Re: [PATCH 1/4] expand x86 arch_shared_info to support linear p2m list

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 21/11/14 12:57, Juergen Gross wrote:
> On 11/21/2014 01:23 PM, Jan Beulich wrote:
>>>>> On 14.11.14 at 10:37, <"jgross@suse.com".non-mime.internet> wrote:
>>> --- a/xen/include/public/arch-x86/xen.h
>>> +++ b/xen/include/public/arch-x86/xen.h
>>> @@ -224,7 +224,12 @@ struct arch_shared_info {
>>>       /* Frame containing list of mfns containing list of mfns
>>> containing p2m. */
>>>       xen_pfn_t     pfn_to_mfn_frame_list_list;
>>>       unsigned long nmi_reason;
>>> -    uint64_t pad[32];
>>> +    /*
>>> +     * Following two fields are valid if pfn_to_mfn_frame_list_list
>>> contains
>>> +     * ~0UL.
>>> +     */
>>> +    unsigned long p2m_vaddr;    /* virtual address of the p2m list */
>>> +    unsigned long p2m_as_root;  /* mfn of the top level page table */
>>
>> xen_pfn_t please. And what does the "as" in the name stand for?
>
> "as" is address space. I can rename it to e.g. "p2m_pgd_mfn".

That is a linuxism in naming, which is also not accurate.

>From my understanding, this frame must be an L4 table for 64bit guests,
and an L3 table for 32bit guests.  I.e. it is effectively a cr3 with
which to use the p2m_vaddr field above?

~Andrew