I did a very simple test :
1, modify qemu/hw/block/virtio-blk.c, let virtio-blk use 256 queue:
s->vq = virtio_add_queue(vdev, 128, virtio_blk_handle_output);
--> s->vq = virtio_add_queue(vdev, 256 , virtio_blk_handle_output);

2, compile qemu and run a VM which boots from virtio-blk disk.

The VM can NOT boot because seabios use macro MAX_QUEUE_NUM as 128.
So, does virtio-pci support more queues?
Looking forward your reply!

-- 
Rather than love ,than money ,than faith,than fame,than fairness,give me truth.