10597 would like a way to set NMI behavior at boot
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Andy Fiddaman <andy@omniosce.org>

*** 21,31 ****
  
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
   */
  /*
!  * Copyright 2018 Joyent, Inc.
   * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
   */
  
  /*
   * PSMI 1.1 extensions are supported only in 2.6 and later versions.
--- 21,31 ----
  
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
   */
  /*
!  * Copyright 2019, Joyent, Inc.
   * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
   */
  
  /*
   * PSMI 1.1 extensions are supported only in 2.6 and later versions.
*** 806,815 ****
--- 806,817 ----
  /* apic NMI handler */
  /*ARGSUSED*/
  void
  apic_nmi_intr(caddr_t arg, struct regs *rp)
  {
+         nmi_action_t action = nmi_action;
+ 
          if (apic_shutdown_processors) {
                  apic_disable_local_apic();
                  return;
          }
  
*** 817,838 ****
  
          if (!lock_try(&apic_nmi_lock))
                  return;
          apic_num_nmis++;
  
-         if (apic_kmdb_on_nmi && psm_debugger()) {
-                 debug_enter("NMI received: entering kmdb\n");
-         } else if (apic_panic_on_nmi) {
-                 /* Keep panic from entering kmdb. */
-                 nopanicdebug = 1;
-                 panic("NMI received\n");
-         } else {
                  /*
                   * prom_printf is the best shot we have of something which is
                   * problem free from high level/NMI type of interrupts
                   */
                  prom_printf("NMI received\n");
          }
  
          lock_clear(&apic_nmi_lock);
  }
  
--- 819,863 ----
  
          if (!lock_try(&apic_nmi_lock))
                  return;
          apic_num_nmis++;
  
          /*
+          * "nmi_action" always over-rides the older way of doing this, unless we
+          * can't actually drop into kmdb when requested.
+          */
+         if (action == NMI_ACTION_KMDB && !psm_debugger())
+                 action = NMI_ACTION_UNSET;
+ 
+         if (action == NMI_ACTION_UNSET) {
+                 if (apic_kmdb_on_nmi && psm_debugger())
+                         action = NMI_ACTION_KMDB;
+                 else if (apic_panic_on_nmi)
+                         action = NMI_ACTION_PANIC;
+                 else
+                         action = NMI_ACTION_IGNORE;
+         }
+ 
+         switch (action) {
+         case NMI_ACTION_IGNORE:
+                 /*
                   * prom_printf is the best shot we have of something which is
                   * problem free from high level/NMI type of interrupts
                   */
                  prom_printf("NMI received\n");
+                 break;
+ 
+         case NMI_ACTION_PANIC:
+                 /* Keep panic from entering kmdb. */
+                 nopanicdebug = 1;
+                 panic("NMI received\n");
+                 break;
+ 
+         case NMI_ACTION_KMDB:
+         default:
+                 debug_enter("NMI received: entering kmdb\n");
+                 break;
          }
  
          lock_clear(&apic_nmi_lock);
  }