IB/uverbs: Export ib_umem_get()/ib_umem_release() to modules

Export ib_umem_get()/ib_umem_release() and put low-level drivers in
control of when to call ib_umem_get() to pin and DMA map userspace,
rather than always calling it in ib_uverbs_reg_mr() before calling the
low-level driver's reg_user_mr method.

Also move these functions to be in the ib_core module instead of
ib_uverbs, so that driver modules using them do not depend on
ib_uverbs.

This has a number of advantages:
 - It is better design from the standpoint of making generic code a
   library that can be used or overridden by device-specific code as
   the details of specific devices dictate.
 - Drivers that do not need to pin userspace memory regions do not
   need to take the performance hit of calling ib_mem_get().  For
   example, although I have not tried to implement it in this patch,
   the ipath driver should be able to avoid pinning memory and just
   use copy_{to,from}_user() to access userspace memory regions.
 - Buffers that need special mapping treatment can be identified by
   the low-level driver.  For example, it may be possible to solve
   some Altix-specific memory ordering issues with mthca CQs in
   userspace by mapping CQ buffers with extra flags.
 - Drivers that need to pin and DMA map userspace memory for things
   other than memory regions can use ib_umem_get() directly, instead
   of hacks using extra parameters to their reg_phys_mr method.  For
   example, the mlx4 driver that is pending being merged needs to pin
   and DMA map QP and CQ buffers, but it does not need to create a
   memory key for these buffers.  So the cleanest solution is for mlx4
   to call ib_umem_get() in the create_qp and create_cq methods.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

include/rdma/ib_umem.h

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2007 Cisco Systems.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef IB_UMEM_H
+#define IB_UMEM_H
+
+#include <linux/list.h>
+#include <linux/scatterlist.h>
+
+struct ib_ucontext;
+
+struct ib_umem {
+	struct ib_ucontext     *context;
+	size_t			length;
+	int			offset;
+	int			page_size;
+	int                     writable;
+	struct list_head	chunk_list;
+};
+
+struct ib_umem_chunk {
+	struct list_head	list;
+	int                     nents;
+	int                     nmap;
+	struct scatterlist      page_list[0];
+};
+
+#ifdef CONFIG_INFINIBAND_USER_MEM
+
+struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
+			    size_t size, int access);
+void ib_umem_release(struct ib_umem *umem);
+int ib_umem_page_count(struct ib_umem *umem);
+
+#else /* CONFIG_INFINIBAND_USER_MEM */
+
+#include <linux/err.h>
+
+static inline struct ib_umem *ib_umem_get(struct ib_ucontext *context,
+					  unsigned long addr, size_t size,
+					  int access) {
+	return ERR_PTR(-EINVAL);
+}
+static inline void ib_umem_release(struct ib_umem *umem) { }
+static inline int ib_umem_page_count(struct ib_umem *umem) { return 0; }
+
+#endif /* CONFIG_INFINIBAND_USER_MEM */
+
+#endif /* IB_UMEM_H */

include/rdma/ib_verbs.h

@@ -5,7 +5,7 @@
  * Copyright (c) 2004 Topspin Corporation.  All rights reserved.
  * Copyright (c) 2004 Voltaire Corporation.  All rights reserved.
  * Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
- * Copyright (c) 2005, 2006 Cisco Systems.  All rights reserved.
+ * Copyright (c) 2005, 2006, 2007 Cisco Systems.  All rights reserved.
  *
  * This software is available to you under a choice of one of two
  * licenses.  You may choose to be licensed under the terms of the GNU
@@ -710,6 +710,7 @@ struct ib_ucontext {
 	struct list_head	qp_list;
 	struct list_head	srq_list;
 	struct list_head	ah_list;
+	int			closing;
 };
 
 struct ib_uobject {
@@ -723,23 +724,6 @@ struct ib_uobject {
 	int			live;
 };
 
-struct ib_umem {
-	unsigned long		user_base;
-	unsigned long		virt_base;
-	size_t			length;
-	int			offset;
-	int			page_size;
-	int                     writable;
-	struct list_head	chunk_list;
-};
-
-struct ib_umem_chunk {
-	struct list_head	list;
-	int                     nents;
-	int                     nmap;
-	struct scatterlist      page_list[0];
-};
-
 struct ib_udata {
 	void __user *inbuf;
 	void __user *outbuf;
@@ -752,11 +736,6 @@ struct ib_udata {
 	 ((void *) &((struct ib_umem_chunk *) 0)->page_list[1] -	\
 	  (void *) &((struct ib_umem_chunk *) 0)->page_list[0]))
 
-struct ib_umem_object {
-	struct ib_uobject	uobject;
-	struct ib_umem		umem;
-};
-
 struct ib_pd {
 	struct ib_device       *device;
 	struct ib_uobject      *uobject;
@@ -1003,7 +982,8 @@ struct ib_device {
 						  int mr_access_flags,
 						  u64 *iova_start);
 	struct ib_mr *             (*reg_user_mr)(struct ib_pd *pd,
-						  struct ib_umem *region,
+						  u64 start, u64 length,
+						  u64 virt_addr,
 						  int mr_access_flags,
 						  struct ib_udata *udata);
 	int                        (*query_mr)(struct ib_mr *mr,