diff options
Diffstat (limited to 'mm/hmm.c')
| -rw-r--r-- | mm/hmm.c | 573 |
1 files changed, 372 insertions, 201 deletions
@@ -160,6 +160,32 @@ static void hmm_invalidate_range(struct hmm *hmm, up_read(&hmm->mirrors_sem); } +static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm) +{ + struct hmm_mirror *mirror; + struct hmm *hmm = mm->hmm; + + down_write(&hmm->mirrors_sem); + mirror = list_first_entry_or_null(&hmm->mirrors, struct hmm_mirror, + list); + while (mirror) { + list_del_init(&mirror->list); + if (mirror->ops->release) { + /* + * Drop mirrors_sem so callback can wait on any pending + * work that might itself trigger mmu_notifier callback + * and thus would deadlock with us. + */ + up_write(&hmm->mirrors_sem); + mirror->ops->release(mirror); + down_write(&hmm->mirrors_sem); + } + mirror = list_first_entry_or_null(&hmm->mirrors, + struct hmm_mirror, list); + } + up_write(&hmm->mirrors_sem); +} + static void hmm_invalidate_range_start(struct mmu_notifier *mn, struct mm_struct *mm, unsigned long start, @@ -185,6 +211,7 @@ static void hmm_invalidate_range_end(struct mmu_notifier *mn, } 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, }; @@ -206,13 +233,24 @@ int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm) if (!mm || !mirror || !mirror->ops) return -EINVAL; +again: mirror->hmm = hmm_register(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); + if (mirror->hmm->mm == NULL) { + /* + * A racing hmm_mirror_unregister() is about to destroy the hmm + * struct. Try again to allocate a new one. + */ + up_write(&mirror->hmm->mirrors_sem); + mirror->hmm = NULL; + goto again; + } else { + list_add(&mirror->list, &mirror->hmm->mirrors); + up_write(&mirror->hmm->mirrors_sem); + } return 0; } @@ -227,11 +265,32 @@ EXPORT_SYMBOL(hmm_mirror_register); */ void hmm_mirror_unregister(struct hmm_mirror *mirror) { - struct hmm *hmm = mirror->hmm; + bool should_unregister = false; + struct mm_struct *mm; + struct hmm *hmm; + if (mirror->hmm == NULL) + return; + + hmm = mirror->hmm; down_write(&hmm->mirrors_sem); - list_del(&mirror->list); + list_del_init(&mirror->list); + should_unregister = list_empty(&hmm->mirrors); + mirror->hmm = NULL; + mm = hmm->mm; + hmm->mm = NULL; up_write(&hmm->mirrors_sem); + + if (!should_unregister || mm == NULL) + return; + + spin_lock(&mm->page_table_lock); + if (mm->hmm == hmm) + mm->hmm = NULL; + spin_unlock(&mm->page_table_lock); + + mmu_notifier_unregister_no_release(&hmm->mmu_notifier, mm); + kfree(hmm); } EXPORT_SYMBOL(hmm_mirror_unregister); @@ -240,110 +299,275 @@ struct hmm_vma_walk { unsigned long last; bool fault; bool block; - bool write; }; -static int hmm_vma_do_fault(struct mm_walk *walk, - unsigned long addr, - hmm_pfn_t *pfn) +static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr, + bool write_fault, uint64_t *pfn) { unsigned int flags = FAULT_FLAG_ALLOW_RETRY | 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; int r; flags |= hmm_vma_walk->block ? 0 : FAULT_FLAG_ALLOW_RETRY; - flags |= hmm_vma_walk->write ? FAULT_FLAG_WRITE : 0; + flags |= write_fault ? FAULT_FLAG_WRITE : 0; r = handle_mm_fault(vma, addr, flags); if (r & VM_FAULT_RETRY) return -EBUSY; if (r & VM_FAULT_ERROR) { - *pfn = HMM_PFN_ERROR; + *pfn = range->values[HMM_PFN_ERROR]; return -EFAULT; } return -EAGAIN; } -static void hmm_pfns_special(hmm_pfn_t *pfns, - unsigned long addr, - unsigned long end) -{ - for (; addr < end; addr += PAGE_SIZE, pfns++) - *pfns = HMM_PFN_SPECIAL; -} - static int hmm_pfns_bad(unsigned long addr, unsigned long end, struct mm_walk *walk) { - struct hmm_range *range = walk->private; - hmm_pfn_t *pfns = range->pfns; + 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] = HMM_PFN_ERROR; + pfns[i] = range->values[HMM_PFN_ERROR]; return 0; } -static void hmm_pfns_clear(hmm_pfn_t *pfns, - unsigned long addr, - unsigned long end) -{ - for (; addr < end; addr += PAGE_SIZE, pfns++) - *pfns = 0; -} - -static int hmm_vma_walk_hole(unsigned long addr, - unsigned long end, - struct mm_walk *walk) +/* + * hmm_vma_walk_hole() - handle a range lacking valid pmd or pte(s) + * @start: 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 + * Returns: 0 on success, -EAGAIN 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; - hmm_pfn_t *pfns = range->pfns; + 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] = HMM_PFN_EMPTY; - if (hmm_vma_walk->fault) { + pfns[i] = range->values[HMM_PFN_NONE]; + if (fault || write_fault) { int ret; - ret = hmm_vma_do_fault(walk, addr, &pfns[i]); + ret = hmm_vma_do_fault(walk, addr, write_fault, + &pfns[i]); if (ret != -EAGAIN) return ret; } } - return hmm_vma_walk->fault ? -EAGAIN : 0; + return (fault || write_fault) ? -EAGAIN : 0; } -static int hmm_vma_walk_clear(unsigned long addr, - unsigned long end, - struct mm_walk *walk) +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_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; - hmm_pfn_t *pfns = range->pfns; + + *fault = *write_fault = false; + if (!hmm_vma_walk->fault) + return; + + /* We aren't ask to do anything ... */ + if (!(pfns & range->flags[HMM_PFN_VALID])) + return; + /* If this is device memory than 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; - hmm_vma_walk->last = addr; + if (!hmm_vma_walk->fault) { + *fault = *write_fault = false; + return; + } + + for (i = 0; i < npages; ++i) { + hmm_pte_need_fault(hmm_vma_walk, pfns[i], cpu_flags, + fault, write_fault); + if ((*fault) || (*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; - for (; addr < end; addr += PAGE_SIZE, i++) { - pfns[i] = 0; - if (hmm_vma_walk->fault) { - int ret; + 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); +} - ret = hmm_vma_do_fault(walk, addr, &pfns[i]); - if (ret != -EAGAIN) - return ret; +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]; +} + +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) + pte_index(addr); + for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) + pfns[i] = hmm_pfn_from_pfn(range, pfn) | cpu_flags; + hmm_vma_walk->last = end; + return 0; +} + +static inline uint64_t pte_to_hmm_pfn_flags(struct hmm_range *range, pte_t pte) +{ + if (pte_none(pte) || !pte_present(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; + struct vm_area_struct *vma = walk->vma; + bool fault, write_fault; + uint64_t cpu_flags; + pte_t pte = *ptep; + uint64_t orig_pfn = *pfn; + + *pfn = range->values[HMM_PFN_NONE]; + cpu_flags = pte_to_hmm_pfn_flags(range, pte); + hmm_pte_need_fault(hmm_vma_walk, orig_pfn, cpu_flags, + &fault, &write_fault); + + if (pte_none(pte)) { + 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_pfn_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(vma->vm_mm, + pmdp, addr); + return -EAGAIN; + } + return 0; + } + + /* Report error for everything else */ + *pfn = range->values[HMM_PFN_ERROR]; + return -EFAULT; } - return hmm_vma_walk->fault ? -EAGAIN : 0; + if (fault || write_fault) + goto fault; + + *pfn = hmm_pfn_from_pfn(range, pte_pfn(pte)) | cpu_flags; + return 0; + +fault: + 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, @@ -353,26 +577,20 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, { struct hmm_vma_walk *hmm_vma_walk = walk->private; struct hmm_range *range = hmm_vma_walk->range; - struct vm_area_struct *vma = walk->vma; - hmm_pfn_t *pfns = range->pfns; + uint64_t *pfns = range->pfns; unsigned long addr = start, i; - bool write_fault; - hmm_pfn_t flag; pte_t *ptep; i = (addr - range->start) >> PAGE_SHIFT; - flag = vma->vm_flags & VM_READ ? HMM_PFN_READ : 0; - write_fault = hmm_vma_walk->fault & hmm_vma_walk->write; again: if (pmd_none(*pmdp)) return hmm_vma_walk_hole(start, end, walk); - if (pmd_huge(*pmdp) && vma->vm_flags & VM_HUGETLB) + if (pmd_huge(*pmdp) && (range->vma->vm_flags & VM_HUGETLB)) return hmm_pfns_bad(start, end, walk); if (pmd_devmap(*pmdp) || pmd_trans_huge(*pmdp)) { - unsigned long pfn; pmd_t pmd; /* @@ -388,17 +606,8 @@ again: barrier(); if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd)) goto again; - if (pmd_protnone(pmd)) - return hmm_vma_walk_clear(start, end, walk); - if (write_fault && !pmd_write(pmd)) - return hmm_vma_walk_clear(start, end, walk); - - pfn = pmd_pfn(pmd) + pte_index(addr); - flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0; - for (; addr < end; addr += PAGE_SIZE, i++, pfn++) - pfns[i] = hmm_pfn_t_from_pfn(pfn) | flag; - return 0; + return hmm_vma_handle_pmd(walk, addr, end, &pfns[i], pmd); } if (pmd_bad(*pmdp)) @@ -406,79 +615,43 @@ again: ptep = pte_offset_map(pmdp, addr); for (; addr < end; addr += PAGE_SIZE, ptep++, i++) { - pte_t pte = *ptep; - - pfns[i] = 0; + int r; - if (pte_none(pte)) { - pfns[i] = HMM_PFN_EMPTY; - if (hmm_vma_walk->fault) - goto fault; - continue; + 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 (!pte_present(pte)) { - swp_entry_t entry = pte_to_swp_entry(pte); - - if (!non_swap_entry(entry)) { - if (hmm_vma_walk->fault) - goto fault; - continue; - } - - /* - * This is a special swap entry, ignore migration, use - * device and report anything else as error. - */ - if (is_device_private_entry(entry)) { - pfns[i] = hmm_pfn_t_from_pfn(swp_offset(entry)); - if (is_write_device_private_entry(entry)) { - pfns[i] |= HMM_PFN_WRITE; - } else if (write_fault) - goto fault; - pfns[i] |= HMM_PFN_DEVICE_UNADDRESSABLE; - pfns[i] |= flag; - } else if (is_migration_entry(entry)) { - if (hmm_vma_walk->fault) { - pte_unmap(ptep); - hmm_vma_walk->last = addr; - migration_entry_wait(vma->vm_mm, - pmdp, addr); - return -EAGAIN; - } - continue; - } else { - /* Report error for everything else */ - pfns[i] = HMM_PFN_ERROR; - } - continue; - } - - if (write_fault && !pte_write(pte)) - goto fault; - - pfns[i] = hmm_pfn_t_from_pfn(pte_pfn(pte)) | flag; - pfns[i] |= pte_write(pte) ? HMM_PFN_WRITE : 0; - continue; - -fault: - pte_unmap(ptep); - /* Fault all pages in range */ - return hmm_vma_walk_clear(start, end, walk); } pte_unmap(ptep - 1); + hmm_vma_walk->last = addr; return 0; } +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]; +} + +static void hmm_pfns_special(struct hmm_range *range) +{ + unsigned long addr = range->start, i = 0; + + for (; addr < range->end; addr += PAGE_SIZE, i++) + range->pfns[i] = range->values[HMM_PFN_SPECIAL]; +} + /* * hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses - * @vma: virtual memory area containing the virtual address range - * @range: used to track snapshot validity - * @start: range virtual start address (inclusive) - * @end: range virtual end address (exclusive) - * @entries: array of hmm_pfn_t: provided by the caller, filled in by function - * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, 0 success + * @range: range being snapshotted + * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid + * vma permission, 0 success * * This snapshots the CPU page table for a range of virtual addresses. Snapshot * validity is tracked by range struct. See hmm_vma_range_done() for further @@ -491,26 +664,17 @@ fault: * NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS * MEMORY CORRUPTION ! YOU HAVE BEEN WARNED ! */ -int hmm_vma_get_pfns(struct vm_area_struct *vma, - struct hmm_range *range, - unsigned long start, - unsigned long end, - hmm_pfn_t *pfns) +int hmm_vma_get_pfns(struct hmm_range *range) { + struct vm_area_struct *vma = range->vma; struct hmm_vma_walk hmm_vma_walk; struct mm_walk mm_walk; struct hmm *hmm; - /* FIXME support hugetlb fs */ - if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { - hmm_pfns_special(pfns, start, end); - return -EINVAL; - } - /* Sanity check, this really should not happen ! */ - if (start < vma->vm_start || start >= vma->vm_end) + if (range->start < vma->vm_start || range->start >= vma->vm_end) return -EINVAL; - if (end < vma->vm_start || end > vma->vm_end) + if (range->end < vma->vm_start || range->end > vma->vm_end) return -EINVAL; hmm = hmm_register(vma->vm_mm); @@ -520,10 +684,24 @@ int hmm_vma_get_pfns(struct vm_area_struct *vma, if (!hmm->mmu_notifier.ops) return -EINVAL; + /* FIXME support hugetlb fs */ + if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { + hmm_pfns_special(range); + return -EINVAL; + } + + if (!