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linux-sg2042/mm/hmm.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2013 Red Hat Inc.
*
* Authors: Jérôme Glisse <jglisse@redhat.com>
*/
/*
* Refer to include/linux/hmm.h for information about heterogeneous memory
* management or HMM for short.
*/
#include <linux/pagewalk.h>
#include <linux/hmm.h>
#include <linux/init.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/swapops.h>
#include <linux/hugetlb.h>
#include <linux/memremap.h>
#include <linux/sched/mm.h>
#include <linux/jump_label.h>
#include <linux/dma-mapping.h>
#include <linux/mmu_notifier.h>
#include <linux/memory_hotplug.h>
static struct mmu_notifier *hmm_alloc_notifier(struct mm_struct *mm)
{
struct hmm *hmm;
hmm = kzalloc(sizeof(*hmm), GFP_KERNEL);
if (!hmm)
return ERR_PTR(-ENOMEM);
init_waitqueue_head(&hmm->wq);
INIT_LIST_HEAD(&hmm->mirrors);
init_rwsem(&hmm->mirrors_sem);
INIT_LIST_HEAD(&hmm->ranges);
spin_lock_init(&hmm->ranges_lock);
hmm->notifiers = 0;
return &hmm->mmu_notifier;
}
static void hmm_free_notifier(struct mmu_notifier *mn)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
WARN_ON(!list_empty(&hmm->ranges));
WARN_ON(!list_empty(&hmm->mirrors));
kfree(hmm);
}
static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
struct hmm_mirror *mirror;
/*
* Since hmm_range_register() holds the mmget() lock hmm_release() is
* prevented as long as a range exists.
*/
WARN_ON(!list_empty_careful(&hmm->ranges));
down_read(&hmm->mirrors_sem);
list_for_each_entry(mirror, &hmm->mirrors, list) {
/*
* Note: The driver is not allowed to trigger
* hmm_mirror_unregister() from this thread.
*/
if (mirror->ops->release)
mirror->ops->release(mirror);
}
up_read(&hmm->mirrors_sem);
}
static void notifiers_decrement(struct hmm *hmm)
{
unsigned long flags;
spin_lock_irqsave(&hmm->ranges_lock, flags);
hmm->notifiers--;
if (!hmm->notifiers) {
struct hmm_range *range;
list_for_each_entry(range, &hmm->ranges, list) {
if (range->valid)
continue;
range->valid = true;
}
wake_up_all(&hmm->wq);
}
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
}
static int hmm_invalidate_range_start(struct mmu_notifier *mn,
const struct mmu_notifier_range *nrange)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
struct hmm_mirror *mirror;
struct hmm_range *range;
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&hmm->ranges_lock, flags);
hmm->notifiers++;
list_for_each_entry(range, &hmm->ranges, list) {
if (nrange->end < range->start || nrange->start >= range->end)
continue;
range->valid = false;
}
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
if (mmu_notifier_range_blockable(nrange))
down_read(&hmm->mirrors_sem);
else if (!down_read_trylock(&hmm->mirrors_sem)) {
ret = -EAGAIN;
goto out;
}
list_for_each_entry(mirror, &hmm->mirrors, list) {
int rc;
rc = mirror->ops->sync_cpu_device_pagetables(mirror, nrange);
if (rc) {
if (WARN_ON(mmu_notifier_range_blockable(nrange) ||
rc != -EAGAIN))
continue;
ret = -EAGAIN;
break;
}
}
up_read(&hmm->mirrors_sem);
out:
if (ret)
notifiers_decrement(hmm);
return ret;
}
static void hmm_invalidate_range_end(struct mmu_notifier *mn,
const struct mmu_notifier_range *nrange)
{
struct hmm *hmm = container_of(mn, struct hmm, mmu_notifier);
notifiers_decrement(hmm);
}
static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
.release = hmm_release,
.invalidate_range_start = hmm_invalidate_range_start,
.invalidate_range_end = hmm_invalidate_range_end,
.alloc_notifier = hmm_alloc_notifier,
.free_notifier = hmm_free_notifier,
};
/*
* hmm_mirror_register() - register a mirror against an mm
*
* @mirror: new mirror struct to register
* @mm: mm to register against
* Return: 0 on success, -ENOMEM if no memory, -EINVAL if invalid arguments
*
* To start mirroring a process address space, the device driver must register
* an HMM mirror struct.
