Merge tag 'x86-core-2023-07-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fix from Thomas Gleixner:
 "A single fix for the mechanism to park CPUs with an INIT IPI.

  On shutdown or kexec, the kernel tries to park the non-boot CPUs with
  an INIT IPI. But the same code path is also used by the crash utility.
  If the CPU which panics is not the boot CPU then it sends an INIT IPI
  to the boot CPU which resets the machine.

  Prevent this by validating that the CPU which runs the stop mechanism
  is the boot CPU. If not, leave the other CPUs in HLT"

* tag 'x86-core-2023-07-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/smp: Don't send INIT to boot CPU

Author: torvalds

arch/x86/kernel/smpboot.c

@@ -1348,6 +1348,14 @@ bool smp_park_other_cpus_in_init(void)
 	if (apic->wakeup_secondary_cpu_64 || apic->wakeup_secondary_cpu)
 		return false;
 
+	/*
+	 * If this is a crash stop which does not execute on the boot CPU,
+	 * then this cannot use the INIT mechanism because INIT to the boot
+	 * CPU will reset the machine.
+	 */
+	if (this_cpu)
+		return false;
+
 	for_each_present_cpu(cpu) {
 		if (cpu == this_cpu)
 			continue;