@@ -37,6 +37,10 @@ MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
MODULE_LICENSE("GPL");
+static int modparam_list_all;
+module_param_named(list_all, modparam_list_all, int, 0444);
+MODULE_PARM_DESC(list_all, "List all fw-cfg items under by_name sysfs folder.");
+
/* selector key values for "well-known" fw_cfg entries */
#define FW_CFG_SIGNATURE 0x00
#define FW_CFG_ID 0x01
@@ -452,6 +456,10 @@ static int fw_cfg_register_file(const struct fw_cfg_file *f)
int err;
struct fw_cfg_sysfs_entry *entry;
+ /* skip listing item if name does not begin with "opt/" */
+ if (!modparam_list_all && strncmp(f->name, "opt/", 4))
+ return 0;
+
/* allocate new entry */
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
Per the QEMU fw_cfg documentation, items targeted at guest-side userspace should have names beginning with the string "opt/". This patch limits the default sysfs fw_cfg listing to items named "opt/*". The "opt/" prefix on a fw_cfg item name may be interpreted as being analogous to bit 2 in ACPI's _STA object return value (i.e., "show in UI"). A full listing of all fw_cfg items can still be made available by enabling the 'list_all' module parameter, also introduced by this patch. Suggested-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Gabriel Somlo <somlo@cmu.edu> --- Sorry it took me this long to whip together the few lines of code below -- end-of-semester craziness happened, and I'm just beginning to recover... :) I've (somewhat reluctantly) modified the fw-cfg sysfs driver to only show blobs named "opt/*" by default, at Michael's request. Even though my instinct tells me hardcoding "opt/" in the source feels a bit like mixing in policy, the argument that "opt/" is analogous to the ACPI "hide from u/i" bit does make a lot of sense. Personally, I can live with non-"opt/" blobs being hidden by default, particularly since I'm still allowing them to be listed via the "list-all" module parameter. I'm cc-ing everyone I can remember showing any interest in this driver and/or offering help and feedback, for a chance to comment (with apologies if I left out anyone). Absent any further objections, I'm personally OK with defaulting to "opt/"-only blobs being shown to userspace. Thanks again for all the help and feedback, --Gabriel drivers/firmware/qemu_fw_cfg.c | 8 ++++++++ 1 file changed, 8 insertions(+)