qemu-storage-daemon: Add --monitor option

This adds and parses the --monitor option, so that a QMP monitor can be
used in the storage daemon. The monitor offers commands defined in the
QAPI schema at storage-daemon/qapi/qapi-schema.json.

The --monitor options currently allows to create multiple monitors with
the same ID. This part of the interface is considered unstable. We will
reject such configurations as soon as we have a design for the monitor
subsystem to perform these checks. (In the system emulator, we depend on
QemuOpts rejecting duplicate IDs.)

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-21-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Makefile

@@ -128,7 +128,28 @@ GENERATED_QAPI_FILES += $(QAPI_MODULES:%=qapi/qapi-events-%.c)
 GENERATED_QAPI_FILES += qapi/qapi-introspect.c qapi/qapi-introspect.h
 GENERATED_QAPI_FILES += qapi/qapi-doc.texi
 
+# The following list considers only the storage daemon main module. All other
+# modules are currently shared with the main schema, so we don't actually
+# generate additional files.
+
+GENERATED_STORAGE_DAEMON_QAPI_FILES = storage-daemon/qapi/qapi-commands.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-commands.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-emit-events.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-emit-events.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-events.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-events.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-init-commands.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-init-commands.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-introspect.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-introspect.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-types.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-types.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-visit.h
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-visit.c
+GENERATED_STORAGE_DAEMON_QAPI_FILES += storage-daemon/qapi/qapi-doc.texi
+
 generated-files-y += $(GENERATED_QAPI_FILES)
+generated-files-y += $(GENERATED_STORAGE_DAEMON_QAPI_FILES)
 
 generated-files-y += trace/generated-tcg-tracers.h
 
@@ -651,6 +672,17 @@ qapi-gen-timestamp: $(qapi-modules) $(qapi-py)
 		"GEN","$(@:%-timestamp=%)")
 	@>$@
 
+qapi-modules-storage-daemon = \
+	$(SRC_PATH)/storage-daemon/qapi/qapi-schema.json \
+    $(QAPI_MODULES_STORAGE_DAEMON:%=$(SRC_PATH)/qapi/%.json)
+
+$(GENERATED_STORAGE_DAEMON_QAPI_FILES): storage-daemon/qapi/qapi-gen-timestamp ;
+storage-daemon/qapi/qapi-gen-timestamp: $(qapi-modules-storage-daemon) $(qapi-py)
+	$(call quiet-command,$(PYTHON) $(SRC_PATH)/scripts/qapi-gen.py \
+		-o "storage-daemon/qapi" $<, \
+		"GEN","$(@:%-timestamp=%)")
+	@>$@
+
 QGALIB_GEN=$(addprefix qga/qapi-generated/, qga-qapi-types.h qga-qapi-visit.h qga-qapi-commands.h qga-qapi-init-commands.h)
 $(qga-obj-y): $(QGALIB_GEN)
 
@@ -749,6 +781,7 @@ clean: recurse-clean
 	rm -f trace/generated-tracers-dtrace.h*
 	rm -f $(foreach f,$(generated-files-y),$(f) $(f)-timestamp)
 	rm -f qapi-gen-timestamp
+	rm -f storage-daemon/qapi/qapi-gen-timestamp
 	rm -rf qga/qapi-generated
 	rm -f config-all-devices.mak
 

Makefile.objs

@@ -31,8 +31,8 @@ endif # CONFIG_SOFTMMU or CONFIG_TOOLS
 # storage-daemon-obj-y is code used by qemu-storage-daemon (these objects are
 # used for system emulation, too, but specified separately there)
 
-storage-daemon-obj-y = block/ qom/
-storage-daemon-obj-y += blockdev.o blockdev-nbd.o iothread.o
+storage-daemon-obj-y = block/ monitor/ qapi/ qom/ storage-daemon/
+storage-daemon-obj-y += blockdev.o blockdev-nbd.o iothread.o job-qmp.o
 storage-daemon-obj-$(CONFIG_WIN32) += os-win32.o
 storage-daemon-obj-$(CONFIG_POSIX) += os-posix.o
 

monitor/Makefile.objs

@@ -2,3 +2,5 @@ obj-y += misc.o
 common-obj-y += monitor.o qmp.o hmp.o
 common-obj-y += qmp-cmds.o qmp-cmds-control.o
 common-obj-y += hmp-cmds.o
+
+storage-daemon-obj-y += monitor.o qmp.o qmp-cmds-control.o

qapi/Makefile.objs

@@ -31,3 +31,8 @@ obj-y += qapi-events.o
 obj-y += $(QAPI_TARGET_MODULES:%=qapi-commands-%.o)
 obj-y += qapi-commands.o
 obj-y += qapi-init-commands.o
+
+QAPI_MODULES_STORAGE_DAEMON = block-core char common control crypto
+QAPI_MODULES_STORAGE_DAEMON += introspect job qom sockets pragma transaction
+
+storage-daemon-obj-y += $(QAPI_MODULES_STORAGE_DAEMON:%=qapi-commands-%.o)

qapi/transaction.json

@@ -5,7 +5,7 @@
 # = Transactions
 ##
 
-{ 'include': 'block.json' }
+{ 'include': 'block-core.json' }
 
 ##
 # @Abort:

qemu-storage-daemon.c

@@ -31,13 +31,15 @@
 #include "block/nbd.h"
 #include "chardev/char.h"
 #include "crypto/init.h"
+#include "monitor/monitor.h"
+#include "monitor/monitor-internal.h"
 
 #include "qapi/error.h"
-#include "qapi/qapi-commands-block.h"
-#include "qapi/qapi-commands-block-core.h"
 #include "qapi/qapi-visit-block.h"
 #include "qapi/qapi-visit-block-core.h"
+#include "qapi/qapi-visit-control.h"
 #include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
 #include "qapi/qobject-input-visitor.h"
 
