1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES.
3 *
4 */
5 #ifndef __IO_PAGETABLE_H
6 #define __IO_PAGETABLE_H
7
8 #include <linux/interval_tree.h>
9 #include <linux/mutex.h>
10 #include <linux/kref.h>
11 #include <linux/xarray.h>
12
13 #include "iommufd_private.h"
14
15 struct iommu_domain;
16
17 /*
18 * Each io_pagetable is composed of intervals of areas which cover regions of
19 * the iova that are backed by something. iova not covered by areas is not
20 * populated in the page table. Each area is fully populated with pages.
21 *
22 * iovas are in byte units, but must be iopt->iova_alignment aligned.
23 *
24 * pages can be NULL, this means some other thread is still working on setting
25 * up or tearing down the area. When observed under the write side of the
26 * domain_rwsem a NULL pages must mean the area is still being setup and no
27 * domains are filled.
28 *
29 * storage_domain points at an arbitrary iommu_domain that is holding the PFNs
30 * for this area. It is locked by the pages->mutex. This simplifies the locking
31 * as the pages code can rely on the storage_domain without having to get the
32 * iopt->domains_rwsem.
33 *
34 * The io_pagetable::iova_rwsem protects node
35 * The iopt_pages::mutex protects pages_node
36 * iopt and iommu_prot are immutable
37 * The pages::mutex protects num_accesses
38 */
39 struct iopt_area {
40 struct interval_tree_node node;
41 struct interval_tree_node pages_node;
42 struct io_pagetable *iopt;
43 struct iopt_pages *pages;
44 struct iommu_domain *storage_domain;
45 /* How many bytes into the first page the area starts */
46 unsigned int page_offset;
47 /* IOMMU_READ, IOMMU_WRITE, etc */
48 int iommu_prot;
49 bool prevent_access : 1;
50 unsigned int num_accesses;
51 };
52
53 struct iopt_allowed {
54 struct interval_tree_node node;
55 };
56
57 struct iopt_reserved {
58 struct interval_tree_node node;
59 void *owner;
60 };
61
62 int iopt_area_fill_domains(struct iopt_area *area, struct iopt_pages *pages);
63 void iopt_area_unfill_domains(struct iopt_area *area, struct iopt_pages *pages);
64
65 int iopt_area_fill_domain(struct iopt_area *area, struct iommu_domain *domain);
66 void iopt_area_unfill_domain(struct iopt_area *area, struct iopt_pages *pages,
67 struct iommu_domain *domain);
68 void iopt_area_unmap_domain(struct iopt_area *area,
69 struct iommu_domain *domain);
70
iopt_area_index(struct iopt_area * area)71 static inline unsigned long iopt_area_index(struct iopt_area *area)
72 {
73 return area->pages_node.start;
74 }
75
iopt_area_last_index(struct iopt_area * area)76 static inline unsigned long iopt_area_last_index(struct iopt_area *area)
77 {
78 return area->pages_node.last;
79 }
80
iopt_area_iova(struct iopt_area * area)81 static inline unsigned long iopt_area_iova(struct iopt_area *area)
82 {
83 return area->node.start;
84 }
85
iopt_area_last_iova(struct iopt_area * area)86 static inline unsigned long iopt_area_last_iova(struct iopt_area *area)
87 {
88 return area->node.last;
89 }
90
iopt_area_length(struct iopt_area * area)91 static inline size_t iopt_area_length(struct iopt_area *area)
92 {
93 return (area->node.last - area->node.start) + 1;
94 }
95
96 /*
97 * Number of bytes from the start of the iopt_pages that the iova begins.
