Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936131AbcJXOuY (ORCPT ); Mon, 24 Oct 2016 10:50:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51314 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757593AbcJXOuU (ORCPT ); Mon, 24 Oct 2016 10:50:20 -0400 Date: Mon, 24 Oct 2016 16:50:16 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Wanpeng Li Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Yunhong Jiang , Wanpeng Li Subject: Re: [PATCH v3 5/5] KVM: LAPIC: add APIC Timer periodic/oneshot mode VMX preemption timer support Message-ID: <20161024145016.GA2247@potion> References: <1477304593-3453-1-git-send-email-wanpeng.li@hotmail.com> <1477304593-3453-6-git-send-email-wanpeng.li@hotmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1477304593-3453-6-git-send-email-wanpeng.li@hotmail.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Mon, 24 Oct 2016 14:50:20 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1768 Lines: 42 2016-10-24 18:23+0800, Wanpeng Li: > From: Wanpeng Li > > Most windows guests still utilize APIC Timer periodic/oneshot mode > instead of tsc-deadline mode, and the APIC Timer periodic/oneshot > mode are still emulated by high overhead hrtimer on host. This patch > converts the expected expire time of the periodic/oneshot mode to > guest deadline tsc in order to leverage VMX preemption timer logic > for APIC Timer tsc-deadline mode. After each preemption timer vmexit > preemption timer is restarted to emulate LVTT current-count register > is automatically reloaded from the initial-count register when the > count reaches 0. This patch reduces ~5600 cycles for each APIC Timer > periodic mode operation virtualization. > > Cc: Paolo Bonzini > Cc: Radim Krčmář > Cc: Yunhong Jiang > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/lapic.c | 117 ++++++++++++++++++++++++++++++++++++++------------- > arch/x86/kvm/lapic.h | 1 + > 2 files changed, 89 insertions(+), 29 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > @@ -2005,8 +2060,12 @@ void kvm_inject_apic_timer_irqs(struct kvm_vcpu *vcpu) > > if (atomic_read(&apic->lapic_timer.pending) > 0) { > kvm_apic_local_deliver(apic, APIC_LVTT); > - if (apic_lvtt_tscdeadline(apic)) > + if (apic_lvtt_period(apic)) This should remain apic_lvtt_tscdeadline(). I can change that when applying to kvm/queue. > + apic->lapic_timer.tscdeadline = 0; > + if (apic_lvtt_oneshot(apic)) { > apic->lapic_timer.tscdeadline = 0; > + apic->lapic_timer.target_expiration = ktime_set(0, 0); > + } > atomic_set(&apic->lapic_timer.pending, 0); > } > }