Initialize IA32_FEATURE_CONTROL MSR in reset and migration

The recent KVM patch adds IA32_FEATURE_CONTROL support. QEMU needs
to clear this MSR when reset vCPU and keep the value of it when
migration. This patch add this feature.
Signed-off-by: NArthur Chunqi Li <yzt356@gmail.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

target-i386/cpu.h

@@ -301,6 +301,7 @@
 #define MSR_IA32_APICBASE_BSP           (1<<8)
 #define MSR_IA32_APICBASE_ENABLE        (1<<11)
 #define MSR_IA32_APICBASE_BASE          (0xfffff<<12)
+#define MSR_IA32_FEATURE_CONTROL        0x0000003a
 #define MSR_TSC_ADJUST                  0x0000003b
 #define MSR_IA32_TSCDEADLINE            0x6e0
 
@@ -813,6 +814,7 @@ typedef struct CPUX86State {
 
     uint64_t mcg_status;
     uint64_t msr_ia32_misc_enable;
+    uint64_t msr_ia32_feature_control;
 
     /* exception/interrupt handling */
     int error_code;

target-i386/kvm.c

@@ -1121,6 +1121,7 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         if (hyperv_vapic_recommended()) {
             kvm_msr_entry_set(&msrs[n++], HV_X64_MSR_APIC_ASSIST_PAGE, 0);
         }
+        kvm_msr_entry_set(&msrs[n++], MSR_IA32_FEATURE_CONTROL, env->msr_ia32_feature_control);
     }
     if (env->mcg_cap) {
         int i;
@@ -1345,6 +1346,7 @@ static int kvm_get_msrs(X86CPU *cpu)
     if (has_msr_misc_enable) {
         msrs[n++].index = MSR_IA32_MISC_ENABLE;
     }
+    msrs[n++].index = MSR_IA32_FEATURE_CONTROL;
 
     if (!env->tsc_valid) {
         msrs[n++].index = MSR_IA32_TSC;
@@ -1443,6 +1445,8 @@ static int kvm_get_msrs(X86CPU *cpu)
         case MSR_IA32_MISC_ENABLE:
             env->msr_ia32_misc_enable = msrs[i].data;
             break;
+        case MSR_IA32_FEATURE_CONTROL:
+            env->msr_ia32_feature_control = msrs[i].data;
         default:
             if (msrs[i].index >= MSR_MC0_CTL &&
                 msrs[i].index < MSR_MC0_CTL + (env->mcg_cap & 0xff) * 4) {

target-i386/machine.c

@@ -435,6 +435,14 @@ static bool misc_enable_needed(void *opaque)
     return env->msr_ia32_misc_enable != MSR_IA32_MISC_ENABLE_DEFAULT;
 }
 
+static bool feature_control_needed(void *opaque)
+{
+    X86CPU *cpu = opaque;
+    CPUX86State *env = &cpu->env;
+
+    return env->msr_ia32_feature_control != 0;
+}
+
 static const VMStateDescription vmstate_msr_ia32_misc_enable = {
     .name = "cpu/msr_ia32_misc_enable",
     .version_id = 1,
@@ -446,6 +454,17 @@ static const VMStateDescription vmstate_msr_ia32_misc_enable = {
     }
 };
 
+static const VMStateDescription vmstate_msr_ia32_feature_control = {
+    .name = "cpu/msr_ia32_feature_control",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        VMSTATE_UINT64(env.msr_ia32_feature_control, X86CPU),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_x86_cpu = {
     .name = "cpu",
     .version_id = 12,
@@ -571,6 +590,9 @@ const VMStateDescription vmstate_x86_cpu = {
         }, {
             .vmsd = &vmstate_msr_ia32_misc_enable,
             .needed = misc_enable_needed,
+        }, {
+            .vmsd = &vmstate_msr_ia32_feature_control,
+            .needed = feature_control_needed,
         } , {
             /* empty */
         }