virtio_ring: introduce dma sync api for virtqueue

These API has been introduced:

* virtqueue_dma_need_sync
* virtqueue_dma_sync_single_range_for_cpu
* virtqueue_dma_sync_single_range_for_device

These APIs can be used together with the premapped mechanism to sync the
DMA address.

Signed-off-by: Xuan Zhuo <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>

drivers/virtio/virtio_ring.c

···
 }
 EXPORT_SYMBOL_GPL(virtqueue_dma_mapping_error);
 
+/**
+ * virtqueue_dma_need_sync - check a dma address needs sync
+ * @_vq: the struct virtqueue we're talking about.
+ * @addr: DMA address
+ *
+ * Check if the dma address mapped by the virtqueue_dma_map_* APIs needs to be
+ * synchronized
+ *
+ * return bool
+ */
+bool virtqueue_dma_need_sync(struct virtqueue *_vq, dma_addr_t addr)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	if (!vq->use_dma_api)
+		return false;
+
+	return dma_need_sync(vring_dma_dev(vq), addr);
+}
+EXPORT_SYMBOL_GPL(virtqueue_dma_need_sync);
+
+/**
+ * virtqueue_dma_sync_single_range_for_cpu - dma sync for cpu
+ * @_vq: the struct virtqueue we're talking about.
+ * @addr: DMA address
+ * @offset: DMA address offset
+ * @size: buf size for sync
+ * @dir: DMA direction
+ *
+ * Before calling this function, use virtqueue_dma_need_sync() to confirm that
+ * the DMA address really needs to be synchronized
+ *
+ */
+void virtqueue_dma_sync_single_range_for_cpu(struct virtqueue *_vq,
+					     dma_addr_t addr,
+					     unsigned long offset, size_t size,
+					     enum dma_data_direction dir)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct device *dev = vring_dma_dev(vq);
+
+	if (!vq->use_dma_api)
+		return;
+
+	dma_sync_single_range_for_cpu(dev, addr, offset, size,
+				      DMA_BIDIRECTIONAL);
+}
+EXPORT_SYMBOL_GPL(virtqueue_dma_sync_single_range_for_cpu);
+
+/**
+ * virtqueue_dma_sync_single_range_for_device - dma sync for device
+ * @_vq: the struct virtqueue we're talking about.
+ * @addr: DMA address
+ * @offset: DMA address offset
+ * @size: buf size for sync
+ * @dir: DMA direction
+ *
+ * Before calling this function, use virtqueue_dma_need_sync() to confirm that
+ * the DMA address really needs to be synchronized
+ */
+void virtqueue_dma_sync_single_range_for_device(struct virtqueue *_vq,
+						dma_addr_t addr,
+						unsigned long offset, size_t size,
+						enum dma_data_direction dir)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct device *dev = vring_dma_dev(vq);
+
+	if (!vq->use_dma_api)
+		return;
+
+	dma_sync_single_range_for_device(dev, addr, offset, size,
+					 DMA_BIDIRECTIONAL);
+}
+EXPORT_SYMBOL_GPL(virtqueue_dma_sync_single_range_for_device);
+
 MODULE_LICENSE("GPL");

include/linux/virtio.h

···
 				      size_t size, enum dma_data_direction dir,
 				      unsigned long attrs);
 int virtqueue_dma_mapping_error(struct virtqueue *_vq, dma_addr_t addr);
+
+bool virtqueue_dma_need_sync(struct virtqueue *_vq, dma_addr_t addr);
+void virtqueue_dma_sync_single_range_for_cpu(struct virtqueue *_vq, dma_addr_t addr,
+					     unsigned long offset, size_t size,
+					     enum dma_data_direction dir);
+void virtqueue_dma_sync_single_range_for_device(struct virtqueue *_vq, dma_addr_t addr,
+						unsigned long offset, size_t size,
+						enum dma_data_direction dir);
 #endif /* _LINUX_VIRTIO_H */