Re: [PATCH v5 3/3] arm64,ppc64le/kdump: pass dm-crypt keys to kdump kernel

[Rob Herring]

On Wed, Feb 25, 2026 at 12:04 AM Coiby Xu <coxu@xxxxxxxxxx> wrote:
>
> CONFIG_CRASH_DM_CRYPT has been introduced to support LUKS-encrypted
> device dump target by addressing two challenges [1],
>  - Kdump kernel may not be able to decrypt the LUKS partition. For some
>    machines, a system administrator may not have a chance to enter the
>    password to decrypt the device in kdump initramfs after the 1st kernel
>    crashes
>
>  - LUKS2 by default use the memory-hard Argon2 key derivation function
>    which is quite memory-consuming compared to the limited memory reserved
>    for kdump.
>
> To also enable this feature for ARM64 and PowerPC, the missing piece is
> to let the kdump kernel know where to find the dm-crypt keys which are
> randomly stored in memory reserved for kdump. Introduce a new device
> tree property dmcryptkeys [2] as similar to elfcorehdr to pass the
> memory address of the stored info of dm-crypt keys to the kdump kernel.
> Since this property is only needed by the kdump kernel, it won't be
> exposed to user space.
>
> [1] https://lore.kernel.org/all/20250502011246.99238-1-coxu@xxxxxxxxxx/
> [2] https://github.com/devicetree-org/dt-schema/pull/181
>
> Cc: Arnaud Lefebvre <arnaud.lefebvre@xxxxxxxxxxxxxxxx>
> Cc: Baoquan he <bhe@xxxxxxxxxx>
> Cc: Dave Young <dyoung@xxxxxxxxxx>
> Cc: Kairui Song <ryncsn@xxxxxxxxx>
> Cc: Pingfan Liu <kernelfans@xxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Thomas Staudt <tstaudt@xxxxxxxxxx>
> Cc: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Christophe Leroy (CS GROUP) <chleroy@xxxxxxxxxx>
> Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
> ---
>  arch/arm64/kernel/machine_kexec_file.c |  4 ++++
>  arch/powerpc/kexec/elf_64.c            |  4 ++++
>  drivers/of/fdt.c                       | 21 +++++++++++++++++++++
>  drivers/of/kexec.c                     | 19 +++++++++++++++++++
>  4 files changed, 48 insertions(+)

Acked-by: Rob Herring (Arm) <robh@xxxxxxxxxx>