1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright © 2022 Intel Corporation
4 */
5 #ifndef __XE_PT_WALK__
6 #define __XE_PT_WALK__
7
8 #include <linux/pagewalk.h>
9 #include <linux/types.h>
10
11 /**
12 * struct xe_ptw - base class for driver pagetable subclassing.
13 * @children: Pointer to an array of children if any.
14 *
15 * Drivers could subclass this, and if it's a page-directory, typically
16 * embed an array of xe_ptw pointers.
17 */
18 struct xe_ptw {
19 struct xe_ptw **children;
20 };
21
22 /**
23 * struct xe_pt_walk - Embeddable struct for walk parameters
24 */
25 struct xe_pt_walk {
26 /** @ops: The walk ops used for the pagewalk */
27 const struct xe_pt_walk_ops *ops;
28 /**
29 * @shifts: Array of page-table entry shifts used for the
30 * different levels, starting out with the leaf level 0
31 * page-shift as the first entry. It's legal for this pointer to be
32 * changed during the walk.
33 */
34 const u64 *shifts;
35 /** @max_level: Highest populated level in @sizes */
36 unsigned int max_level;
37 /**
38 * @shared_pt_mode: Whether to skip all entries that are private
39 * to the address range and called only for entries that are
40 * shared with other address ranges. Such entries are referred to
41 * as shared pagetables.
42 */
43 bool shared_pt_mode;
44 };
45
46 /**
47 * typedef xe_pt_entry_fn - gpu page-table-walk callback-function
48 * @parent: The parent page.table.
49 * @offset: The offset (number of entries) into the page table.
50 * @level: The level of @parent.
51 * @addr: The virtual address.
52 * @next: The virtual address for the next call, or end address.
53 * @child: Pointer to pointer to child page-table at this @offset. The
54 * function may modify the value pointed to if, for example, allocating a
55 * child page table.
56 * @action: The walk action to take upon return. See <linux/pagewalk.h>.
57 * @walk: The walk parameters.
58 */
59 typedef int (*xe_pt_entry_fn)(struct xe_ptw *parent, pgoff_t offset,
60 unsigned int level, u64 addr, u64 next,
61 struct xe_ptw **child,
62 enum page_walk_action *action,
63 struct xe_pt_walk *walk);
64
65 /**
66 * struct xe_pt_walk_ops - Walk callbacks.
67 */
68 struct xe_pt_walk_ops {
69 /**
70 * @pt_entry: Callback to be called for each page table entry prior
71 * to descending to the next level. The returned value of the action
72 * function parameter is honored.
73 */
74 xe_pt_entry_fn pt_entry;
75 /**
76 * @pt_post_descend: Callback to be called for each page table entry
77 * after return from descending to the next level. The returned value
78 * of the action function parameter is ignored.
79 */
80 xe_pt_entry_fn pt_post_descend;
81 };
82
83 int xe_pt_walk_range(struct xe_ptw *parent, unsigned int level,
84 u64 addr, u64 end, struct xe_pt_walk *walk);
85
86 int xe_pt_walk_shared(struct xe_ptw *parent, unsigned int level,
87 u64 addr, u64 end, struct xe_pt_walk *walk);
88
89 /**
90 * xe_pt_covers - Whether the address range covers an entire entry in @level
91 * @addr: Start of the range.
92 * @end: End of range + 1.
93 * @level: Page table level.
94 * @walk: Page table walk info.
95 *
96 * This function is a helper to aid in determining whether a leaf page table
97 * entry can be inserted at this @level.
98 *
99 * Return: Whether the range provided covers exactly an entry at this level.
100 */
xe_pt_covers(u64 addr,u64 end,unsigned int level,const struct xe_pt_walk * walk)101 static inline bool xe_pt_covers(u64 addr, u64 end, unsigned int level,
102 const struct xe_pt_walk *walk)
103 {
104 u64 pt_size = 1ull << walk->shifts[level];
105
106 return end - addr == pt_size && IS_ALIGNED(addr, pt_size);
107 }
108
109 /**
110 * xe_pt_num_entries: Number of page-table entries of a given range at this
111 * level
112 * @addr: Start address.
113 * @end: End address.
114 * @level: Page table level.
115 * @walk: Walk info.
116 *
117 * Return: The number of page table entries at this level between @start and
118 * @end.
119 */
120 static inline pgoff_t
xe_pt_num_entries(u64 addr,u64 end,unsigned int level,const struct xe_pt_walk * walk)121 xe_pt_num_entries(u64 addr, u64 end, unsigned int level,
122 const struct xe_pt_walk *walk)
123 {
124 u64 pt_size = 1ull << walk->shifts[level];
125
126 return (round_up(end, pt_size) - round_down(addr, pt_size)) >>
127 walk->shifts[level];
128 }
129
130 /**
131 * xe_pt_offset: Offset of the page-table entry for a given address.
132 * @addr: The address.
133 * @level: Page table level.
134 * @walk: Walk info.
135 *
136 * Return: The page table entry offset for the given address in a
137 * page table with size indicated by @level.
138 */
139 static inline pgoff_t
xe_pt_offset(u64 addr,unsigned int level,const struct xe_pt_walk * walk)140 xe_pt_offset(u64 addr, unsigned int level, const struct xe_pt_walk *walk)
141 {
142 if (level < walk->max_level)
143 addr &= ((1ull << walk->shifts[level + 1]) - 1);
144
145 return addr >> walk->shifts[level];
146 }
147
148 #endif
149