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 <[email protected]>
---
Reviewed-by: Andrii Anisov <[email protected]>
--
Sincerely,
Andrii Anisov.
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