The FW_CFG_DATA_GENERATOR allows any object to produce
blob of data consumable by the fw_cfg device.
Reviewed-by: Laszlo Ersek <ler...@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
docs/specs/fw_cfg.txt | 9 ++++++-
include/hw/nvram/fw_cfg.h | 52 +++++++++++++++++++++++++++++++++++++++
hw/nvram/fw_cfg.c | 36 +++++++++++++++++++++++++++
3 files changed, 96 insertions(+), 1 deletion(-)
diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt
index 8f1ebc66fa..bc16daa38a 100644
--- a/docs/specs/fw_cfg.txt
+++ b/docs/specs/fw_cfg.txt
@@ -219,7 +219,7 @@ To check the result, read the "control" field:
= Externally Provided Items =
-As of v2.4, "file" fw_cfg items (i.e., items with selector keys above
+Since v2.4, "file" fw_cfg items (i.e., items with selector keys above
FW_CFG_FILE_FIRST, and with a corresponding entry in the fw_cfg file
directory structure) may be inserted via the QEMU command line, using
the following syntax:
@@ -230,6 +230,13 @@ Or
-fw_cfg [name=]<item_name>,string=<string>
+Since v5.1, QEMU allows some objects to generate fw_cfg-specific content,
+the content is then associated with a "file" item using the 'gen_id' option
+in the command line, using the following syntax:
+
+ -object <generator-type>,id=<generated_id>,[generator-specific-options] \
+ -fw_cfg [name=]<item_name>,gen_id=<generated_id>
+
See QEMU man page for more documentation.
Using item_name with plain ASCII characters only is recommended.
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index 25d9307018..ca69666847 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -9,11 +9,43 @@
#define TYPE_FW_CFG "fw_cfg"
#define TYPE_FW_CFG_IO "fw_cfg_io"
#define TYPE_FW_CFG_MEM "fw_cfg_mem"
+#define TYPE_FW_CFG_DATA_GENERATOR_INTERFACE "fw_cfg-data-generator"
#define FW_CFG(obj) OBJECT_CHECK(FWCfgState, (obj), TYPE_FW_CFG)
#define FW_CFG_IO(obj) OBJECT_CHECK(FWCfgIoState, (obj), TYPE_FW_CFG_IO)
#define FW_CFG_MEM(obj) OBJECT_CHECK(FWCfgMemState, (obj), TYPE_FW_CFG_MEM)
+#define FW_CFG_DATA_GENERATOR_CLASS(class) \
+ OBJECT_CLASS_CHECK(FWCfgDataGeneratorClass, (class), \
+ TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)
+#define FW_CFG_DATA_GENERATOR_GET_CLASS(obj) \
+ OBJECT_GET_CLASS(FWCfgDataGeneratorClass, (obj), \
+ TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)
+
+typedef struct FWCfgDataGeneratorClass {
+ /*< private >*/
+ InterfaceClass parent_class;
+ /*< public >*/
+
+ /**
+ * get_data:
+ * @obj: the object implementing this interface
+ *
+ * Returns: pointer to start of the generated item data
+ *
+ * The returned pointer is a QObject weak reference, @obj owns
+ * the reference and may free it at any time in the future.
+ */
+ const void *(*get_data)(Object *obj);
+ /**
+ * get_length:
+ * @obj: the object implementing this interface
+ *
+ * Returns: the size of the generated item data in bytes
+ */
+ size_t (*get_length)(Object *obj);
+} FWCfgDataGeneratorClass;
+
typedef struct fw_cfg_file FWCfgFile;
#define FW_CFG_ORDER_OVERRIDE_VGA 70
@@ -263,6 +295,26 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char
*filename,
void *fw_cfg_modify_file(FWCfgState *s, const char *filename, void *data,
size_t len);
+/**
+ * fw_cfg_add_from_generator:
+ * @s: fw_cfg device being modified
+ * @filename: name of new fw_cfg file item
+ * @gen_id: name of object implementing FW_CFG_DATA_GENERATOR interface
+ * @errp: pointer to a NULL initialized error object
+ *
+ * Add a new NAMED fw_cfg item with the content generated from the
+ * @gen_id object. The data generated by the @gen_id object is copied
+ * into the data structure of the fw_cfg device.
+ * The next available (unused) selector key starting at FW_CFG_FILE_FIRST
+ * will be used; also, a new entry will be added to the file directory
+ * structure residing at key value FW_CFG_FILE_DIR, containing the item name,
+ * data size, and assigned selector key value.
+ *
+ * Returns: the size of the generated item data on success, or 0 on errors.
+ */
+size_t fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+ const char *gen_id, Error **errp);
+
FWCfgState *fw_cfg_init_io_dma(uint32_t iobase, uint32_t dma_iobase,
AddressSpace *dma_as);
FWCfgState *fw_cfg_init_io(uint32_t iobase);
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 8dd50c2c72..84578e83aa 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -1032,6 +1032,36 @@ void *fw_cfg_modify_file(FWCfgState *s, const char
*filename,
return NULL;
}
+size_t fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+ const char *gen_id, Error **errp)
+{
+ FWCfgDataGeneratorClass *klass;
+ Object *obj;
+ size_t size;
+
+ obj = object_resolve_path_component(object_get_objects_root(), gen_id);
+ if (!obj) {
+ error_setg(errp, "Cannot find object ID '%s'", gen_id);
+ return 0;
+ }
+ if (!object_dynamic_cast(obj, TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)) {
+ error_setg(errp, "Object ID '%s' is not a '%s' subclass",
+ gen_id, TYPE_FW_CFG_DATA_GENERATOR_INTERFACE);
+ return 0;
+ }
+ klass = FW_CFG_DATA_GENERATOR_GET_CLASS(obj);
+ size = klass->get_length(obj);
+ if (size == 0) {
+ error_setg(errp, "Object ID '%s' failed to generate fw_cfg data",
+ gen_id);
+ return 0;
+ }
+ fw_cfg_add_file(s, filename, g_memdup(klass->get_data(obj), (guint)size),
+ size);
+
+ return size;
+}
+
static void fw_cfg_machine_reset(void *opaque)
{
MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
@@ -1333,12 +1363,18 @@ static const TypeInfo fw_cfg_mem_info = {
.class_init = fw_cfg_mem_class_init,
};
+static const TypeInfo fw_cfg_data_generator_interface_info = {
+ .name = TYPE_FW_CFG_DATA_GENERATOR_INTERFACE,
+ .parent = TYPE_INTERFACE,
+ .class_size = sizeof(FWCfgDataGeneratorClass),
+};
static void fw_cfg_register_types(void)
{
type_register_static(&fw_cfg_info);
type_register_static(&fw_cfg_io_info);
type_register_static(&fw_cfg_mem_info);
+ type_register_static(&fw_cfg_data_generator_interface_info);
}
type_init(fw_cfg_register_types)
--
2.21.3
