diff options
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 49ac13872e09..becf640e369c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -95,6 +95,13 @@ module_param(halt_poll_ns_shrink, uint, 0644); EXPORT_SYMBOL_GPL(halt_poll_ns_shrink); /* + * Allow direct access (from KVM or the CPU) without MMU notifier protection + * to unpinned pages. + */ +static bool allow_unsafe_mappings; +module_param(allow_unsafe_mappings, bool, 0444); + +/* * Ordering of locks: * * kvm->lock --> kvm->slots_lock --> kvm->irq_lock @@ -2811,6 +2818,9 @@ static kvm_pfn_t kvm_resolve_pfn(struct kvm_follow_pfn *kfp, struct page *page, * reference to such pages would cause KVM to prematurely free a page * it doesn't own (KVM gets and puts the one and only reference). * Don't allow those pages until the FIXME is resolved. + * + * Don't grab a reference for pins, callers that pin pages are required + * to check refcounted_page, i.e. must not blindly release the pfn. */ if (map) { pfn = map->pfn; @@ -2929,6 +2939,14 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma, bool write_fault = kfp->flags & FOLL_WRITE; int r; + /* + * Remapped memory cannot be pinned in any meaningful sense. Bail if + * the caller wants to pin the page, i.e. access the page outside of + * MMU notifier protection, and unsafe umappings are disallowed. + */ + if (kfp->pin && !allow_unsafe_mappings) + return -EINVAL; + r = follow_pfnmap_start(&args); if (r) { /* |