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/vm/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/kconfig.h> 13 #include <linux/pgtable.h> 14 15 #include <linux/device.h> 16 #include <linux/migrate.h> 17 #include <linux/memremap.h> 18 #include <linux/completion.h> 19 #include <linux/mmu_notifier.h> 20 21 /* 22 * On output: 23 * 0 - The page is faultable and a future call with 24 * HMM_PFN_REQ_FAULT could succeed. 25 * HMM_PFN_VALID - the pfn field points to a valid PFN. This PFN is at 26 * least readable. If dev_private_owner is !NULL then this could 27 * point at a DEVICE_PRIVATE page. 28 * HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID) 29 * HMM_PFN_ERROR - accessing the pfn is impossible and the device should 30 * fail. ie poisoned memory, special pages, no vma, etc 31 * 32 * On input: 33 * 0 - Return the current state of the page, do not fault it. 34 * HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault() 35 * will fail 36 * HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault() 37 * will fail. Must be combined with HMM_PFN_REQ_FAULT. 38 */ 39 enum hmm_pfn_flags { 40 /* Output flags */ 41 HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1), 42 HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2), 43 HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3), 44 45 /* Input flags */ 46 HMM_PFN_REQ_FAULT = HMM_PFN_VALID, 47 HMM_PFN_REQ_WRITE = HMM_PFN_WRITE, 48 49 HMM_PFN_FLAGS = HMM_PFN_VALID | HMM_PFN_WRITE | HMM_PFN_ERROR, 50 }; 51 52 /* 53 * hmm_pfn_to_page() - return struct page pointed to by a device entry 54 * 55 * This must be called under the caller 'user_lock' after a successful 56 * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID 57 * already. 58 */ 59 static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn) 60 { 61 return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS); 62 } 63 64 /* 65 * struct hmm_range - track invalidation lock on virtual address range 66 * 67 * @notifier: a mmu_interval_notifier that includes the start/end 68 * @notifier_seq: result of mmu_interval_read_begin() 69 * @start: range virtual start address (inclusive) 70 * @end: range virtual end address (exclusive) 71 * @hmm_pfns: array of pfns (big enough for the range) 72 * @default_flags: default flags for the range (write, read, ... see hmm doc) 73 * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter 74 * @dev_private_owner: owner of device private pages 75 */ 76 struct hmm_range { 77 struct mmu_interval_notifier *notifier; 78 unsigned long notifier_seq; 79 unsigned long start; 80 unsigned long end; 81 unsigned long *hmm_pfns; 82 unsigned long default_flags; 83 unsigned long pfn_flags_mask; 84 void *dev_private_owner; 85 }; 86 87 /* 88 * Please see Documentation/vm/hmm.rst for how to use the range API. 89 */ 90 int hmm_range_fault(struct hmm_range *range); 91 92 /* 93 * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range 94 * 95 * When waiting for mmu notifiers we need some kind of time out otherwise we 96 * could potentialy wait for ever, 1000ms ie 1s sounds like a long time to 97 * wait already. 98 */ 99 #define HMM_RANGE_DEFAULT_TIMEOUT 1000 100 101 #endif /* LINUX_HMM_H */ 102