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Message-ID: <20240325103911.2651793-12-kirill.shutemov@linux.intel.com>
Date: Mon, 25 Mar 2024 12:39:05 +0200
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
Elena Reshetova <elena.reshetova@...el.com>,
Jun Nakajima <jun.nakajima@...el.com>,
Rick Edgecombe <rick.p.edgecombe@...el.com>,
Tom Lendacky <thomas.lendacky@....com>,
"Kalra, Ashish" <ashish.kalra@....com>,
Sean Christopherson <seanjc@...gle.com>,
"Huang, Kai" <kai.huang@...el.com>,
Baoquan He <bhe@...hat.com>,
kexec@...ts.infradead.org,
linux-coco@...ts.linux.dev,
linux-kernel@...r.kernel.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Dave Hansen <dave.hansen@...el.com>
Subject: [PATCHv9 11/17] 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 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@...ux.intel.com>
Reviewed-by: Dave Hansen <dave.hansen@...el.com>
---
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 6f1b379e3b38..f29969428443 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)
--
2.43.0
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