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 */ hmm_pfn_to_page(unsigned long hmm_pfn)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 */ hmm_pfn_to_map_order(unsigned long hmm_pfn)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