1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * Copyright 2013 Red Hat Inc. |
4 | * |
5 | * Authors: Jérôme Glisse <jglisse@redhat.com> |
6 | * |
7 | * See Documentation/mm/hmm.rst for reasons and overview of what HMM is. |
8 | */ |
9 | #ifndef LINUX_HMM_H |
10 | #define LINUX_HMM_H |
11 | |
12 | #include <linux/mm.h> |
13 | |
14 | struct mmu_interval_notifier; |
15 | |
16 | /* |
17 | * On output: |
18 | * 0 - The page is faultable and a future call with |
19 | * HMM_PFN_REQ_FAULT could succeed. |
20 | * HMM_PFN_VALID - the pfn field points to a valid PFN. This PFN is at |
21 | * least readable. If dev_private_owner is !NULL then this could |
22 | * point at a DEVICE_PRIVATE page. |
23 | * HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID) |
24 | * HMM_PFN_ERROR - accessing the pfn is impossible and the device should |
25 | * fail. ie poisoned memory, special pages, no vma, etc |
26 | * |
27 | * On input: |
28 | * 0 - Return the current state of the page, do not fault it. |
29 | * HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault() |
30 | * will fail |
31 | * HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault() |
32 | * will fail. Must be combined with HMM_PFN_REQ_FAULT. |
33 | */ |
34 | enum hmm_pfn_flags { |
35 | /* Output fields and flags */ |
36 | HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1), |
37 | HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2), |
38 | HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3), |
39 | HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8), |
40 | |
41 | /* Input flags */ |
42 | HMM_PFN_REQ_FAULT = HMM_PFN_VALID, |
43 | HMM_PFN_REQ_WRITE = HMM_PFN_WRITE, |
44 | |
45 | HMM_PFN_FLAGS = 0xFFUL << HMM_PFN_ORDER_SHIFT, |
46 | }; |
47 | |
48 | /* |
49 | * hmm_pfn_to_page() - return struct page pointed to by a device entry |
50 | * |
51 | * This must be called under the caller 'user_lock' after a successful |
52 | * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID |
53 | * already. |
54 | */ |
55 | static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn) |
56 | { |
57 | return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS); |
58 | } |
59 | |
60 | /* |
61 | * hmm_pfn_to_map_order() - return the CPU mapping size order |
62 | * |
63 | * This is optionally useful to optimize processing of the pfn result |
64 | * array. It indicates that the page starts at the order aligned VA and is |
65 | * 1<<order bytes long. Every pfn within an high order page will have the |
66 | * same pfn flags, both access protections and the map_order. The caller must |
67 | * be careful with edge cases as the start and end VA of the given page may |
68 | * extend past the range used with hmm_range_fault(). |
69 | * |
70 | * This must be called under the caller 'user_lock' after a successful |
71 | * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID |
72 | * already. |
73 | */ |
74 | static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn) |
75 | { |
76 | return (hmm_pfn >> HMM_PFN_ORDER_SHIFT) & 0x1F; |
77 | } |
78 | |
79 | /* |
80 | * struct hmm_range - track invalidation lock on virtual address range |
81 | * |
82 | * @notifier: a mmu_interval_notifier that includes the start/end |
83 | * @notifier_seq: result of mmu_interval_read_begin() |
84 | * @start: range virtual start address (inclusive) |
85 | * @end: range virtual end address (exclusive) |
86 | * @hmm_pfns: array of pfns (big enough for the range) |
87 | * @default_flags: default flags for the range (write, read, ... see hmm doc) |
88 | * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter |
89 | * @dev_private_owner: owner of device private pages |
90 | */ |
91 | struct hmm_range { |
92 | struct mmu_interval_notifier *notifier; |
93 | unsigned long notifier_seq; |
94 | unsigned long start; |
95 | unsigned long end; |
96 | unsigned long *hmm_pfns; |
97 | unsigned long default_flags; |
98 | unsigned long pfn_flags_mask; |
99 | void *dev_private_owner; |
100 | }; |
101 | |
102 | /* |
103 | * Please see Documentation/mm/hmm.rst for how to use the range API. |
104 | */ |
105 | int hmm_range_fault(struct hmm_range *range); |
106 | |
107 | /* |
108 | * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range |
109 | * |
110 | * When waiting for mmu notifiers we need some kind of time out otherwise we |
111 | * could potentially wait for ever, 1000ms ie 1s sounds like a long time to |
112 | * wait already. |
113 | */ |
114 | #define HMM_RANGE_DEFAULT_TIMEOUT 1000 |
115 | |
116 | #endif /* LINUX_HMM_H */ |
117 | |