Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939361AbcJXPD2 (ORCPT ); Mon, 24 Oct 2016 11:03:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43910 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933214AbcJXPD1 (ORCPT ); Mon, 24 Oct 2016 11:03:27 -0400 Date: Mon, 24 Oct 2016 17:03:23 +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: [PATCH 6/5] KVM: x86: fix periodic lapic timer with hrtimers Message-ID: <20161024150323.GB2247@potion> References: <1477304593-3453-1-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: <1477304593-3453-1-git-send-email-wanpeng.li@hotmail.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Mon, 24 Oct 2016 15:03:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3066 Lines: 87 I have only compile-tested it, but it should optimize the switch and also fix two bugs. The first one is major. This needs that the deadline clearing in [5/5] is fixed. ---8<--- We must start the hrimer even if the expiration is already in the past, otherwise the periodic timer would not rearm the hrtimer. And computing next expiration of a period timer does not require current time. The period should be constant, so it is more precise to add the period to the last expiration time. This fixes a time difference between hrtimer expiration and apic->lapic_timer.target_expiration. Signed-off-by: Radim Krčmář --- arch/x86/kvm/lapic.c | 38 +++++++++++++------------------------- 1 file changed, 13 insertions(+), 25 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index f4734fe12803..6244988418be 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1350,19 +1350,19 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic) static void start_sw_period(struct kvm_lapic *apic) { - ktime_t now; - - now = apic->lapic_timer.timer.base->get_time(); - if (!apic->lapic_timer.period) return; - if (likely(ktime_after(apic->lapic_timer.target_expiration, now))) - hrtimer_start(&apic->lapic_timer.timer, - apic->lapic_timer.target_expiration, - HRTIMER_MODE_ABS_PINNED); - else + if (apic_lvtt_oneshot(apic) && + ktime_after(apic->lapic_timer.target_expiration, + apic->lapic_timer.timer.base->get_time())) { apic_timer_expired(apic); + return; + } + + hrtimer_start(&apic->lapic_timer.timer, + apic->lapic_timer.target_expiration, + HRTIMER_MODE_ABS_PINNED); } static bool set_target_expiration(struct kvm_lapic *apic) @@ -1414,10 +1414,11 @@ static bool set_target_expiration(struct kvm_lapic *apic) static void advance_periodic_target_expiration(struct kvm_lapic *apic) { - apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, rdtsc()) + + apic->lapic_timer.tscdeadline += nsec_to_cycles(apic->vcpu, apic->lapic_timer.period); - apic->lapic_timer.target_expiration = ktime_add_ns(apic->lapic_timer.timer.base->get_time(), - apic->lapic_timer.period); + apic->lapic_timer.target_expiration = + ktime_add_ns(apic->lapic_timer.target_expiration, + apic->lapic_timer.period); } bool kvm_lapic_hv_timer_in_use(struct kvm_vcpu *vcpu) @@ -1481,19 +1482,6 @@ void kvm_lapic_switch_to_hv_timer(struct kvm_vcpu *vcpu) WARN_ON(apic->lapic_timer.hv_timer_in_use); - if (apic_lvtt_period(apic)) { - ktime_t remaining, now; - u64 tscl = rdtsc(); - - now = apic->lapic_timer.timer.base->get_time(); - remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); - if (ktime_to_ns(remaining) < 0) - remaining = ktime_set(0, 0); - - apic->lapic_timer.tscdeadline = kvm_read_l1_tsc(apic->vcpu, tscl) + - nsec_to_cycles(apic->vcpu, ktime_to_ns(remaining)); - apic->lapic_timer.target_expiration = ktime_add_ns(now, ktime_to_ns(remaining)); - } start_hv_timer(apic); } EXPORT_SYMBOL_GPL(kvm_lapic_switch_to_hv_timer); -- 2.10.1