Xen devel - May 2013 - How to reserve Xen's private memory space on guests' page table

Hi all,

I am looking at the paravirtualized memory management and trying to
understand the page level protection on x86-64. Xen reserve a large private
space in the middle of the virtual memory space, so I think when Xen
initialize a new domianU, it should set corresponding mappings and access
privileges for Xen''s private area on domainU''s initial page
tables?
However, I did not find where Xen does these operations on creating a
domain. Can anyone help me solve the confusion? A lot of appreciation !!

Thanks,

Xinxin


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On Wed, 2013-05-01 at 07:09 +0100, Xinxin Jin wrote:
> Hi all,
> 
> 
> I am looking at the paravirtualized memory management and trying to
> understand the page level protection on x86-64. Xen reserve a large
> private space in the middle of the virtual memory space, so I think
> when Xen initialize a new domianU, it should set corresponding
> mappings and access privileges for Xen''s private area on
domainU''s
> initial page tables? However, I did not find where Xen does these
> operations on creating a domain. Can anyone help me solve the
> confusion? A lot of appreciation !! 
init_guest_l4_table seems like the relevant function from what I can
tell.

For 32-bit guests I think create_pae_xen_mappings + usages of
PGT_pae_xen_l2 are what you should be looking at.

Ian.