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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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10
Documentation/admin-guide/kernel-parameters.txt
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@@ -1196,15 +1196,21 @@
updating original EFI memory map.
Region of memory which aa attribute is added to is
from ss to ss+nn.
If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
attribute is added to range 0x100000000-0x180000000 and
0x10a0000000-0x1120000000.
If efi_fake_mem=8G@9G:0x40000 is specified, the
EFI_MEMORY_SP(0x40000) attribute is added to
range 0x240000000-0x43fffffff.
Using this parameter you can do debugging of EFI memmap
related feature. For example, you can do debugging of
related features. For example, you can do debugging of
Address Range Mirroring feature even if your box
doesn't support it.
doesn't support it, or mark specific memory as
"soft reserved".
efivar_ssdt= [EFI; X86] Name of an EFI variable that contains an SSDT
that is to be dynamically loaded by Linux. If there are