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};
 83
 84#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
 85
 86int ib_umem_odp_get(struct ib_ucontext *context, struct ib_umem *umem);
 87
 88void ib_umem_odp_release(struct ib_umem *umem);
 89
 90/*
 91 * The lower 2 bits of the DMA address signal the R/W permissions for
 92 * the entry. To upgrade the permissions, provide the appropriate
 93 * bitmask to the map_dma_pages function.
 94 *
 95 * Be aware that upgrading a mapped address might result in change of
 96 * the DMA address for the page.
 97 */
 98#define ODP_READ_ALLOWED_BIT  (1<<0ULL)
 99#define ODP_WRITE_ALLOWED_BIT (1<<1ULL)
100
101#define ODP_DMA_ADDR_MASK (~(ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT))
102
103int ib_umem_odp_map_dma_pages(struct ib_umem *umem, u64 start_offset, u64 bcnt,
104			      u64 access_mask, unsigned long current_seq);
105
106void ib_umem_odp_unmap_dma_pages(struct ib_umem *umem, u64 start_offset,
107				 u64 bound);
108
109void rbt_ib_umem_insert(struct umem_odp_node *node, struct rb_root *root);
110void rbt_ib_umem_remove(struct umem_odp_node *node, struct rb_root *root);
111typedef int (*umem_call_back)(struct ib_umem *item, u64 start, u64 end,
112			      void *cookie);
113/*
114 * Call the callback on each ib_umem in the range. Returns the logical or of
115 * the return values of the functions called.
116 */
117int rbt_ib_umem_for_each_in_range(struct rb_root *root, u64 start, u64 end,
118				  umem_call_back cb, void *cookie);
119
120struct umem_odp_node *rbt_ib_umem_iter_first(struct rb_root *root,
121					     u64 start, u64 last);
122struct umem_odp_node *rbt_ib_umem_iter_next(struct umem_odp_node *node,
123					    u64 start, u64 last);
124
125static inline int ib_umem_mmu_notifier_retry(struct ib_umem *item,
126					     unsigned long mmu_seq)
127{
128	/*
129	 * This code is strongly based on the KVM code from
130	 * mmu_notifier_retry. Should be called with
131	 * the relevant locks taken (item->odp_data->umem_mutex
132	 * and the ucontext umem_mutex semaphore locked for read).
133	 */
134
135	/* Do not allow page faults while the new ib_umem hasn't seen a state
136	 * with zero notifiers yet, and doesn't have its own valid set of
137	 * private counters. */
138	if (!item->odp_data->mn_counters_active)
139		return 1;
140
141	if (unlikely(item->odp_data->notifiers_count))
142		return 1;
143	if (item->odp_data->notifiers_seq != mmu_seq)
144		return 1;
145	return 0;
146}
147
148#else /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
149
150static inline int ib_umem_odp_get(struct ib_ucontext *context,
151				  struct ib_umem *umem)
152{
153	return -EINVAL;
154}
155
156static inline void ib_umem_odp_release(struct ib_umem *umem) {}
157
158#endif /* CONFIG_INFINIBAND_ON_DEMAND_PAGING */
159
160#endif /* IB_UMEM_ODP_H */