Re: [PATCH v2 1/2] LoongArch: use generic interface to support crashkernel=X,[high,low]

[Huacai Chen]

Hi, Youling,

On Thu, Dec 28, 2023 at 9:24 AM Huacai Chen <chenhuacai@xxxxxxxxxx> wrote:
>
> Hi, Youling,
>
> I squashed the two patches and applied here:
> https://github.com/chenhuacai/linux/commits/loongarch-next
>
> You can verify whether everything works.
With this patch applied I found there is something wrong in
/proc/iomem, and I fixed it with [1], could you please help to review
it?

[1] https://lore.kernel.org/kexec/20231229080213.2622204-1-chenhuacai@xxxxxxxxxxx/T/#u

Huacai

>
> Huacai
>
> On Wed, Dec 27, 2023 at 8:31 PM Youling Tang <youling.tang@xxxxxxxxxxx> wrote:
> >
> > From: Youling Tang <tangyouling@xxxxxxxxxx>
> >
> > LoongArch already supports two crashkernel regions in kexec-tools, so we
> > can directly use the common interface to support crashkernel=X,[hign,low]
> > after commit 0ab97169aa05("crash_core: add generic function to do reservation").
> >
> > 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();
> >
> > 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:
> > 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@2560M                   //low=512M
> > 11) crashkernel=1G,high crashkernel=0M,low   //high=1G, low=0M
> >
> > Recommended usage in general:
> > 1) In the case of small memory: crashkernel=512M
> > 2) In the case of large memory: crashkernel=1024M,high crashkernel=128M,low
> >
> > Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxx>
> > ---
> > v2:
> > Submit information and format adjustments.
> >
> >  arch/loongarch/Kconfig                  |  3 ++
> >  arch/loongarch/include/asm/crash_core.h | 11 ++++++
> >  arch/loongarch/kernel/setup.c           | 46 ++++++-------------------
> >  3 files changed, 25 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..189cd9575758 100644
> > --- a/arch/loongarch/kernel/setup.c
> > +++ b/arch/loongarch/kernel/setup.c
> > @@ -252,38 +252,23 @@ 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);
> > +       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);
> >  }
> >
> >  static void __init fdt_setup(void)
> > @@ -357,7 +342,7 @@ 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 +452,6 @@ 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
> >
> >