*
* The caller cannot unregister the hmm_mirror while any ranges are
* registered.
*
* Callers using this function must put a call to mmu_notifier_synchronize()
* in their module exit functions.
*/
int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
{
struct mmu_notifier *mn;
lockdep_assert_held_write(&mm->mmap_sem);
/* Sanity check */
if (!mm || !mirror || !mirror->ops)
return -EINVAL;
mn = mmu_notifier_get_locked(&hmm_mmu_notifier_ops, mm);
if (IS_ERR(mn))
return PTR_ERR(mn);
mirror->hmm = container_of(mn, struct hmm, mmu_notifier);
down_write(&mirror->hmm->mirrors_sem);
list_add(&mirror->list, &mirror->hmm->mirrors);
up_write(&mirror->hmm->mirrors_sem);
return 0;
}
EXPORT_SYMBOL(hmm_mirror_register);
/*
* hmm_mirror_unregister() - unregister a mirror
*
* @mirror: mirror struct to unregister
*
* Stop mirroring a process address space, and cleanup.
*/
void hmm_mirror_unregister(struct hmm_mirror *mirror)
{
struct hmm *hmm = mirror->hmm;
down_write(&hmm->mirrors_sem);
list_del(&mirror->list);
up_write(&hmm->mirrors_sem);
mmu_notifier_put(&hmm->mmu_notifier);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
struct hmm_vma_walk {
struct hmm_range *range;
struct dev_pagemap *pgmap;
unsigned long last;
unsigned int flags;
};
static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr,
bool write_fault, uint64_t *pfn)
{
unsigned int flags = FAULT_FLAG_REMOTE;
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
struct vm_area_struct *vma = walk->vma;
vm_fault_t ret;
if (!vma)
goto err;
if (hmm_vma_walk->flags & HMM_FAULT_ALLOW_RETRY)
flags |= FAULT_FLAG_ALLOW_RETRY;
if (write_fault)
flags |= FAULT_FLAG_WRITE;
ret = handle_mm_fault(vma, addr, flags);
if (ret & VM_FAULT_RETRY) {
/* Note, handle_mm_fault did up_read(&mm->mmap_sem)) */
return -EAGAIN;
}
if (ret & VM_FAULT_ERROR)
goto err;
return -EBUSY;
err:
*pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
}
static int hmm_pfns_bad(unsigned long addr,
unsigned long end,
struct mm_walk *walk)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
uint64_t *pfns = range->pfns;
unsigned long i;
i = (addr - range->start) >> PAGE_SHIFT;
for (; addr < end; addr += PAGE_SIZE, i++)
pfns[i] = range->values[HMM_PFN_ERROR];
return 0;
}
/*
* hmm_vma_walk_hole_() - handle a range lacking valid pmd or pte(s)
* @addr: range virtual start address (inclusive)
* @end: range virtual end address (exclusive)
* @fault: should we fault or not ?
* @write_fault: write fault ?
* @walk: mm_walk structure
* Return: 0 on success, -EBUSY after page fault, or page fault error
*
* This function will be called whenever pmd_none() or pte_none() returns true,
* or whenever there is no page directory covering the virtual address range.
