LoongArch: Use generic interface to support crashkernel=X,[high,low]

LoongArch already supports two crashkernel regions in kexec-tools, so we
can directly use the common interface to support crashkernel=X,[high,low]
after commit 0ab97169aa0517079b ("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>, then define CRASH_ALIGN,
   CRASH_ADDR_LOW_MAX and CRASH_ADDR_HIGH_MAX and 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@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 65731b060e3fef98cb97f03695ca8757ee197700..f2633dd87a97433dba3a7fec6b74462ef68088ce 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -877,9 +877,9 @@
                        memory region [offset, offset + size] for that kernel
                        image. If '@offset' is omitted, then a suitable offset
                        is selected automatically.
-                       [KNL, X86-64, ARM64, RISCV] Select a region under 4G first, and
-                       fall back to reserve region above 4G when '@offset'
-                       hasn't been specified.
+                       [KNL, X86-64, ARM64, RISCV, LoongArch] Select a region
+                       under 4G first, and fall back to reserve region above
+                       4G when '@offset' hasn't been specified.
                        See Documentation/admin-guide/kdump/kdump.rst for further details.
 
        crashkernel=range1:size1[,range2:size2,...][@offset]
@@ -890,25 +890,27 @@
                        Documentation/admin-guide/kdump/kdump.rst for an example.
 
        crashkernel=size[KMG],high
-                       [KNL, X86-64, ARM64, RISCV] range could be above 4G.
+                       [KNL, X86-64, ARM64, RISCV, LoongArch] range could be
+                       above 4G.
                        Allow kernel to allocate physical memory region from top,
                        so could be above 4G if system have more than 4G ram
                        installed. Otherwise memory region will be allocated
                        below 4G, if available.
                        It will be ignored if crashkernel=X is specified.
        crashkernel=size[KMG],low
-                       [KNL, X86-64, ARM64, RISCV] range under 4G. When crashkernel=X,high
-                       is passed, kernel could allocate physical memory region
-                       above 4G, that cause second kernel crash on system
-                       that require some amount of low memory, e.g. swiotlb
-                       requires at least 64M+32K low memory, also enough extra
-                       low memory is needed to make sure DMA buffers for 32-bit
-                       devices won't run out. Kernel would try to allocate
+                       [KNL, X86-64, ARM64, RISCV, LoongArch] range under 4G.
+                       When crashkernel=X,high is passed, kernel could allocate
+                       physical memory region above 4G, that cause second kernel
+                       crash on system that require some amount of low memory,
+                       e.g. swiotlb requires at least 64M+32K low memory, also
+                       enough extra low memory is needed to make sure DMA buffers
+                       for 32-bit devices won't run out. Kernel would try to allocate
                        default size of memory below 4G automatically. The default
                        size is platform dependent.
                          --> x86: max(swiotlb_size_or_default() + 8MiB, 256MiB)
                          --> arm64: 128MiB
                          --> riscv: 128MiB
+                         --> loongarch: 128MiB
                        This one lets the user specify own low range under 4G
                        for second kernel instead.
                        0: to disable low allocation.

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index ede2ef26726a8d9f58dacebed5ee9efd1f2a4e0e..c997223beae0035bc787eecf0aace8d900f9693c 100644 (file)
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -594,6 +594,9 @@ 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 (file)
index 0000000..218bdbf
--- /dev/null
+++ b/arch/loongarch/include/asm/crash_core.h
@@ -0,0 +1,12 @@
+/* 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 15d366b8407c3acbde526918c5846513f080c7ce..edf2bba80130670364e144ad301868a7dfd3bf93 100644 (file)
--- 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;
 
-       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)
@@ -363,7 +348,7 @@ out:
 void __init platform_init(void)
 {
        arch_reserve_vmcore();
-       arch_parse_crashkernel();
+       arch_reserve_crashkernel();
 
 #ifdef CONFIG_ACPI_TABLE_UPGRADE
        acpi_table_upgrade();
@@ -473,15 +458,6 @@ 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,