xref: /linux/drivers/gpu/drm/xe/xe_pt_walk.h (revision 28f587adb69957125241a8df359b68b134f3c4a1)
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  * @staging: Pointer to an array of staging if any.
15  *
16  * Drivers could subclass this, and if it's a page-directory, typically
17  * embed an array of xe_ptw pointers.
18  */
19 struct xe_ptw {
20 	struct xe_ptw **children;
21 	struct xe_ptw **staging;
22 };
23 
24 /**
25  * struct xe_pt_walk - Embeddable struct for walk parameters
26  */
27 struct xe_pt_walk {
28 	/** @ops: The walk ops used for the pagewalk */
29 	const struct xe_pt_walk_ops *ops;
30 	/**
31 	 * @shifts: Array of page-table entry shifts used for the
32 	 * different levels, starting out with the leaf level 0
33 	 * page-shift as the first entry. It's legal for this pointer to be
34 	 * changed during the walk.
35 	 */
36 	const u64 *shifts;
37 	/** @max_level: Highest populated level in @sizes */
38 	unsigned int max_level;
39 	/**
40 	 * @shared_pt_mode: Whether to skip all entries that are private
41 	 * to the address range and called only for entries that are
42 	 * shared with other address ranges. Such entries are referred to
43 	 * as shared pagetables.
44 	 */
45 	bool shared_pt_mode;
46 	/** @staging: Walk staging PT structure */
47 	bool staging;
48 };
49 
50 /**
51  * typedef xe_pt_entry_fn - gpu page-table-walk callback-function
52  * @parent: The parent page.table.
53  * @offset: The offset (number of entries) into the page table.
54  * @level: The level of @parent.
55  * @addr: The virtual address.
56  * @next: The virtual address for the next call, or end address.
57  * @child: Pointer to pointer to child page-table at this @offset. The
58  * function may modify the value pointed to if, for example, allocating a
59  * child page table.
60  * @action: The walk action to take upon return. See <linux/pagewalk.h>.
61  * @walk: The walk parameters.
62  */
63 typedef int (*xe_pt_entry_fn)(struct xe_ptw *parent, pgoff_t offset,
64 			      unsigned int level, u64 addr, u64 next,
65 			      struct xe_ptw **child,
66 			      enum page_walk_action *action,
67 			      struct xe_pt_walk *walk);
68 
69 /**
70  * struct xe_pt_walk_ops - Walk callbacks.
71  */
72 struct xe_pt_walk_ops {
73 	/**
74 	 * @pt_entry: Callback to be called for each page table entry prior
75 	 * to descending to the next level. The returned value of the action
76 	 * function parameter is honored.
77 	 */
78 	xe_pt_entry_fn pt_entry;
79 	/**
80 	 * @pt_post_descend: Callback to be called for each page table entry
81 	 * after return from descending to the next level. The returned value
82 	 * of the action function parameter is ignored.
83 	 */
84 	xe_pt_entry_fn pt_post_descend;
85 };
86 
87 int xe_pt_walk_range(struct xe_ptw *parent, unsigned int level,
88 		     u64 addr, u64 end, struct xe_pt_walk *walk);
89 
90 int xe_pt_walk_shared(struct xe_ptw *parent, unsigned int level,
91 		      u64 addr, u64 end, struct xe_pt_walk *walk);
92 
93 /**
94  * xe_pt_covers - Whether the address range covers an entire entry in @level
95  * @addr: Start of the range.
96  * @end: End of range + 1.
97  * @level: Page table level.
98  * @walk: Page table walk info.
99  *
100  * This function is a helper to aid in determining whether a leaf page table
101  * entry can be inserted at this @level.
102  *
103  * Return: Whether the range provided covers exactly an entry at this level.
104  */
xe_pt_covers(u64 addr,u64 end,unsigned int level,const struct xe_pt_walk * walk)105 static inline bool xe_pt_covers(u64 addr, u64 end, unsigned int level,
106 				const struct xe_pt_walk *walk)
107 {
108 	u64 pt_size = 1ull << walk->shifts[level];
109 
110 	return end - addr == pt_size && IS_ALIGNED(addr, pt_size);
111 }
112 
113 /**
114  * xe_pt_num_entries: Number of page-table entries of a given range at this
115  * level
116  * @addr: Start address.
117  * @end: End address.
118  * @level: Page table level.
119  * @walk: Walk info.
120  *
121  * Return: The number of page table entries at this level between @start and
122  * @end.
123  */
124 static inline pgoff_t
xe_pt_num_entries(u64 addr,u64 end,unsigned int level,const struct xe_pt_walk * walk)125 xe_pt_num_entries(u64 addr, u64 end, unsigned int level,
126 		  const struct xe_pt_walk *walk)
127 {
128 	u64 pt_size = 1ull << walk->shifts[level];
129 
130 	return (round_up(end, pt_size) - round_down(addr, pt_size)) >>
131 		walk->shifts[level];
132 }
133 
134 /**
135  * xe_pt_offset: Offset of the page-table entry for a given address.
136  * @addr: The address.
137  * @level: Page table level.
138  * @walk: Walk info.
139  *
140  * Return: The page table entry offset for the given address in a
141  * page table with size indicated by @level.
142  */
143 static inline pgoff_t
xe_pt_offset(u64 addr,unsigned int level,const struct xe_pt_walk * walk)144 xe_pt_offset(u64 addr, unsigned int level, const struct xe_pt_walk *walk)
145 {
146 	if (level < walk->max_level)
147 		addr &= ((1ull << walk->shifts[level + 1]) - 1);
148 
149 	return addr >> walk->shifts[level];
150 }
151 
152 #endif
153