IB/core: add support to create a unsafe global rkey to ib_create_pd

Instead of exposing ib_get_dma_mr to ULPs and letting them use it more or
less unchecked, this moves the capability of creating a global rkey into
the RDMA core, where it can be easily audited.  It also prints a warning
everytime this feature is used as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx4/mad.c

@@ -1897,7 +1897,7 @@ static int create_pv_resources(struct ib_device *ibdev, int slave, int port,
 		goto err_buf;
 	}
 
-	ctx->pd = ib_alloc_pd(ctx->ib_dev);
+	ctx->pd = ib_alloc_pd(ctx->ib_dev, 0);
 	if (IS_ERR(ctx->pd)) {
 		ret = PTR_ERR(ctx->pd);
 		pr_err("Couldn't create tunnel PD (%d)\n", ret);