kvm: x86: Introduce kvmclock device to save/restore its state
If kvmclock is used, which implies the kernel supports it, register a
kvmclock device with the sysbus. Its main purpose is to save and restore
the kernel state on migration, but this will also allow to visualize it
one day.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
CC: Glauber Costa <glommer@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/hw/kvmclock.c b/hw/kvmclock.c
new file mode 100644
index 0000000..b6ceddf
--- /dev/null
+++ b/hw/kvmclock.c
@@ -0,0 +1,125 @@
+/*
+ * QEMU KVM support, paravirtual clock device
+ *
+ * Copyright (C) 2011 Siemens AG
+ *
+ * Authors:
+ * Jan Kiszka <jan.kiszka@siemens.com>
+ *
+ * This work is licensed under the terms of the GNU GPL version 2.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "sysemu.h"
+#include "sysbus.h"
+#include "kvm.h"
+#include "kvmclock.h"
+
+#if defined(CONFIG_KVM_PARA) && defined(KVM_CAP_ADJUST_CLOCK)
+
+#include <linux/kvm.h>
+#include <linux/kvm_para.h>
+
+typedef struct KVMClockState {
+ SysBusDevice busdev;
+ uint64_t clock;
+ bool clock_valid;
+} KVMClockState;
+
+static void kvmclock_pre_save(void *opaque)
+{
+ KVMClockState *s = opaque;
+ struct kvm_clock_data data;
+ int ret;
+
+ if (s->clock_valid) {
+ return;
+ }
+ ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
+ if (ret < 0) {
+ fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
+ data.clock = 0;
+ }
+ s->clock = data.clock;
+ /*
+ * If the VM is stopped, declare the clock state valid to avoid re-reading
+ * it on next vmsave (which would return a different value). Will be reset
+ * when the VM is continued.
+ */
+ s->clock_valid = !vm_running;
+}
+
+static int kvmclock_post_load(void *opaque, int version_id)
+{
+ KVMClockState *s = opaque;
+ struct kvm_clock_data data;
+
+ data.clock = s->clock;
+ data.flags = 0;
+ return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
+}
+
+static void kvmclock_vm_state_change(void *opaque, int running, int reason)
+{
+ KVMClockState *s = opaque;
+
+ if (running) {
+ s->clock_valid = false;
+ }
+}
+
+static int kvmclock_init(SysBusDevice *dev)
+{
+ KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
+
+ qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
+ return 0;
+}
+
+static const VMStateDescription kvmclock_vmsd = {
+ .name = "kvmclock",
+ .version_id = 1,
+ .minimum_version_id = 1,
+ .minimum_version_id_old = 1,
+ .pre_save = kvmclock_pre_save,
+ .post_load = kvmclock_post_load,
+ .fields = (VMStateField[]) {
+ VMSTATE_UINT64(clock, KVMClockState),
+ VMSTATE_END_OF_LIST()
+ }
+};
+
+static SysBusDeviceInfo kvmclock_info = {
+ .qdev.name = "kvmclock",
+ .qdev.size = sizeof(KVMClockState),
+ .qdev.vmsd = &kvmclock_vmsd,
+ .qdev.no_user = 1,
+ .init = kvmclock_init,
+};
+
+/* Note: Must be called after VCPU initialization. */
+void kvmclock_create(void)
+{
+ if (kvm_enabled() &&
+ first_cpu->cpuid_kvm_features & (1ULL << KVM_FEATURE_CLOCKSOURCE)) {
+ sysbus_create_simple("kvmclock", -1, NULL);
+ }
+}
+
+static void kvmclock_register_device(void)
+{
+ if (kvm_enabled()) {
+ sysbus_register_withprop(&kvmclock_info);
+ }
+}
+
+device_init(kvmclock_register_device);
+
+#else /* !(CONFIG_KVM_PARA && KVM_CAP_ADJUST_CLOCK) */
+
+void kvmclock_create(void)
+{
+}
+#endif /* !(CONFIG_KVM_PARA && KVM_CAP_ADJUST_CLOCK) */