*/
static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end,
bool fault, bool write_fault,
struct mm_walk *walk)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
uint64_t *pfns = range->pfns;
unsigned long i;
hmm_vma_walk->last = addr;
i = (addr - range->start) >> PAGE_SHIFT;
if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE))
return -EPERM;
for (; addr < end; addr += PAGE_SIZE, i++) {
pfns[i] = range->values[HMM_PFN_NONE];
if (fault || write_fault) {
int ret;
ret = hmm_vma_do_fault(walk, addr, write_fault,
&pfns[i]);
if (ret != -EBUSY)
return ret;
}
}
return (fault || write_fault) ? -EBUSY : 0;
}
static inline void hmm_pte_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
uint64_t pfns, uint64_t cpu_flags,
bool *fault, bool *write_fault)
{
struct hmm_range *range = hmm_vma_walk->range;
if (hmm_vma_walk->flags & HMM_FAULT_SNAPSHOT)
return;
/*
* So we not only consider the individual per page request we also
* consider the default flags requested for the range. The API can
* be used 2 ways. The first one where the HMM user coalesces
* multiple page faults into one request and sets flags per pfn for
* those faults. The second one where the HMM user wants to pre-
* fault a range with specific flags. For the latter one it is a
* waste to have the user pre-fill the pfn arrays with a default
* flags value.
*/
pfns = (pfns & range->pfn_flags_mask) | range->default_flags;
/* We aren't ask to do anything ... */
if (!(pfns & range->flags[HMM_PFN_VALID]))
return;
/* If this is device memory then only fault if explicitly requested */
if ((cpu_flags & range->flags[HMM_PFN_DEVICE_PRIVATE])) {
/* Do we fault on device memory ? */
if (pfns & range->flags[HMM_PFN_DEVICE_PRIVATE]) {
*write_fault = pfns & range->flags[HMM_PFN_WRITE];
*fault = true;
}
return;
}
/* If CPU page table is not valid then we need to fault */
*fault = !(cpu_flags & range->flags[HMM_PFN_VALID]);
/* Need to write fault ? */
if ((pfns & range->flags[HMM_PFN_WRITE]) &&
!(cpu_flags & range->flags[HMM_PFN_WRITE])) {
*write_fault = true;
*fault = true;
}
}
static void hmm_range_need_fault(const struct hmm_vma_walk *hmm_vma_walk,
const uint64_t *pfns, unsigned long npages,
uint64_t cpu_flags, bool *fault,
bool *write_fault)
{
unsigned long i;
if (hmm_vma_walk->flags & HMM_FAULT_SNAPSHOT) {
*fault = *write_fault = false;
return;
}
*fault = *write_fault = false;
for (i = 0; i < npages; ++i) {
hmm_pte_need_fault(hmm_vma_walk, pfns[i], cpu_flags,
fault, write_fault);
if ((*write_fault))
return;
}
}
static int hmm_vma_walk_hole(unsigned long addr, unsigned long end,
struct mm_walk *walk)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
bool fault, write_fault;
unsigned long i, npages;
uint64_t *pfns;
i = (addr - range->start) >> PAGE_SHIFT;
npages = (end - addr) >> PAGE_SHIFT;
pfns = &range->pfns[i];
hmm_range_need_fault(hmm_vma_walk, pfns, npages,
0, &fault, &write_fault);
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
}
static inline uint64_t pmd_to_hmm_pfn_flags(struct hmm_range *range, pmd_t pmd)
{
if (pmd_protnone(pmd))
return 0;
return pmd_write(pmd) ? range->flags[HMM_PFN_VALID] |
range->flags[HMM_PFN_WRITE] :
range->flags[HMM_PFN_VALID];
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
unsigned long end, uint64_t *pfns, pmd_t pmd)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
unsigned long pfn, npages, i;
bool fault, write_fault;
uint64_t cpu_flags;
npages = (end - addr) >> PAGE_SHIFT;
cpu_flags = pmd_to_hmm_pfn_flags(range, pmd);
hmm_range_need_fault(hmm_vma_walk, pfns, npages, cpu_flags,
&fault, &write_fault);
if (pmd_protnone(pmd) || fault || write_fault)
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) {
if (pmd_devmap(pmd)) {
hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
hmm_vma_walk->pgmap);
if (unlikely(!hmm_vma_walk->pgmap))
return -EBUSY;
}
pfns[i] = hmm_device_entry_from_pfn(range, pfn) | cpu_flags;
}
