qemu: cpu hotplug: Move loops to qemuDomainSetVcpusFlags

qemuDomainHotplugVcpus/qemuDomainHotunplugVcpus are complex enough in
regards of adding one CPU. Additionally it will be desired to reuse
those functions later with specific vCPU hotplug.

Move the loops for adding vCPUs into qemuDomainSetVcpusFlags so that the
helpers can be made simpler and more straightforward.

src/qemu/qemu_driver.c

@@ -4694,10 +4694,9 @@ qemuDomainDelCgroupForThread(virCgroupPtr cgroup,
 static int
 qemuDomainHotplugAddVcpu(virQEMUDriverPtr driver,
                          virDomainObjPtr vm,
-                         unsigned int nvcpus)
+                         unsigned int vcpu)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    size_t i;
     int ret = -1;
     int oldvcpus = virDomainDefGetVcpus(vm->def);
     int vcpus = oldvcpus;
@@ -4709,13 +4708,10 @@ qemuDomainHotplugAddVcpu(virQEMUDriverPtr driver,
 
     qemuDomainObjEnterMonitor(driver, vm);
 
-    for (i = vcpus; i < nvcpus; i++) {
-        /* Online new CPU */
-        if (qemuMonitorSetCPU(priv->mon, i, true) < 0)
+    if (qemuMonitorSetCPU(priv->mon, vcpu, true) < 0)
         goto exit_monitor;
 
     vcpus++;
-    }
 
     /* After hotplugging the CPUs we need to re-detect threads corresponding
      * to the virtual CPUs. Some older versions don't provide the thread ID
@@ -4747,35 +4743,33 @@ qemuDomainHotplugAddVcpu(virQEMUDriverPtr driver,
                                             &mem_mask, -1) < 0)
         goto cleanup;
 
-    for (i = oldvcpus; i < nvcpus; i++) {
     if (priv->cgroup) {
         cgroup_vcpu =
             qemuDomainAddCgroupForThread(priv->cgroup,
                                          VIR_CGROUP_THREAD_VCPU,
-                                             i, mem_mask,
-                                             cpupids[i]);
+                                         vcpu, mem_mask,
+                                         cpupids[vcpu]);
         if (!cgroup_vcpu)
             goto cleanup;
     }
 
     /* Inherit def->cpuset */
     if (vm->def->cpumask) {
-            if (qemuDomainHotplugAddPin(vm->def->cpumask, i,
+        if (qemuDomainHotplugAddPin(vm->def->cpumask, vcpu,
                                     &vm->def->cputune.vcpupin,
                                     &vm->def->cputune.nvcpupin) < 0)
             goto cleanup;
 
-            if (qemuDomainHotplugPinThread(vm->def->cpumask, i, cpupids[i],
-                                           cgroup_vcpu) < 0)
+        if (qemuDomainHotplugPinThread(vm->def->cpumask, vcpu, cpupids[vcpu],
+                                       cgroup_vcpu) < 0) {
             goto cleanup;
         }
-        virCgroupFree(&cgroup_vcpu);
+    }
 
-        if (qemuProcessSetSchedParams(i, cpupids[i],
+    if (qemuProcessSetSchedParams(vcpu, cpupids[vcpu],
                                   vm->def->cputune.nvcpusched,
                                   vm->def->cputune.vcpusched) < 0)
         goto cleanup;
-    }
 
     priv->nvcpupids = ncpupids;
     VIR_FREE(priv->vcpupids);
@@ -4790,7 +4784,7 @@ qemuDomainHotplugAddVcpu(virQEMUDriverPtr driver,
     if (virDomainObjIsActive(vm) &&
         virDomainDefSetVcpus(vm->def, vcpus) < 0)
         ret = -1;
-    virDomainAuditVcpu(vm, oldvcpus, nvcpus, "update", ret == 0);
+    virDomainAuditVcpu(vm, oldvcpus, vcpus, "update", ret == 0);
     if (cgroup_vcpu)
         virCgroupFree(&cgroup_vcpu);
     return ret;
@@ -4804,10 +4798,9 @@ qemuDomainHotplugAddVcpu(virQEMUDriverPtr driver,
 static int
 qemuDomainHotplugDelVcpu(virQEMUDriverPtr driver,
                          virDomainObjPtr vm,
-                         unsigned int nvcpus)
+                         unsigned int vcpu)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    size_t i;
     int ret = -1;
     int oldvcpus = virDomainDefGetVcpus(vm->def);
     int vcpus = oldvcpus;
@@ -4816,13 +4809,10 @@ qemuDomainHotplugDelVcpu(virQEMUDriverPtr driver,
 
     qemuDomainObjEnterMonitor(driver, vm);
 
-    for (i = vcpus - 1; i >= nvcpus; i--) {
-        /* Offline old CPU */
-        if (qemuMonitorSetCPU(priv->mon, i, false) < 0)
+    if (qemuMonitorSetCPU(priv->mon, vcpu, false) < 0)
         goto exit_monitor;
 
     vcpus--;
-    }
 
     /* After hotplugging the CPUs we need to re-detect threads corresponding
      * to the virtual CPUs. Some older versions don't provide the thread ID
@@ -4854,16 +4844,14 @@ qemuDomainHotplugDelVcpu(virQEMUDriverPtr driver,
         goto cleanup;
     }
 
-    for (i = oldvcpus - 1; i >= nvcpus; i--) {
     if (qemuDomainDelCgroupForThread(priv->cgroup,
-                                         VIR_CGROUP_THREAD_VCPU, i) < 0)
+                                     VIR_CGROUP_THREAD_VCPU, vcpu) < 0)
         goto cleanup;
 
     /* Free vcpupin setting */
     virDomainPinDel(&vm->def->cputune.vcpupin,
                     &vm->def->cputune.nvcpupin,
-                        i);
-    }
+                    vcpu);
 
     priv->nvcpupids = ncpupids;
     VIR_FREE(priv->vcpupids);
@@ -4877,7 +4865,7 @@ qemuDomainHotplugDelVcpu(virQEMUDriverPtr driver,
     if (virDomainObjIsActive(vm) &&
         virDomainDefSetVcpus(vm->def, vcpus) < 0)
         ret = -1;
-    virDomainAuditVcpu(vm, oldvcpus, nvcpus, "update", ret == 0);
+    virDomainAuditVcpu(vm, oldvcpus, vcpus, "update", ret == 0);
     return ret;
 
  exit_monitor:
@@ -5020,12 +5008,16 @@ qemuDomainSetVcpusFlags(virDomainPtr dom, unsigned int nvcpus,
 
     if (def) {
         if (nvcpus > virDomainDefGetVcpus(def)) {
-            if (qemuDomainHotplugAddVcpu(driver, vm, nvcpus) < 0)
+            for (i = virDomainDefGetVcpus(def); i < nvcpus; i++) {
+                if (qemuDomainHotplugAddVcpu(driver, vm, i) < 0)
                     goto endjob;
+            }
         } else {
-            if (qemuDomainHotplugDelVcpu(driver, vm, nvcpus) < 0)
+            for (i = virDomainDefGetVcpus(def) - 1; i >= nvcpus; i--) {
+                if (qemuDomainHotplugDelVcpu(driver, vm, i) < 0)
                     goto endjob;
             }
+        }
 
         if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
             goto endjob;