2 * QEMU KVM support, paravirtual clock device
4 * Copyright (C) 2011 Siemens AG
7 * Jan Kiszka <jan.kiszka@siemens.com>
9 * This work is licensed under the terms of the GNU GPL version 2.
10 * See the COPYING file in the top-level directory.
12 * Contributions after 2012-01-13 are licensed under the terms of the
13 * GNU GPL, version 2 or (at your option) any later version.
16 #include "qemu-common.h"
17 #include "qemu/host-utils.h"
18 #include "sysemu/sysemu.h"
19 #include "sysemu/kvm.h"
21 #include "hw/sysbus.h"
22 #include "hw/kvm/clock.h"
24 #include <linux/kvm.h>
25 #include <linux/kvm_para.h>
27 #define TYPE_KVM_CLOCK "kvmclock"
28 #define KVM_CLOCK(obj) OBJECT_CHECK(KVMClockState, (obj), TYPE_KVM_CLOCK)
30 typedef struct KVMClockState {
39 struct pvclock_vcpu_time_info {
42 uint64_t tsc_timestamp;
44 uint32_t tsc_to_system_mul;
48 } __attribute__((__packed__)); /* 32 bytes */
50 static uint64_t kvmclock_current_nsec(KVMClockState *s)
52 CPUState *cpu = first_cpu;
53 CPUX86State *env = cpu->env_ptr;
54 hwaddr kvmclock_struct_pa = env->system_time_msr & ~1ULL;
55 uint64_t migration_tsc = env->tsc;
56 struct pvclock_vcpu_time_info time;
62 if (!(env->system_time_msr & 1ULL)) {
63 /* KVM clock not active */
67 cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time));
69 assert(time.tsc_timestamp <= migration_tsc);
70 delta = migration_tsc - time.tsc_timestamp;
71 if (time.tsc_shift < 0) {
72 delta >>= -time.tsc_shift;
74 delta <<= time.tsc_shift;
77 mulu64(&nsec_lo, &nsec_hi, delta, time.tsc_to_system_mul);
78 nsec = (nsec_lo >> 32) | (nsec_hi << 32);
79 return nsec + time.system_time;
82 static void kvmclock_vm_state_change(void *opaque, int running,
85 KVMClockState *s = opaque;
87 int cap_clock_ctrl = kvm_check_extension(kvm_state, KVM_CAP_KVMCLOCK_CTRL);
91 struct kvm_clock_data data = {};
92 uint64_t time_at_migration = kvmclock_current_nsec(s);
94 s->clock_valid = false;
96 /* We can't rely on the migrated clock value, just discard it */
97 if (time_at_migration) {
98 s->clock = time_at_migration;
101 data.clock = s->clock;
102 ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
104 fprintf(stderr, "KVM_SET_CLOCK failed: %s\n", strerror(ret));
108 if (!cap_clock_ctrl) {
112 ret = kvm_vcpu_ioctl(cpu, KVM_KVMCLOCK_CTRL, 0);
114 if (ret != -EINVAL) {
115 fprintf(stderr, "%s: %s\n", __func__, strerror(-ret));
121 struct kvm_clock_data data;
124 if (s->clock_valid) {
128 kvm_synchronize_all_tsc();
130 ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
132 fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
135 s->clock = data.clock;
138 * If the VM is stopped, declare the clock state valid to
139 * avoid re-reading it on next vmsave (which would return
140 * a different value). Will be reset when the VM is continued.
142 s->clock_valid = true;
146 static void kvmclock_realize(DeviceState *dev, Error **errp)
148 KVMClockState *s = KVM_CLOCK(dev);
150 qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
153 static const VMStateDescription kvmclock_vmsd = {
156 .minimum_version_id = 1,
157 .fields = (VMStateField[]) {
158 VMSTATE_UINT64(clock, KVMClockState),
159 VMSTATE_END_OF_LIST()
163 static void kvmclock_class_init(ObjectClass *klass, void *data)
165 DeviceClass *dc = DEVICE_CLASS(klass);
167 dc->realize = kvmclock_realize;
168 dc->vmsd = &kvmclock_vmsd;
171 static const TypeInfo kvmclock_info = {
172 .name = TYPE_KVM_CLOCK,
173 .parent = TYPE_SYS_BUS_DEVICE,
174 .instance_size = sizeof(KVMClockState),
175 .class_init = kvmclock_class_init,
178 /* Note: Must be called after VCPU initialization. */
179 void kvmclock_create(void)
181 X86CPU *cpu = X86_CPU(first_cpu);
184 cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
185 (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
186 sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
190 static void kvmclock_register_types(void)
192 type_register_static(&kvmclock_info);
195 type_init(kvmclock_register_types)