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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 00119C433E6 for ; Mon, 31 Aug 2020 12:48:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0F7B206E3 for ; Mon, 31 Aug 2020 12:48:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="LNasvsZ7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727930AbgHaMsX (ORCPT ); Mon, 31 Aug 2020 08:48:23 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:33937 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726927AbgHaMsV (ORCPT ); Mon, 31 Aug 2020 08:48:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598878099; 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=cnx3CjRYB9hGIWsNjQqszr2co7+0ihfxtc0QgvVHV+M=; b=LNasvsZ7SbEDYQjMM8xGySdh47Bqssi4QRR6ArndKIreMwD47UyY/ENbizOi6N3MK23wz3 I7TKbXDI2orI6jBeu/uMcB2qDBnShIL7Tj7c+zuCf8IZwherbJ4BLcdrqzKtt4o/p5y9+c zDg+mLx+uanv+ZI3VOSmYYDU9XzTgnE= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-484-1codpAUsPsWPQLHyynoZuQ-1; Mon, 31 Aug 2020 08:48:15 -0400 X-MC-Unique: 1codpAUsPsWPQLHyynoZuQ-1 Received: by mail-wr1-f69.google.com with SMTP id r15so3175982wrt.8 for ; Mon, 31 Aug 2020 05:48:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=cnx3CjRYB9hGIWsNjQqszr2co7+0ihfxtc0QgvVHV+M=; b=aAyCxCUsbOjeUmu/u0FZEVr60fnuhX7fKaZVMlonuNvrFQv3g3AUFtV8W+c27Qw324 ilVN6CbuvWLEeihn8SyE0M6pQ8vPwe3c5GHEDnp2K7f3JetvmeX9koigne1YTa6XpvDP CiN/VDulGxiJ3l4uk/Hp9md52H1lV2c396Bugp0fhVSoUffTN+XdAvBW2nENqNBojcMH JNhq+p8iYhBDv1qaw3kOLjtiHhtRb+D+ThnaoSSO7i44L74NCfI99RZGjtiSC34lb99G mtR3g2Sf0fqtkWSohcMS++73DsJ8xYiTJkCqHNPFPwqKFpwuOtCCwZTctuEsr/gmllRj 5e8A== X-Gm-Message-State: AOAM530ZseR9QKhCCbjVPieVTfoiDnpxq+Nh2lDNiigkwXLosPDgPkMa iewMhVA7Gdw6vBFvShtvP8wLlT3L+OqqpJmjqnH9onz1rYD2X0uBgCTyfm5FNtY2MdWcRLPsg6J 6l299HB2UMfOY X-Received: by 2002:a1c:2e17:: with SMTP id u23mr1319221wmu.73.1598878094354; Mon, 31 Aug 2020 05:48:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwc3ks723eU0MJaIHVO/d8tt1FXCDACXwreTLs0dlEDnbVrsUC4Kux9ZLcT5gY6wvSD7o4bJg== X-Received: by 2002:a1c:2e17:: with SMTP id u23mr1319205wmu.73.1598878094196; Mon, 31 Aug 2020 05:48:14 -0700 (PDT) Received: from vitty.brq.redhat.com (g-server-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id 62sm12384616wre.60.2020.08.31.05.48.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Aug 2020 05:48:13 -0700 (PDT) From: Vitaly Kuznetsov To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Wanpeng Li , Jim Mattson , Joerg Roedel Subject: Re: [PATCH] KVM: LAPIC: Reset timer_advance_ns if timer mode switch In-Reply-To: <1598578508-14134-1-git-send-email-wanpengli@tencent.com> References: <1598578508-14134-1-git-send-email-wanpengli@tencent.com> Date: Mon, 31 Aug 2020 14:48:12 +0200 Message-ID: <87a6ybx9pv.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Wanpeng Li writes: > From: Wanpeng Li > > per-vCPU timer_advance_ns should be set to 0 if timer mode is not tscdeadline > otherwise we waste cpu cycles in the function lapic_timer_int_injected(), lapic_timer_int_injected is just a test, kvm_wait_lapic_expire() (__kvm_wait_lapic_expire()) maybe? > especially on AMD platform which doesn't support tscdeadline mode. We can > reset timer_advance_ns to the initial value if switch back to > tscdealine 'tscdeadline' > timer mode. > > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/lapic.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 654649b..abc296d 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1499,10 +1499,16 @@ static void apic_update_lvtt(struct kvm_lapic *apic) > kvm_lapic_set_reg(apic, APIC_TMICT, 0); > apic->lapic_timer.period = 0; > apic->lapic_timer.tscdeadline = 0; > + if (timer_mode == APIC_LVT_TIMER_TSCDEADLINE && > + lapic_timer_advance_dynamic) > + apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_NS_INIT; > } > apic->lapic_timer.timer_mode = timer_mode; > limit_periodic_timer_frequency(apic); > } > + if (timer_mode != APIC_LVT_TIMER_TSCDEADLINE && > + lapic_timer_advance_dynamic) > + apic->lapic_timer.timer_advance_ns = 0; > } > > /* -- Vitaly