if (hmm_vma_walk->pgmap) {
put_dev_pagemap(hmm_vma_walk->pgmap);
hmm_vma_walk->pgmap = NULL;
}
hmm_vma_walk->last = end;
return 0;
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
/* stub to allow the code below to compile */
int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
unsigned long end, uint64_t *pfns, pmd_t pmd);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte)
{
if (pte_none(pte) || !pte_present(pte) || pte_protnone(pte))
return 0;
return pte_write(pte) ? range->flags[HMM_PFN_VALID] |
range->flags[HMM_PFN_WRITE] :
range->flags[HMM_PFN_VALID];
}
static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
unsigned long end, pmd_t *pmdp, pte_t *ptep,
uint64_t *pfn)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
bool fault, write_fault;
uint64_t cpu_flags;
pte_t pte = *ptep;
uint64_t orig_pfn = *pfn;
*pfn = range->values[HMM_PFN_NONE];
fault = write_fault = false;
if (pte_none(pte)) {
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, 0,
&fault, &write_fault);
if (fault || write_fault)
goto fault;
return 0;
}
if (!pte_present(pte)) {
swp_entry_t entry = pte_to_swp_entry(pte);
if (!non_swap_entry(entry)) {
cpu_flags = pte_to_hmm_pfn_flags(range, pte);
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
&fault, &write_fault);
if (fault || write_fault)
goto fault;
return 0;
}
/*
* This is a special swap entry, ignore migration, use
* device and report anything else as error.
*/
if (is_device_private_entry(entry)) {
cpu_flags = range->flags[HMM_PFN_VALID] |
range->flags[HMM_PFN_DEVICE_PRIVATE];
cpu_flags |= is_write_device_private_entry(entry) ?
range->flags[HMM_PFN_WRITE] : 0;
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
&fault, &write_fault);
if (fault || write_fault)
goto fault;
*pfn = hmm_device_entry_from_pfn(range,
swp_offset(entry));
*pfn |= cpu_flags;
return 0;
}
if (is_migration_entry(entry)) {
if (fault || write_fault) {
pte_unmap(ptep);
hmm_vma_walk->last = addr;
migration_entry_wait(walk->mm, pmdp, addr);
return -EBUSY;
}
return 0;
}
/* Report error for everything else */
*pfn = range->values[HMM_PFN_ERROR];
return -EFAULT;
} else {
cpu_flags = pte_to_hmm_pfn_flags(range, pte);
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
&fault, &write_fault);
}
if (fault || write_fault)
goto fault;
if (pte_devmap(pte)) {
hmm_vma_walk->pgmap = get_dev_pagemap(pte_pfn(pte),
hmm_vma_walk->pgmap);
if (unlikely(!hmm_vma_walk->pgmap))
return -EBUSY;
} else if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) && pte_special(pte)) {
*pfn = range->values[HMM_PFN_SPECIAL];
return -EFAULT;
}
*pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags;
return 0;
fault:
if (hmm_vma_walk->pgmap) {
put_dev_pagemap(hmm_vma_walk->pgmap);
hmm_vma_walk->pgmap = NULL;
}
pte_unmap(ptep);
/* Fault any virtual address we were asked to fault */
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
}
static int hmm_vma_walk_pmd(pmd_t *pmdp,
unsigned long start,
unsigned long end,
struct mm_walk *walk)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
uint64_t *pfns = range->pfns;
unsigned long addr = start, i;
pte_t *ptep;
pmd_t pmd;
again:
pmd = READ_ONCE(*pmdp);
if (pmd_none(pmd))
return hmm_vma_walk_hole(start, end, walk);
if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
bool fault, write_fault;
unsigned long npages;
uint64_t *pfns;
i = (addr - range->start) >> PAGE_SHIFT;
npages = (end - addr) >> PAGE_SHIFT;
pfns = &range->pfns[i];
hmm_range_need_fault(hmm_vma_walk, pfns, npages,
0, &fault, &write_fault);
if (fault || write_fault) {
hmm_vma_walk->last = addr;
pmd_migration_entry_wait(walk->mm, pmdp);
return -EBUSY;
}
return 0;
} else if (!pmd_present(pmd))
return hmm_pfns_bad(start, end, walk);
if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) {
/*
* No need to take pmd_lock here, even if some other thread
* is splitting the huge pmd we will get that event through
* mmu_notifier callback.
