kernel/drivers/firmware/efi/Kconfig, branch linux-6.9.y

efi: Add tee-based EFI variable driver

2023-12-11T10:19:18Z

When the flash is not owned by the non-secure world, accessing the EFI variables is straight-forward and done via EFI Runtime Variable Services. In this case, critical variables for system integrity and security are normally stored in the dedicated secure storage and can only be manipulated directly from the secure world. Usually, small embedded devices don't have the special dedicated secure storage. The eMMC device with an RPMB partition is becoming more common, and we can use this RPMB partition to store the EFI Variables. The eMMC device is typically owned by the non-secure world (Linux in our case). There is an existing solution utilizing eMMC RPMB partition for EFI Variables, it is implemented by interacting with TEE (OP-TEE in this case), StandaloneMM (as EFI Variable Service Pseudo TA), eMMC driver and tee-supplicant. The last piece is the tee-based variable access driver to interact with TEE and StandaloneMM. So let's add the kernel functions needed. This feature is implemented as a kernel module. StMM PTA has TA_FLAG_DEVICE_ENUM_SUPP flag when registered to OP-TEE so that this tee_stmm_efi module is probed after tee-supplicant starts, since "SetVariable" EFI Runtime Variable Service requires to interact with tee-supplicant. Acked-by: Sumit Garg Co-developed-by: Ilias Apalodimas Signed-off-by: Ilias Apalodimas Signed-off-by: Masahisa Kojima Signed-off-by: Ard Biesheuvel

arch: Remove Itanium (IA-64) architecture

2023-09-11T08:13:17Z

The Itanium architecture is obsolete, and an informal survey [0] reveals that any residual use of Itanium hardware in production is mostly HP-UX or OpenVMS based. The use of Linux on Itanium appears to be limited to enthusiasts that occasionally boot a fresh Linux kernel to see whether things are still working as intended, and perhaps to churn out some distro packages that are rarely used in practice. None of the original companies behind Itanium still produce or support any hardware or software for the architecture, and it is listed as 'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers that contributed on behalf of those companies (nor anyone else, for that matter) have been willing to support or maintain the architecture upstream or even be responsible for applying the odd fix. The Intel firmware team removed all IA-64 support from the Tianocore/EDK2 reference implementation of EFI in 2018. (Itanium is the original architecture for which EFI was developed, and the way Linux supports it deviates significantly from other architectures.) Some distros, such as Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have dropped support years ago. While the argument is being made [1] that there is a 'for the common good' angle to being able to build and run existing projects such as the Grid Community Toolkit [2] on Itanium for interoperability testing, the fact remains that none of those projects are known to be deployed on Linux/ia64, and very few people actually have access to such a system in the first place. Even if there were ways imaginable in which Linux/ia64 could be put to good use today, what matters is whether anyone is actually doing that, and this does not appear to be the case. There are no emulators widely available, and so boot testing Itanium is generally infeasible for ordinary contributors. GCC still supports IA-64 but its compile farm [3] no longer has any IA-64 machines. GLIBC would like to get rid of IA-64 [4] too because it would permit some overdue code cleanups. In summary, the benefits to the ecosystem of having IA-64 be part of it are mostly theoretical, whereas the maintenance overhead of keeping it supported is real. So let's rip off the band aid, and remove the IA-64 arch code entirely. This follows the timeline proposed by the Debian/ia64 maintainer [5], which removes support in a controlled manner, leaving IA-64 in a known good state in the most recent LTS release. Other projects will follow once the kernel support is removed. [0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/ [1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/ [2] https://gridcf.org/gct-docs/latest/index.html [3] https://cfarm.tetaneutral.net/machines/list/ [4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/ [5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/ Acked-by: Tony Luck Signed-off-by: Ard Biesheuvel

efi/libstub: Implement support for unaccepted memory

2023-06-06T14:58:23Z

UEFI Specification version 2.9 introduces the concept of memory acceptance: Some Virtual Machine platforms, such as Intel TDX or AMD SEV-SNP, requiring memory to be accepted before it can be used by the guest. Accepting happens via a protocol specific for the Virtual Machine platform. Accepting memory is costly and it makes VMM allocate memory for the accepted guest physical address range. It's better to postpone memory acceptance until memory is needed. It lowers boot time and reduces memory overhead. The kernel needs to know what memory has been accepted. Firmware communicates this information via memory map: a new memory type -- EFI_UNACCEPTED_MEMORY -- indicates such memory. Range-based tracking works fine for firmware, but it gets bulky for the kernel: e820 (or whatever the arch uses) has to be modified on every page acceptance. It leads to table fragmentation and there's a limited number of entries in the e820 table. Another option is to mark such memory as usable in e820 and track if the range has been accepted in a bitmap. One bit in the bitmap represents a naturally aligned power-2-sized region of address space -- unit. For x86, unit size is 2MiB: 4k of the bitmap is enough to track 64GiB or physical address space. In the worst-case scenario -- a huge hole in the middle of the address space -- It needs 256MiB to handle 4PiB of the address space. Any unaccepted memory that is not aligned to unit_size gets accepted upfront. The bitmap is allocated and constructed in the EFI stub and passed down to the kernel via EFI configuration table. allocate_e820() allocates the bitmap if unaccepted memory is present, according to the size of unaccepted region. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20230606142637.5171-4-kirill.shutemov@linux.intel.com

