From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: When is the page table built for migration destination ?
Date: Mon, 09 Sep 2013 11:58:01 +0200
Message-ID: <522D9BA9.90303@redhat.com>
References: <CALSEb2fia0tjLRRozL9L27B_sQM8hFPn07oOrJJqAOchLYx5-g@mail.gmail.com> <522D834A.2050309@redhat.com> <CALSEb2fxqHkS_8exXOTKpMxs+jbs1yvDSxGi3Nyk=C8DiKiw9Q@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
To: Sunil <infinite.questions@gmail.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from mail-ea0-f179.google.com ([209.85.215.179]:61902 "EHLO
	mail-ea0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751275Ab3IIJ56 (ORCPT <rfc822;kvm@vger.kernel.org>);
	Mon, 9 Sep 2013 05:57:58 -0400
Received: by mail-ea0-f179.google.com with SMTP id b10so2992455eae.38
        for <kvm@vger.kernel.org>; Mon, 09 Sep 2013 02:57:57 -0700 (PDT)
In-Reply-To: <CALSEb2fxqHkS_8exXOTKpMxs+jbs1yvDSxGi3Nyk=C8DiKiw9Q@mail.gmail.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

Il 09/09/2013 11:38, Sunil ha scritto:
> Thanks Paolo.
> 
> I am using KVM with EPT support, so I understand this will require
> gfn->pfn translation.  Going through the code, looks like function
> tdp_page_fault() is responsible for setting up this mapping.
> 
> Though the page table is constructed lazily, I understand the page
> contents are already transferred during migration. Can you please
> explain or point to function names which finds the correct page
> contents for given gfn  ? (looks like pte is created in
> __direct_map())

GFNs are looked up through the memory slots array.  Look at
gfn_to_memslot, gfn_to_hva, and related functions in
virt/kvm/kvm_main.c; also the __gfn_to_memslot and __gfn_to_hva_memslot
inlines in include/linux/kvm_host.h.

Paolo