*
* So just read pmd value and check again it's a transparent
* huge or device mapping one and compute corresponding pfn
* values.
*/
pmd = pmd_read_atomic(pmdp);
barrier();
if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd))
goto again;
i = (addr - range->start) >> PAGE_SHIFT;
return hmm_vma_handle_pmd(walk, addr, end, &pfns[i], pmd);
}
/*
* We have handled all the valid cases above ie either none, migration,
* huge or transparent huge. At this point either it is a valid pmd
* entry pointing to pte directory or it is a bad pmd that will not
* recover.
*/
if (pmd_bad(pmd))
return hmm_pfns_bad(start, end, walk);
ptep = pte_offset_map(pmdp, addr);
i = (addr - range->start) >> PAGE_SHIFT;
for (; addr < end; addr += PAGE_SIZE, ptep++, i++) {
int r;
r = hmm_vma_handle_pte(walk, addr, end, pmdp, ptep, &pfns[i]);
if (r) {
/* hmm_vma_handle_pte() did unmap pte directory */
hmm_vma_walk->last = addr;
return r;
}
}
if (hmm_vma_walk->pgmap) {
/*
* We do put_dev_pagemap() here and not in hmm_vma_handle_pte()
* so that we can leverage get_dev_pagemap() optimization which
* will not re-take a reference on a pgmap if we already have
* one.
*/
put_dev_pagemap(hmm_vma_walk->pgmap);
hmm_vma_walk->pgmap = NULL;
}
pte_unmap(ptep - 1);
hmm_vma_walk->last = addr;
return 0;
}
#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && \
defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
static inline uint64_t pud_to_hmm_pfn_flags(struct hmm_range *range, pud_t pud)
{
if (!pud_present(pud))
return 0;
return pud_write(pud) ? range->flags[HMM_PFN_VALID] |
range->flags[HMM_PFN_WRITE] :
range->flags[HMM_PFN_VALID];
}
static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
struct mm_walk *walk)
{
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
unsigned long addr = start, next;
pmd_t *pmdp;
pud_t pud;
int ret;
again:
pud = READ_ONCE(*pudp);
if (pud_none(pud))
return hmm_vma_walk_hole(start, end, walk);
if (pud_huge(pud) && pud_devmap(pud)) {
unsigned long i, npages, pfn;
uint64_t *pfns, cpu_flags;
bool fault, write_fault;
if (!pud_present(pud))
return hmm_vma_walk_hole(start, end, walk);
i = (addr - range->start) >> PAGE_SHIFT;
npages = (end - addr) >> PAGE_SHIFT;
pfns = &range->pfns[i];
cpu_flags = pud_to_hmm_pfn_flags(range, pud);
hmm_range_need_fault(hmm_vma_walk, pfns, npages,
cpu_flags, &fault, &write_fault);
if (fault || write_fault)
return hmm_vma_walk_hole_(addr, end, fault,
write_fault, walk);
pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
for (i = 0; i < npages; ++i, ++pfn) {
hmm_vma_walk->pgmap = get_dev_pagemap(pfn,
hmm_vma_walk->pgmap);
if (unlikely(!hmm_vma_walk->pgmap))
return -EBUSY;
pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
cpu_flags;
}
if (hmm_vma_walk->pgmap) {
put_dev_pagemap(hmm_vma_walk->pgmap);
hmm_vma_walk->pgmap = NULL;
}
hmm_vma_walk->last = end;
return 0;
}
split_huge_pud(walk->vma, pudp, addr);
if (pud_none(*pudp))
goto again;
pmdp = pmd_offset(pudp, addr);
do {
next = pmd_addr_end(addr, end);
ret = hmm_vma_walk_pmd(pmdp, addr, next, walk);
if (ret)
return ret;
} while (pmdp++, addr = next, addr != end);
return 0;
}
#else
#define hmm_vma_walk_pud NULL
#endif
#ifdef CONFIG_HUGETLB_PAGE
static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
