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 }
51
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