libvirt/qemu - support persistent modification of devices

This patch adds functions for modify domain's persistent definition.
To do error recovery in easy way, we use a copy of vmdef and update it.

The whole sequence will be:

  make a copy of domain definition.

  if (flags & MODIFY_CONFIG)
      update copied domain definition
  if (flags & MODIF_LIVE)
      do hotplug.
  if (no error)
      save copied one to the file and update cached definition.
  else
      discard copied definition.

This patch is mixuture of Eric Blake's work and mine.
From: Eric Blake <eblake@redhat.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

(virDomainObjCopyPersistentDef): make a copy of persistent vm definition
(qemuDomainAttach/Detach/UpdateDeviceConfig) : callbacks. now empty
(qemuDomainModifyDeviceFlags): add support for MODIFY_CONFIG and MODIFY_CURRENT

src/conf/domain_conf.c

@@ -9510,3 +9510,22 @@ cleanup:
 
     return ret;
 }
+
+
+virDomainDefPtr
+virDomainObjCopyPersistentDef(virCapsPtr caps, virDomainObjPtr dom)
+{
+    char *xml;
+    virDomainDefPtr cur, ret;
+
+    cur = virDomainObjGetPersistentDef(caps, dom);
+
+    xml = virDomainDefFormat(cur, VIR_DOMAIN_XML_WRITE_FLAGS);
+    if (!xml)
+        return NULL;
+
+    ret = virDomainDefParseString(caps, xml, VIR_DOMAIN_XML_READ_FLAGS);
+
+    VIR_FREE(xml);
+    return ret;
+}

src/conf/domain_conf.h

@@ -1288,6 +1288,9 @@ int virDomainObjSetDefTransient(virCapsPtr caps,
 virDomainDefPtr
 virDomainObjGetPersistentDef(virCapsPtr caps,
                              virDomainObjPtr domain);
+virDomainDefPtr
+virDomainObjCopyPersistentDef(virCapsPtr caps, virDomainObjPtr dom);
+
 void virDomainRemoveInactive(virDomainObjListPtr doms,
                              virDomainObjPtr dom);
 

src/libvirt_private.syms

@@ -287,7 +287,7 @@ virDomainMemballoonModelTypeToString;
 virDomainNetDefFree;
 virDomainNetTypeToString;
 virDomainObjAssignDef;
-virDomainObjSetDefTransient;
+virDomainObjCopyPersistentDef;
 virDomainObjGetPersistentDef;
 virDomainObjIsDuplicate;
 virDomainObjListDeinit;
@@ -297,6 +297,7 @@ virDomainObjListInit;
 virDomainObjListNumOfDomains;
 virDomainObjLock;
 virDomainObjRef;
+virDomainObjSetDefTransient;
 virDomainObjUnlock;
 virDomainObjUnref;
 virDomainRemoveInactive;

src/qemu/qemu_driver.c

@@ -4076,6 +4076,46 @@ qemuDomainUpdateDeviceLive(virDomainObjPtr vm,
     return ret;
 }
 
+static int
+qemuDomainAttachDeviceConfig(virDomainDefPtr vmdef ATTRIBUTE_UNUSED,
+                             virDomainDeviceDefPtr dev)
+{
+    switch (dev->type) {
+    default:
+         qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                         _("persistent attach of device is not supported"));
+         return -1;
+    }
+    return 0;
+}
+
+
+static int
+qemuDomainDetachDeviceConfig(virDomainDefPtr vmdef ATTRIBUTE_UNUSED,
+                             virDomainDeviceDefPtr dev)
+{
+    switch (dev->type) {
+    default:
+        qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                        _("persistent detach of device is not supported"));
+        return -1;
+    }
+    return 0;
+}
+
+static int
+qemuDomainUpdateDeviceConfig(virDomainDefPtr vmdef ATTRIBUTE_UNUSED,
+                             virDomainDeviceDefPtr dev)
+{
+    switch (dev->type) {
+    default:
+        qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                         _("persistent update of device is not supported"));
+        return -1;
+    }
+    return 0;
+}
+
 /* Actions for qemuDomainModifyDeviceFlags */
 enum {
     QEMU_DEVICE_ATTACH,
@@ -4091,6 +4131,7 @@ qemuDomainModifyDeviceFlags(virDomainPtr dom, const char *xml,
     struct qemud_driver *driver = dom->conn->privateData;
     virBitmapPtr qemuCaps = NULL;
     virDomainObjPtr vm = NULL;
+    virDomainDefPtr vmdef = NULL;
     virDomainDeviceDefPtr dev = NULL;
     bool force = (flags & VIR_DOMAIN_DEVICE_MODIFY_FORCE) != 0;
     int ret = -1;
@@ -4100,12 +4141,6 @@ qemuDomainModifyDeviceFlags(virDomainPtr dom, const char *xml,
                   (action == QEMU_DEVICE_UPDATE ?
                    VIR_DOMAIN_DEVICE_MODIFY_FORCE : 0), -1);
 