98 * iopt_area_start_byte() / PAGE_SIZE encodes the starting page index
99 * iopt_area_start_byte() % PAGE_SIZE encodes the offset within that page
100 */
iopt_area_start_byte(struct iopt_area * area,unsigned long iova)101 static inline unsigned long iopt_area_start_byte(struct iopt_area *area,
102 unsigned long iova)
103 {
104 if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
105 WARN_ON(iova < iopt_area_iova(area) ||
106 iova > iopt_area_last_iova(area));
107 return (iova - iopt_area_iova(area)) + area->page_offset +
108 iopt_area_index(area) * PAGE_SIZE;
109 }
110
iopt_area_iova_to_index(struct iopt_area * area,unsigned long iova)111 static inline unsigned long iopt_area_iova_to_index(struct iopt_area *area,
112 unsigned long iova)
113 {
114 return iopt_area_start_byte(area, iova) / PAGE_SIZE;
115 }
116
117 #define __make_iopt_iter(name) \
118 static inline struct iopt_##name *iopt_##name##_iter_first( \
119 struct io_pagetable *iopt, unsigned long start, \
120 unsigned long last) \
121 { \
122 struct interval_tree_node *node; \
123 \
124 lockdep_assert_held(&iopt->iova_rwsem); \
125 node = interval_tree_iter_first(&iopt->name##_itree, start, \
126 last); \
127 if (!node) \
128 return NULL; \
129 return container_of(node, struct iopt_##name, node); \
130 } \
131 static inline struct iopt_##name *iopt_##name##_iter_next( \
132 struct iopt_##name *last_node, unsigned long start, \
133 unsigned long last) \
134 { \
135 struct interval_tree_node *node; \
136 \
137 node = interval_tree_iter_next(&last_node->node, start, last); \
138 if (!node) \
139 return NULL; \
140 return container_of(node, struct iopt_##name, node); \
141 }
142
143 __make_iopt_iter(area)
144 __make_iopt_iter(allowed)
145 __make_iopt_iter(reserved)
146
147 struct iopt_area_contig_iter {
148 unsigned long cur_iova;
149 unsigned long last_iova;
150 struct iopt_area *area;
151 };
152 struct iopt_area *iopt_area_contig_init(struct iopt_area_contig_iter *iter,
153 struct io_pagetable *iopt,
154 unsigned long iova,
155 unsigned long last_iova);
156 struct iopt_area *iopt_area_contig_next(struct iopt_area_contig_iter *iter);
157
iopt_area_contig_done(struct iopt_area_contig_iter * iter)158 static inline bool iopt_area_contig_done(struct iopt_area_contig_iter *iter)
159 {
160 return iter->area && iter->last_iova <= iopt_area_last_iova(iter->area);
161 }
162
163 /*
164 * Iterate over a contiguous list of areas that span the iova,last_iova range.
165 * The caller must check iopt_area_contig_done() after the loop to see if
166 * contiguous areas existed.
167 */
168 #define iopt_for_each_contig_area(iter, area, iopt, iova, last_iova) \
169 for (area = iopt_area_contig_init(iter, iopt, iova, last_iova); area; \
170 area = iopt_area_contig_next(iter))
171
172 enum {
173 IOPT_PAGES_ACCOUNT_NONE = 0,
174 IOPT_PAGES_ACCOUNT_USER = 1,
175 IOPT_PAGES_ACCOUNT_MM = 2,
176 };
177
178 /*
179 * This holds a pinned page list for multiple areas of IO address space. The
180 * pages always originate from a linear chunk of userspace VA. Multiple
181 * io_pagetable's, through their iopt_area's, can share a single iopt_pages
182 * which avoids multi-pinning and double accounting of page consumption.
183 *
184 * indexes in this structure are measured in PAGE_SIZE units, are 0 based from
185 * the start of the uptr and extend to npages. pages are pinned dynamically
186 * according to the intervals in the access_itree and domains_itree, npinned
187 * records the current number of pages pinned.
188 */
189 struct iopt_pages {
190 struct kref kref;
191 struct mutex mutex;
192 size_t npages;
193 size_t npinned;
194 size_t last_npinned;
195 struct task_struct *source_task;
196 struct mm_struct *source_mm;
197 struct user_struct *source_user;
198 void __user *uptr;
199 bool writable:1;
200 u8 account_mode;
201
202 struct xarray pinned_pfns;
203 /* Of iopt_pages_access::node */
204 struct rb_root_cached access_itree;
205 /* Of iopt_area::pages_node */
206 struct rb_root_cached domains_itree;
207 };
208
209 struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length,
210 bool writable);
211 void iopt_release_pages(struct kref *kref);
iopt_put_pages(struct iopt_pages * pages)212 static inline void iopt_put_pages(struct iopt_pages *pages)
213 {
214 kref_put(&pages->kref, iopt_release_pages);
215 }
216
217 void iopt_pages_fill_from_xarray(struct iopt_pages *pages, unsigned long start,
218 unsigned long last, struct page **out_pages);
219 int iopt_pages_fill_xarray(struct iopt_pages *pages, unsigned long start,
220 unsigned long last, struct page **out_pages);
221 void iopt_pages_unfill_xarray(struct iopt_pages *pages, unsigned long start,
222 unsigned long last);
223
224 int iopt_area_add_access(struct iopt_area *area, unsigned long start,
225 unsigned long last, struct page **out_pages,
226 unsigned int flags);
227 void iopt_area_remove_access(struct iopt_area *area, unsigned long start,
228 unsigned long last);
229 int iopt_pages_rw_access(struct iopt_pages *pages, unsigned long start_byte,
230 void *data, unsigned long length, unsigned int flags);
231
232 /*
233 * Each interval represents an active iopt_access_pages(), it acts as an
234 * interval lock that keeps the PFNs pinned and stored in the xarray.
235 */
236 struct iopt_pages_access {
237 struct interval_tree_node node;
238 unsigned int users;
239 };
240
241 #endif
242