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

JIRA: https://issues.redhat.com/browse/RHEL-118444

commit 6447828
Author: Nikolay Borisov <nik.borisov@suse.com>
Date:   Tue Feb 25 16:33:48 2025 +0200

    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

Signed-off-by: David Arcari <darcari@redhat.com>

Author: darcari

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

@@ -583,6 +583,28 @@ 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)
 {
@@ -1772,28 +1794,6 @@ 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;