Re: [Xen-devel] [PATCH 09/12] xen/arm: mm: Use {, un}map_domain_page() to map/unmap Xen page-tables

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

On 24.04.19 19:59, Julien Grall wrote:
> Currently, the virtual address of the 3rd level page-tables is obtained
> using mfn_to_virt().
>
> On Arm32, mfn_to_virt can only work on xenheap page. While in practice
> all the page-tables updated will reside in xenheap, in practive the
> page-tables covering Xen memory (e.g xen_mapping) is part of Xen binary.
>
> Furthermore, a follow-up change will update xen_pt_update_entry() to
> walk all the levels and therefore be more generic. Some of the
> page-tables will also part of Xen memory and therefore will not be
> reachable using mfn_to_virt().
>
> The easiest way to reach those pages is to use {, un}map_domain_page().
> While on arm32 this means an extra mapping in the normal cases, this is not
> very important as xen page-tables are not updated often.
>
> In order to allow future change in the way Xen page-tables are mapped,
> two new helpers are introduced to map/unmap the page-tables.
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> ---

Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>

--
Sincerely,
Andrii Anisov.

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