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 */
19struct 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 */
27struct 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 */
63typedef 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 */
72struct 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
87int xe_pt_walk_range(struct xe_ptw *parent, unsigned int level,
88 u64 addr, u64 end, struct xe_pt_walk *walk);
89
90int 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 */
105static 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 */
124static inline pgoff_t
125xe_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 */
143static inline pgoff_t
144xe_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

source code of linux/drivers/gpu/drm/xe/xe_pt_walk.h