virtio: allow drivers to validate features
Some drivers can't support all features in all configurations. At the
moment we blindly set FEATURES_OK and later FAILED. Support this better
by adding a callback drivers can use to do some early checks.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 400d70b..48230a5 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -232,6 +232,12 @@ static int virtio_dev_probe(struct device *_d)
if (device_features & (1ULL << i))
__virtio_set_bit(dev, i);
+ if (drv->validate) {
+ err = drv->validate(dev);
+ if (err)
+ goto err;
+ }
+
err = virtio_finalize_features(dev);
if (err)
goto err;
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 04b0d3f..7edfbdb 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -167,6 +167,7 @@ struct virtio_driver {
unsigned int feature_table_size;
const unsigned int *feature_table_legacy;
unsigned int feature_table_size_legacy;
+ int (*validate)(struct virtio_device *dev);
int (*probe)(struct virtio_device *dev);
void (*scan)(struct virtio_device *dev);
void (*remove)(struct virtio_device *dev);