Merge tag 'x86_misc_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc x86 fixes from Borislav Petkov:

 - Fix a wrong check in the function reporting whether a CPU executes
   (or not) a NMI handler

 - Ratelimit unknown NMIs messages in order to not potentially slow down
   the machine

 - Other fixlets

* tag 'x86_misc_for_v6.9_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/nmi: Fix the inverse "in NMI handler" check
  Documentation/maintainer-tip: Add C++ tail comments exception
  Documentation/maintainer-tip: Add Closes tag
  x86/nmi: Rate limit unknown NMI messages
  Documentation/kernel-parameters: Add spec_rstack_overflow to mitigations=off

1 files changed, 4 insertions, 4 deletions

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 397ef9fcf5e99b..56e7a9e2737a01 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -304,13 +304,13 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 
 	__this_cpu_add(nmi_stats.unknown, 1);
 
-	pr_emerg("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
-		 reason, smp_processor_id());
+	pr_emerg_ratelimited("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+			     reason, smp_processor_id());
 
 	if (unknown_nmi_panic || panic_on_unrecovered_nmi)
 		nmi_panic(regs, "NMI: Not continuing");
 
-	pr_emerg("Dazed and confused, but trying to continue\n");
+	pr_emerg_ratelimited("Dazed and confused, but trying to continue\n");
 }
 NOKPROBE_SYMBOL(unknown_nmi_error);
 
@@ -637,7 +637,7 @@ void nmi_backtrace_stall_check(const struct cpumask *btp)
 			msgp = nmi_check_stall_msg[idx];
 			if (nsp->idt_ignored_snap != READ_ONCE(nsp->idt_ignored) && (idx & 0x1))
 				modp = ", but OK because ignore_nmis was set";
-			if (nmi_seq & ~0x1)
+			if (nmi_seq & 0x1)
 				msghp = " (CPU currently in NMI handler function)";
 			else if (nsp->idt_nmi_seq_snap + 1 == nmi_seq)
 				msghp = " (CPU exited one NMI handler function)";