1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <errno.h>
3 #include <pthread.h>
4 #include <stdio.h>
5 #include <stdlib.h>
6 #include <string.h>
7 #include <signal.h>
8 #include <stdint.h>
9 #include <sys/sysinfo.h>
10
11 #include "kvm_util.h"
12
13 static struct kvm_vm *vm1;
14 static struct kvm_vm *vm2;
15 static int __eventfd;
16 static bool done;
17
18 /*
19 * KVM de-assigns based on eventfd *and* GSI, but requires unique eventfds when
20 * assigning (the API isn't symmetrical). Abuse the oddity and use a per-task
21 * GSI base to avoid false failures due to cross-task de-assign, i.e. so that
22 * the secondary doesn't de-assign the primary's eventfd and cause assign to
23 * unexpectedly succeed on the primary.
24 */
25 #define GSI_BASE_PRIMARY 0x20
26 #define GSI_BASE_SECONDARY 0x30
27
juggle_eventfd_secondary(struct kvm_vm * vm,int eventfd)28 static void juggle_eventfd_secondary(struct kvm_vm *vm, int eventfd)
29 {
30 int r, i;
31
32 /*
33 * The secondary task can encounter EBADF since the primary can close
34 * the eventfd at any time. And because the primary can recreate the
35 * eventfd, at the safe fd in the file table, the secondary can also
36 * encounter "unexpected" success, e.g. if the close+recreate happens
37 * between the first and second assignments. The secondary's role is
38 * mostly to antagonize KVM, not to detect bugs.
39 */
40 for (i = 0; i < 2; i++) {
41 r = __kvm_irqfd(vm, GSI_BASE_SECONDARY, eventfd, 0);
42 TEST_ASSERT(!r || errno == EBUSY || errno == EBADF,
43 "Wanted success, EBUSY, or EBADF, r = %d, errno = %d",
44 r, errno);
45
46 /* De-assign should succeed unless the eventfd was closed. */
47 r = __kvm_irqfd(vm, GSI_BASE_SECONDARY + i, eventfd, KVM_IRQFD_FLAG_DEASSIGN);
48 TEST_ASSERT(!r || errno == EBADF,
49 "De-assign should succeed unless the fd was closed");
50 }
51 }
52
secondary_irqfd_juggler(void * ign)53 static void *secondary_irqfd_juggler(void *ign)
54 {
55 while (!READ_ONCE(done)) {
56 juggle_eventfd_secondary(vm1, READ_ONCE(__eventfd));
57 juggle_eventfd_secondary(vm2, READ_ONCE(__eventfd));
58 }
59
60 return NULL;
61 }
62
juggle_eventfd_primary(struct kvm_vm * vm,int eventfd)63 static void juggle_eventfd_primary(struct kvm_vm *vm, int eventfd)
64 {
65 int r1, r2;
66
67 /*
68 * At least one of the assigns should fail. KVM disallows assigning a
69 * single eventfd to multiple GSIs (or VMs), so it's possible that both
70 * assignments can fail, too.
71 */
72 r1 = __kvm_irqfd(vm, GSI_BASE_PRIMARY, eventfd, 0);
73 TEST_ASSERT(!r1 || errno == EBUSY,
74 "Wanted success or EBUSY, r = %d, errno = %d", r1, errno);
75
76 r2 = __kvm_irqfd(vm, GSI_BASE_PRIMARY + 1, eventfd, 0);
77 TEST_ASSERT(r1 || (r2 && errno == EBUSY),
78 "Wanted failure (EBUSY), r1 = %d, r2 = %d, errno = %d",
79 r1, r2, errno);
80
81 /*
82 * De-assign should always succeed, even if the corresponding assign
83 * failed.
84 */
85 kvm_irqfd(vm, GSI_BASE_PRIMARY, eventfd, KVM_IRQFD_FLAG_DEASSIGN);
86 kvm_irqfd(vm, GSI_BASE_PRIMARY + 1, eventfd, KVM_IRQFD_FLAG_DEASSIGN);
87 }
88
main(int argc,char * argv[])89 int main(int argc, char *argv[])
90 {
91 pthread_t racing_thread;
92 int r, i;
93
94 /* Create "full" VMs, as KVM_IRQFD requires an in-kernel IRQ chip. */
95 vm1 = vm_create(1);
96 vm2 = vm_create(1);
97
98 WRITE_ONCE(__eventfd, kvm_new_eventfd());
99
100 kvm_irqfd(vm1, 10, __eventfd, 0);
101
102 r = __kvm_irqfd(vm1, 11, __eventfd, 0);
103 TEST_ASSERT(r && errno == EBUSY,
104 "Wanted EBUSY, r = %d, errno = %d", r, errno);
105
106 r = __kvm_irqfd(vm2, 12, __eventfd, 0);
107 TEST_ASSERT(r && errno == EBUSY,
108 "Wanted EBUSY, r = %d, errno = %d", r, errno);
109
110 /*
111 * De-assign all eventfds, along with multiple eventfds that were never
112 * assigned. KVM's ABI is that de-assign is allowed so long as the
113 * eventfd itself is valid.
114 */
115 kvm_irqfd(vm1, 11, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
116 kvm_irqfd(vm1, 12, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
117 kvm_irqfd(vm1, 13, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
118 kvm_irqfd(vm1, 14, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
119 kvm_irqfd(vm1, 10, READ_ONCE(__eventfd), KVM_IRQFD_FLAG_DEASSIGN);
120
121 close(__eventfd);
122
123 pthread_create(&racing_thread, NULL, secondary_irqfd_juggler, vm2);
124
125 for (i = 0; i < 10000; i++) {
126 WRITE_ONCE(__eventfd, kvm_new_eventfd());
127
128 juggle_eventfd_primary(vm1, __eventfd);
129 juggle_eventfd_primary(vm2, __eventfd);
130 close(__eventfd);
131 }
132
133 WRITE_ONCE(done, true);
134 pthread_join(racing_thread, NULL);
135 }
136