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x86/efi: Add efi_fake_mem support for EFI_MEMORY_SP

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Given that EFI_MEMORY_SP is platform BIOS policy decision for marking
memory ranges as "reserved for a specific purpose" there will inevitably
be scenarios where the BIOS omits the attribute in situations where it
is desired. Unlike other attributes if the OS wants to reserve this
memory from the kernel the reservation needs to happen early in init. So
early, in fact, that it needs to happen before e820__memblock_setup()
which is a pre-requisite for efi_fake_memmap() that wants to allocate
memory for the updated table.

Introduce an x86 specific efi_fake_memmap_early() that can search for
attempts to set EFI_MEMORY_SP via efi_fake_mem and update the e820 table
accordingly.

The KASLR code that scans the command line looking for user-directed
memory reservations also needs to be updated to consider
"efi_fake_mem=nn@ss:0x40000" requests.

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Dan Williams
2019-11-06 17:43:26 -08:00
committed by Rafael J. Wysocki
parent 16993c0f0a
commit 199c847176
8 changed files with 147 additions and 23 deletions
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8
arch/x86/include/asm/efi.h
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@@ -263,4 +263,12 @@ static inline void efi_reserve_boot_services(void)
}
#endif /* CONFIG_EFI */
#ifdef CONFIG_EFI_FAKE_MEMMAP
extern void __init efi_fake_memmap_early(void);
#else
static inline void efi_fake_memmap_early(void)
{
}
#endif
#endif /* _ASM_X86_EFI_H */