vhost: allow per device message handler

This patch allow device to register its own message handler during
vhost_dev_init(). vDPA device will use it to implement its own DMA
mapping logic.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20200326140125.19794-3-jasowang@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/net.c

@@ -1324,7 +1324,8 @@ static int vhost_net_open(struct inode *inode, struct file *f)
 	}
 	vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
 		       UIO_MAXIOV + VHOST_NET_BATCH,
-		       VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT);
+		       VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT,
+		       NULL);
 
 	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
 	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);

drivers/vhost/scsi.c

@@ -1628,7 +1628,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 		vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;
 	}
 	vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV,
-		       VHOST_SCSI_WEIGHT, 0);
+		       VHOST_SCSI_WEIGHT, 0, NULL);
 
 	vhost_scsi_init_inflight(vs, NULL);
 

drivers/vhost/vhost.c

@@ -457,7 +457,9 @@ static size_t vhost_get_desc_size(struct vhost_virtqueue *vq,
 
 void vhost_dev_init(struct vhost_dev *dev,
 		    struct vhost_virtqueue **vqs, int nvqs,
-		    int iov_limit, int weight, int byte_weight)
+		    int iov_limit, int weight, int byte_weight,
+		    int (*msg_handler)(struct vhost_dev *dev,
+				       struct vhost_iotlb_msg *msg))
 {
 	struct vhost_virtqueue *vq;
 	int i;
@@ -473,6 +475,7 @@ void vhost_dev_init(struct vhost_dev *dev,
 	dev->iov_limit = iov_limit;
 	dev->weight = weight;
 	dev->byte_weight = byte_weight;
+	dev->msg_handler = msg_handler;
 	init_llist_head(&dev->work_list);
 	init_waitqueue_head(&dev->wait);
 	INIT_LIST_HEAD(&dev->read_list);
@@ -1178,7 +1181,12 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
 		ret = -EINVAL;
 		goto done;
 	}
-	if (vhost_process_iotlb_msg(dev, &msg)) {
+
+	if (dev->msg_handler)
+		ret = dev->msg_handler(dev, &msg);
+	else
+		ret = vhost_process_iotlb_msg(dev, &msg);
+	if (ret) {
 		ret = -EFAULT;
 		goto done;
 	}

drivers/vhost/vhost.h

@@ -174,11 +174,15 @@ struct vhost_dev {
 	int weight;
 	int byte_weight;
 	u64 kcov_handle;
+	int (*msg_handler)(struct vhost_dev *dev,
+			   struct vhost_iotlb_msg *msg);
 };
 
 bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);
 void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs,
-		    int nvqs, int iov_limit, int weight, int byte_weight);
+		    int nvqs, int iov_limit, int weight, int byte_weight,
+		    int (*msg_handler)(struct vhost_dev *dev,
+				       struct vhost_iotlb_msg *msg));
 long vhost_dev_set_owner(struct vhost_dev *dev);
 bool vhost_dev_has_owner(struct vhost_dev *dev);
 long vhost_dev_check_owner(struct vhost_dev *);

drivers/vhost/vsock.c

@@ -621,7 +621,7 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
 
 	vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
 		       UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
-		       VHOST_VSOCK_WEIGHT);
+		       VHOST_VSOCK_WEIGHT, NULL);
 
 	file->private_data = vsock;
 	spin_lock_init(&vsock->send_pkt_list_lock);