Merge tag 'x86-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core x86 updates from Ingo Molnar:
"Boot code changes:

- A large series of changes to reorganize th

Merge tag 'x86-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core x86 updates from Ingo Molnar:
"Boot code changes:

- A large series of changes to reorganize the x86 boot code into a
better isolated and easier to maintain base of PIC early startup
code in arch/x86/boot/startup/, by Ard Biesheuvel.

Motivation & background:

| Since commit
|
| c88d71508e36 ("x86/boot/64: Rewrite startup_64() in C")
|
| dated Jun 6 2017, we have been using C code on the boot path in a way
| that is not supported by the toolchain, i.e., to execute non-PIC C
| code from a mapping of memory that is different from the one provided
| to the linker. It should have been obvious at the time that this was a
| bad idea, given the need to sprinkle fixup_pointer() calls left and
| right to manipulate global variables (including non-pointer variables)
| without crashing.
|
| This C startup code has been expanding, and in particular, the SEV-SNP
| startup code has been expanding over the past couple of years, and
| grown many of these warts, where the C code needs to use special
| annotations or helpers to access global objects.

This tree includes the first phase of this work-in-progress x86
boot code reorganization.

Scalability enhancements and micro-optimizations:

- Improve code-patching scalability (Eric Dumazet)

- Remove MFENCEs for X86_BUG_CLFLUSH_MONITOR (Andrew Cooper)

CPU features enumeration updates:

- Thorough reorganization and cleanup of CPUID parsing APIs (Ahmed S.
Darwish)

- Fix, refactor and clean up the cacheinfo code (Ahmed S. Darwish,
Thomas Gleixner)

- Update CPUID bitfields to x86-cpuid-db v2.3 (Ahmed S. Darwish)

Memory management changes:

- Allow temporary MMs when IRQs are on (Andy Lutomirski)

- Opt-in to IRQs-off activate_mm() (Andy Lutomirski)

- Simplify choose_new_asid() and generate better code (Borislav
Petkov)

- Simplify 32-bit PAE page table handling (Dave Hansen)

- Always use dynamic memory layout (Kirill A. Shutemov)

- Make SPARSEMEM_VMEMMAP the only memory model (Kirill A. Shutemov)

- Make 5-level paging support unconditional (Kirill A. Shutemov)

- Stop prefetching current->mm->mmap_lock on page faults (Mateusz
Guzik)

- Predict valid_user_address() returning true (Mateusz Guzik)

- Consolidate initmem_init() (Mike Rapoport)

FPU support and vector computing:

- Enable Intel APX support (Chang S. Bae)

- Reorgnize and clean up the xstate code (Chang S. Bae)

- Make task_struct::thread constant size (Ingo Molnar)

- Restore fpu_thread_struct_whitelist() to fix
CONFIG_HARDENED_USERCOPY=y (Kees Cook)

- Simplify the switch_fpu_prepare() + switch_fpu_finish() logic (Oleg
Nesterov)

- Always preserve non-user xfeatures/flags in __state_perm (Sean
Christopherson)

Microcode loader changes:

- Help users notice when running old Intel microcode (Dave Hansen)

- AMD: Do not return error when microcode update is not necessary
(Annie Li)

- AMD: Clean the cache if update did not load microcode (Boris
Ostrovsky)

Code patching (alternatives) changes:

- Simplify, reorganize and clean up the x86 text-patching code (Ingo
Molnar)

- Make smp_text_poke_batch_process() subsume
smp_text_poke_batch_finish() (Nikolay Borisov)

- Refactor the {,un}use_temporary_mm() code (Peter Zijlstra)

Debugging support:

- Add early IDT and GDT loading to debug relocate_kernel() bugs
(David Woodhouse)

- Print the reason for the last reset on modern AMD CPUs (Yazen
Ghannam)

- Add AMD Zen debugging document (Mario Limonciello)

- Fix opcode map (!REX2) superscript tags (Masami Hiramatsu)

- Stop decoding i64 instructions in x86-64 mode at opcode (Masami
Hiramatsu)

CPU bugs and bug mitigations:

- Remove X86_BUG_MMIO_UNKNOWN (Borislav Petkov)

- Fix SRSO reporting on Zen1/2 with SMT disabled (Borislav Petkov)

