kernel/arch/x86/boot/compressed/misc.h, branch linux-rolling-stable

x86/boot: Drop unused sev_enable() fallback

2025-11-20T20:12:48Z

The misc.h header is not included by the EFI stub, which is the only C caller of sev_enable(). This means the fallback for cases where CONFIG_AMD_MEM_ENCRYPT is not set is never used, so it can be dropped. Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://patch.msgid.link/20250909080631.2867579-6-ardb+git@google.com

x86/sev: Disentangle #VC handling code from startup code

2025-05-05T05:07:29Z

Most of the SEV support code used to reside in a single C source file that was included in two places: the core kernel, and the decompressor. The code that is actually shared with the decompressor was moved into a separate, shared source file under startup/, on the basis that the decompressor also executes from the early 1:1 mapping of memory. However, while the elaborate #VC handling and instruction decoding that it involves is also performed by the decompressor, it does not actually occur in the core kernel at early boot, and therefore, does not need to be part of the confined early startup code. So split off the #VC handling code and move it back into arch/x86/coco where it came from, into another C source file that is included from both the decompressor and the core kernel. Code movement only - no functional change intended. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Arnd Bergmann Cc: David Woodhouse Cc: Dionna Amalie Glaze Cc: H. Peter Anvin Cc: Kees Cook Cc: Kevin Loughlin Cc: Len Brown Cc: Linus Torvalds Cc: Rafael J. Wysocki Cc: Tom Lendacky Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20250504095230.2932860-31-ardb+git@google.com

x86/sev: Move instruction decoder into separate source file

2025-05-04T13:53:06Z

As a first step towards disentangling the SEV #VC handling code -which is shared between the decompressor and the core kernel- from the SEV startup code, move the decompressor's copy of the instruction decoder into a separate source file. Code movement only - no functional change intended. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Arnd Bergmann Cc: David Woodhouse Cc: Dionna Amalie Glaze Cc: H. Peter Anvin Cc: Kees Cook Cc: Kevin Loughlin Cc: Len Brown Cc: Linus Torvalds Cc: Rafael J. Wysocki Cc: Tom Lendacky Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20250504095230.2932860-30-ardb+git@google.com

mm: rework accept memory helpers

2024-09-02T03:26:07Z

Make accept_memory() and range_contains_unaccepted_memory() take 'start' and 'size' arguments instead of 'start' and 'end'. Remove accept_page(), replacing it with direct calls to accept_memory(). The accept_page() name is going to be used for a different function. Link: https://lkml.kernel.org/r/20240809114854.3745464-6-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Suggested-by: David Hildenbrand Cc: Borislav Petkov Cc: Johannes Weiner Cc: Matthew Wilcox Cc: Mel Gorman Cc: Mike Rapoport (Microsoft) Cc: Tom Lendacky Cc: Vlastimil Babka Signed-off-by: Andrew Morton

x86/boot: Add a message about ignored early NMIs

2024-02-06T09:51:11Z

Commit 78a509fba9c9 ("x86/boot: Ignore NMIs during very early boot") added an empty handler in early boot stage to avoid boot failure due to spurious NMIs. Add a diagnostic message to show that early NMIs have occurred. [ bp: Touchups. ] [ Committer note: tested by stopping the guest really early and injecting NMIs through qemu's monitor. Result: early console in setup code Spurious early NMIs ignored: 13 ... ] Suggested-by: Borislav Petkov Suggested-by: H. Peter Anvin Signed-off-by: Jun'ichi Nomura Signed-off-by: Borislav Petkov (AMD) Acked-by: Kirill A. Shutemov Link: https://lore.kernel.org/lkml/20231130103339.GCZWhlA196uRklTMNF@fat_crate.local

x86/boot: Add error_putdec() helper

2024-02-06T09:50:21Z

Add a helper to print decimal numbers to early console. Suggested-by: Borislav Petkov (AMD) Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Jun'ichi Nomura Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/lkml/20240123112624.GBZa-iYP1l9SSYtr-V@fat_crate.local/ Link: https://lore.kernel.org/r/20240202035052.17963-1-junichi.nomura@nec.com

x86/boot: Ignore NMIs during very early boot

2023-11-30T08:55:40Z

When there are two racing NMIs on x86, the first NMI invokes NMI handler and the 2nd NMI is latched until IRET is executed. If panic on NMI and panic kexec are enabled, the first NMI triggers panic and starts booting the next kernel via kexec. Note that the 2nd NMI is still latched. During the early boot of the next kernel, once an IRET is executed as a result of a page fault, then the 2nd NMI is unlatched and invokes the NMI handler. However, NMI handler is not set up at the early stage of boot, which results in a boot failure. Avoid such problems by setting up a NOP handler for early NMIs. [ mingo: Refined the changelog. ] Signed-off-by: Jun'ichi Nomura Signed-off-by: Derek Barbosa Signed-off-by: Ingo Molnar Cc: Kees Cook Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Andy Lutomirski Cc: "H. Peter Anvin" Cc: Peter Zijlstra

x86/boot: Rename conflicting 'boot_params' pointer to 'boot_params_ptr'

2023-10-18T10:03:03Z

The x86 decompressor is built and linked as a separate executable, but it shares components with the kernel proper, which are either #include'd as C files, or linked into the decompresor as a static library (e.g, the EFI stub) Both the kernel itself and the decompressor define a global symbol 'boot_params' to refer to the boot_params struct, but in the former case, it refers to the struct directly, whereas in the decompressor, it refers to a global pointer variable referring to the struct boot_params passed by the bootloader or constructed from scratch. This ambiguity is unfortunate, and makes it impossible to assign this decompressor variable from the x86 EFI stub, given that declaring it as extern results in a clash. So rename the decompressor version (whose scope is limited) to boot_params_ptr. [ mingo: Renamed 'boot_params_p' to 'boot_params_ptr' for clarity ] Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: linux-kernel@vger.kernel.org

x86/decompressor: Assign paging related global variables earlier

2023-08-07T18:42:11Z

There is no need to defer the assignment of the paging related global variables 'pgdir_shift' and 'ptrs_per_p4d' until after the trampoline is cleaned up, so assign them as soon as it is clear that 5-level paging will be enabled. Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230807162720.545787-9-ardb@kernel.org

x86/boot/compressed: Handle unaccepted memory

2023-06-06T15:17:24Z

The firmware will pre-accept the memory used to run the stub. But, the stub is responsible for accepting the memory into which it decompresses the main kernel. Accept memory just before decompression starts. The stub is also responsible for choosing a physical address in which to place the decompressed kernel image. The KASLR mechanism will randomize this physical address. Since the accepted memory region is relatively small, KASLR would be quite ineffective if it only used the pre-accepted area (EFI_CONVENTIONAL_MEMORY). Ensure that KASLR randomizes among the entire physical address space by also including EFI_UNACCEPTED_MEMORY. Signed-off-by: Kirill A. Shutemov Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Liam Merwick Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20230606142637.5171-5-kirill.shutemov@linux.intel.com