x86: kdump: use generic interface to simplify crashkernel reservation code

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.

[bhe@redhat.com: move crash_low_size_default() code into <asm/crash_core.h>]
Link: https://lkml.kernel.org/r/ZQpeAjOmuMJBFw1/@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20230914033142.676708-7-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Jiahao <chenjiahao16@huawei.com>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 66bfabae8814919c61902da3cdc77a45d9efa775..36b2f12f31c3fdc6ae4e779a6c4f5240d6cb5306 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2062,6 +2062,9 @@ config ARCH_SUPPORTS_CRASH_DUMP
 config ARCH_SUPPORTS_CRASH_HOTPLUG
        def_bool y
 
+config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+       def_bool CRASH_CORE
+
 config PHYSICAL_START
        hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
        default "0x1000000"

diff --git a/arch/x86/include/asm/crash_core.h b/arch/x86/include/asm/crash_core.h
new file mode 100644 (file)
index 0000000..76af98f
--- /dev/null
+++ b/arch/x86/include/asm/crash_core.h
@@ -0,0 +1,42 @@
+/* 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.
+ */
+extern unsigned long swiotlb_size_or_default(void);
+
+#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()
+
+static inline unsigned long crash_low_size_default(void)
+{
+#ifdef CONFIG_X86_64
+       return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
+#else
+       return 0;
+#endif
+}
+
+#endif /* _X86_CRASH_CORE_H */

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 655c0481290537ffaf246f03e45f6c5be449adf4..25a3f9a100f6815f59417e1b3635d9415a0f4238 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -466,155 +466,29 @@ 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)
+static void __init arch_reserve_crashkernel(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 0;
-}
-
-static void __init 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));
-
-       crashk_res.start = crash_base;
-       crashk_res.end   = crash_base + crash_size - 1;
-       insert_resource(&iomem_resource, &crashk_res);
+       reserve_crashkernel_generic(cmdline, crash_size, crash_base,
+                                   low_size, high);
 }
 
 static struct resource standard_io_resources[] = {
@@ -1228,7 +1102,7 @@ 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();