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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 45A18C04AAC for ; Mon, 20 May 2019 11:41:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2421C20645 for ; Mon, 20 May 2019 11:41:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731102AbfETLl1 (ORCPT ); Mon, 20 May 2019 07:41:27 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:33249 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730632AbfETLl0 (ORCPT ); Mon, 20 May 2019 07:41:26 -0400 Received: by mail-wr1-f66.google.com with SMTP id d9so1254843wrx.0 for ; Mon, 20 May 2019 04:41:25 -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=fE+RFyZyDUMaLhpUHBd7W8JMDRw/RtTMk4wk4VaAuU8=; b=QwV1Vnh9gG4cJTK/b+dVtRAGpaIDEw2ijPMa9aNpsjb7HgJfU1PMtrppbjLj7CZbuv 00VdJCE8RMe2aFFKx9wdRw4j/4KfuT7GpUkLHv7UtZaJAH+r1x97EVfvBapJdNeCGCK9 d+5pCR61CDLOKFrUUByxVJ14VUsEQs7anq7X2JBFOnvSkR4xJe/Uy5Z9ToSdLDNxAW85 CgCfvsRUfgccDUrr8wJaXtYss37xqTsKlEVYNs7NvOXxH4VtRP/Otcrqf1kC79nid6M2 kzheJNwGerpIcXgyTko2PeBemteSWWb+rogEfmBlO+ufBpGl4Yow1A2qFgr84ujidQ38 k1AA== X-Gm-Message-State: APjAAAXTtrgGGjvajR6Wt3xA/jr8/cpIDAI3VMWUhQ+3jJ8k/ANM3JbG 7oRWLGRXOWSA/n1faNoL2Cbsrw== X-Google-Smtp-Source: APXvYqyYQoknmXEgL6TPhActsY14UfsNRIHZOxsu1Wq1NvswtjnabDPg3J+gMjvgKyjf79tZM+7ZSg== X-Received: by 2002:adf:f741:: with SMTP id z1mr45344362wrp.14.1558352485112; Mon, 20 May 2019 04:41:25 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:ac04:eef9:b257:b844? ([2001:b07:6468:f312:ac04:eef9:b257:b844]) by smtp.gmail.com with ESMTPSA id s3sm33334241wre.97.2019.05.20.04.41.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 May 2019 04:41:24 -0700 (PDT) Subject: Re: [PATCH v4 4/5] KVM: LAPIC: Delay trace advance expire delta To: Wanpeng Li Cc: LKML , kvm , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Sean Christopherson , Liran Alon References: <1558340289-6857-1-git-send-email-wanpengli@tencent.com> <1558340289-6857-5-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: <024a0c93-f8a3-abe0-85de-fa41babf06a0@redhat.com> Date: Mon, 20 May 2019 13:41:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 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 20/05/19 13:36, Wanpeng Li wrote: >> Hmm, yeah, that makes sense. The location of the tracepoint is a bit >> weird, but I guess we can add a comment in the code. > Do you need me to post a new patchset? :) No problem. The final patch that I committed is this: diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index c12b090f4fad..f8615872ae64 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1502,27 +1502,27 @@ static inline void __wait_lapic_expire(struct kvm_vcpu *vcpu, u64 guest_cycles) } static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu, - u64 guest_tsc, u64 tsc_deadline) + s64 advance_expire_delta) { struct kvm_lapic *apic = vcpu->arch.apic; u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns; u64 ns; /* too early */ - if (guest_tsc < tsc_deadline) { - ns = (tsc_deadline - guest_tsc) * 1000000ULL; + if (advance_expire_delta < 0) { + ns = -advance_expire_delta * 1000000ULL; do_div(ns, vcpu->arch.virtual_tsc_khz); timer_advance_ns -= min((u32)ns, timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP); } else { /* too late */ - ns = (guest_tsc - tsc_deadline) * 1000000ULL; + ns = advance_expire_delta * 1000000ULL; do_div(ns, vcpu->arch.virtual_tsc_khz); timer_advance_ns += min((u32)ns, timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP); } - if (abs(guest_tsc - tsc_deadline) < LAPIC_TIMER_ADVANCE_ADJUST_DONE) + if (abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_DONE) apic->lapic_timer.timer_advance_adjust_done = true; if (unlikely(timer_advance_ns > 5000)) { timer_advance_ns = 0; @@ -1545,13 +1545,13 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu) tsc_deadline = apic->lapic_timer.expired_tscdeadline; apic->lapic_timer.expired_tscdeadline = 0; guest_tsc = kvm_read_l1_tsc(vcpu, rdtsc()); - trace_kvm_wait_lapic_expire(vcpu->vcpu_id, guest_tsc - tsc_deadline); + apic->lapic_timer.advance_expire_delta = guest_tsc - tsc_deadline; if (guest_tsc < tsc_deadline) __wait_lapic_expire(vcpu, tsc_deadline - guest_tsc); if (unlikely(!apic->lapic_timer.timer_advance_adjust_done)) - adjust_lapic_timer_advance(vcpu, guest_tsc, tsc_deadline); + adjust_lapic_timer_advance(vcpu, apic->lapic_timer.advance_expire_delta); } static void start_sw_tscdeadline(struct kvm_lapic *apic) diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index d6d049ba3045..3e72a255543d 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -32,6 +32,7 @@ struct kvm_timer { u64 tscdeadline; u64 expired_tscdeadline; u32 timer_advance_ns; + s64 advance_expire_delta; atomic_t pending; /* accumulated triggered timers */ bool hv_timer_in_use; bool timer_advance_adjust_done; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e7e57de50a3c..35631505421c 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8008,6 +8008,13 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) ++vcpu->stat.exits; guest_exit_irqoff(); + if (lapic_in_kernel(vcpu)) { + s64 delta = vcpu->arch.apic->lapic_timer.advance_expire_delta; + if (delta != S64_MIN) { + trace_kvm_wait_lapic_expire(vcpu->vcpu_id, delta); + vcpu->arch.apic->lapic_timer.advance_expire_delta = S64_MIN; + } + } local_irq_enable(); preempt_enable(); so that KVM tracks whether wait_lapic_expire was called, and do not invoke the tracepoint if not. Thanks, Paolo