-    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
-        qemuReportError(VIR_ERR_OPERATION_INVALID,
-                        "%s", _("cannot modify the persistent configuration of a domain"));
-        return -1;
-    }
-
     qemuDriverLock(driver);
     vm = virDomainFindByUUID(&driver->domains, dom->uuid);
     if (!vm) {
@@ -4119,12 +4154,27 @@ qemuDomainModifyDeviceFlags(virDomainPtr dom, const char *xml,
     if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0)
         goto cleanup;
 
-    if (!virDomainObjIsActive(vm)) {
+    if (virDomainObjIsActive(vm)) {
-        qemuReportError(VIR_ERR_OPERATION_INVALID,
+        if (flags == VIR_DOMAIN_DEVICE_MODIFY_CURRENT)
-                        "%s", _("cannot attach device on inactive domain"));
+            flags |= VIR_DOMAIN_DEVICE_MODIFY_LIVE;
-        goto endjob;
+    } else {
+        if (flags == VIR_DOMAIN_DEVICE_MODIFY_CURRENT)
+            flags |= VIR_DOMAIN_DEVICE_MODIFY_CONFIG;
+        /* check consistency between flags and the vm state */
+        if (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE) {
+            qemuReportError(VIR_ERR_OPERATION_INVALID,
+                            "%s",
+                            _("cannot do live update a device on "
+                              "inactive domain"));
+            goto endjob;
+        }
     }
 
+    if ((flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) && !vm->persistent) {
+         qemuReportError(VIR_ERR_OPERATION_INVALID,
+                         "%s", _("cannot modify device on transient domain"));
+         goto endjob;
+    }
     dev = virDomainDeviceDefParse(driver->caps, vm->def, xml,
                                   VIR_DOMAIN_XML_INACTIVE);
     if (dev == NULL)
@@ -4135,35 +4185,68 @@ qemuDomainModifyDeviceFlags(virDomainPtr dom, const char *xml,
                                    &qemuCaps) < 0)
         goto endjob;
 
-    switch (action) {
+    if (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG) {
-    case QEMU_DEVICE_ATTACH:
+        /* Make a copy for updated domain. */
-        ret = qemuDomainAttachDeviceLive(vm, dev, dom, qemuCaps);
+        vmdef = virDomainObjCopyPersistentDef(driver->caps, vm);
-        break;
+        if (!vmdef)
-    case QEMU_DEVICE_DETACH:
+            goto endjob;
-        ret = qemuDomainDetachDeviceLive(vm, dev, dom, qemuCaps);
+        switch (action) {
-        break;
+        case QEMU_DEVICE_ATTACH:
-    case QEMU_DEVICE_UPDATE:
+            ret = qemuDomainAttachDeviceConfig(vmdef, dev);
-        ret = qemuDomainUpdateDeviceLive(vm, dev, dom, qemuCaps, force);
+            break;
-        break;
+        case QEMU_DEVICE_DETACH:
-    default:
+            ret = qemuDomainDetachDeviceConfig(vmdef, dev);
-        qemuReportError(VIR_ERR_INTERNAL_ERROR,
+            break;
-                        _("unknown domain modify action %d"), action);
+        case QEMU_DEVICE_UPDATE:
-        break;
+            ret = qemuDomainUpdateDeviceConfig(vmdef, dev);
-    }
+            break;
+        default:
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            _("unknown domain modify action %d"), action);
+            break;
+        }
+    } else
+        ret = 0;
 
-    /*
+    if (!ret && (flags & VIR_DOMAIN_DEVICE_MODIFY_LIVE)) {
-     * update domain status forcibly because the domain status may be changed
+        switch (action) {
-     * even if we attach the device failed. For example, a new controller may
+        case QEMU_DEVICE_ATTACH:
-     * be created.
+            ret = qemuDomainAttachDeviceLive(vm, dev, dom, qemuCaps);
-     */
+            break;
-    if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0)
+        case QEMU_DEVICE_DETACH:
-        ret = -1;
+            ret = qemuDomainDetachDeviceLive(vm, dev, dom, qemuCaps);
+            break;
+        case QEMU_DEVICE_UPDATE:
+            ret = qemuDomainUpdateDeviceLive(vm, dev, dom, qemuCaps, force);
+            break;
+        default:
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            _("unknown domain modify action %d"), action);
+            break;
+        }
+        /*
+         * update domain status forcibly because the domain status may be
+         * changed even if we attach the device failed. For example, a
+         * For example, a new controller may be created.
+         */
+        if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0)
+            ret = -1;
+    }
+    /* Finally, if no error until here, we can save config. */
+    if (!ret && (flags & VIR_DOMAIN_DEVICE_MODIFY_CONFIG)) {
+        ret = virDomainSaveConfig(driver->configDir, vmdef);
+        if (!ret) {
+            virDomainObjAssignDef(vm, vmdef, false);
+            vmdef = NULL;
+        }
+    }
 
 endjob:
     if (qemuDomainObjEndJob(vm) == 0)
         vm = NULL;
 
 cleanup:
+    virDomainDefFree(vmdef);
     virDomainDeviceDefFree(dev);
     if (vm)
         virDomainObjUnlock(vm);