Index: head/usr.sbin/bhyve/atpic.c
===================================================================
--- head/usr.sbin/bhyve/atpic.c	(revision 252335)
+++ head/usr.sbin/bhyve/atpic.c	(revision 252336)
@@ -1,68 +1,67 @@
 /*-
  * Copyright (c) 2011 NetApp, Inc.
  * All rights reserved.
  *
  * 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 NETAPP, INC ``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 NETAPP, INC OR CONTRIBUTORS 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.
  *
  * $FreeBSD$
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 
 #include <stdio.h>
 #include <string.h>
 #include <assert.h>
 
 #include "inout.h"
 
-/*
- * FreeBSD only writes to the 8259 interrupt controllers to put them in a
- * shutdown state.
- *
- * So, we just ignore the writes.
- */
-
 #define	IO_ICU1		0x20
 #define	IO_ICU2		0xA0
 #define	ICU_IMR_OFFSET	1
 
 static int
 atpic_handler(struct vmctx *ctx, int vcpu, int in, int port, int bytes,
 	      uint32_t *eax, void *arg)
 {
 	if (bytes != 1)
 		return (-1);
 
-	if (in)
-		return (-1);
+	if (in) {
+		if (port & ICU_IMR_OFFSET) {
+			/* all interrupts masked */
+			*eax = 0xff;
+		} else {
+			*eax = 0x00;
+		}
+	}
 
 	/* Pretend all writes to the 8259 are alright */
 	return (0);
 }
 
 INOUT_PORT(atpic, IO_ICU1, IOPORT_F_INOUT, atpic_handler);
 INOUT_PORT(atpic, IO_ICU1 + ICU_IMR_OFFSET, IOPORT_F_INOUT, atpic_handler);
 INOUT_PORT(atpic, IO_ICU2, IOPORT_F_INOUT, atpic_handler);
 INOUT_PORT(atpic, IO_ICU2 + ICU_IMR_OFFSET, IOPORT_F_INOUT, atpic_handler);