On Thu, Jun 20, 2024 at 09:32:05AM +0200, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@xxxxxxxxxx>
>
> Between kexec and confidential VM support, handling the EFI memory maps
> correctly on x86 is already proving to be rather difficult (as opposed
> to other EFI architectures which manage to never modify the EFI memory
> map to begin with)
>
> EFI fake memory map support is essentially a development hack (for
> testing new support for the 'special purpose' and 'more reliable' EFI
> memory attributes) that leaked into production code. The regions marked
> in this manner are not actually recognized as such by the firmware
> itself or the EFI stub (and never have), and marking memory as 'more
> reliable' seems rather futile if the underlying memory is just ordinary
> RAM.
>
> Marking memory as 'special purpose' in this way is also dubious, but may
> be in use in production code nonetheless. However, the same should be
> achievable by using the memmap= command line option with the ! operator.
>
> EFI fake memmap support is not enabled by any of the major distros
> (Debian, Fedora, SUSE, Ubuntu) and does not exist on other
> architectures, so let's drop support for it.
>
> Cc: Taku Izumi <izumi.taku@xxxxxxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 21 ---
> arch/x86/Kconfig | 20 --
> arch/x86/boot/compressed/kaslr.c | 43 +----
> arch/x86/include/asm/efi.h | 15 --
> arch/x86/kernel/setup.c | 1 -
> arch/x86/platform/efi/efi.c | 2 -
> arch/x86/platform/efi/fake_mem.c | 197 --------------------
> arch/x86/platform/efi/memmap.c | 1 +
> drivers/firmware/efi/libstub/x86-stub.c | 2 +-
> 9 files changed, 11 insertions(+), 291 deletions(-)
I obviously like this:
Acked-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
I don't see the author or anyone else objecting, I guess queue it?
Or if you feel like you wanna give folks a full cycle, you could queue it for
the next MW...
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
