powerpc/powernv: Pull all HMI events before panic.

In the event of unrecovered HMI the existing code panics as soon as
it receives the first unrecovered HMI event. This makes host to report
partial information about HMIs before panic. There may be more errors
which would have caused the HMI and hence more HMI event would have been
generated waiting to be pulled by host. This patch implements a logic to
pull and display all the HMI event before going down panic path.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/opal-hmi.c

@@ -235,6 +235,8 @@ static void hmi_event_handler(struct work_struct *work)
 	struct OpalHMIEvent *hmi_evt;
 	struct OpalHmiEvtNode *msg_node;
 	uint8_t disposition;
+	struct opal_msg msg;
+	int unrecoverable = 0;
 
 	spin_lock_irqsave(&opal_hmi_evt_lock, flags);
 	while (!list_empty(&opal_hmi_evt_list)) {
@@ -250,14 +252,34 @@ static void hmi_event_handler(struct work_struct *work)
 
 		/*
 		 * Check if HMI event has been recovered or not. If not
-		 * then we can't continue, invoke panic.
+		 * then kernel can't continue, we need to panic.
+		 * But before we do that, display all the HMI event
+		 * available on the list and set unrecoverable flag to 1.
 		 */
 		if (disposition != OpalHMI_DISPOSITION_RECOVERED)
-			panic("Unrecoverable HMI exception");
+			unrecoverable = 1;
 
 		spin_lock_irqsave(&opal_hmi_evt_lock, flags);
 	}
 	spin_unlock_irqrestore(&opal_hmi_evt_lock, flags);
+
+	if (unrecoverable) {
+		/* Pull all HMI events from OPAL before we panic. */
+		while (opal_get_msg(__pa(&msg), sizeof(msg)) == OPAL_SUCCESS) {
+			u32 type;
+
+			type = be32_to_cpu(msg.msg_type);
+
+			/* skip if not HMI event */
+			if (type != OPAL_MSG_HMI_EVT)
+				continue;
+
+			/* HMI event info starts from param[0] */
+			hmi_evt = (struct OpalHMIEvent *)&msg.params[0];
+			print_hmi_event_info(hmi_evt);
+		}
+		panic("Unrecoverable HMI exception");
+	}
 }
 
 static DECLARE_WORK(hmi_event_work, hmi_event_handler);