vdpa: introduce config op to get valid iova range

This patch introduce a config op to get valid iova range from the vDPA
device.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20201023090043.14430-2-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

include/linux/vdpa.h

@@ -52,6 +52,16 @@ struct vdpa_device {
 	int nvqs;
 };
 
+/**
+ * vDPA IOVA range - the IOVA range support by the device
+ * @first: start of the IOVA range
+ * @last: end of the IOVA range
+ */
+struct vdpa_iova_range {
+	u64 first;
+	u64 last;
+};
+
 /**
  * vDPA_config_ops - operations for configuring a vDPA device.
  * Note: vDPA device drivers are required to implement all of the
@@ -151,6 +161,10 @@ struct vdpa_device {
  * @get_generation:		Get device config generation (optional)
  *				@vdev: vdpa device
  *				Returns u32: device generation
+ * @get_iova_range:		Get supported iova range (optional)
+ *				@vdev: vdpa device
+ *				Returns the iova range supported by
+ *				the device.
  * @set_map:			Set device memory mapping (optional)
  *				Needed for device that using device
  *				specific DMA translation (on-chip IOMMU)
@@ -216,6 +230,7 @@ struct vdpa_config_ops {
 	void (*set_config)(struct vdpa_device *vdev, unsigned int offset,
 			   const void *buf, unsigned int len);
 	u32 (*get_generation)(struct vdpa_device *vdev);
+	struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
 
 	/* DMA ops */
 	int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb);