/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copyright 2013 Red Hat Inc.
*
* Authors: Jérôme Glisse <jglisse@redhat.com>
*
* See Documentation/vm/hmm.rst for reasons and overview of what HMM is.
*/
#ifndef LINUX_HMM_H
#define LINUX_HMM_H
#include <linux/kconfig.h>
#include <asm/pgtable.h>
#include <linux/device.h>
#include <linux/migrate.h>
#include <linux/memremap.h>
#include <linux/completion.h>
#include <linux/mmu_notifier.h>
/*
* hmm_pfn_flag_e - HMM flag enums
*
* Flags:
* HMM_PFN_VALID: pfn is valid. It has, at least, read permission.
* HMM_PFN_WRITE: CPU page table has write permission set
*
* The driver provides a flags array for mapping page protections to device
* PTE bits. If the driver valid bit for an entry is bit 3,
* i.e., (entry & (1 << 3)), then the driver must provide
* an array in hmm_range.flags with hmm_range.flags[HMM_PFN_VALID] == 1 << 3.
* Same logic apply to all flags. This is the same idea as vm_page_prot in vma
* except that this is per device driver rather than per architecture.
*/
enum hmm_pfn_flag_e {
HMM_PFN_VALID = 0,
HMM_PFN_WRITE,
HMM_PFN_FLAG_MAX
};
/*
* hmm_pfn_value_e - HMM pfn special value
*
* Flags:
* HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory
* HMM_PFN_NONE: corresponding CPU page table entry is pte_none()
* HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the
* result of vmf_insert_pfn() or vm_insert_page(). Therefore, it should not
* be mirrored by a device, because the entry will never have HMM_PFN_VALID
* set and the pfn value is undefined.
*
* Driver provides values for none entry, error entry, and special entry.
* Driver can alias (i.e., use same value) error and special, but
* it should not alias none with error or special.
*
* HMM pfn value returned by hmm_vma_get_pfns() or hmm_vma_fault() will be:
* hmm_range.values[HMM_PFN_ERROR] if CPU page table entry is poisonous,
* hmm_range.values[HMM_PFN_NONE] if there is no CPU page table entry,
* hmm_range.values[HMM_PFN_SPECIAL] if CPU page table entry is a special one
*/
enum hmm_pfn_value_e {
HMM_PFN_ERROR,
HMM_PFN_NONE,
HMM_PFN_SPECIAL,
HMM_PFN_VALUE_MAX
};
/*
* struct hmm_range - track invalidation lock on virtual address range
*
* @notifier: a mmu_interval_notifier that includes the start/end
* @notifier_seq: result of mmu_interval_read_begin()
* @start: range virtual start address (inclusive)
* @end: range virtual end address (exclusive)
* @pfns: array of pfns (big enough for the range)
* @flags: pfn flags to match device driver page table
* @values: pfn value for some special case (none, special, error, ...)
* @default_flags: default flags for the range (write, read, ... see hmm doc)
* @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
* @pfn_shift: pfn shift value (should be <= PAGE_SHIFT)
* @dev_private_owner: owner of device private pages
*/
struct hmm_range {
struct mmu_interval_notifier *notifier;
unsigned long notifier_seq;
unsigned long start;
unsigned long end;
uint64_t *pfns;
const uint64_t *flags;
const uint64_t *values;
uint64_t default_flags;
uint64_t pfn_flags_mask;
uint8_t pfn_shift;
void *dev_private_owner;
};
/*
* hmm_device_entry_to_page() - return struct page pointed to by a device entry
* @range: range use to decode device entry value
* @entry: device entry value to get corresponding struct page from
* Return: struct page pointer if entry is a valid, NULL otherwise
*
* If the device entry is valid (ie valid flag set) then return the struct page
* matching the entry value. Otherwise return NULL.
*/
static inline struct page *hmm_device_entry_to_page(const struct hmm_range *range,
uint64_t entry)
{
if (entry == range->values[HMM_PFN_NONE])
return NULL;
if (entry == range->values[HMM_PFN_ERROR])
return NULL;
if (entry == range->values[HMM_PFN_SPECIAL])
return NULL;
if (!(entry & range->flags[HMM_PFN_VALID]))
return NULL;
return pfn_to_page(entry >> range->pfn_shift);
}
/*
* Please see Documentation/vm/hmm.rst for how to use the range API.
*/
long hmm_range_fault(struct hmm_range *range);
/*
* HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
*
* When waiting for mmu notifiers we need some kind of time out otherwise we
* could potentialy wait for ever, 1000ms ie 1s sounds like a long time to
* wait already.
*/
#define HMM_RANGE_DEFAULT_TIMEOUT 1000
#endif /* LINUX_HMM_H */
