Re: [PATCH v1 8/9] qom: add command to print initial properties

[Igor Mammedov]

On Tue, 29 Mar 2022 00:15:38 +0300
Maxim Davydov <maxim.davydov@openvz.org> wrote:

> The command "query-init-properties" is needed to get values of properties
> after initialization (not only default value). It makes sense, for example,
> when working with x86_64-cpu.
> All machine types (and x-remote-object, because its init uses machime
> type's infrastructure) should be skipped, because only the one instance can
> be correctly initialized.

It might be obvious to you but I couldn't parse above commit message at all.
Pls rephrase and explain in more detail what you are trying to achieve.

> 
> Signed-off-by: Maxim Davydov <maxim.davydov@openvz.org>
> ---
>  qapi/qom.json      |  69 ++++++++++++++++++++++++++
>  qom/qom-qmp-cmds.c | 121 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 190 insertions(+)
> 
> diff --git a/qapi/qom.json b/qapi/qom.json
> index eeb5395ff3..1eedc441eb 100644
> --- a/qapi/qom.json
> +++ b/qapi/qom.json
> @@ -949,3 +949,72 @@
>  ##
>  { 'command': 'object-del', 'data': {'id': 'str'},
>    'allow-preconfig': true }
> +
> +##
> +# @InitValue:
> +#
> +# Not all objects have default values but they have "initial" values.
> +#
> +# @name: property name
> +#
> +# @value: Current value (default or after initialization. It makes sence,
> +#         for example, for x86-cpus)
> +#
> +# Since: 7.0
> +#
> +##
> +{ 'struct': 'InitValue',
> +  'data': { 'name': 'str',
> +            '*value': 'any' } }
> +
> +##
> +# @ClassProperties:
> +#
> +# Initial values of properties that are owned by the class
> +#
> +# @classname: name of the class that owns appropriate properties
> +#
> +# @classprops: List of class properties
> +#
> +# Since: 7.0
> +#
> +##
> +{ 'struct': 'ClassProperties',
> +  'data': { 'classname': 'str',
> +            '*classprops': [ 'InitValue' ] } }
> +
> +##
> +# @InitProps:
> +#
> +# List of properties and their values that are available after class
> +# initialization. So it important to know default value of the property
> +# even if it doesn't have "QObject *defval"
> +#
> +# @name: Object name
> +#
> +# @props: List of properties
> +#
> +# Notes: a value in each property was defval if it's available
> +#        otherwise it's obtained via "(ObjectPropertyAccessor*) get"
> +#        immediately after initialization of device object.
> +#
> +# Since: 7.0
> +#
> +##
> +{ 'struct': 'InitProps',
> +  'data': { 'name': 'str',
> +            'props': [ 'ClassProperties' ] } }
> +
> +##
> +# @query-init-properties:
> +#
> +# Returns list of all objects (except all types related with machine type)
> +# with all properties and their "default" values that  will be available
> +# after initialization. The main purpose of this command is to be used to
> +# build table with all machine-type-specific properties
> +#
> +# Since: 7.0
> +#
> +##
> +{ 'command': 'query-init-properties',
> +  'returns': [ 'InitProps' ] }
> diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
> index 2d6f41ecc7..c1bb3f1f8b 100644
> --- a/qom/qom-qmp-cmds.c
> +++ b/qom/qom-qmp-cmds.c
> @@ -27,6 +27,7 @@
>  #include "qemu/cutils.h"
>  #include "qom/object_interfaces.h"
>  #include "qom/qom-qobject.h"
> +#include "hw/boards.h"
>  
>  ObjectPropertyInfoList *qmp_qom_list(const char *path, Error **errp)
>  {
> @@ -235,3 +236,123 @@ void qmp_object_del(const char *id, Error **errp)
>  {
>      user_creatable_del(id, errp);
>  }
> +
> +static void query_object_prop(InitValueList **props_list, ObjectProperty 
> *prop,
> +                              Object *obj, Error **errp)
> +{
> +    InitValue *prop_info = NULL;
> +
> +    /* Skip inconsiderable properties */
> +    if (strcmp(prop->name, "type") == 0 ||
> +        strcmp(prop->name, "realized") == 0 ||
