x86/mce/inject: Remove call to mce_notify_irq()

The call to mce_notify_irq() has been there since the initial version of
the soft inject mce machinery, introduced in

  ea149b3 ("x86, mce: add basic error injection infrastructure").

At that time it was functional since injecting an MCE resulted in the
following call chain:

  raise_mce()
    ->machine_check_poll()
        ->mce_log() - sets notfiy_user_bit
  ->mce_notify_user() (current mce_notify_irq) consumed the bit and called the
  usermode helper.

However, with the introduction of

  011d826 ("RAS: Add a Corrected Errors Collector")

the code got moved around and the usermode helper began to be called via the
early notifier mce_first_notifier() rendering the call in raise_local()
defunct as the mce_need_notify bit (ex notify_user) is only being set from the
early notifier.

Remove the noop call and make mce_notify_irq() static.

No functional changes.

Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250225143348.268469-1-nik.borisov@suse.com

Author: Nikolay Borisov

arch/x86/include/asm/mce.h

@@ -296,8 +296,6 @@ enum mcp_flags {
 
 void machine_check_poll(enum mcp_flags flags, mce_banks_t *b);
 
-bool mce_notify_irq(void);
-
 DECLARE_PER_CPU(struct mce, injectm);
 
 /* Disable CMCI/polling for MCA bank claimed by firmware */

arch/x86/kernel/cpu/mce/core.c

@@ -584,6 +584,28 @@ bool mce_is_correctable(struct mce *m)
 }
 EXPORT_SYMBOL_GPL(mce_is_correctable);
 
+/*
+ * Notify the user(s) about new machine check events.
+ * Can be called from interrupt context, but not from machine check/NMI
+ * context.
+ */
+static bool mce_notify_irq(void)
+{
+	/* Not more than two messages every minute */
+	static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
+
+	if (test_and_clear_bit(0, &mce_need_notify)) {
+		mce_work_trigger();
+
+		if (__ratelimit(&ratelimit))
+			pr_info(HW_ERR "Machine check events logged\n");
+
+		return true;
+	}
+
+	return false;
+}
+
 static int mce_early_notifier(struct notifier_block *nb, unsigned long val,
 			      void *data)
 {
@@ -1773,28 +1795,6 @@ static void mce_timer_delete_all(void)
 		del_timer_sync(&per_cpu(mce_timer, cpu));
 }
 
-/*
- * Notify the user(s) about new machine check events.
- * Can be called from interrupt context, but not from machine check/NMI
- * context.
- */
-bool mce_notify_irq(void)
-{
-	/* Not more than two messages every minute */
-	static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
-
-	if (test_and_clear_bit(0, &mce_need_notify)) {
-		mce_work_trigger();
-
-		if (__ratelimit(&ratelimit))
-			pr_info(HW_ERR "Machine check events logged\n");
-
-		return true;
-	}
-	return false;
-}
-EXPORT_SYMBOL_GPL(mce_notify_irq);
-
 static void __mcheck_cpu_mce_banks_init(void)
 {
 	struct mce_bank *mce_banks = this_cpu_ptr(mce_banks_array);

arch/x86/kernel/cpu/mce/inject.c

@@ -229,7 +229,6 @@ static int raise_local(void)
 	} else if (m->status) {
 		pr_info("Starting machine check poll CPU %d\n", cpu);
 		raise_poll(m);
-		mce_notify_irq();
 		pr_info("Machine check poll done on CPU %d\n", cpu);
 	} else
 		m->finished = 0;