On Fri, Dec 06, 2024 at 10:11:02AM +0000, Kevin Brodsky wrote:

kernel_pgtables_set_pkey() allows setting the pkey of all page table
pages in swapper_pg_dir, recursively. This will be needed by
kpkeys_hardened_pgtables, as it relies on all PTPs being mapped with
a non-default pkey. Those initial kernel page tables cannot
practically be assigned a non-default pkey right when they are
allocated, so mutating them during (early) boot is required.

Signed-off-by: Kevin Brodsky <redacted>
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It feels that some sort of locking is called for in
kernel_pgtables_set_pkey(), but I couldn't figure out what would be
appropriate.

init_mm.page_table_lock is typically the one used to serialize kernel
page tables IIRC.