On 2023/8/29 20:16, Baoquan He wrote:
> With the help of newly changed function parse_crashkernel() and
> generic reserve_crashkernel_generic(), crashkernel reservation can be
> simplified by steps:
>
> 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(), and do the ARCH specific work if
> needed.
>
> 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
> arch/x86/Kconfig.
>
> When adding DEFAULT_CRASH_KERNEL_LOW_SIZE, add crash_low_size_default()
> to calculate crashkernel low memory because x86_64 has special
> requirement.
>
> The old reserve_crashkernel_low() and reserve_crashkernel() can be
> removed.
>
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> ---
> arch/x86/Kconfig | 3 +
> arch/x86/include/asm/crash_core.h | 34 +++++++
> arch/x86/kernel/setup.c | 144 ++++--------------------------
> 3 files changed, 53 insertions(+), 128 deletions(-)
> create mode 100644 arch/x86/include/asm/crash_core.h
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 8d9e4b362572..c4539dc35985 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2037,6 +2037,9 @@ config KEXEC_FILE
> config ARCH_HAS_KEXEC_PURGATORY
> def_bool KEXEC_FILE
>
> +config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> + def_bool CRASH_CORE
> +
> config KEXEC_SIG
> bool "Verify kernel signature during kexec_file_load() syscall"
> depends on KEXEC_FILE
> diff --git a/arch/x86/include/asm/crash_core.h b/arch/x86/include/asm/crash_core.h
> new file mode 100644
> index 000000000000..5fc5e4f94521
> --- /dev/null
> +++ b/arch/x86/include/asm/crash_core.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _X86_CRASH_CORE_H
> +#define _X86_CRASH_CORE_H
> +
> +/* 16M alignment for crash kernel regions */
> +#define CRASH_ALIGN SZ_16M
> +
> +/*
> + * Keep the crash kernel below this limit.
> + *
> + * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
> + * due to mapping restrictions.
> + *
> + * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
> + * the upper limit of system RAM in 4-level paging mode. Since the kdump
> + * jump could be from 5-level paging to 4-level paging, the jump will fail if
> + * the kernel is put above 64 TB, and during the 1st kernel bootup there's
> + * no good way to detect the paging mode of the target kernel which will be
> + * loaded for dumping.
> + */
> +
> +#ifdef CONFIG_X86_32
> +# define CRASH_ADDR_LOW_MAX SZ_512M
> +# define CRASH_ADDR_HIGH_MAX SZ_512M
> +#else
> +# define CRASH_ADDR_LOW_MAX SZ_4G
> +# define CRASH_ADDR_HIGH_MAX SZ_64T
> +#endif
> +
> +# define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
> +
> +extern unsigned long crash_low_size_default(void);
> +
> +#endif /* _X86_CRASH_CORE_H */
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 382c66d2cf71..559a5c4141db 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -474,152 +474,40 @@ static void __init memblock_x86_reserve_range_setup_data(void)
> /*
> * --------- Crashkernel reservation ------------------------------
> */
> -
> -/* 16M alignment for crash kernel regions */
> -#define CRASH_ALIGN SZ_16M
> -
> -/*
> - * Keep the crash kernel below this limit.
> - *
> - * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
> - * due to mapping restrictions.
> - *
> - * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
> - * the upper limit of system RAM in 4-level paging mode. Since the kdump
> - * jump could be from 5-level paging to 4-level paging, the jump will fail if
> - * the kernel is put above 64 TB, and during the 1st kernel bootup there's
> - * no good way to detect the paging mode of the target kernel which will be
> - * loaded for dumping.
> - */
> -#ifdef CONFIG_X86_32
> -# define CRASH_ADDR_LOW_MAX SZ_512M
> -# define CRASH_ADDR_HIGH_MAX SZ_512M
> -#else
> -# define CRASH_ADDR_LOW_MAX SZ_4G
> -# define CRASH_ADDR_HIGH_MAX SZ_64T
> -#endif
> -
> -static int __init reserve_crashkernel_low(void)
> +unsigned long crash_low_size_default(void)
> {
> #ifdef CONFIG_X86_64
> - unsigned long long base, low_base = 0, low_size = 0;
> - unsigned long low_mem_limit;
> - int ret;
> -
> - low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
> -
> - /* crashkernel=Y,low */
> - ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
> - if (ret) {
> - /*
> - * two parts from kernel/dma/swiotlb.c:
> - * -swiotlb size: user-specified with swiotlb= or default.
