Index: head/sys/powerpc/powernv/opal_hmi.c
===================================================================
--- head/sys/powerpc/powernv/opal_hmi.c	(revision 348844)
+++ head/sys/powerpc/powernv/opal_hmi.c	(revision 348845)
@@ -1,76 +1,122 @@
 /*-
  * Copyright (c) 2019 Justin Hibbits
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/types.h>
+#include <sys/eventhandler.h>
 #include <sys/kernel.h>
 #include <sys/systm.h>
+#include <sys/endian.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
 
 #include <machine/spr.h>
 #include <machine/trap.h>
 #include "opal.h"
 
+struct opal_hmi_event {
+	uint8_t 	version;
+	uint8_t 	severity;
+	uint8_t 	type;
+	uint8_t 	disposition;
+	uint8_t 	rsvd_1[4];
+	uint64_t	hmer;
+	uint64_t	tfmr;
+	union {
+		struct {
+			uint8_t 	xstop_type;
+			uint8_t 	rsvd_2[3];
+			uint32_t	xstop_reason;
+			union {
+				uint32_t	pir;
+				uint32_t	chip_id;
+			};
+		};
+	};
+};
+
+#define	HMI_DISP_RECOVERED	0
+#define	HMI_DISP_NOT_RECOVERED	1
+
+static void
+opal_hmi_event_handler(void *unused, struct opal_msg *msg)
+{
+	struct opal_hmi_event	evt;
+
+	memcpy(&evt, &msg->params, sizeof(evt));
+	printf("Hypervisor Maintenance Event received"
+	    "(Severity %d, type %d, HMER: %016lx).\n",
+	    evt.severity, evt.type, evt.hmer);
+
+	if (evt.disposition == HMI_DISP_NOT_RECOVERED)
+		panic("Unrecoverable hypervisor maintenance exception on CPU %d",
+		    evt.pir);
+
+	return;
+}
+
 static int
 opal_hmi_handler(struct trapframe *frame)
 {
 	int err;
 
 	err = opal_call(OPAL_HANDLE_HMI);
 
 	if (err == OPAL_SUCCESS) {
 		mtspr(SPR_HMER, 0);
 		return (0);
 	}
 
 	printf("HMI handler failed!  OPAL error code: %d\n", err);
 
 	return (-1);
 }
 
 static void
 opal_setup_hmi(void *data)
 {
 	/* This only works for OPAL, so first make sure we have it. */
 	if (opal_check() != 0)
 		return;
 
 	if (opal_call(OPAL_CHECK_TOKEN, OPAL_HANDLE_HMI) == OPAL_TOKEN_PRESENT)
 		hmi_handler = opal_hmi_handler;
 	else {
 		printf("Warning: No OPAL HMI handler found.\n");
 		return;
 	}
 
+	EVENTHANDLER_REGISTER(OPAL_HMI_EVT, opal_hmi_event_handler, NULL,
+	    EVENTHANDLER_PRI_ANY);
+
 	if (bootverbose)
 		printf("Installed OPAL HMI handler.\n");
 }
 
-SYSINIT(opal_setup_hmi, SI_SUB_HYPERVISOR, SI_ORDER_ANY, opal_setup_hmi, NULL);
+SYSINIT(opal_setup_hmi, SI_SUB_CPU, SI_ORDER_ANY, opal_setup_hmi, NULL);