 #include "qemu-common.h"
@@ -51,6 +53,9 @@
 #include "qemu/option.h"
 #include "qom/object_interfaces.h"
 
+#include "storage-daemon/qapi/qapi-commands.h"
+#include "storage-daemon/qapi/qapi-init-commands.h"
+
 #include "sysemu/runstate.h"
 #include "trace/control.h"
 
@@ -61,6 +66,11 @@ void qemu_system_killed(int signal, pid_t pid)
     exit_requested = true;
 }
 
+void qmp_quit(Error **errp)
+{
+    exit_requested = true;
+}
+
 static void help(void)
 {
     printf(
@@ -87,6 +97,9 @@ static void help(void)
 "                         export the specified block node over NBD\n"
 "                         (requires --nbd-server)\n"
 "\n"
+"  --monitor [chardev=]name[,mode=control][,pretty[=on|off]]\n"
+"                         configure a QMP monitor\n"
+"\n"
 "  --nbd-server addr.type=inet,addr.host=<host>,addr.port=<port>\n"
 "               [,tls-creds=<id>][,tls-authz=<id>]\n"
 "  --nbd-server addr.type=unix,addr.path=<path>\n"
@@ -110,6 +123,7 @@ enum {
     OPTION_BLOCKDEV = 256,
     OPTION_CHARDEV,
     OPTION_EXPORT,
+    OPTION_MONITOR,
     OPTION_NBD_SERVER,
     OPTION_OBJECT,
 };
@@ -125,6 +139,17 @@ static QemuOptsList qemu_object_opts = {
     },
 };
 
+static void init_qmp_commands(void)
+{
+    qmp_init_marshal(&qmp_commands);
+    qmp_register_command(&qmp_commands, "query-qmp-schema",
+                         qmp_query_qmp_schema, QCO_ALLOW_PRECONFIG);
+
+    QTAILQ_INIT(&qmp_cap_negotiation_commands);
+    qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
+                         qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
+}
+
 static void init_export(BlockExport *export, Error **errp)
 {
     switch (export->type) {
@@ -145,6 +170,7 @@ static void process_options(int argc, char *argv[])
         {"chardev", required_argument, NULL, OPTION_CHARDEV},
         {"export", required_argument, NULL, OPTION_EXPORT},
         {"help", no_argument, NULL, 'h'},
+        {"monitor", required_argument, NULL, OPTION_MONITOR},
         {"nbd-server", required_argument, NULL, OPTION_NBD_SERVER},
         {"object", required_argument, NULL, OPTION_OBJECT},
         {"trace", required_argument, NULL, 'T'},
@@ -219,6 +245,21 @@ static void process_options(int argc, char *argv[])
                 qapi_free_BlockExport(export);
                 break;
             }
+        case OPTION_MONITOR:
+            {
+                Visitor *v;
+                MonitorOptions *monitor;
+
+                v = qobject_input_visitor_new_str(optarg, "chardev",
+                                                  &error_fatal);
+                visit_type_MonitorOptions(v, NULL, &monitor, &error_fatal);
+                visit_free(v);
+
+                /* TODO Catch duplicate monitor IDs */
+                monitor_init(monitor, false, &error_fatal);
+                qapi_free_MonitorOptions(monitor);
+                break;
+            }
         case OPTION_NBD_SERVER:
             {
                 Visitor *v;
@@ -280,6 +321,8 @@ int main(int argc, char *argv[])
     qemu_add_opts(&qemu_trace_opts);
     qcrypto_init(&error_fatal);
     bdrv_init();
+    monitor_init_globals_core();
+    init_qmp_commands();
 
     if (!trace_init_backends()) {
         return EXIT_FAILURE;

scripts/qapi/gen.py

@@ -44,6 +44,11 @@ class QAPIGen:
         return ''
 
     def write(self, output_dir):
+        # Include paths starting with ../ are used to reuse modules of the main
+        # schema in specialised schemas. Don't overwrite the files that are
+        # already generated for the main schema.
+        if self.fname.startswith('../'):
+            return
         pathname = os.path.join(output_dir, self.fname)
         odir = os.path.dirname(pathname)
         if odir:

storage-daemon/Makefile.objs

@@ -0,0 +1 @@
+storage-daemon-obj-y += qapi/

storage-daemon/qapi/Makefile.objs

@@ -0,0 +1 @@
+storage-daemon-obj-y += qapi-commands.o qapi-init-commands.o qapi-introspect.o

storage-daemon/qapi/qapi-schema.json

@@ -0,0 +1,26 @@
+# -*- Mode: Python -*-
+
+# Note that modules are shared with the QEMU main schema under the assumption
+# that the storage daemon schema is a subset of the main schema. For the shared
+# modules, no code is generated here, but we reuse the code files generated
+# from the main schema.
+#
+# If you wish to extend the storage daemon schema to contain things that are
+# not in the main schema, be aware that array types of types defined in shared
+# modules are only generated if an array of the respective type is already used
+# in the main schema. Therefore, if you use such arrays, you may need to define
+# the array type in the main schema, even if it is unused outside of the
+# storage daemon.
+
+{ 'include': '../../qapi/pragma.json' }
+
+{ 'include': '../../qapi/block-core.json' }
+{ 'include': '../../qapi/char.json' }
+{ 'include': '../../qapi/common.json' }
+{ 'include': '../../qapi/control.json' }
+{ 'include': '../../qapi/crypto.json' }
+{ 'include': '../../qapi/introspect.json' }
+{ 'include': '../../qapi/job.json' }
+{ 'include': '../../qapi/qom.json' }
+{ 'include': '../../qapi/sockets.json' }
+{ 'include': '../../qapi/transaction.json' }