diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index 8c5d86cb66..50dc93091d 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -198,6 +198,15 @@ static size_t virtio_9p_msize_limit(V9fsState *s)
     return (VIRTQUEUE_MAX_SIZE - 2) * guestPageSize;
 }
 
+static size_t virtio_9p_response_buffer_size(V9fsPDU *pdu)
+{
+    V9fsState *s = pdu->s;
+    V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
+    VirtQueueElement *elem = v->elems[pdu->idx];
+
+    return iov_size(elem->in_sg, elem->in_num);
+}
+
 static const V9fsTransport virtio_9p_transport = {
     .pdu_vmarshal = virtio_pdu_vmarshal,
     .pdu_vunmarshal = virtio_pdu_vunmarshal,
@@ -205,6 +214,7 @@ static const V9fsTransport virtio_9p_transport = {
     .init_out_iov_from_pdu = virtio_init_out_iov_from_pdu,
     .push_and_notify = virtio_9p_push_and_notify,
     .msize_limit = virtio_9p_msize_limit,
+    .response_buffer_size = virtio_9p_response_buffer_size,
 };
 
 static void virtio_9p_device_realize(DeviceState *dev, Error **errp)