The following commit has been merged into the x86/cc branch of tip:
Commit-ID: 06fa48d85b09b3e67afeda220bc19f7102b53beb
Gitweb: https://git.kernel.org/tip/06fa48d85b09b3e67afeda220bc19f7102b53beb
Author: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 14 Jun 2024 12:58:57 +03:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Mon, 17 Jun 2024 17:46:08 +02:00
x86/mm: Make e820__end_ram_pfn() cover E820_TYPE_ACPI ranges
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 pre-allocated 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>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxx>
Tested-by: Tao Liu <ltao@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240614095904.1345461-13-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 68b09f7..4893d30 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -828,7 +828,7 @@ 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;
@@ -839,7 +839,8 @@ 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;
@@ -865,12 +866,12 @@ 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)
|