diff --git a/arch/powerpc/kernel/hmi.c b/arch/powerpc/kernel/hmi.c
new file mode 100644
index 0000000..e3f738e
--- /dev/null
+++ b/arch/powerpc/kernel/hmi.c
@@ -0,0 +1,56 @@
+/*
+ * Hypervisor Maintenance Interrupt (HMI) handling.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.
+ *
+ * Copyright 2015 IBM Corporation
+ * Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
+ */
+
+#undef DEBUG
+
+#include <linux/types.h>
+#include <linux/compiler.h>
+#include <asm/paca.h>
+#include <asm/hmi.h>
+
+void wait_for_subcore_guest_exit(void)
+{
+	int i;
+
+	/*
+	 * NULL bitmap pointer indicates that KVM module hasn't
+	 * been loaded yet and hence no guests are running.
+	 * If no KVM is in use, no need to co-ordinate among threads
+	 * as all of them will always be in host and no one is going
+	 * to modify TB other than the opal hmi handler.
+	 * Hence, just return from here.
+	 */
+	if (!local_paca->sibling_subcore_state)
+		return;
+
+	for (i = 0; i < MAX_SUBCORE_PER_CORE; i++)
+		while (local_paca->sibling_subcore_state->in_guest[i])
+			cpu_relax();
+}
+
+void wait_for_tb_resync(void)
+{
+	if (!local_paca->sibling_subcore_state)
+		return;
+
+	while (test_bit(CORE_TB_RESYNC_REQ_BIT,
+				&local_paca->sibling_subcore_state->flags))
+		cpu_relax();
+}