[PATCH 5/5] kvm: x86: Introduce kvmclock device to save/restore its state

[Jan Kiszka <jan.kiszka@xxxxxx>]

From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>

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@xxxxxxxxxxx>
CC: Glauber Costa <glommer@xxxxxxxxxx>
---
 target-i386/kvm.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 70 insertions(+), 1 deletions(-)

diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index a4ccc7f..32310fa 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -29,6 +29,7 @@
 #include "hw/apic.h"
 #include "ioport.h"
 #include "kvm_x86.h"
+#include "hw/sysbus.h"
 
 #ifdef CONFIG_KVM_PARA
 #include <linux/kvm_para.h>
@@ -309,6 +310,64 @@ void kvm_inject_x86_mce(CPUState *cenv, int bank, uint64_t status,
 #endif
 }
 
+#ifdef KVM_CAP_ADJUST_CLOCK
+typedef struct KVMClockState {
+    SysBusDevice busdev;
+    uint64_t clock;
+    struct kvm_clock_data data;
+} KVMClockState;
+
+static void kvmclock_pre_save(void *opaque)
+{
+    KVMClockState *s = opaque;
+    struct kvm_clock_data data;
+    int ret;
+
+    ret = kvm_vm_ioctl(KVM_GET_CLOCK, &data);
+    if (ret < 0) {
+        fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
+        data.clock = 0;
+    }
+    s->clock = data.clock;
+}
+
+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_SET_CLOCK, &data);
+}
+
+static int kvmclock_init(SysBusDevice *dev)
+{
+    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,
+};
+#endif /* KVM_CAP_ADJUST_CLOCK */
+
 int kvm_arch_init_vcpu(CPUState *env)
 {
     struct {
@@ -337,7 +396,6 @@ int kvm_arch_init_vcpu(CPUState *env)
     env->cpuid_svm_features  &= kvm_x86_get_supported_cpuid(0x8000000A,
                                                             0, R_EDX);
 
-
     cpuid_i = 0;
 
 #ifdef CONFIG_KVM_PARA
@@ -444,6 +502,13 @@ int kvm_arch_init_vcpu(CPUState *env)
     }
 #endif
 
+#ifdef KVM_CAP_ADJUST_CLOCK
+    if (cpu_is_bsp(env) &&
+        (env->cpuid_kvm_features & (1ULL << KVM_FEATURE_CLOCKSOURCE))) {
+        sysbus_create_simple("kvmclock", -1, NULL);
+    }
+#endif
+
     return kvm_vcpu_ioctl(env, KVM_SET_CPUID2, &cpuid_data);
 }
 
@@ -535,6 +600,10 @@ int kvm_arch_init(int smp_cpus)
     int ret;
     struct utsname utsname;
 
+#ifdef KVM_CAP_ADJUST_CLOCK
+    sysbus_register_withprop(&kvmclock_info);
+#endif
+
     ret = kvm_get_supported_msrs();
     if (ret < 0) {
         return ret;
-- 
1.7.1

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