[PATCH v1 5/8] kho: add read-only Kexec Handover mode

[sashiko-bot at kernel.org]

> Add CONFIG_KEXEC_HANDOVER_READONLY and the 'kho_ro=<pa>' kernel
> command-line parameter to support traversing a preserved KHO tree in
> read-only mode without taking ownership of or modifying KHO metadata or
> reclaiming preserved pages into the page allocator.
> 
> When booted with 'kho_ro=<pa>', preserved KHO metadata (FDT, radix-tree
> nodes, and vmalloc chunks) lies outside the kernel's direct map and is
> mapped read-only (PAGE_KERNEL_RO), with the FDT and radix-tree nodes
> mapped lazily on first visit and kept cached. This allows
> kho_retrieve_subtree(), kho_restore_vmalloc(), and
> kho_ro_lookup_folio_order() to inspect the preserved KHO state while
> leaving it intact.
> 
> Also export kho_ro_map_folio() and kho_ro_unmap() so callers (such as
> kho_block, LUO, and file handlers) can map preserved folios verified
> against the KHO radix tree with the desired page protections.
> 
> Signed-off-by: Pasha Tatashin <pasha.tatashin at soleen.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261019021111.990394-1-pasha.tatashin@soleen.com?part=5