diff options
Diffstat (limited to 'arch/x86/kvm/mmu/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index a9a23e058555..8e853a5fc867 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -1556,6 +1556,17 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) { bool flush = false; + /* + * To prevent races with vCPUs faulting in a gfn using stale data, + * zapping a gfn range must be protected by mmu_invalidate_in_progress + * (and mmu_invalidate_seq). The only exception is memslot deletion; + * in that case, SRCU synchronization ensures that SPTEs are zapped + * after all vCPUs have unlocked SRCU, guaranteeing that vCPUs see the + * invalid slot. + */ + lockdep_assert_once(kvm->mmu_invalidate_in_progress || + lockdep_is_held(&kvm->slots_lock)); + if (kvm_memslots_have_rmaps(kvm)) flush = __kvm_rmap_zap_gfn_range(kvm, range->slot, range->start, range->end, @@ -1884,14 +1895,10 @@ static bool sp_has_gptes(struct kvm_mmu_page *sp) if (is_obsolete_sp((_kvm), (_sp))) { \ } else -#define for_each_gfn_valid_sp(_kvm, _sp, _gfn) \ +#define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ for_each_valid_sp(_kvm, _sp, \ &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ - if ((_sp)->gfn != (_gfn)) {} else - -#define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ - for_each_gfn_valid_sp(_kvm, _sp, _gfn) \ - if (!sp_has_gptes(_sp)) {} else + if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) { @@ -7063,15 +7070,15 @@ static void kvm_mmu_zap_memslot_pages_and_flush(struct kvm *kvm, /* * Since accounting information is stored in struct kvm_arch_memory_slot, - * shadow pages deletion (e.g. unaccount_shadowed()) requires that all - * gfns with a shadow page have a corresponding memslot. Do so before - * the memslot goes away. + * all MMU pages that are shadowing guest PTEs must be zapped before the + * memslot is deleted, as freeing such pages after the memslot is freed + * will result in use-after-free, e.g. in unaccount_shadowed(). */ for (i = 0; i < slot->npages; i++) { struct kvm_mmu_page *sp; gfn_t gfn = slot->base_gfn + i; - for_each_gfn_valid_sp(kvm, sp, gfn) + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { |