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Commit b3bb62d1 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

virtio: add legacy feature table support 



virtio-blk has some legacy feature bits that modern drivers
must not negotiate, but are needed for old legacy hosts
(that e.g. don't support virtio-scsi).
Allow a separate legacy feature table for such cases.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent c102659d

drivers/virtio/virtio.c

+24 −1
Original line number Original line Diff line number Diff line
@@ -113,6 +113,13 @@ void virtio_check_driver_offered_feature(const struct virtio_device *vdev, 
	for (i = 0; i < drv->feature_table_size; i++)

	for (i = 0; i < drv->feature_table_size; i++)

		if (drv->feature_table[i] == fbit)

		if (drv->feature_table[i] == fbit)

			return;

			return;



	if (drv->feature_table_legacy) {

		for (i = 0; i < drv->feature_table_size_legacy; i++)

			if (drv->feature_table_legacy[i] == fbit)

				return;

	}



	BUG();

	BUG();

}

}

EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);

EXPORT_SYMBOL_GPL(virtio_check_driver_offered_feature);
@@ -161,6 +168,7 @@ static int virtio_dev_probe(struct device *_d) 
	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);

	u64 device_features;

	u64 device_features;

	u64 driver_features;

	u64 driver_features;

	u64 driver_features_legacy;

	unsigned status;

	unsigned status;





	/* We have a driver! */

	/* We have a driver! */
@@ -177,7 +185,22 @@ static int virtio_dev_probe(struct device *_d) 
		driver_features |= (1ULL << f);

		driver_features |= (1ULL << f);

	}

	}





	/* Some drivers have a separate feature table for virtio v1.0 */

	if (drv->feature_table_legacy) {

		driver_features_legacy = 0;

		for (i = 0; i < drv->feature_table_size_legacy; i++) {

			unsigned int f = drv->feature_table_legacy[i];

			BUG_ON(f >= 64);

			driver_features_legacy |= (1ULL << f);

		}

	} else {

		driver_features_legacy = driver_features;

	}



	if (driver_features & device_features & (1ULL << VIRTIO_F_VERSION_1))

		dev->features = driver_features & device_features;

		dev->features = driver_features & device_features;

	else

		dev->features = driver_features_legacy & device_features;





	/* Transport features always preserved to pass to finalize_features. */

	/* Transport features always preserved to pass to finalize_features. */

	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)

	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)

include/linux/virtio.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -130,6 +130,8 @@ int virtio_device_restore(struct virtio_device *dev); 
 * @id_table: the ids serviced by this driver.

 * @id_table: the ids serviced by this driver.

 * @feature_table: an array of feature numbers supported by this driver.

 * @feature_table: an array of feature numbers supported by this driver.

 * @feature_table_size: number of entries in the feature table array.

 * @feature_table_size: number of entries in the feature table array.

 * @feature_table_legacy: same as feature_table but when working in legacy mode.

 * @feature_table_size_legacy: number of entries in feature table legacy array.

 * @probe: the function to call when a device is found.  Returns 0 or -errno.

 * @probe: the function to call when a device is found.  Returns 0 or -errno.

 * @remove: the function to call when a device is removed.

 * @remove: the function to call when a device is removed.

 * @config_changed: optional function to call when the device configuration

 * @config_changed: optional function to call when the device configuration
@@ -140,6 +142,8 @@ struct virtio_driver { 
	const struct virtio_device_id *id_table;

	const struct virtio_device_id *id_table;

	const unsigned int *feature_table;

	const unsigned int *feature_table;

	unsigned int feature_table_size;

	unsigned int feature_table_size;

	const unsigned int *feature_table_legacy;

	unsigned int feature_table_size_legacy;

	int (*probe)(struct virtio_device *dev);

	int (*probe)(struct virtio_device *dev);

	void (*scan)(struct virtio_device *dev);

	void (*scan)(struct virtio_device *dev);

	void (*remove)(struct virtio_device *dev);

	void (*remove)(struct virtio_device *dev);