efi: libstub: Always enable initrd command line loader and bump version

2022-12-01T15:08:18Z

In preparation for setting a cross-architecture baseline for EFI boot support, remove the Kconfig option that permits the command line initrd loader to be disabled. Also, bump the minor version so that any image built with the new version can be identified as supporting this. Acked-by: Leif Lindholm Reviewed-by: Daniel Kiper Signed-off-by: Ard Biesheuvel

efi: x86: Move EFI runtime map sysfs code to arch/x86

2022-11-18T08:14:09Z

The EFI runtime map code is only wired up on x86, which is the only architecture that has a need for it in its implementation of kexec. So let's move this code under arch/x86 and drop all references to it from generic code. To ensure that the efi_runtime_map_init() is invoked at the appropriate time use a 'sync' subsys_initcall() that will be called right after the EFI initcall made from generic code where the original invocation of efi_runtime_map_init() resided. Signed-off-by: Ard Biesheuvel Reviewed-by: Dave Young

efi: runtime-maps: Clarify purpose and enable by default for kexec

2022-11-18T08:14:09Z

The current Kconfig logic for CONFIG_EFI_RUNTIME_MAPS does not convey that without it, a kexec kernel is not able to boot in EFI mode at all. So clarify this, and make the option only configurable via the menu system if CONFIG_EXPERT is set. Signed-off-by: Ard Biesheuvel Reviewed-by: Dave Young

efi: memmap: Move EFI fake memmap support into x86 arch tree

2022-11-18T08:14:09Z

The EFI fake memmap support is specific to x86, which manipulates the EFI memory map in various different ways after receiving it from the EFI stub. On other architectures, we have managed to push back on this, and the EFI memory map is kept pristine. So let's move the fake memmap code into the x86 arch tree, where it arguably belongs. Signed-off-by: Ard Biesheuvel

efi: libstub: Undeprecate the command line initrd loader

2022-11-18T08:14:08Z

The initrd= command line loader can be useful for development, but it was limited to loading files from the same file system as the loaded kernel (and it didn't work on x86 mixed mode). As both issues have been fixed, and the initrd= can now be used with files residing on any simple file system exposed by the EFI firmware, let's permit it to be enabled on RISC-V and LoongArch, which did not support it up to this point. Note that LoadFile2 remains the preferred option, as it is much simpler to use and implement, but generic loaders (including the UEFI shell) may not implement this so there, initrd= can now be used as well (if enabled in the build) Signed-off-by: Ard Biesheuvel

efi: libstub: Remove zboot signing from build options

2022-10-21T09:09:40Z

The zboot decompressor series introduced a feature to sign the PE/COFF kernel image for secure boot as part of the kernel build. This was necessary because there are actually two images that need to be signed: the kernel with the EFI stub attached, and the decompressor application. This is a bit of a burden, because it means that the images must be signed on the the same system that performs the build, and this is not realistic for distros. During the next cycle, we will introduce changes to the zboot code so that the inner image no longer needs to be signed. This means that the outer PE/COFF image can be handled as usual, and be signed later in the release process. Let's remove the associated Kconfig options now so that they don't end up in a LTS release while already being deprecated. Signed-off-by: Ard Biesheuvel

efi/libstub: implement generic EFI zboot

2022-09-20T07:50:30Z

Implement a minimal EFI app that decompresses the real kernel image and launches it using the firmware's LoadImage and StartImage boot services. This removes the need for any arch-specific hacks. Note that on systems that have UEFI secure boot policies enabled, LoadImage/StartImage require images to be signed, or their hashes known a priori, in order to be permitted to boot. There are various possible strategies to work around this requirement, but they all rely either on overriding internal PI/DXE protocols (which are not part of the EFI spec) or omitting the firmware provided LoadImage() and StartImage() boot services, which is also undesirable, given that they encapsulate platform specific policies related to secure boot and measured boot, but also related to memory permissions (whether or not and which types of heap allocations have both write and execute permissions.) The only generic and truly portable way around this is to simply sign both the inner and the outer image with the same key/cert pair, so this is what is implemented here. Signed-off-by: Ard Biesheuvel