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Date: Tue, 26 Dec 2023 18:56:28 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Youling Tang <youling.tang@...look.com>
Cc: WANG Xuerui <kernel@...0n.name>, Baoquan He <bhe@...hat.com>, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org, Youling Tang <tangyouling@...inos.cn>
Subject: Re: [PATCH] LoongArch: use generic interface to support crashkernel=X,[high,low]
Hi, Youling,
On Mon, Dec 25, 2023 at 10:18 PM Youling Tang <youling.tang@...look.com> wrote:
>
> From: Youling Tang <tangyouling@...inos.cn>
>
> LoongArch already supports two crashkernel regions in kexec-tools, so we
> can directly use the common interface to support crashkernel=X,[hign,low].
>
> With the help of newly changed function parse_crashkernel() and generic
> reserve_crashkernel_generic(), crashkernel reservation can be simplified
> by steps:
It is better to refer the commits introduce those changes.
>
> 1) Add a new header file <asm/crash_core.h>, and define CRASH_ALIGN,
> CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
> DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;
>
> 2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
> reserve_crashkernel_generic();
>
> 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
> arch/loongarch/Kconfig.
>
> One can reserve the crash kernel from high memory above DMA zone range
> by explicitly passing "crashkernel=X,high"; or reserve a memory range
> below 4G with "crashkernel=X,low". Besides, there are few rules need
> to take notice:
>
> 1) "crashkernel=X,[high,low]" will be ignored if "crashkernel=size"
> is specified.
> 2) "crashkernel=X,low" is valid only when "crashkernel=X,high" is passed
> and there is enough memory to be allocated under 4G.
> 3) When allocating crashkernel above 4G and no "crashkernel=X,low" is
> specified, a 128M low memory will be allocated automatically for
> swiotlb bounce buffer.
> See Documentation/admin-guide/kernel-parameters.txt for more information.
>
> Following test cases have been performed as expected:
It is better to group them into "Recommended use cases", "Valid use
cases (not recommended)" and "Invalid use cases".
> 1) crashkernel=256M //low=256M
> 2) crashkernel=1G //low=1G
> 3) crashkernel=4G //high=4G, low=128M(default)
> 4) crashkernel=4G crashkernel=256M,high //high=4G, low=128M(default), high is ignored
> 5) crashkernel=4G crashkernel=256M,low //high=4G, low=128M(default), low is ignored
> 6) crashkernel=4G,high //high=4G, low=128M(default)
> 7) crashkernel=256M,low //low=0M, invalid
> 8) crashkernel=4G,high crashkernel=256M,low //high=4G, low=256M
> 9) crashkernel=4G,high crashkernel=4G,low //high=0M, low=0M, invalid
> 10) crashkernel=512M@...0M //low=512M
> 11) crashkernel=1G,high crashkernel=0M,low //high=1G, low=0M
>
> Signed-off-by: Youling Tang <tangyouling@...inos.cn>
> ---
> arch/loongarch/Kconfig | 3 ++
> arch/loongarch/include/asm/crash_core.h | 11 ++++++
> arch/loongarch/kernel/setup.c | 48 +++++++------------------
> 3 files changed, 27 insertions(+), 35 deletions(-)
> create mode 100644 arch/loongarch/include/asm/crash_core.h
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index ee123820a476..02060b2ac3f2 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -575,6 +575,9 @@ config ARCH_SELECTS_CRASH_DUMP
> depends on CRASH_DUMP
> select RELOCATABLE
>
> +config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> + def_bool CRASH_CORE
> +
> config RELOCATABLE
> bool "Relocatable kernel"
> help
> diff --git a/arch/loongarch/include/asm/crash_core.h b/arch/loongarch/include/asm/crash_core.h
> new file mode 100644
> index 000000000000..1f7040d8ed0f
> --- /dev/null
> +++ b/arch/loongarch/include/asm/crash_core.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef _LOONGARCH_CRASH_CORE_H
> +#define _LOONGARCH_CRASH_CORE_H
> +
> +#define CRASH_ALIGN SZ_2M
> +
> +#define CRASH_ADDR_LOW_MAX SZ_4G
> +#define CRASH_ADDR_HIGH_MAX memblock_end_of_DRAM()
> +
> +extern phys_addr_t memblock_end_of_DRAM(void);
> +#endif
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index d183a745fb85..2a69a36419da 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -252,38 +252,25 @@ static void __init arch_reserve_vmcore(void)
> #endif
> }
>
> -/* 2MB alignment for crash kernel regions */
> -#define CRASH_ALIGN SZ_2M
> -#define CRASH_ADDR_MAX SZ_4G
> -
> -static void __init arch_parse_crashkernel(void)
> +static void __init arch_reserve_crashkernel(void)
> {
> -#ifdef CONFIG_KEXEC
> - int ret;
> - unsigned long long total_mem;
> + unsigned long long low_size = 0;
> unsigned long long crash_base, crash_size;
> + char *cmdline = boot_command_line;
> + bool high = false;
> + int ret;
>
> - total_mem = memblock_phys_mem_size();
> - ret = parse_crashkernel(boot_command_line, total_mem,
> - &crash_size, &crash_base,
> - NULL, NULL);
> - if (ret < 0 || crash_size <= 0)
> + if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> return;
>
> - if (crash_base <= 0) {
> - crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, CRASH_ALIGN, CRASH_ADDR_MAX);
> - if (!crash_base) {
> - pr_warn("crashkernel reservation failed - No suitable area found.\n");
> - return;
> - }
> - } else if (!memblock_phys_alloc_range(crash_size, CRASH_ALIGN, crash_base, crash_base + crash_size)) {
> - pr_warn("Invalid memory region reserved for crash kernel\n");
> + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> + &crash_size, &crash_base,
> + &low_size, &high);
This line can be merged with its above line.
> + if (ret)
> return;
> - }
>
> - crashk_res.start = crash_base;
> - crashk_res.end = crash_base + crash_size - 1;
> -#endif
> + reserve_crashkernel_generic(cmdline, crash_size, crash_base,
> + low_size, high);
They can be in one line.
Huacai
> }
>
> static void __init fdt_setup(void)
> @@ -357,7 +344,7 @@ static void __init bootcmdline_init(char **cmdline_p)
> void __init platform_init(void)
> {
> arch_reserve_vmcore();
> - arch_parse_crashkernel();
> + arch_reserve_crashkernel();
>
> #ifdef CONFIG_ACPI_TABLE_UPGRADE
> acpi_table_upgrade();
> @@ -467,15 +454,6 @@ static void __init resource_init(void)
> request_resource(res, &data_resource);
> request_resource(res, &bss_resource);
> }
> -
> -#ifdef CONFIG_KEXEC
> - if (crashk_res.start < crashk_res.end) {
> - insert_resource(&iomem_resource, &crashk_res);
> - pr_info("Reserving %ldMB of memory at %ldMB for crashkernel\n",
> - (unsigned long)((crashk_res.end - crashk_res.start + 1) >> 20),
> - (unsigned long)(crashk_res.start >> 20));
> - }
> -#endif
> }
>
> static int __init add_legacy_isa_io(struct fwnode_handle *fwnode,
> --
> 2.40.0
>
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