- Restructure and harmonize the various CPU bug mitigation methods
(David Kaplan)

- Fix spectre_v2 mitigation default on Intel (Pawan Gupta)

MSR API:

- Large MSR code and API cleanup (Xin Li)

- In-kernel MSR API type cleanups and renames (Ingo Molnar)

PKEYS:

- Simplify PKRU update in signal frame (Chang S. Bae)

NMI handling code:

- Clean up, refactor and simplify the NMI handling code (Sohil Mehta)

- Improve NMI duration console printouts (Sohil Mehta)

Paravirt guests interface:

- Restrict PARAVIRT_XXL to 64-bit only (Kirill A. Shutemov)

SEV support:

- Share the sev_secrets_pa value again (Tom Lendacky)

x86 platform changes:

- Introduce the <asm/amd/> header namespace (Ingo Molnar)

- i2c: piix4, x86/platform: Move the SB800 PIIX4 FCH definitions to
<asm/amd/fch.h> (Mario Limonciello)

Fixes and cleanups:

- x86 assembly code cleanups and fixes (Uros Bizjak)

- Misc fixes and cleanups (Andi Kleen, Andy Lutomirski, Andy
Shevchenko, Ard Biesheuvel, Bagas Sanjaya, Baoquan He, Borislav
Petkov, Chang S. Bae, Chao Gao, Dan Williams, Dave Hansen, David
Kaplan, David Woodhouse, Eric Biggers, Ingo Molnar, Josh Poimboeuf,
Juergen Gross, Malaya Kumar Rout, Mario Limonciello, Nathan
Chancellor, Oleg Nesterov, Pawan Gupta, Peter Zijlstra, Shivank
Garg, Sohil Mehta, Thomas Gleixner, Uros Bizjak, Xin Li)"

* tag 'x86-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (331 commits)
x86/bugs: Fix spectre_v2 mitigation default on Intel
x86/bugs: Restructure ITS mitigation
x86/xen/msr: Fix uninitialized variable 'err'
x86/msr: Remove a superfluous inclusion of <asm/asm.h>
x86/paravirt: Restrict PARAVIRT_XXL to 64-bit only
x86/mm/64: Make 5-level paging support unconditional
x86/mm/64: Make SPARSEMEM_VMEMMAP the only memory model
x86/mm/64: Always use dynamic memory layout
x86/bugs: Fix indentation due to ITS merge
x86/cpuid: Rename hypervisor_cpuid_base()/for_each_possible_hypervisor_cpuid_base() to cpuid_base_hypervisor()/for_each_possible_cpuid_base_hypervisor()
x86/cpu/intel: Rename CPUID(0x2) descriptors iterator parameter
x86/cacheinfo: Rename CPUID(0x2) descriptors iterator parameter
x86/cpuid: Rename cpuid_get_leaf_0x2_regs() to cpuid_leaf_0x2()
x86/cpuid: Rename have_cpuid_p() to cpuid_feature()
x86/cpuid: Set <asm/cpuid/api.h> as the main CPUID header
x86/cpuid: Move CPUID(0x2) APIs into <cpuid/api.h>
x86/msr: Add rdmsrl_on_cpu() compatibility wrapper
x86/mm: Fix kernel-doc descriptions of various pgtable methods
x86/asm-offsets: Export certain 'struct cpuinfo_x86' fields for 64-bit asm use too
x86/boot: Defer initialization of VM space related global variables
...

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Merge branch 'x86/asm' into x86/core, to merge dependent commits

Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:

6f5bf947bab0 Merge tag 'its-

Merge branch 'x86/asm' into x86/core, to merge dependent commits

Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:

6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Signed-off-by: Ingo Molnar <mingo@kernel.org>

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selftests/kexec: Add x86_64 selftest for kexec-jump and exception handling

Add a self test which exercises both the kexec-jump facility, and the
kexec exception handling.

Invoke a trivial payload w

selftests/kexec: Add x86_64 selftest for kexec-jump and exception handling

Add a self test which exercises both the kexec-jump facility, and the
kexec exception handling.

Invoke a trivial payload which just does an int3 and returns,
flip-flopping its entry point for the next invocation between two
implementations of the same thing.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250326142404.256980-5-dwmw2@infradead.org

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