135 lines
4.4 KiB
C
135 lines
4.4 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/vm/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/kconfig.h>
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#include <asm/pgtable.h>
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#include <linux/device.h>
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#include <linux/migrate.h>
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#include <linux/memremap.h>
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#include <linux/completion.h>
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#include <linux/mmu_notifier.h>
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/*
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* hmm_pfn_flag_e - HMM flag enums
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*
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* Flags:
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* HMM_PFN_VALID: pfn is valid. It has, at least, read permission.
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* HMM_PFN_WRITE: CPU page table has write permission set
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*
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* The driver provides a flags array for mapping page protections to device
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* PTE bits. If the driver valid bit for an entry is bit 3,
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* i.e., (entry & (1 << 3)), then the driver must provide
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* an array in hmm_range.flags with hmm_range.flags[HMM_PFN_VALID] == 1 << 3.
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* Same logic apply to all flags. This is the same idea as vm_page_prot in vma
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* except that this is per device driver rather than per architecture.
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*/
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enum hmm_pfn_flag_e {
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HMM_PFN_VALID = 0,
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HMM_PFN_WRITE,
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HMM_PFN_FLAG_MAX
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};
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/*
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* hmm_pfn_value_e - HMM pfn special value
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*
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* Flags:
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* HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory
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* HMM_PFN_NONE: corresponding CPU page table entry is pte_none()
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* HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the
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* result of vmf_insert_pfn() or vm_insert_page(). Therefore, it should not
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* be mirrored by a device, because the entry will never have HMM_PFN_VALID
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* set and the pfn value is undefined.
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*
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* Driver provides values for none entry, error entry, and special entry.
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* Driver can alias (i.e., use same value) error and special, but
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* it should not alias none with error or special.
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*
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* HMM pfn value returned by hmm_vma_get_pfns() or hmm_vma_fault() will be:
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* hmm_range.values[HMM_PFN_ERROR] if CPU page table entry is poisonous,
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* hmm_range.values[HMM_PFN_NONE] if there is no CPU page table entry,
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* hmm_range.values[HMM_PFN_SPECIAL] if CPU page table entry is a special one
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*/
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enum hmm_pfn_value_e {
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HMM_PFN_ERROR,
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HMM_PFN_NONE,
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HMM_PFN_SPECIAL,
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HMM_PFN_VALUE_MAX
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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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* @pfns: array of pfns (big enough for the range)
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* @flags: pfn flags to match device driver page table
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* @values: pfn value for some special case (none, special, error, ...)
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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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* @pfn_shift: pfn shift value (should be <= PAGE_SHIFT)
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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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uint64_t *pfns;
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const uint64_t *flags;
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const uint64_t *values;
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uint64_t default_flags;
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uint64_t pfn_flags_mask;
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uint8_t pfn_shift;
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void *dev_private_owner;
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};
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/*
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* hmm_device_entry_to_page() - return struct page pointed to by a device entry
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* @range: range use to decode device entry value
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* @entry: device entry value to get corresponding struct page from
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* Return: struct page pointer if entry is a valid, NULL otherwise
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*
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* If the device entry is valid (ie valid flag set) then return the struct page
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* matching the entry value. Otherwise return NULL.
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*/
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static inline struct page *hmm_device_entry_to_page(const struct hmm_range *range,
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uint64_t entry)
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{
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if (entry == range->values[HMM_PFN_NONE])
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return NULL;
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if (entry == range->values[HMM_PFN_ERROR])
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return NULL;
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if (entry == range->values[HMM_PFN_SPECIAL])
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return NULL;
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if (!(entry & range->flags[HMM_PFN_VALID]))
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return NULL;
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return pfn_to_page(entry >> range->pfn_shift);
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}
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/*
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* Please see Documentation/vm/hmm.rst for how to use the range API.
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*/
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long 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 potentialy 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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