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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 CCABEC2BA19 for ; Wed, 22 Apr 2020 00:49:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A59F42070B for ; Wed, 22 Apr 2020 00:49:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZRepC3bJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726386AbgDVAtF (ORCPT ); Tue, 21 Apr 2020 20:49:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726012AbgDVAtF (ORCPT ); Tue, 21 Apr 2020 20:49:05 -0400 Received: from mail-oi1-x242.google.com (mail-oi1-x242.google.com [IPv6:2607:f8b0:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26640C0610D5; Tue, 21 Apr 2020 17:49:05 -0700 (PDT) Received: by mail-oi1-x242.google.com with SMTP id t199so447505oif.7; Tue, 21 Apr 2020 17:49:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=fyWIvNsFDIbDhj5AHIg5Xemvwg92lR3Mt2pRS9IX/eY=; b=ZRepC3bJo7TngfHSxmUTuuwFth5NE423gQHfzhrwqKOW/rG5flMB9dP4weA4JGtEHy UOBQ4Lf1S1PdyWACh3vfJi+ahA2GTwmdqRTMkpI2odZ1aVL0cmeI4P3R+JuMjM6MgytQ BBqEyteRb5uhGwjNUkbcjf0X/8GMIgRTWOgHzd70a+ST/Ejez9ptO9rYQk/v71Xf42Yw 5YsUN63ngS+fYMnpRva8OJhT/fudkSJYWu0RBS6xqRLaXVBKgoYt48ip6j8vFF82b0c1 kVJaUDUc9DIjdq5gzUf2jw/IG4Fcq1OEV6pL8Zt6C2WhiSUTp0gE5zargeJiJLOLexqp F8ww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=fyWIvNsFDIbDhj5AHIg5Xemvwg92lR3Mt2pRS9IX/eY=; b=gwQakFJCVVSkmXm8oGpNBnINI2anJVUX5YPDcId0V15c/pmqZ31LOHBCHbFhYfliek wgkezHM8fvUyEZXLfT0YN48D6YZ09iyf6dn5nsSqpWMMrjjUqih2UHV1p6V1XH4lrZDs kUU8HmI60nSHGpvg1CdAh1zbvmf91/sPe2WDtX7g1fh+SZmt3JDeXcua0Rh+6dUocdLr vTDviTJHdBU+JqFcnodDj3nZd2BdnkEwy/nP419ER8hGyG2HnoLabCVmCX+GJUB2AUgQ KdipwNXEcsIlWIrVN96HfQJWHipE/b85dAHIp1hTnO/eiYJ6MDNbaeVJujB4woZj+Em3 JENg== X-Gm-Message-State: AGi0Pub4UlEXzEZa4xixzgiXi0GShIUZR7K+kROMdt5J+cV9763+HSnd zpEtsFqg13p3PzYZWUlbC86FtmOgJBzSqdxBBWU= X-Google-Smtp-Source: APiQypLD9AwSNYzuxvfQfpcQ099bZV8Nz8y3kuAYm1wHcLyTZkfVBsJCzZstjc+PvCkJN1SfCN9lsgMQMrz02HpXq8w= X-Received: by 2002:aca:2801:: with SMTP id 1mr4840905oix.141.1587516544513; Tue, 21 Apr 2020 17:49:04 -0700 (PDT) MIME-Version: 1.0 References: <1587468026-15753-1-git-send-email-wanpengli@tencent.com> <1587468026-15753-2-git-send-email-wanpengli@tencent.com> In-Reply-To: From: Wanpeng Li Date: Wed, 22 Apr 2020 08:48:53 +0800 Message-ID: Subject: Re: [PATCH 1/2] KVM: X86: TSCDEADLINE MSR emulation fastpath To: Paolo Bonzini Cc: LKML , kvm , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Haiwei Li Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 21 Apr 2020 at 19:37, Paolo Bonzini wrote: > > On 21/04/20 13:20, Wanpeng Li wrote: > > + case MSR_IA32_TSCDEADLINE: > > + if (!kvm_x86_ops.event_needs_reinjection(vcpu)) { > > + data = kvm_read_edx_eax(vcpu); > > + if (!handle_fastpath_set_tscdeadline(vcpu, data)) > > + ret = EXIT_FASTPATH_CONT_RUN; > > + } > > break; > > Can you explain the event_needs_reinjection case? Also, does this break This is used to catch the case vmexit occurred while another event was being delivered to guest software, I move the vmx_exit_handlers_fastpath() call after vmx_complete_interrupts() which will decode such event and make kvm_event_needs_reinjection return true. > AMD which does not implement the callback? Now I add the tscdeadline msr emulation and vmx-preemption timer fastpath pair for Intel platform. > > > + > > + reg = kvm_lapic_get_reg(apic, APIC_LVTT); > > + if (kvm_apic_hw_enabled(apic) && !(reg & APIC_LVT_MASKED)) { > > + vector = reg & APIC_VECTOR_MASK; > > + kvm_lapic_clear_vector(vector, apic->regs + APIC_TMR); > > + > > + if (vcpu->arch.apicv_active) { > > + if (pi_test_and_set_pir(vector, &vmx->pi_desc)) > > + return; > > + > > + if (pi_test_and_set_on(&vmx->pi_desc)) > > + return; > > + > > + vmx_sync_pir_to_irr(vcpu); > > + } else { > > + kvm_lapic_set_irr(vector, apic); > > + kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu), false); > > + vmx_inject_irq(vcpu); > > + } > > + } > > This is mostly a copy of > > if (kvm_x86_ops.deliver_posted_interrupt(vcpu, vector)) { > kvm_lapic_set_irr(vector, apic); > kvm_make_request(KVM_REQ_EVENT, vcpu); > kvm_vcpu_kick(vcpu); > } > break; > > (is it required to do vmx_sync_pir_to_irr?). So you should not special I observe send notification vector as in kvm_x86_ops.deliver_posted_interrupt() is ~900 cycles worse than vmx_sync_pir_to_irr in my case. It needs to wait guest vmentry, then the physical cpu ack the notification vector, read posted-interrupt desciptor etc. For the non-APICv part, original copy needs to wait inject_pending_event to do these stuff. > case LVTT and move this code to lapic.c instead. But even before that... > > > > > + > > + if (kvm_start_hv_timer(apic)) { > > + if (kvm_check_request(KVM_REQ_PENDING_TIMER, vcpu)) { > > + if (kvm_x86_ops.interrupt_allowed(vcpu)) { > > + kvm_clear_request(KVM_REQ_PENDING_TIMER, vcpu); > > + kvm_x86_ops.fast_deliver_interrupt(vcpu); > > + atomic_set(&apic->lapic_timer.pending, 0); > > + apic->lapic_timer.tscdeadline = 0; > > + return 0; > > + } > > + return 1; > > > Is it actually common that the timer is set back in time and therefore > this code is executed? It is used to handle the already-expired timer. Wanpeng