unsigned long start, unsigned long end,
struct mm_walk *walk)
{
unsigned long addr = start, i, pfn;
struct hmm_vma_walk *hmm_vma_walk = walk->private;
struct hmm_range *range = hmm_vma_walk->range;
struct vm_area_struct *vma = walk->vma;
uint64_t orig_pfn, cpu_flags;
bool fault, write_fault;
spinlock_t *ptl;
pte_t entry;
int ret = 0;
ptl = huge_pte_lock(hstate_vma(vma), walk->mm, pte);
entry = huge_ptep_get(pte);
i = (start - range->start) >> PAGE_SHIFT;
orig_pfn = range->pfns[i];
range->pfns[i] = range->values[HMM_PFN_NONE];
cpu_flags = pte_to_hmm_pfn_flags(range, entry);
fault = write_fault = false;
hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags,
&fault, &write_fault);
if (fault || write_fault) {
ret = -ENOENT;
goto unlock;
}
pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT);
for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
range->pfns[i] = hmm_device_entry_from_pfn(range, pfn) |
cpu_flags;
hmm_vma_walk->last = end;
unlock:
spin_unlock(ptl);
if (ret == -ENOENT)
return hmm_vma_walk_hole_(addr, end, fault, write_fault, walk);
return ret;
}
#else
#define hmm_vma_walk_hugetlb_entry NULL
#endif /* CONFIG_HUGETLB_PAGE */
static void hmm_pfns_clear(struct hmm_range *range,
uint64_t *pfns,
unsigned long addr,
unsigned long end)
{
for (; addr < end; addr += PAGE_SIZE, pfns++)
*pfns = range->values[HMM_PFN_NONE];
}
/*
* hmm_range_register() - start tracking change to CPU page table over a range
* @range: range
* @mm: the mm struct for the range of virtual address
*
* Return: 0 on success, -EFAULT if the address space is no longer valid
*
* Track updates to the CPU page table see include/linux/hmm.h
*/
int hmm_range_register(struct hmm_range *range, struct hmm_mirror *mirror)
{
struct hmm *hmm = mirror->hmm;
unsigned long flags;
range->valid = false;
range->hmm = NULL;
if ((range->start & (PAGE_SIZE - 1)) || (range->end & (PAGE_SIZE - 1)))
return -EINVAL;
if (range->start >= range->end)
return -EINVAL;
/* Prevent hmm_release() from running while the range is valid */
if (!mmget_not_zero(hmm->mmu_notifier.mm))
return -EFAULT;
/* Initialize range to track CPU page table updates. */
spin_lock_irqsave(&hmm->ranges_lock, flags);
range->hmm = hmm;
list_add(&range->list, &hmm->ranges);
/*
* If there are any concurrent notifiers we have to wait for them for
* the range to be valid (see hmm_range_wait_until_valid()).
*/
if (!hmm->notifiers)
range->valid = true;
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
return 0;
}
EXPORT_SYMBOL(hmm_range_register);
/*
* hmm_range_unregister() - stop tracking change to CPU page table over a range
* @range: range
*
* Range struct is used to track updates to the CPU page table after a call to
* hmm_range_register(). See include/linux/hmm.h for how to use it.
*/
void hmm_range_unregister(struct hmm_range *range)
{
struct hmm *hmm = range->hmm;
unsigned long flags;
spin_lock_irqsave(&hmm->ranges_lock, flags);
list_del_init(&range->list);
spin_unlock_irqrestore(&hmm->ranges_lock, flags);
/* Drop reference taken by hmm_range_register() */
mmput(hmm->mmu_notifier.mm);
/*
* The range is now invalid and the ref on the hmm is dropped, so
* poison the pointer. Leave other fields in place, for the caller's
* use.