(vma->vm_flags & VM_READ)) { + /* + * If vma do not allow read access, then assume that it does + * not allow write access, either. Architecture that allow + * write without read access are not supported by HMM, because + * operations such has atomic access would not work. + */ + hmm_pfns_clear(range, range->pfns, range->start, range->end); + return -EPERM; + } + /* Initialize range to track CPU page table update */ - range->start = start; - range->pfns = pfns; - range->end = end; spin_lock(&hmm->lock); range->valid = true; list_add_rcu(&range->list, &hmm->ranges); @@ -541,14 +719,13 @@ int hmm_vma_get_pfns(struct vm_area_struct *vma, mm_walk.pmd_entry = hmm_vma_walk_pmd; mm_walk.pte_hole = hmm_vma_walk_hole; - walk_page_range(start, end, &mm_walk); + walk_page_range(range->start, range->end, &mm_walk); return 0; } EXPORT_SYMBOL(hmm_vma_get_pfns); /* * hmm_vma_range_done() - stop tracking change to CPU page table over a range - * @vma: virtual memory area containing the virtual address range * @range: range being tracked * Returns: false if range data has been invalidated, true otherwise * @@ -568,10 +745,10 @@ EXPORT_SYMBOL(hmm_vma_get_pfns); * * There are two ways to use this : * again: - * hmm_vma_get_pfns(vma, range, start, end, pfns); or hmm_vma_fault(...); + * hmm_vma_get_pfns(range); or hmm_vma_fault(...); * trans = device_build_page_table_update_transaction(pfns); * device_page_table_lock(); - * if (!hmm_vma_range_done(vma, range)) { + * if (!hmm_vma_range_done(range)) { * device_page_table_unlock(); * goto again; * } @@ -579,13 +756,13 @@ EXPORT_SYMBOL(hmm_vma_get_pfns); * device_page_table_unlock(); * * Or: - * hmm_vma_get_pfns(vma, range, start, end, pfns); or hmm_vma_fault(...); + * hmm_vma_get_pfns(range); or hmm_vma_fault(...); * device_page_table_lock(); - * hmm_vma_range_done(vma, range); - * device_update_page_table(pfns); + * hmm_vma_range_done(range); + * device_update_page_table(range->pfns); * device_page_table_unlock(); */ -bool hmm_vma_range_done(struct vm_area_struct *vma, struct hmm_range *range) +bool hmm_vma_range_done(struct hmm_range *range) { unsigned long npages = (range->end - range->start) >> PAGE_SHIFT; struct hmm *hmm; @@ -595,7 +772,7 @@ bool hmm_vma_range_done(struct vm_area_struct *vma, struct hmm_range *range) return false; } - hmm = hmm_register(vma->vm_mm); + hmm = hmm_register(range->vma->vm_mm); if (!hmm) { memset(range->pfns, 0, sizeof(*range->pfns) * npages); return false; @@ -611,36 +788,34 @@ EXPORT_SYMBOL(hmm_vma_range_done); /* * hmm_vma_fault() - try to fault some address in a virtual address range - * @vma: virtual memory area containing the virtual address range - * @range: use to track pfns array content validity - * @start: fault range virtual start address (inclusive) - * @end: fault range virtual end address (exclusive) - * @pfns: array of hmm_pfn_t, only entry with fault flag set will be faulted - * @write: is it a write fault + * @range: range being faulted * @block: allow blocking on fault (if true it sleeps and do not drop mmap_sem) * Returns: 0 success, error otherwise (-EAGAIN means mmap_sem have been drop) * * 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. * - * On error, for one virtual address in the range, the function will set the - * hmm_pfn_t error flag for the corresponding pfn entry. + * On error, for one virtual address in the range, the function will mark the + * corresponding HMM pfn entry with an error flag. * * Expected use pattern: * retry: * down_read(&mm->mmap_sem); * // Find vma and address device wants to fault, initialize hmm_pfn_t * // array accordingly - * ret = hmm_vma_fault(vma, start, end, pfns, allow_retry); + * ret = hmm_vma_fault(range, write, block); * switch (ret) { * case -EAGAIN: - * hmm_vma_range_done(vma, range); + * hmm_vma_range_done(range); * // You might want to rate limit or yield to play nicely, you may * // also commit any valid pfn in the array assuming that you are * // getting true from hmm_vma_range_monitor_end() * goto