fw_cfg: insert fw_cfg file blobs via qemu cmdline
Allow user supplied files to be inserted into the fw_cfg
device before starting the guest. Since fw_cfg_add_file()
already disallows duplicate fw_cfg file names, qemu will
exit with an error message if the user supplies multiple
blobs with the same fw_cfg file name, or if a blob name
collides with a fw_cfg name programmatically added from
within the QEMU source code. A warning message will be
printed if the fw_cfg item name does not begin with the
prefix "opt/", which is recommended for external, user
provided blobs.
Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/vl.c b/vl.c
index d4b2d03..9542095 100644
--- a/vl.c
+++ b/vl.c
@@ -492,6 +492,25 @@
},
};
+static QemuOptsList qemu_fw_cfg_opts = {
+ .name = "fw_cfg",
+ .implied_opt_name = "name",
+ .head = QTAILQ_HEAD_INITIALIZER(qemu_fw_cfg_opts.head),
+ .desc = {
+ {
+ .name = "name",
+ .type = QEMU_OPT_STRING,
+ .help = "Sets the fw_cfg name of the blob to be inserted",
+ }, {
+ .name = "file",
+ .type = QEMU_OPT_STRING,
+ .help = "Sets the name of the file from which\n"
+ "the fw_cfg blob will be loaded",
+ },
+ { /* end of list */ }
+ },
+};
+
/**
* Get machine options
*
@@ -2127,6 +2146,38 @@
return NULL;
}
+static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp)
+{
+ gchar *buf;
+ size_t size;
+ const char *name, *file;
+
+ if (opaque == NULL) {
+ error_report("fw_cfg device not available");
+ return -1;
+ }
+ name = qemu_opt_get(opts, "name");
+ file = qemu_opt_get(opts, "file");
+ if (name == NULL || *name == '\0' || file == NULL || *file == '\0') {
+ error_report("invalid argument value");
+ return -1;
+ }
+ if (strlen(name) > FW_CFG_MAX_FILE_PATH - 1) {
+ error_report("name too long (max. %d char)", FW_CFG_MAX_FILE_PATH - 1);
+ return -1;
+ }
+ if (strncmp(name, "opt/", 4) != 0) {
+ error_report("WARNING: externally provided fw_cfg item names "
+ "should be prefixed with \"opt/\"!");
+ }
+ if (!g_file_get_contents(file, &buf, &size, NULL)) {
+ error_report("can't load %s", file);
+ return -1;
+ }
+ fw_cfg_add_file((FWCfgState *)opaque, name, buf, size);
+ return 0;
+}
+
static int device_help_func(void *opaque, QemuOpts *opts, Error **errp)
{
return qdev_device_help(opts);
@@ -2822,6 +2873,7 @@
qemu_add_opts(&qemu_numa_opts);
qemu_add_opts(&qemu_icount_opts);
qemu_add_opts(&qemu_semihosting_config_opts);
+ qemu_add_opts(&qemu_fw_cfg_opts);
runstate_init();
@@ -3438,6 +3490,12 @@
}
do_smbios_option(opts);
break;
+ case QEMU_OPTION_fwcfg:
+ opts = qemu_opts_parse(qemu_find_opts("fw_cfg"), optarg, 1);
+ if (opts == NULL) {
+ exit(1);
+ }
+ break;
case QEMU_OPTION_enable_kvm:
olist = qemu_find_opts("machine");
qemu_opts_parse(olist, "accel=kvm", 0);
@@ -4274,6 +4332,11 @@
numa_post_machine_init();
+ if (qemu_opts_foreach(qemu_find_opts("fw_cfg"),
+ parse_fw_cfg, fw_cfg_find(), NULL) != 0) {
+ exit(1);
+ }
+
/* init USB devices */
if (usb_enabled()) {
if (foreach_device_config(DEV_USB, usb_parse) < 0)