*/
range->valid = false;
memset(&range->hmm, POISON_INUSE, sizeof(range->hmm));
}
EXPORT_SYMBOL(hmm_range_unregister);
static const struct mm_walk_ops hmm_walk_ops = {
.pud_entry = hmm_vma_walk_pud,
.pmd_entry = hmm_vma_walk_pmd,
.pte_hole = hmm_vma_walk_hole,
.hugetlb_entry = hmm_vma_walk_hugetlb_entry,
};
/**
* hmm_range_fault - try to fault some address in a virtual address range
* @range: range being faulted
* @flags: HMM_FAULT_* flags
*
* Return: the number of valid pages in range->pfns[] (from range start
* address), which may be zero. On error one of the following status codes
* can be returned:
*
* -EINVAL: Invalid arguments or mm or virtual address is in an invalid vma
* (e.g., device file vma).
* -ENOMEM: Out of memory.
* -EPERM: Invalid permission (e.g., asking for write and range is read
* only).
* -EAGAIN: A page fault needs to be retried and mmap_sem was dropped.
* -EBUSY: The range has been invalidated and the caller needs to wait for
* the invalidation to finish.
* -EFAULT: Invalid (i.e., either no valid vma or it is illegal to access
* that range) number of valid pages in range->pfns[] (from
* range start address).
*
* This is similar to a regular CPU page fault except that it will not trigger
* any memory migration if the memory being faulted is not accessible by CPUs
* and caller does not ask for migration.
*
* On error, for one virtual address in the range, the function will mark the
* corresponding HMM pfn entry with an error flag.
*/
long hmm_range_fault(struct hmm_range *range, unsigned int flags)
{
const unsigned long device_vma = VM_IO | VM_PFNMAP | VM_MIXEDMAP;
unsigned long start = range->start, end;
struct hmm_vma_walk hmm_vma_walk;
struct hmm *hmm = range->hmm;
struct vm_area_struct *vma;
int ret;
lockdep_assert_held(&hmm->mmu_notifier.mm->mmap_sem);
do {
/* If range is no longer valid force retry. */
if (!range->valid)
return -EBUSY;
vma = find_vma(hmm->mmu_notifier.mm, start);
if (vma == NULL || (vma->vm_flags & device_vma))
return -EFAULT;
if (!(vma->vm_flags & VM_READ)) {
/*
* If vma do not allow read access, then assume that it
* does not allow write access, either. HMM does not
* support architecture that allow write without read.
*/
hmm_pfns_clear(range, range->pfns,
range->start, range->end);
return -EPERM;
}
hmm_vma_walk.pgmap = NULL;
hmm_vma_walk.last = start;
hmm_vma_walk.flags = flags;
hmm_vma_walk.range = range;
end = min(range->end, vma->vm_end);
walk_page_range(vma->vm_mm, start, end, &hmm_walk_ops,
&hmm_vma_walk);
do {
ret = walk_page_range(vma->vm_mm, start, end,
&hmm_walk_ops, &hmm_vma_walk);
start = hmm_vma_walk.last;
/* Keep trying while the range is valid. */
} while (ret == -EBUSY && range->valid);
if (ret) {
unsigned long i;
i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
hmm_pfns_clear(range, &range->pfns[i],
hmm_vma_walk.last, range->end);
return ret;
}
start = end;
} while (start < range->end);
return (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
}
EXPORT_SYMBOL(hmm_range_fault);
/**
* hmm_range_dma_map - hmm_range_fault() and dma map page all in one.
* @range: range being faulted
* @device: device to map page to
* @daddrs: array of dma addresses for the mapped pages
* @flags: HMM_FAULT_*
*
* Return: the number of pages mapped on success (including zero), or any
* status return from hmm_range_fault() otherwise.
