virtio/console: verify device has config space

Some devices might not implement config space access
(e.g. remoteproc used not to - before 3.9).
virtio/console needs config space access so make it
fail gracefully if not there.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index de03df9dd7c9..26afb56a8073 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1986,6 +1986,12 @@ static int virtcons_probe(struct virtio_device *vdev)
         bool multiport;
         bool early = early_put_chars != NULL;
 
+        if (!vdev->config->get) {
+                dev_err(&vdev->dev, "%s failure: config access disabled\n",
+                        __func__);
+                return -EINVAL;
+        }
+
         /* Ensure to read early_put_chars now */
         barrier();