Messages in this thread | | | Date | Tue, 19 Dec 2023 00:01:02 +0100 | Subject | Re: [PATCH 06/15] arm64: Add KHO support | From | Alexander Graf <> |
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Hey Rob!
On 14.12.23 23:36, Rob Herring wrote: > On Wed, Dec 13, 2023 at 12:04:43AM +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@amazon.com> >> --- >> arch/arm64/Kconfig | 12 ++++++++++++ >> arch/arm64/kernel/setup.c | 2 ++ >> arch/arm64/mm/init.c | 8 ++++++++ >> drivers/of/fdt.c | 41 +++++++++++++++++++++++++++++++++++++++ >> drivers/of/kexec.c | 36 ++++++++++++++++++++++++++++++++++ >> 5 files changed, 99 insertions(+) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 7b071a00425d..1ba338ce7598 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -1501,6 +1501,18 @@ config ARCH_SUPPORTS_CRASH_DUMP >> config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION >> def_bool CRASH_CORE >> >> +config KEXEC_KHO >> + bool "kexec handover" >> + depends on KEXEC >> + select MEMBLOCK_SCRATCH >> + select LIBFDT >> + select CMA >> + help >> + Allow kexec to hand over state across kernels by generating and >> + passing additional metadata to the target kernel. This is useful >> + to keep data or state alive across the kexec. For this to work, >> + both source and target kernels need to have this option enabled. > Why do we have the same kconfig entry twice? Here and x86.
This was how the kexec config options were done when I wrote the patches originally. Since then, looks like Eric DeVolder has cleaned up things quite nicely. I'll adapt the new way.
> >> + >> config TRANS_TABLE >> def_bool y >> depends on HIBERNATION || KEXEC_CORE >> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c >> index 417a8a86b2db..8035b673d96d 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_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..254d82f3383a 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(); >> + > reserve what? It is not obvious what the difference between > kho_reserve_mem() and kho_reserve() are.
Yeah, I agree. I was struggling to find good names for them. What they do is:
kho_reserve() - Reserve CMA memory for later kexec. We use this memory region as scratch memory later. kho_reserve_mem() - Post-KHO. Creates memory reservations inside memblocks for pre-KHO handed over memory.
For v2, I'll change them to kho_reserve_scratch() and kho_reserve_previous_mem() unless you have better ideas :)
> >> 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..af95139351ed 100644 >> --- a/drivers/of/fdt.c >> +++ b/drivers/of/fdt.c >> @@ -1006,6 +1006,44 @@ 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 >> + */ >> +void __init early_init_dt_check_kho(void) >> +{ >> +#ifdef CONFIG_KEXEC_KHO > if (!IS_ENABLED(CONFIG_KEXEC_KHO)) > return; > > You'll need a kho_populate() stub.
Always happy to remove #ifdefs :)
> >> + unsigned long node = chosen_node_offset; >> + u64 kho_start, scratch_start, scratch_size, mem_start, mem_size; >> + const __be32 *p; >> + int l; >> + >> + if ((long)node < 0) >> + return; >> + >> + p = of_get_flat_dt_prop(node, "linux,kho-dt", &l); >> + if (l != (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32)) >> + return; >> + >> + kho_start = dt_mem_next_cell(dt_root_addr_cells, &p); >> + >> + p = of_get_flat_dt_prop(node, "linux,kho-scratch", &l); >> + if (l != (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32)) >> + return; >> + >> + scratch_start = dt_mem_next_cell(dt_root_addr_cells, &p); >> + scratch_size = dt_mem_next_cell(dt_root_addr_cells, &p); >> + >> + p = of_get_flat_dt_prop(node, "linux,kho-mem", &l); >> + if (l != (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32)) >> + return; >> + >> + mem_start = dt_mem_next_cell(dt_root_addr_cells, &p); >> + mem_size = dt_mem_next_cell(dt_root_addr_cells, &p); >> + >> + kho_populate(kho_start, scratch_start, scratch_size, mem_start, mem_size); >> +#endif >> +} >> + >> #ifdef CONFIG_SERIAL_EARLYCON >> >> int __init early_init_dt_scan_chosen_stdout(void) >> @@ -1304,6 +1342,9 @@ void __init early_init_dt_scan_nodes(void) >> >> /* Handle linux,usable-memory-range property */ >> early_init_dt_check_for_usable_mem_range(); >> + >> + /* Handle kexec handover */ >> + early_init_dt_check_kho(); >> } >> >> bool __init early_init_dt_scan(void *params) >> diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c >> index 68278340cecf..a612e6bb8c75 100644 >> --- a/drivers/of/kexec.c >> +++ b/drivers/of/kexec.c >> @@ -264,6 +264,37 @@ static inline int setup_ima_buffer(const struct kimage *image, void *fdt, >> } >> #endif /* CONFIG_IMA_KEXEC */ >> >> +static int kho_add_chosen(const struct kimage *image, void *fdt, int chosen_node) >> +{ >> + int ret = 0; >> + >> +#ifdef CONFIG_KEXEC_KHO > ditto > > Though perhaps image->kho is not defined?
Correct, it is not. But I'm happy to have a few local variables that I stash the image->kho contents inside an ifdef into so we can at least compile check all libfdt invocations.
Alex
Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879
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