From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752579AbaIKOVk (ORCPT ); Thu, 11 Sep 2014 10:21:40 -0400 Received: from mail-wi0-f175.google.com ([209.85.212.175]:61267 "EHLO mail-wi0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751776AbaIKOVi (ORCPT ); Thu, 11 Sep 2014 10:21:38 -0400 Date: Thu, 11 Sep 2014 17:21:21 +0300 From: Gleb Natapov To: Paolo Bonzini Cc: Tang Chen , mtosatti@redhat.com, nadav.amit@gmail.com, jan.kiszka@web.de, kvm@vger.kernel.org, laijs@cn.fujitsu.com, isimatu.yasuaki@jp.fujitsu.com, guz.fnst@cn.fujitsu.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 4/7] kvm, mem-hotplug: Reload L1' apic access page on migration in vcpu_enter_guest(). Message-ID: <20140911142121.GD26540@minantech.com> References: <1410413886-32213-1-git-send-email-tangchen@cn.fujitsu.com> <1410413886-32213-5-git-send-email-tangchen@cn.fujitsu.com> <541169AD.6060908@redhat.com> <20140911101200.GF25317@minantech.com> <54117DB4.307@redhat.com> <20140911113051.GG25317@minantech.com> <54119E01.9000908@redhat.com> <20140911135956.GC26540@minantech.com> <5411AC82.4080005@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5411AC82.4080005@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 11, 2014 at 04:06:58PM +0200, Paolo Bonzini wrote: > Il 11/09/2014 15:59, Gleb Natapov ha scritto: > > > > Suppose vmcs01->APIC_ACCESS_ADDR = 0xf000. During L2 entry > > vmcs02->APIC_ACCESS_ADDR is set to 0xf000 too (by prepare_vmcs02). Now > > 0xf000 is migrated to 0x8000, mmu notifier is called, it forces vmexit, > > but vcpu is in a guest mode so vmcs02->APIC_ACCESS_ADDR is never updated > > to 0x8000 because of "if (!is_guest_mode(vcpu))" check. So what am I > > missing here? > > Right, guest mode isn't left as soon as you execute nested_vmx_vmexit, > because this isn't an L2->L1 exit. So we need an "else" for that "if > (!is_guest_mode(vcpu))", in which case the hpa is ignored and > vmcs12->apic_access_addr is used instead? > As far as I can tell the if that is needed there is: if (!is_guest_mode() || !(vmcs12->secondary_vm_exec_control & ECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) write(PIC_ACCESS_ADDR) In other words if L2 shares L1 apic access page then reload, otherwise do nothing. -- Gleb.