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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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@xxxxxxxx".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


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