[v2,5/7] make hyperv hypercall and guest os id MSRs migratable.

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 1d94a9d..3bfaf87 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -846,6 +846,8 @@  typedef struct CPUX86State {
     uint64_t msr_fixed_counters[MAX_FIXED_COUNTERS];
     uint64_t msr_gp_counters[MAX_GP_COUNTERS];
     uint64_t msr_gp_evtsel[MAX_GP_COUNTERS];
+    uint64_t msr_hv_hypercall;
+    uint64_t msr_hv_guest_os_id;
 
     /* exception/interrupt handling */
     int error_code;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index c1bc8c0..48a747e 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -71,6 +71,7 @@  static bool has_msr_pv_eoi_en;
 static bool has_msr_misc_enable;
 static bool has_msr_kvm_steal_time;
 static int lm_capable_kernel;
+static bool has_msr_hv_hypercall;
 
 static bool has_msr_architectural_pmu;
 static uint32_t num_architectural_pmu_counters;
@@ -464,8 +465,10 @@  int kvm_arch_init_vcpu(CPUState *cs)
     c = &cpuid_data.entries[cpuid_i++];
     c->function = KVM_CPUID_SIGNATURE;
     memcpy(signature, "KVMKVMKVM\0\0\0", 12);
-    if (hyperv_enabled(cpu)) {
+    if (hyperv_enabled(cpu) &&
+        kvm_check_extension(cs->kvm_state, KVM_CAP_HYPERV) > 0) {
         c->eax = HYPERV_CPUID_MIN;
+        has_msr_hv_hypercall = true;
     }
     c->ebx = signature[0];
     c->ecx = signature[1];
@@ -475,7 +478,7 @@  int kvm_arch_init_vcpu(CPUState *cs)
     c->function = KVM_CPUID_FEATURES;
     c->eax = env->features[FEAT_KVM];
 
-    if (hyperv_enabled(cpu)) {
+    if (has_msr_hv_hypercall) {
         memcpy(signature, "Hv#1\0\0\0\0\0\0\0\0", 12);
         c->eax = signature[0];
 
@@ -1176,9 +1179,11 @@  static int kvm_put_msrs(X86CPU *cpu, int level)
             kvm_msr_entry_set(&msrs[n++], MSR_CORE_PERF_GLOBAL_CTRL,
                               env->msr_global_ctrl);
         }
-        if (hyperv_hypercall_available(cpu)) {
-            kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_GUEST_OS_ID, 0);
-            kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_HYPERCALL, 0);
+        if (has_msr_hv_hypercall) {
+            kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_GUEST_OS_ID,
+                              env->msr_hv_guest_os_id);
+            kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_HYPERCALL,
+                              env->msr_hv_hypercall);
         }
         if (cpu->hyperv_vapic) {
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_APIC_ASSIST_PAGE, 0);
@@ -1461,6 +1466,10 @@  static int kvm_get_msrs(X86CPU *cpu)
         }
     }
 
+    if (has_msr_hv_hypercall) {
+        msrs[n++].index = HV_X64_MSR_HYPERCALL;
+        msrs[n++].index = HV_X64_MSR_GUEST_OS_ID;
+    }
     msr_data.info.nmsrs = n;
     ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data);
     if (ret < 0) {
@@ -1565,6 +1574,12 @@  static int kvm_get_msrs(X86CPU *cpu)
         case MSR_P6_EVNTSEL0 ... MSR_P6_EVNTSEL0 + MAX_GP_COUNTERS - 1:
             env->msr_gp_evtsel[index - MSR_P6_EVNTSEL0] = msrs[i].data;
             break;
+        case HV_X64_MSR_HYPERCALL:
+            env->msr_hv_hypercall = msrs[i].data;
+            break;
+        case HV_X64_MSR_GUEST_OS_ID:
+            env->msr_hv_guest_os_id = msrs[i].data;
+            break;
         }
     }
 
diff --git a/target-i386/machine.c b/target-i386/machine.c
index e568da2..3809d06 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -506,6 +506,26 @@  static const VMStateDescription vmstate_msr_architectural_pmu = {
     }
 };
 
+static bool hyperv_hypercall_enable_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->msr_hv_hypercall != 0 || env->msr_hv_guest_os_id != 0;
+}
+
+static const VMStateDescription vmstate_msr_hypercall_hypercall = {
+    .name = "cpu/msr_hyperv_hypercall",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        VMSTATE_UINT64(env.msr_hv_hypercall, X86CPU),
+        VMSTATE_UINT64(env.msr_hv_guest_os_id, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -637,6 +657,9 @@  const VMStateDescription vmstate_x86_cpu = {
         }, {
             .vmsd = &vmstate_msr_architectural_pmu,
             .needed = pmu_enable_needed,
+        }, {
+            .vmsd = &vmstate_msr_hypercall_hypercall,
+            .needed = hyperv_hypercall_enable_needed,
         } , {
             /* empty */
         }