diff options
Diffstat (limited to 'mm/hmm.c')
| -rw-r--r-- | mm/hmm.c | 523 |
1 files changed, 59 insertions, 464 deletions
@@ -26,193 +26,6 @@ #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; @@ -252,18 +65,15 @@ err: return -EFAULT; } -static int hmm_pfns_bad(unsigned long addr, - unsigned long end, - struct mm_walk *walk) +static int hmm_pfns_fill(unsigned long addr, unsigned long end, + struct hmm_range *range, enum hmm_pfn_value_e value) { - 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]; + pfns[i] = range->values[value]; return 0; } @@ -532,8 +342,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, 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; + if (!is_zero_pfn(pte_pfn(pte))) { + *pfn = range->values[HMM_PFN_SPECIAL]; + return -EFAULT; + } + /* + * Since each architecture defines a struct page for the zero + * page, just fall through and treat it like a normal page. + */ } *pfn = hmm_device_entry_from_pfn(range, pte_pfn(pte)) | cpu_flags; @@ -584,7 +400,7 @@ again: } return 0; } else if (!pmd_present(pmd)) - return hmm_pfns_bad(start, end, walk); + return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR); if (pmd_devmap(pmd) || pmd_trans_huge(pmd)) { /* @@ -612,7 +428,7 @@ again: * recover. */ if (pmd_bad(pmd)) - return hmm_pfns_bad(start, end, walk); + return hmm_pfns_fill(start, end, range, HMM_PFN_ERROR); ptep = pte_offset_map(pmdp, addr); i = (addr - range->start) >> PAGE_SHIFT; @@ -770,93 +586,55 @@ unlock: #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) +static int hmm_vma_walk_test(unsigned long start, unsigned long end, + struct mm_walk *walk) { - 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; + struct hmm_vma_walk *hmm_vma_walk = walk->private; + struct hmm_range *range = hmm_vma_walk->range; + struct vm_area_struct *vma = walk->vma; - /* Prevent hmm_release() from running while the range is valid */ - if (!mmget_not_zero(hmm->mmu_notifier.mm)) + /* + * Skip vma ranges that don't have struct page backing them or + * map I/O devices directly. + */ + if (vma->vm_flags & (VM_IO | VM_PFNMAP | VM_MIXEDMAP)) 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 the vma does not allow read access, then assume that it does not + * allow write access either. HMM does not support architectures + * that allow write without read. */ - if (!hmm->notifiers) - range->valid = true; - spin_unlock_irqrestore(&hmm->ranges_lock, flags); - - return 0; -} -EXPORT_SYMBOL(hmm_range_register); + if (!(vma->vm_flags & VM_READ)) { + bool fault, write_fault; -/* - * 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; + /* + * Check to see if a fault is requested for any page in the + * range. + */ + hmm_range_need_fault(hmm_vma_walk, range->pfns + + ((start - range->start) >> PAGE_SHIFT), + (end - start) >> PAGE_SHIFT, + 0, &fault, &write_fault); + if (fault || write_fault) + return -EFAULT; - spin_lock_irqsave(&hmm->ranges_lock, flags); - list_del_init(&range->list); - spin_unlock_irqrestore(&hmm->ranges_lock, flags); + hmm_pfns_fill(start, end, range, HMM_PFN_NONE); + hmm_vma_walk->last = end; - /* Drop reference taken by hmm_range_register() */ - mmput(hmm->mmu_notifier.mm); + /* Skip this vma and continue processing the next vma. */ + return 1; + } - /* - * 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)); + return 0; } -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, + .test_walk = hmm_vma_walk_test, }; /** @@ -889,210 +667,27 @@ static const struct mm_walk_ops hmm_walk_ops = { */ 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 hmm_vma_walk hmm_vma_walk = { + .range = range, + .last = range->start, + .flags = flags, + }; + struct mm_struct *mm = range->notifier->mm; int ret; - lockdep_assert_held(&hmm->mmu_notifier.mm->mmap_sem); + lockdep_assert_held(&mm->mmap_sem); do { /* If range is no longer valid force retry. */ - if (!range->valid) + if (mmu_interval_check_retry(range->notifier, + range->notifier_seq)) return -EBUSY; + ret = walk_page_range(mm, hmm_vma_walk.last, range->end, + &hmm_walk_ops, &hmm_vma_walk); + } while (ret == -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); - + if (ret) + return ret; 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); |