// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright 2013 Red Hat Inc. * * Authors: Jérôme Glisse */ /* * Refer to include/linux/hmm.h for information about heterogeneous memory * management or HMM for short. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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);