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 <[email protected]>
opendata26 · Apr 7, 2017 · 404123c · 404123c
1 parent 2e123b4
commit 404123c
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diff --git 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
@@ -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);