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 
wait_for_subcore_guest_exit(void)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 
wait_for_tb_resync(void)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 }
51