> +        strcmp(prop->name, "hotpluggable") == 0 ||
> +        strcmp(prop->name, "hotplugged") == 0 ||
> +        strcmp(prop->name, "parent_bus") == 0) {
> +        return;
> +    }
> +
> +    prop_info = g_malloc0(sizeof(*prop_info));
> +    prop_info->name = g_strdup(prop->name);
> +    prop_info->value = NULL;
> +    if (prop->defval) {
> +        prop_info->value = qobject_ref(prop->defval);
> +    } else if (prop->get) {
> +        /*
> +         * crash-information in x86-cpu uses errp to return current state.
> +         * So, after requesting this property it returns  GenericError:
> +         * "No crash occured"
> +         */
> +        if (strcmp(prop->name, "crash-information") != 0) {
> +            prop_info->value = object_property_get_qobject(obj, prop->name,
> +                                                           errp);
> +        }
> +    }
> +    prop_info->has_value = !!prop_info->value;
> +
> +    QAPI_LIST_PREPEND(*props_list, prop_info);
> +}
> +
> +typedef struct QIPData {
> +    InitPropsList **dev_list;
> +    Error **errp;
> +} QIPData;
> +
> +static void query_init_properties_tramp(gpointer list_data, gpointer opaque)
> +{
> +    ObjectClass *k = list_data;
> +    Object *obj;
> +    ObjectClass *parent;
> +    GHashTableIter iter;
> +
> +    QIPData *data = opaque;
> +    ClassPropertiesList *class_props_list = NULL;
> +    InitProps *dev_info;
> +
> +    /* Only one machine can be initialized correctly (it's already happened) 
> */
> +    if (object_class_dynamic_cast(k, TYPE_MACHINE)) {
> +        return;
> +    }
> +
> +    const char *klass_name = object_class_get_name(k);
> +    /*
> +     * Uses machine type infrastructure with notifiers. It causes immediate
> +     * notify and SEGSEGV during remote_object_machine_done
> +     */
> +    if (strcmp(klass_name, "x-remote-object") == 0) {
> +        return;
> +    }
> +
> +    dev_info = g_malloc0(sizeof(*dev_info));
> +    dev_info->name = g_strdup(klass_name);
> +
> +    obj = object_new_with_class(k);
> +
> +    /*
> +     * Part of ObjectPropertyIterator infrastructure, but we need more 
> precise
> +     * control of current class to dump appropriate features
> +     * This part was taken out from loop because first initialization differ
> +     * from other reinitializations
> +     */
> +    parent = object_get_class(obj);
> +    g_hash_table_iter_init(&iter, obj->properties);
> +    const char *prop_owner_name = object_get_typename(obj);
> +    do {
> +        InitValueList *prop_list = NULL;
> +        ClassProperties *class_data;
> +
> +        gpointer key, val;
> +        while (g_hash_table_iter_next(&iter, &key, &val)) {
> +            query_object_prop(&prop_list, (ObjectProperty *)val, obj,
> +                              data->errp);
> +        }
> +        class_data = g_malloc0(sizeof(*class_data));
> +        class_data->classname = g_strdup(prop_owner_name);
> +        class_data->classprops = prop_list;
> +        class_data->has_classprops = !!prop_list;
> +
> +        QAPI_LIST_PREPEND(class_props_list, class_data);
> +
> +        if (!parent) {
> +            break;
> +        }
> +        g_hash_table_iter_init(&iter, parent->properties);
> +        prop_owner_name = object_class_get_name(parent);
> +        parent = object_class_get_parent(parent);
> +    } while (true);
> +    dev_info->props = class_props_list;
> +    object_unref(OBJECT(obj));
> +
> +    QAPI_LIST_PREPEND(*(data->dev_list), dev_info);
> +}
> +
> +InitPropsList *qmp_query_init_properties(Error **errp)
> +{
> +    GSList *typename_list = object_class_get_list(TYPE_OBJECT, false);
> +
> +    InitPropsList *dev_list = NULL;
> +    QIPData data = { &dev_list, errp };
> +    g_slist_foreach(typename_list, query_init_properties_tramp, &data);
> +    g_slist_free(typename_list);
> +
> +    return dev_list;
> +}