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    SubjectRe: [PATCH v13 4/8] x86: kdump: move reserve_crashkernel[_low]() into crash_core.c
    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@huawei.com>
    > Tested-by: John Donnelly <John.p.donnelly@oracle.com>
    > ---
    > 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?

    > -
    > - /* 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?

    > +{
    > +#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
    >

    --
    Sincerely yours,
    Mike.

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