*/
long hmm_range_dma_map(struct hmm_range *range, struct device *device,
dma_addr_t *daddrs, unsigned int flags)
{
unsigned long i, npages, mapped;
long ret;
ret = hmm_range_fault(range, flags);
if (ret <= 0)
return ret ? ret : -EBUSY;
npages = (range->end - range->start) >> PAGE_SHIFT;
for (i = 0, mapped = 0; i < npages; ++i) {
enum dma_data_direction dir = DMA_TO_DEVICE;
struct page *page;
/*
* FIXME need to update DMA API to provide invalid DMA address
* value instead of a function to test dma address value. This
* would remove lot of dumb code duplicated accross many arch.
*
* For now setting it to 0 here is good enough as the pfns[]
* value is what is use to check what is valid and what isn't.
*/
daddrs[i] = 0;
page = hmm_device_entry_to_page(range, range->pfns[i]);
if (page == NULL)
continue;
/* Check if range is being invalidated */
if (!range->valid) {
ret = -EBUSY;
goto unmap;
}
/* If it is read and write than map bi-directional. */
if (range->pfns[i] & range->flags[HMM_PFN_WRITE])
dir = DMA_BIDIRECTIONAL;
daddrs[i] = dma_map_page(device, page, 0, PAGE_SIZE, dir);
if (dma_mapping_error(device, daddrs[i])) {
ret = -EFAULT;
goto unmap;
}
mapped++;
}
return mapped;
unmap:
for (npages = i, i = 0; (i < npages) && mapped; ++i) {
enum dma_data_direction dir = DMA_TO_DEVICE;
struct page *page;
page = hmm_device_entry_to_page(range, range->pfns[i]);
if (page == NULL)
continue;
if (dma_mapping_error(device, daddrs[i]))
continue;
/* If it is read and write than map bi-directional. */
if (range->pfns[i] & range->flags[HMM_PFN_WRITE])
dir = DMA_BIDIRECTIONAL;
dma_unmap_page(device, daddrs[i], PAGE_SIZE, dir);
mapped--;
}
return ret;
}
EXPORT_SYMBOL(hmm_range_dma_map);
/**
* hmm_range_dma_unmap() - unmap range of that was map with hmm_range_dma_map()
* @range: range being unmapped
* @device: device against which dma map was done
* @daddrs: dma address of mapped pages
* @dirty: dirty page if it had the write flag set
* Return: number of page unmapped on success, -EINVAL otherwise
*
* Note that caller MUST abide by mmu notifier or use HMM mirror and abide
* to the sync_cpu_device_pagetables() callback so that it is safe here to
* call set_page_dirty(). Caller must also take appropriate locks to avoid
* concurrent mmu notifier or sync_cpu_device_pagetables() to make progress.
*/
long hmm_range_dma_unmap(struct hmm_range *range,
struct device *device,
dma_addr_t *daddrs,
bool dirty)
{
unsigned long i, npages;
long cpages = 0;
/* Sanity check. */
if (range->end <= range->start)
return -EINVAL;
if (!daddrs)
return -EINVAL;
if (!range->pfns)
return -EINVAL;
npages = (range->end - range->start) >> PAGE_SHIFT;
for (i = 0; i < npages; ++i) {
enum dma_data_direction dir = DMA_TO_DEVICE;
struct page *page;
page = hmm_device_entry_to_page(range, range->pfns[i]);
if (page == NULL)
continue;
/* If it is read and write than map bi-directional. */
if (range->pfns[i] & range->flags[HMM_PFN_WRITE]) {
dir = DMA_BIDIRECTIONAL;
/*
* See comments in function description on why it is
* safe here to call set_page_dirty()
*/
if (dirty)
set_page_dirty(page);
}
/* Unmap and clear pfns/dma address */
dma_unmap_page(device, daddrs[i], PAGE_SIZE, dir);
range->pfns[i] = range->values[HMM_PFN_NONE];
/* FIXME see comments in hmm_vma_dma_map() */
daddrs[i] = 0;
cpages++;
}
return cpages;
}
EXPORT_SYMBOL(hmm_range_dma_unmap);
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