hw/s390x/tod-kvm.c

   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);