diff options
| -rw-r--r-- | include/linux/hmm.h | 16 | ||||
| -rw-r--r-- | mm/hmm.c | 44 |
2 files changed, 41 insertions, 19 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h index d0d6760..dd907f6 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -83,8 +83,7 @@ struct hmm; * hmm_pfn_t - HMM uses its own pfn type to keep several flags per page * * Flags: - * HMM_PFN_VALID: pfn is valid - * HMM_PFN_READ: CPU page table has read permission set + * HMM_PFN_VALID: pfn is valid. It has, at least, read permission. * HMM_PFN_WRITE: CPU page table has write permission set * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory * HMM_PFN_EMPTY: corresponding CPU page table entry is pte_none() @@ -97,13 +96,12 @@ struct hmm; typedef unsigned long hmm_pfn_t; #define HMM_PFN_VALID (1 << 0) -#define HMM_PFN_READ (1 << 1) -#define HMM_PFN_WRITE (1 << 2) -#define HMM_PFN_ERROR (1 << 3) -#define HMM_PFN_EMPTY (1 << 4) -#define HMM_PFN_SPECIAL (1 << 5) -#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 6) -#define HMM_PFN_SHIFT 7 +#define HMM_PFN_WRITE (1 << 1) +#define HMM_PFN_ERROR (1 << 2) +#define HMM_PFN_EMPTY (1 << 3) +#define HMM_PFN_SPECIAL (1 << 4) +#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 5) +#define HMM_PFN_SHIFT 6 /* * hmm_pfn_t_to_page() - return struct page pointed to by a valid hmm_pfn_t @@ -417,11 +417,9 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp, hmm_pfn_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: @@ -433,6 +431,7 @@ again: if (pmd_devmap(*pmdp) || pmd_trans_huge(*pmdp)) { unsigned long pfn; + hmm_pfn_t flag = 0; pmd_t pmd; /* @@ -497,7 +496,6 @@ again: } 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); @@ -517,7 +515,7 @@ again: if (write_fault && !pte_write(pte)) goto fault; - pfns[i] = hmm_pfn_t_from_pfn(pte_pfn(pte)) | flag; + pfns[i] = hmm_pfn_t_from_pfn(pte_pfn(pte)); pfns[i] |= pte_write(pte) ? HMM_PFN_WRITE : 0; continue; @@ -534,7 +532,8 @@ fault: /* * hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses * @range: range being snapshotted - * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, 0 success + * 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 @@ -573,6 +572,17 @@ int hmm_vma_get_pfns(struct hmm_range *range) if (!hmm->mmu_notifier.ops) 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->pfns, range->start, range->end); + return -EPERM; + } + /* Initialize range to track CPU page table update */ spin_lock(&hmm->lock); range->valid = true; @@ -686,6 +696,9 @@ EXPORT_SYMBOL(hmm_vma_range_done); * goto retry; * case 0: * break; + * case -ENOMEM: + * case -EINVAL: + * case -EPERM: * default: * // Handle error ! * up_read(&mm->mmap_sem) @@ -727,11 +740,16 @@ int hmm_vma_fault(struct hmm_range *range, bool write, bool block) if (!hmm->mmu_notifier.ops) return -EINVAL; - /* Initialize range to track CPU page table update */ - spin_lock(&hmm->lock); - range->valid = true; - list_add_rcu(&range->list, &hmm->ranges); - spin_unlock(&hmm->lock); + 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->pfns, range->start, range->end); + return -EPERM; + } /* FIXME support hugetlb fs */ if (is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL)) { @@ -739,6 +757,12 @@ int hmm_vma_fault(struct hmm_range *range, bool write, bool block) return 0; } + /* Initialize range to track CPU page table update */ + spin_lock(&hmm->lock); + range->valid = true; + list_add_rcu(&range->list, &hmm->ranges); + spin_unlock(&hmm->lock); + hmm_vma_walk.fault = true; hmm_vma_walk.write = write; hmm_vma_walk.block = block; |
