mei: connection to fixed address clients from user-space

This should be used for debug only.
The feaure is gated by "allow_fixed_address" control exposed in debugfs.
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/debugfs.c

@@ -209,6 +209,12 @@ int mei_dbgfs_register(struct mei_device *dev, const char *name)
 		dev_err(dev->dev, "devstate: registration failed\n");
 		goto err;
 	}
+	f = debugfs_create_bool("allow_fixed_address", S_IRUSR | S_IWUSR, dir,
+				&dev->allow_fixed_address);
+	if (!f) {
+		dev_err(dev->dev, "allow_fixed_address: registration failed\n");
+		goto err;
+	}
 	dev->dbgfs_dir = dir;
 	return 0;
 err:

drivers/misc/mei/main.c

@@ -215,6 +215,11 @@ static ssize_t mei_read(struct file *file, char __user *ubuf,
 
 	cb = mei_cl_read_cb(cl, file);
 	if (!cb) {
+		if (mei_cl_is_fixed_address(cl) && dev->allow_fixed_address) {
+			cb = mei_cl_read_cb(cl, NULL);
+			if (cb)
+				goto copy_buffer;
+		}
 		rets = 0;
 		goto out;
 	}
@@ -389,7 +394,8 @@ static int mei_ioctl_connect_client(struct file *file,
 
 	/* find ME client we're trying to connect to */
 	me_cl = mei_me_cl_by_uuid(dev, &data->in_client_uuid);
-	if (!me_cl || me_cl->props.fixed_address) {
+	if (!me_cl ||
+	    (me_cl->props.fixed_address && !dev->allow_fixed_address)) {
 		dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
 			&data->in_client_uuid);
 		mei_me_cl_put(me_cl);

drivers/misc/mei/mei_dev.h

@@ -476,6 +476,8 @@ const char *mei_pg_state_str(enum mei_pg_state state);
  * @host_clients_map : host clients id pool
  * @me_client_index : last FW client index in enumeration
  *
+ * @allow_fixed_address: allow user space to connect a fixed client
+ *
  * @wd_cl       : watchdog client
  * @wd_state    : watchdog client state
  * @wd_pending  : watchdog command is pending
@@ -567,6 +569,8 @@ struct mei_device {
 	DECLARE_BITMAP(host_clients_map, MEI_CLIENTS_MAX);
 	unsigned long me_client_index;
 
+	u32 allow_fixed_address;
+
 	struct mei_cl wd_cl;
 	enum mei_wd_states wd_state;
 	bool wd_pending;