Gerd, Corey: there's a question for you near the end, please.
On 05/28/20 19:31, Philippe Mathieu-Daudé wrote:
> The 'gen_id' argument refers to a QOM object able to produce
> data consumable by the fw_cfg device. The producer object must
> implement the FW_CFG_DATA_GENERATOR interface.
>
> Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
> ---
> v7:
> - renamed 'blob_id' -> 'gen_id' (danpb)
> - update comment in code (lersek)
> - fixed CODING_STYLE (lersek)
> - use Laszlo's if (SUM(options)) != 1 { error } form
> ---
> softmmu/vl.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index ae5451bc23..cdb1d187ed 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -489,6 +489,11 @@ static QemuOptsList qemu_fw_cfg_opts = {
> .name = "string",
> .type = QEMU_OPT_STRING,
> .help = "Sets content of the blob to be inserted from a string",
> + }, {
> + .name = "gen_id",
> + .type = QEMU_OPT_STRING,
> + .help = "Sets id of the object generating the fw_cfg blob "
> + "to be inserted",
> },
> { /* end of list */ }
> },
> @@ -2020,7 +2025,7 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts,
> Error **errp)
> {
> gchar *buf;
> size_t size;
> - const char *name, *file, *str;
> + const char *name, *file, *str, *gen_id;
> FWCfgState *fw_cfg = (FWCfgState *) opaque;
>
> if (fw_cfg == NULL) {
> @@ -2030,14 +2035,13 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts,
> Error **errp)
> name = qemu_opt_get(opts, "name");
> file = qemu_opt_get(opts, "file");
> str = qemu_opt_get(opts, "string");
> + gen_id = qemu_opt_get(opts, "gen_id");
>
> - /* we need name and either a file or the content string */
> - if (!(nonempty_str(name) && (nonempty_str(file) || nonempty_str(str)))) {
> - error_setg(errp, "invalid argument(s)");
> - return -1;
> - }
> - if (nonempty_str(file) && nonempty_str(str)) {
> - error_setg(errp, "file and string are mutually exclusive");
> + /* we need the name, and exactly one of: file, content string, gen_id */
> + if (!nonempty_str(name) ||
> + nonempty_str(file) + nonempty_str(str) + nonempty_str(gen_id) !=
> 1) {
(1) I believe the indentation of this line is not correct. I think it
should be out-dented by 2 spaces.
> + error_setg(errp, "name, plus exactly one of file,"
> + " string and gen_id, are needed");
> return -1;
> }
> if (strlen(name) > FW_CFG_MAX_FILE_PATH - 1) {
> @@ -2052,6 +2056,8 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts,
> Error **errp)
> if (nonempty_str(str)) {
> size = strlen(str); /* NUL terminator NOT included in fw_cfg blob */
> buf = g_memdup(str, size);
> + } else if (nonempty_str(gen_id)) {
> + return fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
(2) This is no longer correct: fw_cfg_add_from_generator() now returns 0
on failure, but parse_fw_cfg() is supposed to return nonzer on failure.
See the comment on qemu_opts_foreach() -- "parse_fw_cfg" is passed as
the loop callback to qemu_opts_foreach().
Technically, we could simply write
return !fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
but that wouldn't be consistent with the -1 error codes returned
elsewhere from parse_fw_cfg(). So how about:
size_t fw_cfg_size;
fw_cfg_size = fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
return (fw_cfg_size > 0) ? 0 : -1;
I think your testing may have missed this because the problem is only
visible if you have *another* -fw_cfg option on the QEMU command line.
Returning the wrong status code from here terminates the
qemu_opts_foreach() loop, without attempting to set "error_fatal".
Therefore the loop is silently terminated, thus the only symptom would
be that -fw_cfg options beyond the "gen_id" one wouldn't take effect.
(3) I've noticed another *potential* issue, from looking at the larger
context. I apologize for missing it in v6.
See commit bab47d9a75a3 ("Sort the fw_cfg file list", 2016-04-07). (I'm
copying Corey; Gerd is already copied.) From that commit, we have, at
the end of this function:
/* For legacy, keep user files in a specific global order. */
fw_cfg_set_order_override(fw_cfg, FW_CFG_ORDER_OVERRIDE_USER);
fw_cfg_add_file(fw_cfg, name, buf, size);
fw_cfg_reset_order_override(fw_cfg);
This takes effect for "file" and "string", but not for "gen_id". Should
we apply it to "gen_id" as well? (Sorry, I really don't understand what
commit bab47d9a75a3 is about!)
*IF* we want to apply the same logic to "gen_id", then we should
*perhaps* do, on the "nonempty_str(gen_id)" branch:
size_t fw_cfg_size;
fw_cfg_set_order_override(fw_cfg, FW_CFG_ORDER_OVERRIDE_USER);
fw_cfg_size = fw_cfg_add_from_generator(fw_cfg, name, gen_id, errp);
fw_cfg_reset_order_override(fw_cfg);
return (fw_cfg_size > 0) ? 0 : -1;
I think???
Or maybe even use FW_CFG_ORDER_OVERRIDE_DEVICE rather than
FW_CFG_ORDER_OVERRIDE_USER? I don't have the slightest clue.
(I guess if I understood what commit bab47d9a75a3 was about, I'd be less
in doubt now. But that commit only hints at "avoid[ing] any future
issues of moving the file creation" -- I don't know what those issues
were in the first place!)
With (1) optionally fixed, and (2) fixed, I'd be willing to R-b this
patch; but I'm really thrown off by (3).
Thanks,
Laszlo
> } else {
> GError *err = NULL;
> if (!g_file_get_contents(file, &buf, &size, &err)) {
>
