qemu: domain: Prepare for VCPUs vanishing while libvirt is not running

Similarly to devices the guest may allow unplug of the VCPU if libvirt
is down. To avoid problems, refresh the vcpu state on reconnect. Don't
mess with the vcpu state otherwise.

src/qemu/qemu_domain.c

@@ -5764,16 +5764,20 @@ qemuDomainSupportsNewVcpuHotplug(virDomainObjPtr vm)
  * @driver: qemu driver data
  * @vm: domain object
  * @asyncJob: current asynchronous job type
+ * @state: refresh vcpu state
  *
  * Updates vCPU information private data of @vm. Due to historical reasons this
  * function returns success even if some data were not reported by qemu.
  *
+ * If @state is true, the vcpu state is refreshed as reported by the monitor.
+ *
  * Returns 0 on success and -1 on fatal error.
  */
 int
 qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
                           virDomainObjPtr vm,
-                          int asyncJob)
+                          int asyncJob,
+                          bool state)
 {
     virDomainVcpuDefPtr vcpu;
     qemuDomainVcpuPrivatePtr vcpupriv;
@@ -5841,6 +5845,9 @@ qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
         VIR_FREE(vcpupriv->alias);
         VIR_STEAL_PTR(vcpupriv->alias, info[i].alias);
         vcpupriv->enable_id = info[i].id;
+
+        if (hotplug && state)
+            vcpu->online = !!info[i].qom_path;
     }
 
     ret = 0;

src/qemu/qemu_domain.h

@@ -660,7 +660,8 @@ pid_t qemuDomainGetVcpuPid(virDomainObjPtr vm, unsigned int vcpuid);
 int qemuDomainValidateVcpuInfo(virDomainObjPtr vm);
 int qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
                               virDomainObjPtr vm,
-                              int asyncJob);
+                              int asyncJob,
+                              bool state);
 
 bool qemuDomainSupportsNicdev(virDomainDefPtr def,
                               virDomainNetDefPtr net);

src/qemu/qemu_driver.c

@@ -4640,7 +4640,7 @@ qemuDomainHotplugAddVcpu(virQEMUDriverPtr driver,
 
     vcpuinfo->online = true;
 
-    if (qemuDomainRefreshVcpuInfo(driver, vm, QEMU_ASYNC_JOB_NONE) < 0)
+    if (qemuDomainRefreshVcpuInfo(driver, vm, QEMU_ASYNC_JOB_NONE, false) < 0)
         goto cleanup;
 
     if (qemuDomainValidateVcpuInfo(vm) < 0)
@@ -4689,7 +4689,7 @@ qemuDomainHotplugDelVcpu(virQEMUDriverPtr driver,
         goto cleanup;
     }
 
-    if (qemuDomainRefreshVcpuInfo(driver, vm, QEMU_ASYNC_JOB_NONE) < 0)
+    if (qemuDomainRefreshVcpuInfo(driver, vm, QEMU_ASYNC_JOB_NONE, false) < 0)
         goto cleanup;
 
     if (qemuDomainValidateVcpuInfo(vm) < 0) {

src/qemu/qemu_process.c

@@ -3354,6 +3354,9 @@ qemuProcessReconnect(void *opaque)
     ignore_value(virSecurityManagerCheckAllLabel(driver->securityManager,
                                                  obj->def));
 
+    if (qemuDomainRefreshVcpuInfo(driver, obj, QEMU_ASYNC_JOB_NONE, true) < 0)
+        goto error;
+
     if (virSecurityManagerReserveLabel(driver->securityManager, obj->def, obj->pid) < 0)
         goto error;
 
@@ -5234,7 +5237,7 @@ qemuProcessLaunch(virConnectPtr conn,
         goto cleanup;
 
     VIR_DEBUG("Refreshing VCPU info");
-    if (qemuDomainRefreshVcpuInfo(driver, vm, asyncJob) < 0)
+    if (qemuDomainRefreshVcpuInfo(driver, vm, asyncJob, false) < 0)
         goto cleanup;
 
     if (qemuDomainValidateVcpuInfo(vm) < 0)
@@ -6029,7 +6032,7 @@ int qemuProcessAttach(virConnectPtr conn ATTRIBUTE_UNUSED,
     }
 
     VIR_DEBUG("Detecting VCPU PIDs");
-    if (qemuDomainRefreshVcpuInfo(driver, vm, QEMU_ASYNC_JOB_NONE) < 0)
+    if (qemuDomainRefreshVcpuInfo(driver, vm, QEMU_ASYNC_JOB_NONE, false) < 0)
         goto error;
 
     if (qemuDomainValidateVcpuInfo(vm) < 0)