apic: Use apic_id as apic's migration instance_id

instance_id is generated by last_used_id + 1 for a given device type so for QEMU with 3 CPUs instance_id for APICs is a seti of [0, 1, 2] When CPU in the middle is hot-removed and migration started APICs with instance_ids 0 and 2 are transferred in migration stream. However target starts with 2 CPUs and APICs' instance_ids are generated from scratch [0, 1] hence migration fails with error Unknown savevm section or instance 'apic' 2 Fix issue by manually registering APIC's vmsd with apic_id as instance_id, in this case instance_id on target will always match instance_id on source as apic_id is the same for a given cpu instance. Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Igor Mammedov <imammedo@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
qemu · Jul 20, 2016 · f6e9844 · f6e9844
1 parent 9c156f9
commit f6e9844
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Showing 3 changed files with 17 additions and 1 deletion.
diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
@@ -294,11 +294,14 @@ static int apic_load_old(QEMUFile *f, void *opaque, int version_id)
     return 0;
 }
 
+static const VMStateDescription vmstate_apic_common;
+
 static void apic_common_realize(DeviceState *dev, Error **errp)
 {
     APICCommonState *s = APIC_COMMON(dev);
     APICCommonClass *info;
     static DeviceState *vapic;
+    int instance_id = s->id;
 
     info = APIC_COMMON_GET_CLASS(s);
     info->realize(dev, errp);
@@ -313,13 +316,19 @@ static void apic_common_realize(DeviceState *dev, Error **errp)
         info->enable_tpr_reporting(s, true);
     }
 
+    if (s->legacy_instance_id) {
+        instance_id = -1;
+    }
+    vmstate_register_with_alias_id(NULL, instance_id, &vmstate_apic_common,
+                                   s, -1, 0);
 }
 
 static void apic_common_unrealize(DeviceState *dev, Error **errp)
 {
     APICCommonState *s = APIC_COMMON(dev);
     APICCommonClass *info = APIC_COMMON_GET_CLASS(s);
 
+    vmstate_unregister(NULL, &vmstate_apic_common, s);
     info->unrealize(dev, errp);
 
     if (apic_report_tpr_access && info->enable_tpr_reporting) {
@@ -422,14 +431,15 @@ static Property apic_properties_common[] = {
     DEFINE_PROP_UINT8("version", APICCommonState, version, 0x14),
     DEFINE_PROP_BIT("vapic", APICCommonState, vapic_control, VAPIC_ENABLE_BIT,
                     true),
+    DEFINE_PROP_BOOL("legacy-instance-id", APICCommonState, legacy_instance_id,
+                     false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
 static void apic_common_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
-    dc->vmsd = &vmstate_apic_common;
     dc->reset = apic_reset_common;
     dc->props = apic_properties_common;
     dc->realize = apic_common_realize;

diff --git a/include/hw/i386/apic_internal.h b/include/hw/i386/apic_internal.h
@@ -183,6 +183,7 @@ struct APICCommonState {
     uint32_t vapic_control;
     DeviceState *vapic;
     hwaddr vapic_paddr; /* note: persistence via kvmvapic */
+    bool legacy_instance_id;
 };
 
 typedef struct VAPICState {

diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
@@ -382,6 +382,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
         .driver = TYPE_X86_CPU,\
         .property = "fill-mtrr-mask",\
         .value = "off",\
+    },\
+    {\
+        .driver   = "apic",\
+        .property = "legacy-instance-id",\
+        .value    = "on",\
     },
 
 #define PC_COMPAT_2_5 \