| // 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/mm.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 const struct mmu_notifier_ops hmm_mmu_notifier_ops; |
| |
| /** |
| * hmm_get_or_create - register HMM against an mm (HMM internal) |
| * |
| * @mm: mm struct to attach to |
| * Return: an HMM object, either by referencing the existing |
| * (per-process) object, or by creating a new one. |
| * |
| * This is not intended to be used directly by device drivers. If mm already |
| * has an HMM struct then it get a reference on it and returns it. Otherwise |
| * it allocates an HMM struct, initializes it, associate it with the mm and |
| * returns it. |
| */ |
| static struct hmm *hmm_get_or_create(struct mm_struct *mm) |
| { |
| struct hmm *hmm; |
| |
| lockdep_assert_held_write(&mm->mmap_sem); |
| |
| /* Abuse the page_table_lock to also protect mm->hmm. */ |
| spin_lock(&mm->page_table_lock); |
| hmm = mm->hmm; |
| if (mm->hmm && kref_get_unless_zero(&mm->hmm->kref)) |
| goto out_unlock; |
| spin_unlock(&mm->page_table_lock); |
| |
| hmm = kmalloc(sizeof(*hmm), GFP_KERNEL); |
| if (!hmm) |
| return NULL; |
| init_waitqueue_head(&hmm->wq); |
| INIT_LIST_HEAD(&hmm->mirrors); |
| init_rwsem(&hmm->mirrors_sem); |
| hmm->mmu_notifier.ops = NULL; |
| INIT_LIST_HEAD(&hmm->ranges); |
| spin_lock_init(&hmm->ranges_lock); |
| kref_init(&hmm->kref); |
| hmm->notifiers = 0; |
| hmm->mm = mm; |
| |
| hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops; |
| if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) { |
| kfree(hmm); |
| return NULL; |
| } |
| |
| mmgrab(hmm->mm); |
| |
| /* |
| * We hold the exclusive mmap_sem here so we know that mm->hmm is |
| * still NULL or 0 kref, and is safe to update. |
| */ |
| spin_lock(&mm->page_table_lock); |
| mm->hmm = hmm; |
| |
| out_unlock: |
| spin_unlock(&mm->page_table_lock); |
| return hmm; |
| } |
| |
| static void hmm_free_rcu(struct rcu_head *rcu) |
| { |
| struct hmm *hmm = container_of(rcu, struct hmm, rcu); |
| |
| mmdrop(hmm->mm); |
| kfree(hmm); |
| } |
| |
| static void hmm_free(struct kref *kref) |
| { |
| struct hmm *hmm = container_of(kref, struct hmm, kref); |
| |
| spin_lock(&hmm->mm->page_table_lock); |
| if (hmm->mm->hmm == hmm) |
| hmm->mm->hmm = NULL; |
| spin_unlock(&hmm->mm->page_table_lock); |
| |
| mmu_notifier_unregister_no_release(&hmm->mmu_notifier, hmm->mm); |
| mmu_notifier_call_srcu(&hmm->rcu, hmm_free_rcu); |
| } |
| |
| static inline void hmm_put(struct hmm *hmm) |
| { |
| kref_put(&hmm->kref, hmm_free); |
| } |
| |
| 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; |
| |
| /* Bail out if hmm is in the process of being freed */ |
| if (!kref_get_unless_zero(&hmm->kref)) |
| return; |
| |
| /* |
| * 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); |
| |
| hmm_put(hmm); |
| } |
| |
| 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; |
| |
| if (!kref_get_unless_zero(&hmm->kref)) |
| return 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); |
| hmm_put(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); |
| |
| if (!kref_get_unless_zero(&hmm->kref)) |
| return; |
| |
| notifiers_decrement(hmm); |
| hmm_put(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, |
| }; |
| |
| /* |
| * 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. |
| */ |
| int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm) |
| { |
| lockdep_assert_held_write(&mm->mmap_sem); |
| |
| /* Sanity check */ |
| if (!mm || !mirror || !mirror->ops) |
| return -EINVAL; |
| |
| mirror->hmm = hmm_get_or_create(mm); |
| if (!mirror->hmm) |
| return -ENOMEM; |
| |
| 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); |
| hmm_put(hmm); |
| } |
| 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 (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) { |
| *pfn = range->values[HMM_PFN_ERROR]; |
| return -EFAULT; |
| } |
| |
| return -EBUSY; |
| } |
| |
| 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; |
| |
| 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)) { |
| 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->mm)) |
| return -EFAULT; |
| |
| /* Initialize range to track CPU page table updates. */ |
| spin_lock_irqsave(&hmm->ranges_lock, flags); |
| |
| range->hmm = hmm; |
| kref_get(&hmm->kref); |
| 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->mm); |
| hmm_put(hmm); |
| |
| /* |
| * 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); |
| |
| /** |
| * 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; |
| struct mm_walk mm_walk; |
| int ret; |
| |
| lockdep_assert_held(&hmm->mm->mmap_sem); |
| |
| do { |
| /* If range is no longer valid force retry. */ |
| if (!range->valid) |
| return -EBUSY; |
| |
| vma = find_vma(hmm->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; |
| mm_walk.private = &hmm_vma_walk; |
| end = min(range->end, vma->vm_end); |
| |
| mm_walk.vma = vma; |
| mm_walk.mm = vma->vm_mm; |
| mm_walk.pte_entry = NULL; |
| mm_walk.test_walk = NULL; |
| mm_walk.hugetlb_entry = NULL; |
| mm_walk.pud_entry = hmm_vma_walk_pud; |
| mm_walk.pmd_entry = hmm_vma_walk_pmd; |
| mm_walk.pte_hole = hmm_vma_walk_hole; |
| mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry; |
| |
| do { |
| ret = walk_page_range(start, end, &mm_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); |