> - *
> - * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> - * to 8M for other buffers that may need to stay low too. Also
> - * make sure we allocate enough extra low memory so that we
> - * don't run out of DMA buffers for 32-bit devices.
> - */
> - low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> - } else {
> - /* passed with crashkernel=0,low ? */
> - if (!low_size)
> - return 0;
> - }
> -
> - low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
> - if (!low_base) {
> - pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> - (unsigned long)(low_size >> 20));
> - return -ENOMEM;
> - }
> -
> - pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
> - (unsigned long)(low_size >> 20),
> - (unsigned long)(low_base >> 20),
> - (unsigned long)(low_mem_limit >> 20));
> -
> - crashk_low_res.start = low_base;
> - crashk_low_res.end = low_base + low_size - 1;
> - insert_resource(&iomem_resource, &crashk_low_res);
> -#endif
> + return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> +#else
> return 0;
> +#endif
> }
>
> -static void __init reserve_crashkernel(void)
> +static void __init arch_reserve_crashkernel(void)
> {
> - unsigned long long crash_size, crash_base, total_mem;
> + unsigned long long crash_base, crash_size, low_size = 0;
> + char *cmdline = boot_command_line;
> bool high = false;
> int ret;
>
> if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> return;
>
> - total_mem = memblock_phys_mem_size();
> -
> - /* crashkernel=XM */
> - ret = parse_crashkernel(boot_command_line, total_mem,
> - &crash_size, &crash_base, NULL, NULL);
> - if (ret != 0 || crash_size <= 0) {
> - /* crashkernel=X,high */
> - ret = parse_crashkernel_high(boot_command_line, total_mem,
> - &crash_size, &crash_base);
> - if (ret != 0 || crash_size <= 0)
> - return;
> - high = true;
> - }
> + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> + &crash_size, &crash_base,
> + &low_size, &high);
> + if (ret)
> + return;
>
> if (xen_pv_domain()) {
> pr_info("Ignoring crashkernel for a Xen PV domain\n");
> return;
> }
>
> - /* 0 means: find the address automatically */
> - if (!crash_base) {
> - /*
> - * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> - * crashkernel=x,high reserves memory over 4G, also allocates
> - * 256M extra low memory for DMA buffers and swiotlb.
> - * But the extra memory is not required for all machines.
> - * So try low memory first and fall back to high memory
> - * unless "crashkernel=size[KMG],high" is specified.
> - */
> - if (!high)
> - crash_base = memblock_phys_alloc_range(crash_size,
> - CRASH_ALIGN, CRASH_ALIGN,
> - CRASH_ADDR_LOW_MAX);
> - if (!crash_base)
> - crash_base = memblock_phys_alloc_range(crash_size,
> - CRASH_ALIGN, CRASH_ALIGN,
> - CRASH_ADDR_HIGH_MAX);
> - if (!crash_base) {
> - pr_info("crashkernel reservation failed - No suitable area found.\n");
> - return;
> - }
> - } else {
> - unsigned long long start;
> -
> - start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> - crash_base + crash_size);
> - if (start != crash_base) {
> - pr_info("crashkernel reservation failed - memory is in use.\n");
> - return;
> - }
> - }
> -
> - if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> - memblock_phys_free(crash_base, crash_size);
> - return;
> - }
> -
> - pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> - (unsigned long)(crash_size >> 20),
> - (unsigned long)(crash_base >> 20),
> - (unsigned long)(total_mem >> 20));
> + reserve_crashkernel_generic(cmdline, crash_size, crash_base,
> + low_size, high);
>
> - crashk_res.start = crash_base;
> - crashk_res.end = crash_base + crash_size - 1;
> - insert_resource(&iomem_resource, &crashk_res);
> + return;
This can be omitted.
> }
>
> static struct resource standard_io_resources[] = {
> @@ -1231,7 +1119,7 @@ void __init setup_arch(char **cmdline_p)
> * Reserve memory for crash kernel after SRAT is parsed so that it
> * won't consume hotpluggable memory.
> */
> - reserve_crashkernel();
> + arch_reserve_crashkernel();
>
> memblock_find_dma_reserve();
>
>
--
Regards,
Zhen Lei
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