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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 71EC4C4CECD for ; Mon, 27 Apr 2020 18:37:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 584CA205C9 for ; Mon, 27 Apr 2020 18:37:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726580AbgD0Shi (ORCPT ); Mon, 27 Apr 2020 14:37:38 -0400 Received: from mga01.intel.com ([192.55.52.88]:8491 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726189AbgD0Shi (ORCPT ); Mon, 27 Apr 2020 14:37:38 -0400 IronPort-SDR: OIG6xCkYhX128gK8WLaGHjGIayXvJeh+E6Srz+qSIiGjpY7/iQ+83T6BuoodQ0iE3RBwmUubI/ oDkHfSd6lWSQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Apr 2020 11:37:38 -0700 IronPort-SDR: GHzQaaYSS2CVqQZ+1PfWMy+cfbt0jEuiMlFvPP2l2LHV7kW2Hw2WjsCu81fnBBuHIIzJFM74/i etf4UdNP/NVw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,325,1583222400"; d="scan'208";a="247484671" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by fmsmga007.fm.intel.com with ESMTP; 27 Apr 2020 11:37:37 -0700 Date: Mon, 27 Apr 2020 11:37:37 -0700 From: Sean Christopherson To: Wanpeng Li Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Haiwei Li Subject: Re: [PATCH v3 3/5] KVM: VMX: Optimize posted-interrupt delivery for timer fastpath Message-ID: <20200427183737.GP14870@linux.intel.com> References: <1587709364-19090-1-git-send-email-wanpengli@tencent.com> <1587709364-19090-4-git-send-email-wanpengli@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1587709364-19090-4-git-send-email-wanpengli@tencent.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 24, 2020 at 02:22:42PM +0800, Wanpeng Li wrote: > From: Wanpeng Li > > Optimizing posted-interrupt delivery especially for the timer fastpath > scenario, I observe kvm_x86_ops.deliver_posted_interrupt() has more latency > then vmx_sync_pir_to_irr() in the case of timer fastpath scenario, since > it needs to wait vmentry, after that it can handle external interrupt, ack > the notification vector, read posted-interrupt descriptor etc, it is slower > than evaluate and delivery during vmentry immediately approach. Let's skip > sending interrupt to notify target pCPU and replace by vmx_sync_pir_to_irr() > before each cont_run. > > Tested-by: Haiwei Li > Cc: Haiwei Li > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/vmx/vmx.c | 9 ++++++--- > virt/kvm/kvm_main.c | 1 + > 2 files changed, 7 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 5c21027..d21b66b 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -3909,8 +3909,9 @@ static int vmx_deliver_posted_interrupt(struct kvm_vcpu *vcpu, int vector) > if (pi_test_and_set_on(&vmx->pi_desc)) > return 0; > > - if (!kvm_vcpu_trigger_posted_interrupt(vcpu, false)) > - kvm_vcpu_kick(vcpu); > + if (vcpu != kvm_get_running_vcpu() && > + !kvm_vcpu_trigger_posted_interrupt(vcpu, false)) Bad indentation. > + kvm_vcpu_kick(vcpu); > > return 0; > } > @@ -6757,8 +6758,10 @@ static enum exit_fastpath_completion vmx_vcpu_run(struct kvm_vcpu *vcpu) > if (!kvm_need_cancel_enter_guest(vcpu)) { > exit_fastpath = vmx_exit_handlers_fastpath(vcpu); > /* static call is better with retpolines */ > - if (exit_fastpath == EXIT_FASTPATH_CONT_RUN) > + if (exit_fastpath == EXIT_FASTPATH_CONT_RUN) { > + vmx_sync_pir_to_irr(vcpu); > goto cont_run; > + } > } > > return exit_fastpath; > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index e7436d0..6a289d1 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -4633,6 +4633,7 @@ struct kvm_vcpu *kvm_get_running_vcpu(void) > > return vcpu; > } > +EXPORT_SYMBOL_GPL(kvm_get_running_vcpu); > > /** > * kvm_get_running_vcpus - get the per-CPU array of currently running vcpus. > -- > 2.7.4 >