1/*
  2 * Copyright (c) 2014 Mellanox Technologies. All rights reserved.
  3 *
  4 * This software is available to you under a choice of one of two
  5 * licenses.  You may choose to be licensed under the terms of the GNU
  6 * General Public License (GPL) Version 2, available from the file
  7 * COPYING in the main directory of this source tree, or the
  8 * OpenIB.org BSD license below:
  9 *
 10 *     Redistribution and use in source and binary forms, with or
 11 *     without modification, are permitted provided that the following
 12 *     conditions are met:
 13 *
 14 *      - Redistributions of source code must retain the above
 15 *        copyright notice, this list of conditions and the following
 16 *        disclaimer.
 17 *
 18 *      - Redistributions in binary form must reproduce the above
 19 *        copyright notice, this list of conditions and the following
 20 *        disclaimer in the documentation and/or other materials
 21 *        provided with the distribution.
 22 *
 23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 30 * SOFTWARE.
 31 */
 32
 33#ifndef IB_UMEM_ODP_H
 34#define IB_UMEM_ODP_H
 35
 36#include <rdma/ib_umem.h>
 37#include <rdma/ib_verbs.h>
 38#include <linux/interval_tree.h>
 39
 40struct umem_odp_node {
 41	u64 __subtree_last;
 42	struct rb_node rb;
 43};
 44
 45struct ib_umem_odp {
 46	/*
 47	 * An array of the pages included in the on-demand paging umem.
 48	 * Indices of pages that are currently not mapped into the device will
 49	 * contain NULL.
 50	 */
 51	struct page		**page_list;
 52	/*
 53	 * An array of the same size as page_list, with DMA addresses mapped
 54	 * for pages the pages in page_list. The lower two bits designate
 55	 * access permissions. See ODP_READ_ALLOWED_BIT and
 56	 * ODP_WRITE_ALLOWED_BIT.
 57	 */
 58	dma_addr_t		*dma_list;
 59	/*
 60	 * The umem_mutex protects the page_list and dma_list fields of an ODP
 61	 * umem, allowing only a single thread to map/unmap pages. The mutex
 62	 * also protects access to the mmu notifier counters.
 63	 */
 64	struct mutex		umem_mutex;
 65	void			*private; /* for the HW driver to use. */
 66
 67	/* When false, use the notifier counter in the ucontext struct. */
 68	bool mn_counters_active;
 69	int notifiers_seq;
 70	int notifiers_count;
 71
 72	/* A linked list of umems that don't have private mmu notifier
 73	 * counters yet. */
 74	struct list_head no_private_counters;
 75	struct ib_umem		*umem;
 76
 77	/* Tree tracking */
 78	struct umem_odp_node	interval_tree;
 79
 80	struct completion	notifier_completion;
 81	int			dying;
 82	struct work_struct	work;
 83};
 84
 85#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
 86
 87int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem,
 88		    int access);
 89struct ib_umem *ib_alloc_odp_umem(struct ib_ucontext *context,
 90				  unsigned long addr,
 91				  size_t size);
 92
 93void ib_umem_odp_release(struct ib_umem *umem);
 94
 95/*
 96 * The lower 2 bits of the DMA address signal the R/W permissions for
 97 * the entry. To upgrade the permissions, provide the appropriate
 98 * bitmask to the map_dma_pages function.
 99 *
100 * Be aware that upgrading a mapped address might result in change of
101 * the DMA address for the page.
102 */
103#define ODP_READ_ALLOWED_BIT  (1<<0ULL)
104#define ODP_WRITE_ALLOWED_BIT (1<<1ULL)
105
106#define ODP_DMA_ADDR_MASK (~(ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT))
107
108int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 start_offset, u64 bcnt,
109			      u64 access_mask, unsigned long current_seq);
110
111void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 start_offset,
112				 u64 bound);
113
114typedef int (*umem_call_back)(struct ib_umem *item, u64 start, u64 end,
115			      void *cookie);
116/*
117 * Call the callback on each ib_umem in the range. Returns the logical or of
118 * the return values of the functions called.
119 */
120int rbt_ib_umem_for_each_in_range(struct rb_root_cached *root,
121				  u64 start, u64 end,
122				  umem_call_back cb, void *cookie);
123
124/*
125 * Find first region intersecting with address range.
126 * Return NULL if not found
127 */
128struct ib_umem_odp *rbt_ib_umem_lookup(struct rb_root_cached *root,
129				       u64 addr, u64 length);
130
131static inline int ib_umem_mmu_notifier_retry(struct ib_umem *item,
132					     unsigned long mmu_seq)
133{
134	/*
135	 * This code is strongly based on the KVM code from
136	 * mmu_notifier_retry. Should be called with
137	 * the relevant locks taken (item->odp_data->umem_mutex
138	 * and the ucontext umem_mutex semaphore locked for read).
139	 */
140
141	/* Do not allow page faults while the new ib_umem hasn't seen a state
142	 * with zero notifiers yet, and doesn't have its own valid set of
143	 * private counters. */
144	if (!item->odp_data->mn_counters_active)
145		return 1;
146
147	if (unlikely(item->odp_data->notifiers_count))
148		return 1;
149	if (item->odp_data->notifiers_seq != mmu_seq)
150		return 1;
151	return 0;
152}
153
154#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
155
156static inline int ib_umem_odp_get(struct ib_ucontext *context,
157				  struct ib_umem *umem,
158				  int access)
159{
160	return -EINVAL;
161}
162
163static inline struct ib_umem *ib_alloc_odp_umem(struct ib_ucontext *context,
164						unsigned long addr,
165						size_t size)
166{
167	return ERR_PTR(-EINVAL);
168}
169
170static inline void ib_umem_odp_release(struct ib_umem *umem) {}
171
172#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
173
174#endif /* IB_UMEM_ODP_H */