Re: Xen MMU's requirement to pin pages RO andinitial_memory_mapping.

[Stefano Stabellini]

CC'ing Keir in case he knows something I am missing.

On Mon, 16 May 2011, H. Peter Anvin wrote:
> On 05/16/2011 08:41 AM, Konrad Rzeszutek Wilk wrote:
> >> They become pagetable pages when:
> >>
> >> - they are explicitly pinned by pin_pagetable_pfn
> >>
> >> - they are hooked into the current pagetable
> > 
> > Ok, so could we use those two calls to trigger the pagetable walk
> > and mark them RO as appropiate? Which call sites are those? The
> > xen_set_pgd/xen_set_pud/xen_set_pmd ? Presumarily we don't have
> > to do that for the PTE's that are already mapped (as
> > xen_setup_kernel_pagetable, and xen_map_identity_early do this
> > already).
> > 
> >> Like you wrote, considering that the x86_64 version of
> >> kernel_physical_mapping_init hooks the pagetable pages into the
> >> currently used pagetable, it wouldn't be possible to mark the pagetable
> >> pages RO after init_memory_mapping.
> > 
> 
> Doesn't Xen have some kind of compatibility mode which could be used
> during setup?
 
Unfortunately not that I am aware.
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