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6bfef2f919
Now that flags are handled on a fine-grained per-page basis this global flag is redundant and has a confusing overlap with the pfn_flags_mask and default_flags. Normalize the HMM_FAULT_SNAPSHOT behavior into one place. Callers needing the SNAPSHOT behavior should set a pfn_flags_mask and default_flags that always results in a cleared HMM_PFN_VALID. Then no pages will be faulted, and HMM_FAULT_SNAPSHOT is not a special flow that overrides the masking mechanism. As this is the last flag, also remove the flags argument. If future flags are needed they can be part of the struct hmm_range function arguments. Link: https://lore.kernel.org/r/20200327200021.29372-5-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
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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