Re: [Xen-devel] [PATCH v2 22/55] x86_64/mm: switch to new APIs in paging_init

[Wei Liu <wl@xxxxxxx>]

On Mon, Sep 30, 2019 at 11:33:14AM +0100, Hongyan Xia wrote:
> From: Wei Liu <wei.liu2@xxxxxxxxxx>
> 
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> Signed-off-by: Hongyan Xia <hongyax@xxxxxxxxxx>
> 
> ---
> Changed since v1:
>   * use a global mapping for compat_idle_pg_table_l2, otherwise
>     l2_ro_mpt will unmap it.

Hmmm... I wonder why XTF didn't catch this.

If we really want to go all the way to eliminate persistent mappings
for page tables, the code should be changed such that:

1. compat_idle_pg_table_l2 should be changed to store mfn, not va.
2. map and unmap that mfn when access to the compat page table is
   required.

Wei.

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