retry; * case 0: * break; + * case -ENOMEM: + * case -EINVAL: + * case -EPERM: * default: * // Handle error ! * up_read(&mm->mmap_sem) @@ -648,7 +823,7 @@ EXPORT_SYMBOL(hmm_vma_range_done); * } * // Take device driver lock that serialize device page table update * driver_lock_device_page_table_update(); - * hmm_vma_range_done(vma, range); + * hmm_vma_range_done(range); * // Commit pfns we got from hmm_vma_fault() * driver_unlock_device_page_table_update(); * up_read(&mm->mmap_sem) @@ -658,51 +833,54 @@ EXPORT_SYMBOL(hmm_vma_range_done); * * YOU HAVE BEEN WARNED ! */ -int hmm_vma_fault(struct vm_area_struct *vma, - struct hmm_range *range, - unsigned long start, - unsigned long end, - hmm_pfn_t *pfns, - bool write, - bool block) +int hmm_vma_fault(struct hmm_range *range, bool block) { + struct vm_area_struct *vma = range->vma; + unsigned long start = range->start; struct hmm_vma_walk hmm_vma_walk; struct mm_walk mm_walk; struct hmm *hmm; int ret; /* Sanity check, this really should not happen ! */ - if (start < vma->vm_start || start >= vma->vm_end) + if (range->start < vma->vm_start || range->start >= vma->vm_end) return -EINVAL; - if (end < vma->vm_start || end > vma->vm_end) + if (range->end < vma->vm_start || range->end > vma->vm_end) return -EINVAL; hmm = hmm_register(vma->vm_mm); if (!hmm) { - hmm_pfns_clear(pfns, start, end); + hmm_pfns_clear(range, range->pfns, range->start, range->end); return -ENOMEM; } /* Caller must have registered a mirror using hmm_mirror_register() */ if (!hmm->mmu_notifier.ops) return -EINVAL; + /* FIXME support hugetlb fs */ + if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { + hmm_pfns_special(range); + return -EINVAL; + } + + if (!(vma->vm_flags & VM_READ)) { + /* + * If vma do not allow read access, then assume that it does + * not allow write access, either. Architecture that allow + * write without read access are not supported by HMM, because + * operations such has atomic access would not work. + */ + hmm_pfns_clear(range, range->pfns, range->start, range->end); + return -EPERM; + } + /* Initialize range to track CPU page table update */ - range->start = start; - range->pfns = pfns; - range->end = end; spin_lock(&hmm->lock); range->valid = true; list_add_rcu(&range->list, &hmm->ranges); spin_unlock(&hmm->lock); - /* FIXME support hugetlb fs */ - if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { - hmm_pfns_special(pfns, start, end); - return 0; - } - hmm_vma_walk.fault = true; - hmm_vma_walk.write = write; hmm_vma_walk.block = block; hmm_vma_walk.range = range; mm_walk.private = &hmm_vma_walk; @@ -717,7 +895,7 @@ int hmm_vma_fault(struct vm_area_struct *vma, mm_walk.pte_hole = hmm_vma_walk_hole; do { - ret = walk_page_range(start, end, &mm_walk); + ret = walk_page_range(start, range->end, &mm_walk); start = hmm_vma_walk.last; } while (ret == -EAGAIN); @@ -725,8 +903,9 @@ int hmm_vma_fault(struct vm_area_struct *vma, unsigned long i; i = (hmm_vma_walk.last - range->start) >> PAGE_SHIFT; - hmm_pfns_clear(&pfns[i], hmm_vma_walk.last, end); - hmm_vma_range_done(vma, range); + hmm_pfns_clear(range, &range->pfns[i], hmm_vma_walk.last, + range->end); + hmm_vma_range_done(range); } return ret; } @@ -845,13 +1024,6 @@ static void hmm_devmem_release(struct device *dev, void *data) hmm_devmem_radix_release(resource); } -static struct hmm_devmem *hmm_devmem_find(resource_size_t phys) -{ - WARN_ON_ONCE(!rcu_read_lock_held()); - - return radix_tree_lookup(&hmm_devmem_radix, phys >> PA_SECTION_SHIFT); -} - static int hmm_devmem_pages_create(struct hmm_devmem *devmem) { resource_size_t key, align_start, align_size, align_end; @@ -892,9 +1064,8 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem) for (key = align_start; key <= align_end; key += PA_SECTION_SIZE) { struct hmm_devmem *dup; - rcu_read_lock(); - dup = hmm_devmem_find(key); - rcu_read_unlock(); + dup = radix_tree_lookup(&hmm_devmem_radix, + key >> PA_SECTION_SHIFT); if (dup) { dev_err(device, "%s: collides with mapping for %s\n", __func__, dev_name(dup->device)); |