Re: [PATCH v13 4/8] x86: kdump: move reserve_crashkernel[_low]() into crash_core.c

[chenzhou]

On 2020/11/12 16:11, Mike Rapoport wrote:
> On Sat, Oct 31, 2020 at 03:44:33PM +0800, Chen Zhou wrote:
>> Make the functions reserve_crashkernel[_low]() as generic.
>> Arm64 will use these to reimplement crashkernel=X.
>>
>> Signed-off-by: Chen Zhou <chenzhou10@xxxxxxxxxx>
>> Tested-by: John Donnelly <John.p.donnelly@xxxxxxxxxx>
>> ---
>>  arch/x86/include/asm/kexec.h |  25 ++++++
>>  arch/x86/kernel/setup.c      | 151 +-------------------------------
>>  include/linux/crash_core.h   |   4 +
>>  include/linux/kexec.h        |   2 -
>>  kernel/crash_core.c          | 164 +++++++++++++++++++++++++++++++++++
>>  kernel/kexec_core.c          |  17 ----
>>  6 files changed, 195 insertions(+), 168 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
>> index 8cf9d3fd31c7..34afa7b645f9 100644
>> --- a/arch/x86/include/asm/kexec.h
>> +++ b/arch/x86/include/asm/kexec.h
>> @@ -21,6 +21,27 @@
>>  /* 2M 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
>> +
>>  #ifndef __ASSEMBLY__
>>  
>>  #include <linux/string.h>
>> @@ -200,6 +221,10 @@ typedef void crash_vmclear_fn(void);
>>  extern crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss;
>>  extern void kdump_nmi_shootdown_cpus(void);
>>  
>> +#ifdef CONFIG_KEXEC_CORE
>> +extern void __init reserve_crashkernel(void);
>> +#endif
>> +
>>  #endif /* __ASSEMBLY__ */
>>  
>>  #endif /* _ASM_X86_KEXEC_H */
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index 1289f079ad5f..00b3840d30f9 100644
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -25,8 +25,6 @@
>>  
>>  #include <uapi/linux/mount.h>
>>  
>> -#include <xen/xen.h>
>> -
>>  #include <asm/apic.h>
>>  #include <asm/numa.h>
>>  #include <asm/bios_ebda.h>
>> @@ -38,6 +36,7 @@
>>  #include <asm/io_apic.h>
>>  #include <asm/kasan.h>
>>  #include <asm/kaslr.h>
>> +#include <asm/kexec.h>
>>  #include <asm/mce.h>
>>  #include <asm/mtrr.h>
>>  #include <asm/realmode.h>
>> @@ -389,153 +388,7 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>>  	}
>>  }
>>  
>> -/*
>> - * --------- Crashkernel reservation ------------------------------
>> - */
>> -
>> -#ifdef CONFIG_KEXEC_CORE
>> -
>> -/*
>> - * 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)
>> -{
>> -#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, CRASH_ALIGN, 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 0;
>> -}
>> -
>> -static void __init reserve_crashkernel(void)
>> -{
>> -	unsigned long long crash_size, crash_base, total_mem;
>> -	bool high = false;
>> -	int ret;
>> -
>> -	total_mem = memblock_phys_mem_size();
>> -
>> -	/* crashkernel=XM */
>> -	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
>> -	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;
>> -	}
>> -
>> -	if (xen_pv_domain()) {
>> -		pr_info("Ignoring crashkernel for a Xen PV domain\n");
>> -		return;
>> -	}
> This is relevant only to x86, maybe we could move this check to
> setup_arch before calling reserve_crashkernel() to keep it in x86?
Yes, we could move this check to setup_arch.
>
>> -
>> -	/* 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 CRASH_ADDR_LOW_MAX,
>> -		 * 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, CRASH_ALIGN, crash_base,
>> -						  crash_base + crash_size);
>> -		if (start != crash_base) {
>> -			pr_info("crashkernel reservation failed - memory is in use.\n");
>> -			return;
>> -		}
>> -	}
>> -
>> -	if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
>> -		memblock_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));
>> -
>> -	crashk_res.start = crash_base;
>> -	crashk_res.end   = crash_base + crash_size - 1;
>> -	insert_resource(&iomem_resource, &crashk_res);
>> -}
>> -#else
>> +#ifndef CONFIG_KEXEC_CORE
>>  static void __init reserve_crashkernel(void)
>>  {
>>  }
>> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
>> index 206bde8308b2..5021d7c70aee 100644
>> --- a/include/linux/crash_core.h
>> +++ b/include/linux/crash_core.h
>> @@ -69,6 +69,9 @@ extern unsigned char *vmcoreinfo_data;
>>  extern size_t vmcoreinfo_size;
>>  extern u32 *vmcoreinfo_note;
>>  
>> +extern struct resource crashk_res;
>> +extern struct resource crashk_low_res;
>> +
>>  /* raw contents of kernel .notes section */
>>  extern const void __start_notes __weak;
>>  extern const void __stop_notes __weak;
>> @@ -83,5 +86,6 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
>>  		unsigned long long *crash_size, unsigned long long *crash_base);
>>  int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
>>  		unsigned long long *crash_size, unsigned long long *crash_base);
>> +int __init reserve_crashkernel_low(void);
>>  
>>  #endif /* LINUX_CRASH_CORE_H */
>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>> index 9e93bef52968..f301f2f5cfc4 100644
>> --- a/include/linux/kexec.h
>> +++ b/include/linux/kexec.h
>> @@ -337,8 +337,6 @@ extern int kexec_load_disabled;
>>  
>>  /* Location of a reserved region to hold the crash kernel.
