On Wed, Jan 17, 2024 at 02:46:55PM +0000, Alexander Graf wrote:
> We now have all bits in place to support KHO kexecs. This patch adds
> awareness of KHO in the kexec file as well as boot path for arm64 and
> adds the respective kconfig option to the architecture so that it can
> use KHO successfully.
>
> Signed-off-by: Alexander Graf <graf@xxxxxxxxxx>
>
> ---
>
> v1 -> v2:
>
> - test bot warning fix
> - Change kconfig option to ARCH_SUPPORTS_KEXEC_KHO
> - s/kho_reserve_mem/kho_reserve_previous_mem/g
> - s/kho_reserve/kho_reserve_scratch/g
> - Remove / reduce ifdefs for kho fdt code
> ---
> arch/arm64/Kconfig | 3 +++
> arch/arm64/kernel/setup.c | 2 ++
> arch/arm64/mm/init.c | 8 ++++++
> drivers/of/fdt.c | 39 ++++++++++++++++++++++++++++
> drivers/of/kexec.c | 54 +++++++++++++++++++++++++++++++++++++++
> 5 files changed, 106 insertions(+)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 8f6cf1221b6a..44d8923d9db4 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1496,6 +1496,9 @@ config ARCH_SUPPORTS_KEXEC_IMAGE_VERIFY_SIG
> config ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG
> def_bool y
>
> +config ARCH_SUPPORTS_KEXEC_KHO
> + def_bool y
> +
> config ARCH_SUPPORTS_CRASH_DUMP
> def_bool y
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 417a8a86b2db..9aa05b84d202 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -346,6 +346,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
>
> paging_init();
>
> + kho_reserve_previous_mem();
> +
> acpi_table_upgrade();
>
> /* Parse the ACPI tables for possible boot-time configuration */
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 74c1db8ce271..1a8fc91509af 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -358,6 +358,8 @@ void __init bootmem_init(void)
> */
> arch_reserve_crashkernel();
>
> + kho_reserve_scratch();
> +
> memblock_dump_all();
> }
>
> @@ -386,6 +388,12 @@ void __init mem_init(void)
> /* this will put all unused low memory onto the freelists */
> memblock_free_all();
>
> + /*
> + * Now that all KHO pages are marked as reserved, let's flip them back
> + * to normal pages with accurate refcount.
> + */
> + kho_populate_refcount();
> +
> /*
> * Check boundaries twice: Some fundamental inconsistencies can be
> * detected at build time already.
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index bf502ba8da95..f9b9a36fb722 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1006,6 +1006,42 @@ void __init early_init_dt_check_for_usable_mem_range(void)
> memblock_add(rgn[i].base, rgn[i].size);
> }
>
> +/**
> + * early_init_dt_check_kho - Decode info required for kexec handover from DT
> + */
> +static void __init early_init_dt_check_kho(void)
> +{
> + unsigned long node = chosen_node_offset;
> + u64 kho_start, scratch_start, scratch_size, mem_start, mem_size;
> + const __be32 *p;
> + int l;
> +
> + if (!IS_ENABLED(CONFIG_KEXEC_KHO) || (long)node < 0)
> + return;
> +
> + p = of_get_flat_dt_prop(node, "linux,kho-dt", &l);
These need to be documented. chosen node schema lives in dtschema.
> + if (l != (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32))
> + return;
I would just make all these fixed 64-bit values rather than based on
address and size cells. That's what we've done on more recent chosen
properties describing regions.
Rob
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