xref: /openbmc/qemu/hw/s390x/tod-kvm.c (revision 542b10bd)
1 /*
2  * TOD (Time Of Day) clock - KVM implementation
3  *
4  * Copyright 2018 Red Hat, Inc.
5  * Author(s): David Hildenbrand <david@redhat.com>
6  *
7  * This work is licensed under the terms of the GNU GPL, version 2 or later.
8  * See the COPYING file in the top-level directory.
9  */
10 
11 #include "qemu/osdep.h"
12 #include "qapi/error.h"
13 #include "qemu/module.h"
14 #include "sysemu/runstate.h"
15 #include "hw/s390x/tod.h"
16 #include "target/s390x/kvm/pv.h"
17 #include "kvm/kvm_s390x.h"
18 
19 static void kvm_s390_get_tod_raw(S390TOD *tod, Error **errp)
20 {
21     int r;
22 
23     r = kvm_s390_get_clock_ext(&tod->high, &tod->low);
24     if (r == -ENXIO) {
25         r = kvm_s390_get_clock(&tod->high, &tod->low);
26     }
27     if (r) {
28         error_setg(errp, "Unable to get KVM guest TOD clock: %s",
29                    strerror(-r));
30     }
31 }
32 
33 static void kvm_s390_tod_get(const S390TODState *td, S390TOD *tod, Error **errp)
34 {
35     if (td->stopped) {
36         *tod = td->base;
37         return;
38     }
39 
40     kvm_s390_get_tod_raw(tod, errp);
41 }
42 
43 static void kvm_s390_set_tod_raw(const S390TOD *tod, Error **errp)
44 {
45     int r;
46 
47     r = kvm_s390_set_clock_ext(tod->high, tod->low);
48     if (r == -ENXIO) {
49         r = kvm_s390_set_clock(tod->high, tod->low);
50     }
51     if (r) {
52         error_setg(errp, "Unable to set KVM guest TOD clock: %s",
53                    strerror(-r));
54     }
55 }
56 
57 static void kvm_s390_tod_set(S390TODState *td, const S390TOD *tod, Error **errp)
58 {
59     Error *local_err = NULL;
60 
61     /*
62      * Somebody (e.g. migration) set the TOD. We'll store it into KVM to
63      * properly detect errors now but take a look at the runstate to decide
64      * whether really to keep the tod running. E.g. during migration, this
65      * is the point where we want to stop the initially running TOD to fire
66      * it back up when actually starting the migrated guest.
67      */
68     kvm_s390_set_tod_raw(tod, &local_err);
69     if (local_err) {
70         error_propagate(errp, local_err);
71         return;
72     }
73 
74     if (runstate_is_running()) {
75         td->stopped = false;
76     } else {
77         td->stopped = true;
78         td->base = *tod;
79     }
80 }
81 
82 static void kvm_s390_tod_vm_state_change(void *opaque, bool running,
83                                          RunState state)
84 {
85     S390TODState *td = opaque;
86     Error *local_err = NULL;
87 
88     /*
89      * Under PV, the clock is under ultravisor control, hence we cannot restore
90      * it on resume.
91      */
92     if (s390_is_pv()) {
93         return;
94     }
95 
96     if (running && td->stopped) {
97         /* Set the old TOD when running the VM - start the TOD clock. */
98         kvm_s390_set_tod_raw(&td->base, &local_err);
99         if (local_err) {
100             warn_report_err(local_err);
101         }
102         /* Treat errors like the TOD was running all the time. */
103         td->stopped = false;
104     } else if (!running && !td->stopped) {
105         /* Store the TOD when stopping the VM - stop the TOD clock. */
106         kvm_s390_get_tod_raw(&td->base, &local_err);
107         if (local_err) {
108             /* Keep the TOD running in case we could not back it up. */
109             warn_report_err(local_err);
110         } else {
111             td->stopped = true;
112         }
113     }
114 }
115 
116 static void kvm_s390_tod_realize(DeviceState *dev, Error **errp)
117 {
118     S390TODState *td = S390_TOD(dev);
119     S390TODClass *tdc = S390_TOD_GET_CLASS(td);
120     Error *local_err = NULL;
121 
122     tdc->parent_realize(dev, &local_err);
123     if (local_err) {
124         error_propagate(errp, local_err);
125         return;
126     }
127 
128     /*
129      * We need to know when the VM gets started/stopped to start/stop the TOD.
130      * As we can never have more than one TOD instance (and that will never be
131      * removed), registering here and never unregistering is good enough.
132      */
133     qemu_add_vm_change_state_handler(kvm_s390_tod_vm_state_change, td);
134 }
135 
136 static void kvm_s390_tod_class_init(ObjectClass *oc, void *data)
137 {
138     S390TODClass *tdc = S390_TOD_CLASS(oc);
139 
140     device_class_set_parent_realize(DEVICE_CLASS(oc), kvm_s390_tod_realize,
141                                     &tdc->parent_realize);
142     tdc->get = kvm_s390_tod_get;
143     tdc->set = kvm_s390_tod_set;
144 }
145 
146 static void kvm_s390_tod_init(Object *obj)
147 {
148     S390TODState *td = S390_TOD(obj);
149 
150     /*
151      * The TOD is initially running (value stored in KVM). Avoid needless
152      * loading/storing of the TOD when starting a simple VM, so let it
153      * run although the (never started) VM is stopped. For migration, we
154      * will properly set the TOD later.
155      */
156     td->stopped = false;
157 }
158 
159 static const TypeInfo kvm_s390_tod_info = {
160     .name = TYPE_KVM_S390_TOD,
161     .parent = TYPE_S390_TOD,
162     .instance_size = sizeof(S390TODState),
163     .instance_init = kvm_s390_tod_init,
164     .class_init = kvm_s390_tod_class_init,
165     .class_size = sizeof(S390TODClass),
166 };
167 
168 static void register_types(void)
169 {
170     type_register_static(&kvm_s390_tod_info);
171 }
172 type_init(register_types);
173