From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754153AbaIKKrd (ORCPT ); Thu, 11 Sep 2014 06:47:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31877 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082AbaIKKrb (ORCPT ); Thu, 11 Sep 2014 06:47:31 -0400 Message-ID: <54117DB4.307@redhat.com> Date: Thu, 11 Sep 2014 12:47:16 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Gleb Natapov 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(). 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> In-Reply-To: <20140911101200.GF25317@minantech.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 11/09/2014 12:12, Gleb Natapov ha scritto: > On Thu, Sep 11, 2014 at 11:21:49AM +0200, Paolo Bonzini wrote: >> Il 11/09/2014 07:38, Tang Chen ha scritto: >>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>> index 63c4c3e..da6d55d 100644 >>> --- a/arch/x86/kvm/vmx.c >>> +++ b/arch/x86/kvm/vmx.c >>> @@ -7093,6 +7093,11 @@ static void vmx_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set) >>> vmx_set_msr_bitmap(vcpu); >>> } >>> >>> +static void vmx_set_apic_access_page_addr(struct kvm *kvm, hpa_t hpa) >>> +{ >>> + vmcs_write64(APIC_ACCESS_ADDR, hpa); >> >> This has to be guarded by "if (!is_guest_mode(vcpu))". >> > We do need to write it if L1 and L2 share APIC_ACCESS_ADDR and skip > it otherwise, no? Yes, but this would be handled by patch 6: } else if (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm)) { + struct page *page = gfn_to_page(vmx->vcpu.kvm, + APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); exec_control |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES; - vmcs_write64(APIC_ACCESS_ADDR, - page_to_phys(vcpu->kvm->arch.apic_access_page)); + vmcs_write64(APIC_ACCESS_ADDR, page_to_phys(page)); + /* + * Do not pin apic access page in memory so that memory + * hotplug process is able to migrate it. + */ + put_page(page); } However, this is also useless code duplication because the above snippet could reuse vcpu_reload_apic_access_page too. So I think you cannot do the is_guest_mode check in kvm_vcpu_reload_apic_access_page and also not in vmx_reload_apic_access_page. But you could do something like kvm_vcpu_reload_apic_access_page(...) { ... kvm_x86_ops->reload_apic_access_page(...); } EXPORT_SYMBOL_GPL(kvm_vcpu_reload_apic_access_page); /* used in vcpu_enter_guest only */ vcpu_reload_apic_access_page(...) { if (!is_guest_mode(vcpu)) kvm_vcpu_reload_apic_access_page(...) } Paolo