e820__end_of_ram_pfn() is used to calculate max_pfn which, among other things, guides where direct mapping ends. Any memory above max_pfn is not going to be present in the direct mapping. e820__end_of_ram_pfn() finds the end of the ram based on the highest E820_TYPE_RAM range. But it doesn't includes E820_TYPE_ACPI ranges into calculation. Despite the name, E820_TYPE_ACPI covers not only ACPI data, but also EFI tables and might be required by kernel to function properly. Usually the problem is hidden because there is some E820_TYPE_RAM memory above E820_TYPE_ACPI. But crashkernel only presents pre-allocated crash memory as E820_TYPE_RAM on boot. If the preallocated range is small, it can fit under the last E820_TYPE_ACPI range. Modify e820__end_of_ram_pfn() and e820__end_of_low_ram_pfn() to cover E820_TYPE_ACPI memory. The problem was discovered during debugging kexec for TDX guest. TDX guest uses E820_TYPE_ACPI to store the unaccepted memory bitmap and pass it between the kernels on kexec. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> --- arch/x86/kernel/e820.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index fb8cf953380d..99c80680dc9e 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -827,7 +827,7 @@ u64 __init e820__memblock_alloc_reserved(u64 size, u64 align) /* * Find the highest page frame number we have available */ -static unsigned long __init e820_end_pfn(unsigned long limit_pfn, enum e820_type type) +static unsigned long __init e820_end_ram_pfn(unsigned long limit_pfn) { int i; unsigned long last_pfn = 0; @@ -838,7 +838,8 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn, enum e820_type unsigned long start_pfn; unsigned long end_pfn; - if (entry->type != type) + if (entry->type != E820_TYPE_RAM && + entry->type != E820_TYPE_ACPI) continue; start_pfn = entry->addr >> PAGE_SHIFT; @@ -864,12 +865,12 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn, enum e820_type unsigned long __init e820__end_of_ram_pfn(void) { - return e820_end_pfn(MAX_ARCH_PFN, E820_TYPE_RAM); + return e820_end_ram_pfn(MAX_ARCH_PFN); } unsigned long __init e820__end_of_low_ram_pfn(void) { - return e820_end_pfn(1UL << (32 - PAGE_SHIFT), E820_TYPE_RAM); + return e820_end_ram_pfn(1UL << (32 - PAGE_SHIFT)); } static void __init early_panic(char *msg) -- 2.41.0 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec