm->arch.kvmclock_sync_work, > - KVMCLOCK_SYNC_PERIOD); > + if (kvm->created_vcpus == 1) > + schedule_delayed_work(&kvm->arch.kvmclock_sync_work, > + KVMCLOCK_SYNC_PERIOD); This is called with kvm->lock not held, so you can have kvm->created_vcpus == 2 by the time you get here. You can test instead "if (vcpu->vcpu_idx == 0)". Thanks, Paolo