From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: pvops DomU kernels [was Re: "Hotplug Scripts not
	working ..." error on jaunty]
Date: Fri, 23 Oct 2009 13:58:37 -0700
Message-ID: <4AE218FD.6040503@goop.org>
References: <C707D52B.183D7%keir.fraser@eu.citrix.com>
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To: Keir Fraser <keir.fraser@eu.citrix.com>
Cc: Boris Derzhavets <bderzhavets@yahoo.com>, Xen-devel <xen-devel@lists.xensource.com>, Dulloor <dulloor@gmail.com>, "Marc - A. Dahlhaus" <mad@wol.de>
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On 10/23/09 13:48, Keir Fraser wrote:
> On 23/10/2009 21:37, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote:
>
>   
>> Its not at all clear to me what Xen is objecting to here.  There are a
>> few paths where it can end up at could_not_pin in get_page_from_l1e(),
>> but I don't know which one is happening here.  I think it's the "if (
>> unlikely(real_pg_owner != pg_owner) )" conditional, but I don't know
>> what real_pg_owner means here.
>>
>> Keir?
>>     
> If you fail that test it means that the page does not belong to the domain
> that the caller expected. In most cases, that means it was expected to
> belong to the domain making the hypercall, but actually it does not belong
> to it.

The domain is calling update_va_mapping() on itself, and everything
seems to be owned by the domain:

(XEN) mm.c:840:d33 Error getting mfn 18c3 (pfn 21603) from L1 entry 80000000018c3061 for l1e_owner=33, pg_owner=33

The three paths that lead to could_not_pin are:

    if ( real_pg_owner == NULL )
        goto could_not_pin;
...
    if ( unlikely(real_pg_owner != pg_owner) )
    {
        if ( (pg_owner == l1e_owner) || !IS_PRIV_FOR(pg_owner, real_pg_owner) )
            goto could_not_pin;
        pg_owner = real_pg_owner;
    }

and

    if ( (l1f & _PAGE_RW) &&
         ((l1e_owner == pg_owner) || !paging_mode_external(pg_owner)) &&
         !get_page_type(page, PGT_writable_page) )
        goto could_not_pin;

The pte doesn't have RW set, so it must be one of the first two.
Could it be read_pg_owner == NULL?

	J