block: Initial implementation of -blockdev

The new command line option -blockdev works like QMP command
blockdev-add.

The option argument may be given in JSON syntax, exactly as in QMP.
Example usage:

    -blockdev '{"node-name": "foo", "driver": "raw", "file": {"driver": "file", "filename": "foo.img"} }'

The JSON argument doesn't exactly blend into the existing option
syntax, so the traditional KEY=VALUE,... syntax is also supported,
using dotted keys to do the nesting:

    -blockdev node-name=foo,driver=raw,file.driver=file,file.filename=foo.img

This does not yet support lists, but that will be addressed shortly.

Note that calling qmp_blockdev_add() (say via qmp_marshal_block_add())
right away would crash.  We need to stash the configuration for later
instead.  This is crudely done, and bypasses QemuOpts, even though
storing configuration is what QemuOpts is for.  Need to revamp option
infrastructure to support QAPI types like BlockdevOptions.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-Id: <1488317230-26248-22-git-send-email-armbru@redhat.com>

qemu-options.hx

@@ -550,6 +550,13 @@ Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
 using @file{/dev/cdrom} as filename (@pxref{host_drives}).
 ETEXI
 
+DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
+    "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
+    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
+    "          [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
+    "          [,driver specific parameters...]\n"
+    "                configure a block backend\n", QEMU_ARCH_ALL)
+
 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
     "       [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"

vl.c

@@ -95,6 +95,9 @@ int main(int argc, char **argv)
 #include "migration/colo.h"
 #include "sysemu/kvm.h"
 #include "sysemu/hax.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi/qobject-input-visitor.h"
+#include "qapi-visit.h"
 #include "qapi/qmp/qjson.h"
 #include "qemu/option.h"
 #include "qemu/config-file.h"
@@ -2976,6 +2979,13 @@ int main(int argc, char **argv, char **envp)
     Error *main_loop_err = NULL;
     Error *err = NULL;
     bool list_data_dirs = false;
+    typedef struct BlockdevOptions_queue {
+        BlockdevOptions *bdo;
+        Location loc;
+        QSIMPLEQ_ENTRY(BlockdevOptions_queue) entry;
+    } BlockdevOptions_queue;
+    QSIMPLEQ_HEAD(, BlockdevOptions_queue) bdo_queue
+        = QSIMPLEQ_HEAD_INITIALIZER(bdo_queue);
 
     module_call_init(MODULE_INIT_TRACE);
 
@@ -3118,6 +3128,25 @@ int main(int argc, char **argv, char **envp)
                 drive_add(IF_DEFAULT, popt->index - QEMU_OPTION_hda, optarg,
                           HD_OPTS);
                 break;
+            case QEMU_OPTION_blockdev:
+                {
+                    Visitor *v;
+                    BlockdevOptions_queue *bdo;
+
+                    v = qobject_input_visitor_new_str(optarg, "driver", &err);
+                    if (!v) {
+                        error_report_err(err);
+                        exit(1);
+                    }
+
+                    bdo = g_new(BlockdevOptions_queue, 1);
+                    visit_type_BlockdevOptions(v, NULL, &bdo->bdo,
+                                               &error_fatal);
+                    visit_free(v);
+                    loc_save(&bdo->loc);
+                    QSIMPLEQ_INSERT_TAIL(&bdo_queue, bdo, entry);
+                    break;
+                }
             case QEMU_OPTION_drive:
                 if (drive_def(optarg) == NULL) {
                     exit(1);
@@ -4451,6 +4480,16 @@ int main(int argc, char **argv, char **envp)
     }
 
     /* open the virtual block devices */
+    while (!QSIMPLEQ_EMPTY(&bdo_queue)) {
+        BlockdevOptions_queue *bdo = QSIMPLEQ_FIRST(&bdo_queue);
+
+        QSIMPLEQ_REMOVE_HEAD(&bdo_queue, entry);
+        loc_push_restore(&bdo->loc);
+        qmp_blockdev_add(bdo->bdo, &error_fatal);
+        loc_pop(&bdo->loc);
+        qapi_free_BlockdevOptions(bdo->bdo);
+        g_free(bdo);
+    }
     if (snapshot || replay_mode != REPLAY_MODE_NONE) {
         qemu_opts_foreach(qemu_find_opts("drive"), drive_enable_snapshot,
                           NULL, NULL);