117 lines
3.9 KiB
C
117 lines
3.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright 2013 Red Hat Inc.
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*
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* Authors: Jérôme Glisse <jglisse@redhat.com>
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*
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* See Documentation/mm/hmm.rst for reasons and overview of what HMM is.
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*/
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#ifndef LINUX_HMM_H
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#define LINUX_HMM_H
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#include <linux/mm.h>
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struct mmu_interval_notifier;
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/*
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* On output:
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* 0 - The page is faultable and a future call with
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* HMM_PFN_REQ_FAULT could succeed.
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* HMM_PFN_VALID - the pfn field points to a valid PFN. This PFN is at
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* least readable. If dev_private_owner is !NULL then this could
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* point at a DEVICE_PRIVATE page.
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* HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID)
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* HMM_PFN_ERROR - accessing the pfn is impossible and the device should
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* fail. ie poisoned memory, special pages, no vma, etc
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*
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* On input:
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* 0 - Return the current state of the page, do not fault it.
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* HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault()
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* will fail
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* HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault()
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* will fail. Must be combined with HMM_PFN_REQ_FAULT.
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*/
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enum hmm_pfn_flags {
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/* Output fields and flags */
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HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1),
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HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2),
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HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3),
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HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
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/* Input flags */
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HMM_PFN_REQ_FAULT = HMM_PFN_VALID,
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HMM_PFN_REQ_WRITE = HMM_PFN_WRITE,
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HMM_PFN_FLAGS = 0xFFUL << HMM_PFN_ORDER_SHIFT,
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};
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/*
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* hmm_pfn_to_page() - return struct page pointed to by a device entry
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*
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* This must be called under the caller 'user_lock' after a successful
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* mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
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* already.
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*/
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static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn)
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{
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return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS);
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}
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/*
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* hmm_pfn_to_map_order() - return the CPU mapping size order
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*
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* This is optionally useful to optimize processing of the pfn result
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* array. It indicates that the page starts at the order aligned VA and is
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* 1<<order bytes long. Every pfn within an high order page will have the
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* same pfn flags, both access protections and the map_order. The caller must
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* be careful with edge cases as the start and end VA of the given page may
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* extend past the range used with hmm_range_fault().
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*
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* This must be called under the caller 'user_lock' after a successful
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* mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
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* already.
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*/
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static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn)
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{
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return (hmm_pfn >> HMM_PFN_ORDER_SHIFT) & 0x1F;
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}
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/*
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* struct hmm_range - track invalidation lock on virtual address range
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*
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* @notifier: a mmu_interval_notifier that includes the start/end
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* @notifier_seq: result of mmu_interval_read_begin()
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* @start: range virtual start address (inclusive)
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* @end: range virtual end address (exclusive)
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* @hmm_pfns: array of pfns (big enough for the range)
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* @default_flags: default flags for the range (write, read, ... see hmm doc)
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* @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
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* @dev_private_owner: owner of device private pages
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*/
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struct hmm_range {
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struct mmu_interval_notifier *notifier;
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unsigned long notifier_seq;
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unsigned long start;
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unsigned long end;
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unsigned long *hmm_pfns;
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unsigned long default_flags;
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unsigned long pfn_flags_mask;
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void *dev_private_owner;
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};
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/*
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* Please see Documentation/mm/hmm.rst for how to use the range API.
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*/
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int hmm_range_fault(struct hmm_range *range);
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/*
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* HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
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*
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* When waiting for mmu notifiers we need some kind of time out otherwise we
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* could potentially wait for ever, 1000ms ie 1s sounds like a long time to
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* wait already.
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*/
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#define HMM_RANGE_DEFAULT_TIMEOUT 1000
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#endif /* LINUX_HMM_H */
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