x86/microcode: Fix return value for microcode late loading

The return value from stop_machine() might not be consistent.

stop_machine_cpuslocked() returns:
- zero if all functions have returned 0.
- a non-zero value if at least one of the functions returned
a non-zero value.

There is no way to know if it is negative or positive. So make
__reload_late() return 0 on success or negative otherwise.

 [ bp: Unify ret val check and touch up. ]
Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/1587497318-4438-1-git-send-email-mihai.carabas@oracle.com

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

@@ -545,8 +545,7 @@ static int __wait_for_cpus(atomic_t *t, long long timeout)
 /*
  * Returns:
  * < 0 - on error
- *   0 - no update done
- *   1 - microcode was updated
+ *   0 - success (no update done or microcode was updated)
  */
 static int __reload_late(void *info)
 {
@@ -573,11 +572,11 @@ static int __reload_late(void *info)
 	else
 		goto wait_for_siblings;
 
-	if (err > UCODE_NFOUND) {
-		pr_warn("Error reloading microcode on CPU %d\n", cpu);
+	if (err >= UCODE_NFOUND) {
+		if (err == UCODE_ERROR)
+			pr_warn("Error reloading microcode on CPU %d\n", cpu);
+
 		ret = -1;
-	} else if (err == UCODE_UPDATED || err == UCODE_OK) {
-		ret = 1;
 	}
 
 wait_for_siblings:
@@ -608,7 +607,7 @@ static int microcode_reload_late(void)
 	atomic_set(&late_cpus_out, 0);
 
 	ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
-	if (ret > 0)
+	if (ret == 0)
 		microcode_check();
 
 	pr_info("Reload completed, microcode revision: 0x%x\n", boot_cpu_data.microcode);
@@ -649,7 +648,7 @@ static ssize_t reload_store(struct device *dev,
 put:
 	put_online_cpus();
 
-	if (ret >= 0)
+	if (ret == 0)
 		ret = size;
 
 	return ret;