[Qemu-devel] [PATCH v2 2/2] pc: fix migration failure after cpu hot-unplung

[Igor Mammedov <imammedo@redhat.com>]

As described in commit:
 cpu: add migration_id to allow board to provide migration instance_id
set CPUState::migration_id explictly to stable index in pcms->possible_cpus
so that CPU's instance_id on target would match instance_id on source
even if not the last added CPU is removed.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/i386/pc.c         | 9 ++++++---
 include/hw/i386/pc.h | 5 +++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index f56e225..9e72eb3 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1040,13 +1040,16 @@ void pc_acpi_smi_interrupt(void *opaque, int irq, int level)
 }
 
 static X86CPU *pc_new_cpu(const char *typename, int64_t apic_id,
-                          Error **errp)
+                          Error **errp, int migration_id)
 {
     X86CPU *cpu = NULL;
+    CPUState *cs;
     Error *local_err = NULL;
 
     cpu = X86_CPU(object_new(typename));
 
+    cs = CPU(cpu);
+    cs->migration_id = migration_id;
     object_property_set_int(OBJECT(cpu), apic_id, "apic-id", &local_err);
     object_property_set_bool(OBJECT(cpu), true, "realized", &local_err);
 
@@ -1092,7 +1095,7 @@ void pc_hot_add_cpu(const int64_t id, Error **errp)
 
     assert(pcms->possible_cpus->cpus[0].cpu); /* BSP is always present */
     oc = OBJECT_CLASS(CPU_GET_CLASS(pcms->possible_cpus->cpus[0].cpu));
-    cpu = pc_new_cpu(object_class_get_name(oc), apic_id, &local_err);
+    cpu = pc_new_cpu(object_class_get_name(oc), apic_id, &local_err, id);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1156,7 +1159,7 @@ void pc_cpus_init(PCMachineState *pcms)
         pcms->possible_cpus->len++;
         if (i < smp_cpus) {
             cpu = pc_new_cpu(typename, x86_cpu_apic_id_from_index(i),
-                             &error_fatal);
+                             &error_fatal, i);
             pcms->possible_cpus->cpus[i].cpu = CPU(cpu);
             object_unref(OBJECT(cpu));
         }
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 2123532..fea2961 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -373,6 +373,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t *);
         .driver   = "vmxnet3",\
         .property = "romfile",\
         .value    = "",\
+    },\
+    { \
+        .driver   = TYPE_CPU, \
+        .property = "use-migration-id", \
+        .value    = "off", \
     },
 
 #define PC_COMPAT_2_5 \
-- 
1.8.3.1