diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index ff8511d6d8ea..aa71a90f5222 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -55,12 +55,18 @@
  *
  *  For pSeries or server processors:
  *   1. The MMU is off & open firmware is running in real mode.
- *   2. The kernel is entered at __start
+ *   2. The primary CPU enters at __start.
+ *   3. If the RTAS supports "query-cpu-stopped-state", then secondary
+ *      CPUs will enter as directed by "start-cpu" RTAS call, which is
+ *      generic_secondary_smp_init, with PIR in r3.
+ *   4. Else the secondary CPUs will enter at secondary_hold (0x60) as
+ *      directed by the "start-cpu" RTS call, with PIR in r3.
  * -or- For OPAL entry:
- *   1. The MMU is off, processor in HV mode, primary CPU enters at 0
- *      with device-tree in gpr3. We also get OPAL base in r8 and
- *	entry in r9 for debugging purposes
- *   2. Secondary processors enter at 0x60 with PIR in gpr3
+ *   1. The MMU is off, processor in HV mode.
+ *   2. The primary CPU enters at 0 with device-tree in r3, OPAL base
+ *      in r8, and entry in r9 for debugging purposes.
+ *   3. Secondary CPUs enter as directed by OPAL_START_CPU call, which
+ *      is at generic_secondary_smp_init, with PIR in r3.
  *
  *  For Book3E processors:
  *   1. The MMU is on running in AS0 in a state defined in ePAPR
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index b89c6aac48c9..87b4fe75fd45 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -360,8 +360,16 @@ void early_setup_secondary(void)
 #if defined(CONFIG_SMP) || defined(CONFIG_KEXEC_CORE)
 static bool use_spinloop(void)
 {
-	if (!IS_ENABLED(CONFIG_PPC_BOOK3E))
+	if (IS_ENABLED(CONFIG_PPC_BOOK3S)) {
+		/*
+		 * See comments in head_64.S -- not all platforms insert
+		 * secondaries at __secondary_hold and wait at the spin
+		 * loop.
+		 */
+		if (firmware_has_feature(FW_FEATURE_OPAL))
+			return false;
 		return true;
+	}
 
 	/*
 	 * When book3e boots from kexec, the ePAPR spin table does