>>   */
>> -extern struct resource crashk_res;
>> -extern struct resource crashk_low_res;
>>  extern note_buf_t __percpu *crash_notes;
>>  
>>  /* flag to track if kexec reboot is in progress */
>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
>> index 106e4500fd53..d39892bdb9ae 100644
>> --- a/kernel/crash_core.c
>> +++ b/kernel/crash_core.c
>> @@ -7,7 +7,12 @@
>>  #include <linux/crash_core.h>
>>  #include <linux/utsname.h>
>>  #include <linux/vmalloc.h>
>> +#include <linux/memblock.h>
>> +#include <linux/swiotlb.h>
>>  
>> +#include <xen/xen.h>
>> +
>> +#include <asm/kexec.h>
>>  #include <asm/page.h>
>>  #include <asm/sections.h>
>>  
>> @@ -21,6 +26,22 @@ u32 *vmcoreinfo_note;
>>  /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
>>  static unsigned char *vmcoreinfo_data_safecopy;
>>  
>> +/* Location of the reserved area for the crash kernel */
>> +struct resource crashk_res = {
>> +	.name  = "Crash kernel",
>> +	.start = 0,
>> +	.end   = 0,
>> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
>> +	.desc  = IORES_DESC_CRASH_KERNEL
>> +};
>> +struct resource crashk_low_res = {
>> +	.name  = "Crash kernel",
>> +	.start = 0,
>> +	.end   = 0,
>> +	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
>> +	.desc  = IORES_DESC_CRASH_KERNEL
>> +};
>> +
>>  /*
>>   * parsing the "crashkernel" commandline
>>   *
>> @@ -294,6 +315,149 @@ int __init parse_crashkernel_low(char *cmdline,
>>  				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
>>  }
>>  
>> +/*
>> + * --------- Crashkernel reservation ------------------------------
>> + */
>> +
>> +int __init reserve_crashkernel_low(void)
> static?
Ok, i will update in next version.
>
>> +{
>> +#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, CRASH_ALIGN,
>> +			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 0;
>> +}
>> +
>> +#ifdef CONFIG_X86
>> +#ifdef CONFIG_KEXEC_CORE
>> +/*
>> + * reserve_crashkernel() - reserves memory for crash kernel
>> + *
>> + * This function reserves memory area given in "crashkernel=" kernel command
>> + * line parameter. The memory reserved is used by dump capture kernel when
>> + * primary kernel is crashing.
>> + */
>> +void __init reserve_crashkernel(void)
>> +{
>> +	unsigned long long crash_size, crash_base, total_mem;
>> +	bool high = false;
>> +	int ret;
>> +
>> +	total_mem = memblock_phys_mem_size();
>> +
>> +	/* crashkernel=XM */
>> +	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
>> +	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;
>> +	}
>> +
>> +	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 CRASH_ADDR_LOW_MAX,
>> +		 * 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 {
>> +		/* User specifies base address explicitly. */
>> +		unsigned long long start;
>> +
>> +		if (!IS_ALIGNED(crash_base, CRASH_ALIGN)) {
>> +			pr_warn("cannot reserve crashkernel: base address is not %ldMB aligned\n",
>> +				(unsigned long)CRASH_ALIGN >> 20);
>> +			return;
>> +		}
>> +
>> +		start = memblock_phys_alloc_range(crash_size, CRASH_ALIGN, crash_base,
>> +						  crash_base + crash_size);
>> +		if (start != crash_base) {
>> +			pr_info("crashkernel reservation failed - memory is in use.\n");
>> +			return;
>> +		}
>> +	}
>> +
>> +	if (crash_base >= CRASH_ADDR_LOW_MAX && reserve_crashkernel_low()) {
>> +		memblock_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));
>> +
>> +	crashk_res.start = crash_base;
>> +	crashk_res.end   = crash_base + crash_size - 1;
>> +	insert_resource(&iomem_resource, &crashk_res);
>> +}
>> +#endif /* CONFIG_KEXEC_CORE */
>> +#endif
>> +
>>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>>  			  void *data, size_t data_len)
>>  {
>> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
>> index 8798a8183974..2ca887514145 100644
>> --- a/kernel/kexec_core.c
>> +++ b/kernel/kexec_core.c
>> @@ -53,23 +53,6 @@ note_buf_t __percpu *crash_notes;
>>  /* Flag to indicate we are going to kexec a new kernel */
>>  bool kexec_in_progress = false;
>>  
>> -
>> -/* Location of the reserved area for the crash kernel */
>> -struct resource crashk_res = {
>> -	.name  = "Crash kernel",
>> -	.start = 0,
>> -	.end   = 0,
>> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
>> -	.desc  = IORES_DESC_CRASH_KERNEL
>> -};
>> -struct resource crashk_low_res = {
>> -	.name  = "Crash kernel",
>> -	.start = 0,
>> -	.end   = 0,
>> -	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
>> -	.desc  = IORES_DESC_CRASH_KERNEL
>> -};
>> -
>>  int kexec_should_crash(struct task_struct *p)
>>  {
>>  	/*
>> -- 
>> 2.20.1
>>