/* Host publishes avail event idx */
bool event;
+ /* Do DMA mapping by driver */
+ bool premapped;
+
/* Head of free buffer list. */
unsigned int free_head;
/* Number we've added since last sync. */
vq->packed_ring = true;
vq->dma_dev = dma_dev;
vq->use_dma_api = vring_use_dma_api(vdev);
+ vq->premapped = false;
vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
!context;
#endif
vq->dma_dev = dma_dev;
vq->use_dma_api = vring_use_dma_api(vdev);
+ vq->premapped = false;
vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) &&
!context;
}
EXPORT_SYMBOL_GPL(virtqueue_resize);
+/**
+ * virtqueue_set_dma_premapped - set the vring premapped mode
+ * @_vq: the struct virtqueue we're talking about.
+ *
+ * Enable the premapped mode of the vq.
+ *
+ * The vring in premapped mode does not do dma internally, so the driver must
+ * do dma mapping in advance. The driver must pass the dma_address through
+ * dma_address of scatterlist. When the driver got a used buffer from
+ * the vring, it has to unmap the dma address.
+ *
+ * This function must be called immediately after creating the vq, or after vq
+ * reset, and before adding any buffers to it.
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error.
+ * 0: success.
+ * -EINVAL: vring does not use the dma api, so we can not enable premapped mode.
+ */
+int virtqueue_set_dma_premapped(struct virtqueue *_vq)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ u32 num;
+
+ START_USE(vq);
+
+ num = vq->packed_ring ? vq->packed.vring.num : vq->split.vring.num;
+
+ if (num != vq->vq.num_free) {
+ END_USE(vq);
+ return -EINVAL;
+ }
+
+ if (!vq->use_dma_api) {
+ END_USE(vq);
+ return -EINVAL;
+ }
+
+ vq->premapped = true;
+
+ END_USE(vq);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(virtqueue_set_dma_premapped);
+
/* Only available for split ring */
struct virtqueue *vring_new_virtqueue(unsigned int index,
unsigned int num,