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 = !vm_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, int reason)
  63 {
  64     KVMClockState *s = opaque;
  65
  66     if (running) {
  67         s->clock_valid = false;
  68     }
  69 }
  70
  71 static int kvmclock_init(SysBusDevice *dev)
  72 {
  73     KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
  74
  75     qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
  76     return 0;
  77 }
  78
  79 static const VMStateDescription kvmclock_vmsd = {
  80     .name = "kvmclock",
  81     .version_id = 1,
  82     .minimum_version_id = 1,
  83     .minimum_version_id_old = 1,
  84     .pre_save = kvmclock_pre_save,
  85     .post_load = kvmclock_post_load,
  86     .fields = (VMStateField[]) {
  87         VMSTATE_UINT64(clock, KVMClockState),
  88         VMSTATE_END_OF_LIST()
  89     }
  90 };
  91
  92 static SysBusDeviceInfo kvmclock_info = {
  93     .qdev.name = "kvmclock",
  94     .qdev.size = sizeof(KVMClockState),
  95     .qdev.vmsd = &kvmclock_vmsd,
  96     .qdev.no_user = 1,
  97     .init = kvmclock_init,
  98 };
  99
 100 /* Note: Must be called after VCPU initialization. */
 101 void kvmclock_create(void)
 102 {
 103     if (kvm_enabled() &&
 104         first_cpu->cpuid_kvm_features & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
 105                                          (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
 106         sysbus_create_simple("kvmclock", -1, NULL);
 107     }
 108 }
 109
 110 static void kvmclock_register_device(void)
 111 {
 112     if (kvm_enabled()) {
 113         sysbus_register_withprop(&kvmclock_info);
 114     }
 115 }
 116
 117 device_init(kvmclock_register_device);