Messages in this thread Patch in this message | | | From | "Kirill A. Shutemov" <> | Subject | [PATCHv3 5/7] x86/mm: Reserve unaccepted memory bitmap | Date | Fri, 28 Jan 2022 23:59:04 +0300 |
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A given page of memory can only be accepted once. The kernel has a need to accept memory both in the early decompression stage and during normal runtime.
Use a bitmap to communicate the acceptance state of each page between the decompression stage and normal runtime. This eliminates the possibility of attempting to double-accept a page.
Allocate the bitmap during decompression stage and hand it over to the main kernel image via boot_params.
In the runtime kernel, reserve the bitmap's memory to ensure nothing overwrites it.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- arch/x86/kernel/e820.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index bc0657f0deed..3905bd1ca41d 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -1297,6 +1297,16 @@ void __init e820__memblock_setup(void) int i; u64 end; + /* Mark unaccepted memory bitmap reserved */ + if (boot_params.unaccepted_memory) { + unsigned long size; + + /* One bit per 2MB */ + size = DIV_ROUND_UP(e820__end_of_ram_pfn() * PAGE_SIZE, + PMD_SIZE * BITS_PER_BYTE); + memblock_reserve(boot_params.unaccepted_memory, size); + } + /* * The bootstrap memblock region count maximum is 128 entries * (INIT_MEMBLOCK_REGIONS), but EFI might pass us more E820 entries -- 2.34.1
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