From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S943853AbdEZP5k (ORCPT ); Fri, 26 May 2017 11:57:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45718 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751788AbdEZP5f (ORCPT ); Fri, 26 May 2017 11:57:35 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 1AC32C05FFC2 Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=pbonzini@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 1AC32C05FFC2 Subject: Re: [PATCH] KVM: X86: Fix preempt the preemption timer cancel To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Wanpeng Li References: <1495337552-78885-1-git-send-email-wanpeng.li@hotmail.com> From: Paolo Bonzini Message-ID: Date: Fri, 26 May 2017 17:57:32 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: <1495337552-78885-1-git-send-email-wanpeng.li@hotmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 26 May 2017 15:57:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/05/2017 05:32, Wanpeng Li wrote: > CPU0 CPU1 > > vmx_cancel_hv_timer > vCPU0's vmx->hv_deadline_tsc = -1 > > preempt occur > > clear preemption timer field in CPU1's active vmcs > vCPU0's apic_timer.hv_timer_in_use = false > vmx_vcpu_run(vCPU0) > vmx_arm_hv_timer > if (vmx->hv_deadline_tsc == -1) > nothing change > > handle_preemption_timer(vCPU0) > kvm_lapic_expired_hv_timer > WARN_ON(!apic->lapic_timer.hv_timer_in_use); I think it's more like this, what do you think? CPU0 CPU1 preemption timer vmexit handle_preemption_timer(vCPU0) kvm_lapic_expired_hv_timer vmx_cancel_hv_timer vmx->hv_deadline_tsc = -1 vmcs_clear_bits /* hv_timer_in_use still true */ sched_out sched_in kvm_arch_vcpu_load vmx_set_hv_timer write vmx->hv_deadline_tsc vmcs_set_bits /* back in kvm_lapic_expired_hv_timer */ hv_timer_in_use = false ... vmx_vcpu_run vmx_arm_hv_run write preemption timer deadline spurious preemption timer vmexit handle_preemption_timer(vCPU0) kvm_lapic_expired_hv_timer WARN_ON(!apic->lapic_timer.hv_timer_in_use); Thanks, Paolo