On Wed, Apr 29, 2015 at 11:21:53AM -0400, Gabriel L. Somlo wrote:
> 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 <so...@cmu.edu>
> Reviewed-by: Laszlo Ersek <ler...@redhat.com>
Would it make sense to make an illegal prefix a hard failure
instead?
If we don't, we'll be unable to add new file names without
fear of conflicts in the future.
> ---
> docs/specs/fw_cfg.txt | 21 +++++++++++++++++
> qemu-options.hx | 11 +++++++++
> vl.c | 63
> +++++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 95 insertions(+)
>
> diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt
> index 6accd92..74351dd 100644
> --- a/docs/specs/fw_cfg.txt
> +++ b/docs/specs/fw_cfg.txt
> @@ -203,3 +203,24 @@ completes fully overwriting the item's data.
>
> NOTE: This function is deprecated, and will be completely removed
> starting with QEMU v2.4.
> +
> +== Externally Provided Items ==
> +
> +As of 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:
> +
> + -fw_cfg [name=]<item_name>,file=<path>
> +
> +where <item_name> is the fw_cfg item name, and <path> is the location
> +on the host file system of a file containing the data to be inserted.
> +
> +NOTE: Users *SHOULD* choose item names beginning with the prefix "opt/"
> +when using the "-fw_cfg" command line option, to avoid conflicting with
> +item names used internally by QEMU. For instance:
> +
> + -fw_cfg name=opt/my_item_name,file=./my_blob.bin
> +
> +Similarly, QEMU developers *SHOULD NOT* use item names prefixed with
> +"opt/" when inserting items programmatically, e.g. via fw_cfg_add_file().
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 319d971..aa386b4 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -2668,6 +2668,17 @@ STEXI
> @table @option
> ETEXI
>
> +DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
> + "-fw_cfg [name=]<name>,file=<file>\n"
> + " add named fw_cfg entry from file\n",
> + QEMU_ARCH_ALL)
> +STEXI
> +@item -fw_cfg [name=]@var{name},file=@var{file}
> +@findex -fw_cfg
> +Add named fw_cfg entry from file. @var{name} determines the name of
> +the entry in the fw_cfg file directory exposed to the guest.
> +ETEXI
> +
> DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
> "-serial dev redirect the serial port to char device 'dev'\n",
> QEMU_ARCH_ALL)
> diff --git a/vl.c b/vl.c
> index 74c2681..b02b2d4 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -490,6 +490,25 @@ static QemuOptsList qemu_semihosting_config_opts = {
> },
> };
>
> +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
> *
> @@ -2118,6 +2137,38 @@ char *qemu_find_file(int type, const char *name)
> return NULL;
> }
>
> +static int parse_fw_cfg(QemuOpts *opts, void *opaque)
> +{
> + 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(QemuOpts *opts, void *opaque)
> {
> return qdev_device_help(opts);
> @@ -2806,6 +2857,7 @@ int main(int argc, char **argv, char **envp)
> 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();
>
> @@ -3422,6 +3474,12 @@ int main(int argc, char **argv, char **envp)
> }
> 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);
> @@ -4233,6 +4291,11 @@ int main(int argc, char **argv, char **envp)
>
> numa_post_machine_init();
>
> + if (qemu_opts_foreach(qemu_find_opts("fw_cfg"),
> + parse_fw_cfg, fw_cfg_find(), 1) != 0) {
> + exit(1);
> + }
> +
> /* init USB devices */
> if (usb_enabled()) {
> if (foreach_device_config(DEV_USB, usb_parse) < 0)
> --
> 2.1.0
>
