[PATCH v3 2/2] x86/setup: merge several reservations of start of the memory
From: Mike Rapoport <rppt@kernel.org>
Date: 2021-03-02 10:29:38
Also in:
lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Mike Rapoport <redacted> Currently the first several pages are reserved both to avoid leaking their contents on systems with L1TF and to avoid corrupting BIOS memory. Merge the two memory reservations. Signed-off-by: Mike Rapoport <redacted> Reviewed-by: David Hildenbrand <redacted> Acked-by: Borislav Petkov <redacted> --- arch/x86/kernel/setup.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 3e3c6036b023..776fc9b3fafe 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c@@ -713,11 +713,6 @@ static int __init parse_reservelow(char *p) early_param("reservelow", parse_reservelow); -static void __init trim_low_memory_range(void) -{ - memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); -} - static void __init early_reserve_memory(void) { /*
@@ -730,10 +725,17 @@ static void __init early_reserve_memory(void) (unsigned long)__end_of_kernel_reserve - (unsigned long)_text); /* - * Make sure page 0 is always reserved because on systems with - * L1TF its contents can be leaked to user processes. + * The first 4Kb of memory is a BIOS owned area, but generally it is + * not listed as such in the E820 table. + * + * Reserve the first memory page and typically some additional + * memory (64KiB by default) since some BIOSes are known to corrupt + * low memory. See the Kconfig help text for X86_RESERVE_LOW. + * + * In addition, make sure page 0 is always reserved because on + * systems with L1TF its contents can be leaked to user processes. */ - memblock_reserve(0, PAGE_SIZE); + memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); early_reserve_initrd();
@@ -746,7 +748,6 @@ static void __init early_reserve_memory(void) reserve_bios_regions(); trim_snb_memory(); - trim_low_memory_range(); } /*
--
2.28.0