Commit 452639a6 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

vdpa: make sure set_features is invoked for legacy 



Some legacy guests just assume features are 0 after reset.
We detect that config space is accessed before features are
set and set features to 0 automatically.
Note: some legacy guests might not even access config space, if this is
reported in the field we might need to catch a kick to handle these.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 03bea764

drivers/vdpa/vdpa.c

+1 −0
Original line number Diff line number Diff line
@@ -96,6 +96,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent, 
	vdev->dev.release = vdpa_release_dev;

	vdev->index = err;

	vdev->config = config;

	vdev->features_valid = false;



	err = dev_set_name(&vdev->dev, "vdpa%u", vdev->index);

	if (err)

include/linux/vdpa.h

+34 −0
Original line number Diff line number Diff line
@@ -33,12 +33,14 @@ struct vdpa_notification_area { 
 * @dma_dev: the actual device that is performing DMA

 * @config: the configuration ops for this device.

 * @index: device index

 * @features_valid: were features initialized? for legacy guests

 */

struct vdpa_device {

	struct device dev;

	struct device *dma_dev;

	const struct vdpa_config_ops *config;

	unsigned int index;

	bool features_valid;

};



/**
@@ -266,4 +268,36 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev) 
{

	return vdev->dma_dev;

}



static inline void vdpa_reset(struct vdpa_device *vdev)

{

        const struct vdpa_config_ops *ops = vdev->config;



	vdev->features_valid = false;

        ops->set_status(vdev, 0);

}



static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)

{

        const struct vdpa_config_ops *ops = vdev->config;



	vdev->features_valid = true;

        return ops->set_features(vdev, features);

}





static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,

				   void *buf, unsigned int len)

{

        const struct vdpa_config_ops *ops = vdev->config;



	/*

	 * Config accesses aren't supposed to trigger before features are set.

	 * If it does happen we assume a legacy guest.

	 */

	if (!vdev->features_valid)

		vdpa_set_features(vdev, 0);

	ops->get_config(vdev, offset, buf, len);

}



#endif /* _LINUX_VDPA_H */