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Message-ID: <20231214223604.GA1045434-robh@kernel.org>
Date: Thu, 14 Dec 2023 16:36:04 -0600
From: Rob Herring <robh@...nel.org>
To: Alexander Graf <graf@...zon.com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, linux-mm@...ck.org, devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, kexec@...ts.infradead.org, linux-doc@...r.kernel.org, x86@...nel.org, Eric Biederman <ebiederm@...ssion.com>, "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>, Andrew Morton <akpm@...ux-foundation.org>, Mark Rutland <mark.rutland@....com>, Tom Lendacky <thomas.lendacky@....com>, Ashish Kalra <ashish.kalra@....com>, James Gowans <jgowans@...zon.com>, Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>, arnd@...db.de, pbonzini@...hat.com, madvenka@...ux.microsoft.com, Anthony Yznaga <anthony.yznaga@...cle.com>, Usama Arif <usama.arif@...edance.com>, David Woodhouse <dwmw@...zon.co.uk>, Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH 06/15] arm64: Add KHO support
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@...zon.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.
> +
> 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.
> 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.
> + 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?
> + if (!image->kho.dt.buffer || !image->kho.mem_cache.buffer)
> + goto out;
> +
> + pr_debug("Adding kho metadata to DT");
> +
> + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-dt",
> + image->kho.dt.mem, image->kho.dt.memsz);
> + if (ret)
> + goto out;
> +
> + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-scratch",
> + kho_scratch_phys, kho_scratch_len);
> + if (ret)
> + goto out;
> +
> + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, "linux,kho-mem",
> + image->kho.mem_cache.mem,
> + image->kho.mem_cache.bufsz);
> + if (ret)
> + goto out;
> +
> +out:
> +#endif
> + return ret;
> +}
> +
> /*
> * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
> *
> @@ -412,6 +443,11 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
> }
> }
>
> + /* Add kho metadata if this is a KHO image */
> + ret = kho_add_chosen(image, fdt, chosen_node);
> + if (ret)
> + goto out;
> +
> /* add bootargs */
> if (cmdline) {
> ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
> --
> 2.40.1
>
>
>
>
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