Re: [Xen-devel] [PATCH 10/12] xen/arm: mm: Rework Xen page-tables walk during update

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

On 24.04.19 19:59, Julien Grall wrote:
> Currently, xen_pt_update_entry() is only able to update the region covered
> by xen_second (i.e 0 to 0x7fffffff).
>
> Because of the restriction we end to have multiple functions in mm.c
> modifying the page-tables differently.
>
> Furthermore, we never walked the page-tables fully. This means that any
> change in the layout may requires major rewrite of the page-tables code.
>
> Lastly, we have been quite lucky that no one ever tried to pass an address
> outside this range because it would have blown-up.
>
> xen_pt_update_entry() is reworked to walk over the page-tables every
> time. The logic has been borrowed from arch/arm/p2m.c and contain some
> limitations for the time being:
>      - Superpage cannot be shattered
>      - Only level 3 (i.e 4KB) can be done
>
> Note that the parameter 'addr' has been renamed to 'virt' to make clear
> we are dealing with a virtual address.
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> ---
Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>

--
Sincerely,
Andrii Anisov.

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