arch/powerpc/kernel/hmi.c

   1 /*
   2  * Hypervisor Maintenance Interrupt (HMI) handling.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.
  16  *
  17  * Copyright 2015 IBM Corporation
  18  * Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
  19  */
  20
  21 #undef DEBUG
  22
  23 #include <linux/types.h>
  24 #include <linux/compiler.h>
  25 #include <asm/paca.h>
  26 #include <asm/hmi.h>
  27
  28 void wait_for_subcore_guest_exit(void)
  29 {
  30         int i;
  31
  32         /*
  33          * NULL bitmap pointer indicates that KVM module hasn't
  34          * been loaded yet and hence no guests are running.
  35          * If no KVM is in use, no need to co-ordinate among threads
  36          * as all of them will always be in host and no one is going
  37          * to modify TB other than the opal hmi handler.
  38          * Hence, just return from here.
  39          */
  40         if (!local_paca->sibling_subcore_state)
  41                 return;
  42
  43         for (i = 0; i < MAX_SUBCORE_PER_CORE; i++)
  44                 while (local_paca->sibling_subcore_state->in_guest[i])
  45                         cpu_relax();
  46 }
  47
  48 void wait_for_tb_resync(void)
  49 {
  50         if (!local_paca->sibling_subcore_state)
  51                 return;
  52
  53         while (test_bit(CORE_TB_RESYNC_REQ_BIT,
  54                                 &local_paca->sibling_subcore_state->flags))
  55                 cpu_relax();
  56 }