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TOMOYO Linux Cross Reference
Linux/include/linux/hmm.h

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  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 fields and 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         HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
 45 
 46         /* Input flags */
 47         HMM_PFN_REQ_FAULT = HMM_PFN_VALID,
 48         HMM_PFN_REQ_WRITE = HMM_PFN_WRITE,
 49 
 50         HMM_PFN_FLAGS = 0xFFUL << HMM_PFN_ORDER_SHIFT,
 51 };
 52 
 53 /*
 54  * hmm_pfn_to_page() - return struct page pointed to by a device entry
 55  *
 56  * This must be called under the caller 'user_lock' after a successful
 57  * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
 58  * already.
 59  */
 60 static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn)
 61 {
 62         return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS);
 63 }
 64 
 65 /*
 66  * hmm_pfn_to_map_order() - return the CPU mapping size order
 67  *
 68  * This is optionally useful to optimize processing of the pfn result
 69  * array. It indicates that the page starts at the order aligned VA and is
 70  * 1<<order bytes long.  Every pfn within an high order page will have the
 71  * same pfn flags, both access protections and the map_order.  The caller must
 72  * be careful with edge cases as the start and end VA of the given page may
 73  * extend past the range used with hmm_range_fault().
 74  *
 75  * This must be called under the caller 'user_lock' after a successful
 76  * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
 77  * already.
 78  */
 79 static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn)
 80 {
 81         return (hmm_pfn >> HMM_PFN_ORDER_SHIFT) & 0x1F;
 82 }
 83 
 84 /*
 85  * struct hmm_range - track invalidation lock on virtual address range
 86  *
 87  * @notifier: a mmu_interval_notifier that includes the start/end
 88  * @notifier_seq: result of mmu_interval_read_begin()
 89  * @start: range virtual start address (inclusive)
 90  * @end: range virtual end address (exclusive)
 91  * @hmm_pfns: array of pfns (big enough for the range)
 92  * @default_flags: default flags for the range (write, read, ... see hmm doc)
 93  * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
 94  * @dev_private_owner: owner of device private pages
 95  */
 96 struct hmm_range {
 97         struct mmu_interval_notifier *notifier;
 98         unsigned long           notifier_seq;
 99         unsigned long           start;
100         unsigned long           end;
101         unsigned long           *hmm_pfns;
102         unsigned long           default_flags;
103         unsigned long           pfn_flags_mask;
104         void                    *dev_private_owner;
105 };
106 
107 /*
108  * Please see Documentation/vm/hmm.rst for how to use the range API.
109  */
110 int hmm_range_fault(struct hmm_range *range);
111 
112 /*
113  * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
114  *
115  * When waiting for mmu notifiers we need some kind of time out otherwise we
116  * could potentialy wait for ever, 1000ms ie 1s sounds like a long time to
117  * wait already.
118  */
119 #define HMM_RANGE_DEFAULT_TIMEOUT 1000
120 
121 #endif /* LINUX_HMM_H */
122 

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