1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Floating interrupt tests.
4 *
5 * Copyright 2021 Red Hat Inc
6 *
7 * Authors:
8 * David Hildenbrand <david@redhat.com>
9 */
10 #include <libcflat.h>
11 #include <asm/asm-offsets.h>
12 #include <asm/interrupt.h>
13 #include <asm/page.h>
14 #include <asm-generic/barrier.h>
15
16 #include <sclp.h>
17 #include <smp.h>
18 #include <alloc_page.h>
19
wait_for_sclp_int(void)20 static void wait_for_sclp_int(void)
21 {
22 /* Enable SCLP interrupts on this CPU only. */
23 ctl_set_bit(0, CTL0_SERVICE_SIGNAL);
24
25 /* Enable external interrupts and go to the wait state. */
26 wait_for_interrupt(PSW_MASK_EXT);
27 }
28
29 /*
30 * Some KVM versions might mix CPUs when looking for a floating IRQ target,
31 * accidentially detecting a stopped CPU as waiting and resulting in the actually
32 * waiting CPU not getting woken up for the interrupt.
33 */
test_wait_state_delivery(void)34 static void test_wait_state_delivery(void)
35 {
36 SCCBHeader *h;
37 int ret;
38
39 report_prefix_push("wait state delivery");
40
41 if (smp_query_num_cpus() < 3) {
42 report_skip("need at least 3 CPUs for this test");
43 goto out;
44 }
45
46 /* Stop CPU #2. It must succeed because we have at least 3 CPUs */
47 ret = smp_cpu_stop(2);
48 assert(!ret);
49
50 /*
51 * We're going to perform an SCLP service call but expect the
52 * interrupt on CPU #1 while it is in the wait state.
53 */
54 sclp_mark_busy();
55
56 /* Start CPU #1 and let it wait for the interrupt. */
57 ret = smp_cpu_setup(1, PSW_WITH_CUR_MASK(wait_for_sclp_int));
58 /* This must not fail because we have at least 3 CPUs */
59 assert(!ret);
60
61 /*
62 * We'd have to jump trough some hoops to sense e.g., via SIGP
63 * CONDITIONAL EMERGENCY SIGNAL if CPU #1 is already in the
64 * wait state.
65 *
66 * Although not completely reliable, use SIGP SENSE RUNNING STATUS
67 * until not reported as running -- after all, our SCLP processing
68 * will take some time as well and smp_cpu_setup() returns when we're
69 * either already in wait_for_sclp_int() or just about to execute it.
70 */
71 while(smp_sense_running_status(1));
72
73 h = alloc_pages_flags(0, AREA_DMA31);
74 h->length = 4096;
75 ret = servc(SCLP_CMDW_READ_CPU_INFO, __pa(h));
76 if (ret) {
77 sclp_clear_busy();
78 report_fail("SCLP_CMDW_READ_CPU_INFO failed");
79 goto out_destroy;
80 }
81
82 /*
83 * Wait until the interrupt gets delivered on CPU #1, marking the
84 * SCLP requests as done.
85 */
86 sclp_wait_busy();
87
88 report(true, "sclp interrupt delivered");
89
90 out_destroy:
91 free_page(h);
92 smp_cpu_destroy(1);
93 out:
94 report_prefix_pop();
95 }
96
main(void)97 int main(void)
98 {
99 report_prefix_push("firq");
100
101 test_wait_state_delivery();
102
103 report_prefix_pop();
104 return report_summary();
105 }
106