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
  ...

1 files changed, 43 insertions, 44 deletions

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 9a95d00f1423..be93ec7255bf 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -49,27 +49,20 @@ struct nmi_desc {
 	struct list_head head;
 };
 
-static struct nmi_desc nmi_desc[NMI_MAX] = 
-{
-	{
-		.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[0].lock),
-		.head = LIST_HEAD_INIT(nmi_desc[0].head),
-	},
-	{
-		.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[1].lock),
-		.head = LIST_HEAD_INIT(nmi_desc[1].head),
-	},
-	{
-		.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[2].lock),
-		.head = LIST_HEAD_INIT(nmi_desc[2].head),
-	},
-	{
-		.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[3].lock),
-		.head = LIST_HEAD_INIT(nmi_desc[3].head),
-	},
+#define NMI_DESC_INIT(type) { \
+	.lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[type].lock), \
+	.head = LIST_HEAD_INIT(nmi_desc[type].head), \
+}
 
+static struct nmi_desc nmi_desc[NMI_MAX] = {
+	NMI_DESC_INIT(NMI_LOCAL),
+	NMI_DESC_INIT(NMI_UNKNOWN),
+	NMI_DESC_INIT(NMI_SERR),
+	NMI_DESC_INIT(NMI_IO_CHECK),
 };
 
+#define nmi_to_desc(type) (&nmi_desc[type])
+
 struct nmi_stats {
 	unsigned int normal;
 	unsigned int unknown;
@@ -91,6 +84,9 @@ static DEFINE_PER_CPU(struct nmi_stats, nmi_stats);
 static int ignore_nmis __read_mostly;
 
 int unknown_nmi_panic;
+int panic_on_unrecovered_nmi;
+int panic_on_io_nmi;
+
 /*
  * Prevent NMI reason port (0x61) being accessed simultaneously, can
  * only be used in NMI handler.
@@ -104,8 +100,6 @@ static int __init setup_unknown_nmi_panic(char *str)
 }
 __setup("unknown_nmi_panic", setup_unknown_nmi_panic);
 
-#define nmi_to_desc(type) (&nmi_desc[type])
-
 static u64 nmi_longest_ns = 1 * NSEC_PER_MSEC;
 
 static int __init nmi_warning_debugfs(void)
@@ -125,12 +119,12 @@ static void nmi_check_duration(struct nmiaction *action, u64 duration)
 
 	action->max_duration = duration;
 
-	remainder_ns = do_div(duration, (1000 * 1000));
-	decimal_msecs = remainder_ns / 1000;
+	/* Convert duration from nsec to msec */
+	remainder_ns = do_div(duration, NSEC_PER_MSEC);
+	decimal_msecs = remainder_ns / NSEC_PER_USEC;
 
-	printk_ratelimited(KERN_INFO
-		"INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
-		action->handler, duration, decimal_msecs);
+	pr_info_ratelimited("INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
+			    action->handler, duration, decimal_msecs);
 }
 
 static int nmi_handle(unsigned int type, struct pt_regs *regs)
@@ -333,10 +327,9 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 	int handled;
 
 	/*
-	 * Use 'false' as back-to-back NMIs are dealt with one level up.
-	 * Of course this makes having multiple 'unknown' handlers useless
-	 * as only the first one is ever run (unless it can actually determine
-	 * if it caused the NMI)
+	 * As a last resort, let the "unknown" handlers make a
+	 * best-effort attempt to figure out if they can claim
+	 * responsibility for this Unknown NMI.
 	 */
 	handled = nmi_handle(NMI_UNKNOWN, regs);
 	if (handled) {
@@ -366,17 +359,18 @@ static noinstr void default_do_nmi(struct pt_regs *regs)
 	bool b2b = false;
 
 	/*
-	 * CPU-specific NMI must be processed before non-CPU-specific
-	 * NMI, otherwise we may lose it, because the CPU-specific
-	 * NMI can not be detected/processed on other CPUs.
-	 */
-
-	/*
-	 * Back-to-back NMIs are interesting because they can either
-	 * be two NMI or more than two NMIs (any thing over two is dropped
-	 * due to NMI being edge-triggered).  If this is the second half
-	 * of the back-to-back NMI, assume we dropped things and process
-	 * more handlers.  Otherwise reset the 'swallow' NMI behaviour
+	 * Back-to-back NMIs are detected by comparing the RIP of the
+	 * current NMI with that of the previous NMI. If it is the same,
+	 * it is assumed that the CPU did not have a chance to jump back
+	 * into a non-NMI context and execute code in between the two
+	 * NMIs.
+	 *
+	 * They are interesting because even if there are more than two,
+	 * only a maximum of two can be detected (anything over two is
+	 * dropped due to NMI being edge-triggered). If this is the
+	 * second half of the back-to-back NMI, assume we dropped things
+	 * and process more handlers. Otherwise, reset the 'swallow' NMI
+	 * behavior.
 	 */
 	if (regs->ip == __this_cpu_read(last_nmi_rip))
 		b2b = true;
@@ -390,6 +384,11 @@ static noinstr void default_do_nmi(struct pt_regs *regs)
 	if (microcode_nmi_handler_enabled() && microcode_nmi_handler())
 		goto out;
 
+	/*
+	 * CPU-specific NMI must be processed before non-CPU-specific
+	 * NMI, otherwise we may lose it, because the CPU-specific
+	 * NMI can not be detected/processed on other CPUs.
+	 */
 	handled = nmi_handle(NMI_LOCAL, regs);
 	__this_cpu_add(nmi_stats.normal, handled);
 	if (handled) {
@@ -426,13 +425,14 @@ static noinstr void default_do_nmi(struct pt_regs *regs)
 			pci_serr_error(reason, regs);
 		else if (reason & NMI_REASON_IOCHK)
 			io_check_error(reason, regs);
-#ifdef CONFIG_X86_32
+
 		/*
 		 * Reassert NMI in case it became active
 		 * meanwhile as it's edge-triggered:
 		 */
-		reassert_nmi();
-#endif
+		if (IS_ENABLED(CONFIG_X86_32))
+			reassert_nmi();
+
 		__this_cpu_add(nmi_stats.external, 1);
 		raw_spin_unlock(&nmi_reason_lock);
 		goto out;
@@ -751,4 +751,3 @@ void local_touch_nmi(void)
 {
 	__this_cpu_write(last_nmi_rip, 0);
 }
-EXPORT_SYMBOL_GPL(local_touch_nmi);