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 "kvm_s390x.h"
  17
  18 static void kvm_s390_get_tod_raw(S390TOD *tod, Error **errp)
  19 {
  20     int r;
  21
  22     r = kvm_s390_get_clock_ext(&tod->high, &tod->low);
  23     if (r == -ENXIO) {
  24         r = kvm_s390_get_clock(&tod->high, &tod->low);
  25     }
  26     if (r) {
  27         error_setg(errp, "Unable to get KVM guest TOD clock: %s",
  28                    strerror(-r));
  29     }
  30 }
  31
  32 static void kvm_s390_tod_get(const S390TODState *td, S390TOD *tod, Error **errp)
  33 {
  34     if (td->stopped) {
  35         *tod = td->base;
  36         return;
  37     }
  38
  39     kvm_s390_get_tod_raw(tod, errp);
  40 }
  41
  42 static void kvm_s390_set_tod_raw(const S390TOD *tod, Error **errp)
  43 {
  44     int r;
  45
  46     r = kvm_s390_set_clock_ext(tod->high, tod->low);
  47     if (r == -ENXIO) {
  48         r = kvm_s390_set_clock(tod->high, tod->low);
  49     }
  50     if (r) {
  51         error_setg(errp, "Unable to set KVM guest TOD clock: %s",
  52                    strerror(-r));
  53     }
  54 }
  55
  56 static void kvm_s390_tod_set(S390TODState *td, const S390TOD *tod, Error **errp)
  57 {
  58     Error *local_err = NULL;
  59
  60     /*
  61      * Somebody (e.g. migration) set the TOD. We'll store it into KVM to
  62      * properly detect errors now but take a look at the runstate to decide
  63      * whether really to keep the tod running. E.g. during migration, this
  64      * is the point where we want to stop the initially running TOD to fire
  65      * it back up when actually starting the migrated guest.
  66      */
  67     kvm_s390_set_tod_raw(tod, &local_err);
  68     if (local_err) {
  69         error_propagate(errp, local_err);
  70         return;
  71     }
  72
  73     if (runstate_is_running()) {
  74         td->stopped = false;
  75     } else {
  76         td->stopped = true;
  77         td->base = *tod;
  78     }
  79 }
  80
  81 static void kvm_s390_tod_vm_state_change(void *opaque, int running,
  82                                          RunState state)
  83 {
  84     S390TODState *td = opaque;
  85     Error *local_err = NULL;
  86
  87     if (running && td->stopped) {
  88         /* Set the old TOD when running the VM - start the TOD clock. */
  89         kvm_s390_set_tod_raw(&td->base, &local_err);
  90         if (local_err) {
  91             warn_report_err(local_err);
  92         }
  93         /* Treat errors like the TOD was running all the time. */
  94         td->stopped = false;
  95     } else if (!running && !td->stopped) {
  96         /* Store the TOD when stopping the VM - stop the TOD clock. */
  97         kvm_s390_get_tod_raw(&td->base, &local_err);
  98         if (local_err) {
  99             /* Keep the TOD running in case we could not back it up. */
 100             warn_report_err(local_err);
 101         } else {
 102             td->stopped = true;
 103         }
 104     }
 105 }
 106
 107 static void kvm_s390_tod_realize(DeviceState *dev, Error **errp)
 108 {
 109     S390TODState *td = S390_TOD(dev);
 110     S390TODClass *tdc = S390_TOD_GET_CLASS(td);
 111     Error *local_err = NULL;
 112
 113     tdc->parent_realize(dev, &local_err);
 114     if (local_err) {
 115         error_propagate(errp, local_err);
 116         return;
 117     }
 118
 119     /*
 120      * We need to know when the VM gets started/stopped to start/stop the TOD.
 121      * As we can never have more than one TOD instance (and that will never be
 122      * removed), registering here and never unregistering is good enough.
 123      */
 124     qemu_add_vm_change_state_handler(kvm_s390_tod_vm_state_change, td);
 125 }
 126
 127 static void kvm_s390_tod_class_init(ObjectClass *oc, void *data)
 128 {
 129     S390TODClass *tdc = S390_TOD_CLASS(oc);
 130
 131     device_class_set_parent_realize(DEVICE_CLASS(oc), kvm_s390_tod_realize,
 132                                     &tdc->parent_realize);
 133     tdc->get = kvm_s390_tod_get;
 134     tdc->set = kvm_s390_tod_set;
 135 }
 136
 137 static void kvm_s390_tod_init(Object *obj)
 138 {
 139     S390TODState *td = S390_TOD(obj);
 140
 141     /*
 142      * The TOD is initially running (value stored in KVM). Avoid needless
 143      * loading/storing of the TOD when starting a simple VM, so let it
 144      * run although the (never started) VM is stopped. For migration, we
 145      * will properly set the TOD later.
 146      */
 147     td->stopped = false;
 148 }
 149
 150 static TypeInfo kvm_s390_tod_info = {
 151     .name = TYPE_KVM_S390_TOD,
 152     .parent = TYPE_S390_TOD,
 153     .instance_size = sizeof(S390TODState),
 154     .instance_init = kvm_s390_tod_init,
 155     .class_init = kvm_s390_tod_class_init,
 156     .class_size = sizeof(S390TODClass),
 157 };
 158
 159 static void register_types(void)
 160 {
 161     type_register_static(&kvm_s390_tod_info);
 162 }
 163 type_init(register_types);