arch/powerpc/kvm/book3s_hv_hmi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Hypervisor Maintenance Interrupt (HMI) handling.
   4  *
   5  * Copyright 2015 IBM Corporation
   6  * Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
   7  */
   8
   9 #undef DEBUG
  10
  11 #include <linux/types.h>
  12 #include <linux/compiler.h>
  13 #include <asm/paca.h>
  14 #include <asm/hmi.h>
  15 #include <asm/processor.h>
  16
  17 void wait_for_subcore_guest_exit(void)
  18 {
  19         int i;
  20
  21         /*
  22          * NULL bitmap pointer indicates that KVM module hasn't
  23          * been loaded yet and hence no guests are running, or running
  24          * on POWER9 or newer CPU.
  25          *
  26          * If no KVM is in use, no need to co-ordinate among threads
  27          * as all of them will always be in host and no one is going
  28          * to modify TB other than the opal hmi handler.
  29          *
  30          * POWER9 and newer don't need this synchronisation.
  31          *
  32          * Hence, just return from here.
  33          */
  34         if (!local_paca->sibling_subcore_state)
  35                 return;
  36
  37         for (i = 0; i < MAX_SUBCORE_PER_CORE; i++)
  38                 while (local_paca->sibling_subcore_state->in_guest[i])
  39                         cpu_relax();
  40 }
  41
  42 void wait_for_tb_resync(void)
  43 {
  44         if (!local_paca->sibling_subcore_state)
  45                 return;
  46
  47         while (test_bit(CORE_TB_RESYNC_REQ_BIT,
  48                                 &local_paca->sibling_subcore_state->flags))
  49                 cpu_relax();
  50 }