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