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>

include/rdma/ib_verbs.h

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 38a08da..4bdd898 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -1370,10 +1370,13 @@
 
 struct ib_pd {
 	u32			local_dma_lkey;
+	u32			flags;
 	struct ib_device       *device;
 	struct ib_uobject      *uobject;
 	atomic_t          	usecnt; /* count all resources */
 
+	u32			unsafe_global_rkey;
+
 	/*
 	 * Implementation details of the RDMA core, don't use in drivers:
 	 */
@@ -2506,8 +2509,23 @@
 int ib_find_pkey(struct ib_device *device,
 		 u8 port_num, u16 pkey, u16 *index);
 
-struct ib_pd *ib_alloc_pd(struct ib_device *device);
+enum ib_pd_flags {
+	/*
+	 * Create a memory registration for all memory in the system and place
+	 * the rkey for it into pd->unsafe_global_rkey.  This can be used by
+	 * ULPs to avoid the overhead of dynamic MRs.
+	 *
+	 * This flag is generally considered unsafe and must only be used in
+	 * extremly trusted environments.  Every use of it will log a warning
+	 * in the kernel log.
+	 */
+	IB_PD_UNSAFE_GLOBAL_RKEY	= 0x01,
+};
 
+struct ib_pd *__ib_alloc_pd(struct ib_device *device, unsigned int flags,
+		const char *caller);
+#define ib_alloc_pd(device, flags) \
+	__ib_alloc_pd((device), (flags), __func__)
 void ib_dealloc_pd(struct ib_pd *pd);
 
 /**