diff options
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/kvm_main.c | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 7f686251f71..f29abeb6a91 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -104,8 +104,26 @@ static pfn_t fault_pfn; inline int kvm_is_mmio_pfn(pfn_t pfn) { if (pfn_valid(pfn)) { - struct page *page = compound_head(pfn_to_page(pfn)); - return PageReserved(page); + int reserved; + struct page *tail = pfn_to_page(pfn); + struct page *head = compound_trans_head(tail); + reserved = PageReserved(head); + if (head != tail) { + /* + * "head" is not a dangling pointer + * (compound_trans_head takes care of that) + * but the hugepage may have been splitted + * from under us (and we may not hold a + * reference count on the head page so it can + * be reused before we run PageReferenced), so + * we've to check PageTail before returning + * what we just read. + */ + smp_rmb(); + if (PageTail(tail)) + return reserved; + } + return PageReserved(tail); } return true; @@ -352,6 +370,22 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn, return young; } +static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn, + struct mm_struct *mm, + unsigned long address) +{ + struct kvm *kvm = mmu_notifier_to_kvm(mn); + int young, idx; + + idx = srcu_read_lock(&kvm->srcu); + spin_lock(&kvm->mmu_lock); + young = kvm_test_age_hva(kvm, address); + spin_unlock(&kvm->mmu_lock); + srcu_read_unlock(&kvm->srcu, idx); + + return young; +} + static void kvm_mmu_notifier_release(struct mmu_notifier *mn, struct mm_struct *mm) { @@ -368,6 +402,7 @@ static const struct mmu_notifier_ops kvm_mmu_notifier_ops = { .invalidate_range_start = kvm_mmu_notifier_invalidate_range_start, .invalidate_range_end = kvm_mmu_notifier_invalidate_range_end, .clear_flush_young = kvm_mmu_notifier_clear_flush_young, + .test_young = kvm_mmu_notifier_test_young, .change_pte = kvm_mmu_notifier_change_pte, .release = kvm_mmu_notifier_release, }; |