hw/kvmclock.c

   1 /*
   2  * QEMU KVM support, paravirtual clock device
   3  *
   4  * Copyright (C) 2011 Siemens AG
   5  *
   6  * Authors:
   7  *  Jan Kiszka        <jan.kiszka@siemens.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL version 2.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "sysemu.h"
  16 #include "sysbus.h"
  17 #include "kvm.h"
  18 #include "kvmclock.h"
  19
  20 #include <linux/kvm.h>
  21 #include <linux/kvm_para.h>
  22
  23 typedef struct KVMClockState {
  24     SysBusDevice busdev;
  25     uint64_t clock;
  26     bool clock_valid;
  27 } KVMClockState;
  28
  29 static void kvmclock_pre_save(void *opaque)
  30 {
  31     KVMClockState *s = opaque;
  32     struct kvm_clock_data data;
  33     int ret;
  34
  35     if (s->clock_valid) {
  36         return;
  37     }
  38     ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
  39     if (ret < 0) {
  40         fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
  41         data.clock = 0;
  42     }
  43     s->clock = data.clock;
  44     /*
  45      * If the VM is stopped, declare the clock state valid to avoid re-reading
  46      * it on next vmsave (which would return a different value). Will be reset
  47      * when the VM is continued.
  48      */
  49     s->clock_valid = !runstate_is_running();
  50 }
  51
  52 static int kvmclock_post_load(void *opaque, int version_id)
  53 {
  54     KVMClockState *s = opaque;
  55     struct kvm_clock_data data;
  56
  57     data.clock = s->clock;
  58     data.flags = 0;
  59     return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
  60 }
  61
  62 static void kvmclock_vm_state_change(void *opaque, int running,
  63                                      RunState state)
  64 {
  65     KVMClockState *s = opaque;
  66
  67     if (running) {
  68         s->clock_valid = false;
  69     }
  70 }
  71
  72 static int kvmclock_init(SysBusDevice *dev)
  73 {
  74     KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
  75
  76     qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
  77     return 0;
  78 }
  79
  80 static const VMStateDescription kvmclock_vmsd = {
  81     .name = "kvmclock",
  82     .version_id = 1,
  83     .minimum_version_id = 1,
  84     .minimum_version_id_old = 1,
  85     .pre_save = kvmclock_pre_save,
  86     .post_load = kvmclock_post_load,
  87     .fields = (VMStateField[]) {
  88         VMSTATE_UINT64(clock, KVMClockState),
  89         VMSTATE_END_OF_LIST()
  90     }
  91 };
  92
  93 static SysBusDeviceInfo kvmclock_info = {
  94     .qdev.name = "kvmclock",
  95     .qdev.size = sizeof(KVMClockState),
  96     .qdev.vmsd = &kvmclock_vmsd,
  97     .qdev.no_user = 1,
  98     .init = kvmclock_init,
  99 };
 100
 101 /* Note: Must be called after VCPU initialization. */
 102 void kvmclock_create(void)
 103 {
 104     if (kvm_enabled() &&
 105         first_cpu->cpuid_kvm_features & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
 106                                          (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
 107         sysbus_create_simple("kvmclock", -1, NULL);
 108     }
 109 }
 110
 111 static void kvmclock_register_device(void)
 112 {
 113     if (kvm_enabled()) {
 114         sysbus_register_withprop(&kvmclock_info);
 115     }
 116 }
 117
 118 device_init(kvmclock_register_device);