Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 04adc8d..b8d4e9c 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	Intel SMP support routines.
  *
@@ -6,9 +7,6 @@
  *      (c) 2002,2003 Andi Kleen, SuSE Labs.
  *
  *	i386 and x86_64 integration by Glauber Costa <gcosta@redhat.com>
- *
- *	This code is released under the GNU General Public License version 2 or
- *	later.
  */
 
 #include <linux/init.h>
@@ -117,46 +115,6 @@
 static atomic_t stopping_cpu = ATOMIC_INIT(-1);
 static bool smp_no_nmi_ipi = false;
 
-/*
- * this function sends a 'reschedule' IPI to another CPU.
- * it goes straight through and wastes no time serializing
- * anything. Worst case is that we lose a reschedule ...
- */
-static void native_smp_send_reschedule(int cpu)
-{
-	if (unlikely(cpu_is_offline(cpu))) {
-		WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
-		return;
-	}
-	apic->send_IPI(cpu, RESCHEDULE_VECTOR);
-}
-
-void native_send_call_func_single_ipi(int cpu)
-{
-	apic->send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
-}
-
-void native_send_call_func_ipi(const struct cpumask *mask)
-{
-	cpumask_var_t allbutself;
-
-	if (!alloc_cpumask_var(&allbutself, GFP_ATOMIC)) {
-		apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
-		return;
-	}
-
-	cpumask_copy(allbutself, cpu_online_mask);
-	cpumask_clear_cpu(smp_processor_id(), allbutself);
-
-	if (cpumask_equal(mask, allbutself) &&
-	    cpumask_equal(cpu_online_mask, cpu_callout_mask))
-		apic->send_IPI_allbutself(CALL_FUNCTION_VECTOR);
-	else
-		apic->send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
-
-	free_cpumask_var(allbutself);
-}
-
 static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
 {
 	/* We are registered on stopping cpu too, avoid spurious NMI */
@@ -181,6 +139,12 @@
 	irq_exit();
 }
 
+static int register_stop_handler(void)
+{
+	return register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback,
+				    NMI_FLAG_FIRST, "smp_stop");
+}
+
 static void native_stop_other_cpus(int wait)
 {
 	unsigned long flags;
@@ -211,42 +175,44 @@
 		/* sync above data before sending IRQ */
 		wmb();
 
-		apic->send_IPI_allbutself(REBOOT_VECTOR);
+		apic_send_IPI_allbutself(REBOOT_VECTOR);
 
 		/*
-		 * Don't wait longer than a second if the caller
-		 * didn't ask us to wait.
+		 * Don't wait longer than a second for IPI completion. The
+		 * wait request is not checked here because that would
+		 * prevent an NMI shutdown attempt in case that not all
+		 * CPUs reach shutdown state.
 		 */
 		timeout = USEC_PER_SEC;
-		while (num_online_cpus() > 1 && (wait || timeout--))
+		while (num_online_cpus() > 1 && timeout--)
 			udelay(1);
 	}
-	
+
 	/* if the REBOOT_VECTOR didn't work, try with the NMI */
-	if ((num_online_cpus() > 1) && (!smp_no_nmi_ipi))  {
-		if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback,
-					 NMI_FLAG_FIRST, "smp_stop"))
-			/* Note: we ignore failures here */
-			/* Hope the REBOOT_IRQ is good enough */
-			goto finish;
-
-		/* sync above data before sending IRQ */
-		wmb();
-
-		pr_emerg("Shutting down cpus with NMI\n");
-
-		apic->send_IPI_allbutself(NMI_VECTOR);
-
+	if (num_online_cpus() > 1) {
 		/*
-		 * Don't wait longer than a 10 ms if the caller
-		 * didn't ask us to wait.
+		 * If NMI IPI is enabled, try to register the stop handler
+		 * and send the IPI. In any case try to wait for the other
+		 * CPUs to stop.
+		 */
+		if (!smp_no_nmi_ipi && !register_stop_handler()) {
+			/* Sync above data before sending IRQ */
+			wmb();
+
+			pr_emerg("Shutting down cpus with NMI\n");
+
+			apic_send_IPI_allbutself(NMI_VECTOR);
+		}
+		/*
+		 * Don't wait longer than 10 ms if the caller didn't
+		 * reqeust it. If wait is true, the machine hangs here if
+		 * one or more CPUs do not reach shutdown state.
 		 */
 		timeout = USEC_PER_MSEC * 10;
 		while (num_online_cpus() > 1 && (wait || timeout--))
 			udelay(1);
 	}
 
-finish:
 	local_irq_save(flags);
 	disable_local_APIC();
 	mcheck_cpu_clear(this_cpu_ptr(&cpu_info));