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
17void 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
42void 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}
51