Note that the zapping of obsolete roots needs to happen after mmu_lock is dropped, so introduce a separate kvm_arch callback. The two map neatly to the "front" and "back" halves of kvm_mmu_zap_all_fast(). Co-developed-by: Nicolas Saenz Julienne Signed-off-by: Nicolas Saenz Julienne Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 32 ++++++++++++++++++++++++++++++++ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 7 +++++-- 3 files changed, 38 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 097095f71d60..d658cfe31cd9 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -8265,6 +8265,7 @@ bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, { unsigned long attrs = range->arg.attributes; struct kvm_memory_slot *slot = range->slot; + struct kvm_mmu_page *sp; int level; lockdep_assert_held_write(&kvm->mmu_lock); @@ -8320,9 +8321,40 @@ bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, hugepage_set_mixed(slot, gfn, level); } } + + /* + * There are special considerations when applying an memory protection + * attibute against a GPTE page. If set read-only, access/dirty bits + * within that page shouldn't be updated. If set non-accesible, + * accessing a virtual address that requires traversing that GPTE page + * should fault. + * + * On TDP enabled guests, the CPU faults on the GPTE address upon + * detecting such a situation. + * + * On non-TDP, upon detecting this situation, and based on the fact it + * should be a rare occasion, invalidate all the mmu roots. + */ + for (gfn_t gfn = range->start; gfn < range->end; gfn++) { + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { + __kvm_mmu_zap_all_fast_front_half(kvm); + return false; + } + } return false; } +void kvm_arch_post_set_memory_attributes_unlocked(struct kvm *kvm) +{ + /* + * This may also be called if no zap was done in + * kvm_arch_post_set_memory_attributes(). It is not an issue because + * __kvm_mmu_zap_all_fast_back_half() is cheap when it does not do + * anything. + */ + __kvm_mmu_zap_all_fast_back_half(kvm); +} + void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm, struct kvm_memory_slot *slot) { diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index e9c0932f150e..33f3199a855f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2624,6 +2624,7 @@ bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm, struct kvm_gfn_range *range); bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, struct kvm_gfn_range *range); +void kvm_arch_post_set_memory_attributes_unlocked(struct kvm *kvm); bool kvm_mem_attributes_valid(struct kvm *kvm, unsigned long attrs); u64 kvm_supported_mem_attributes(struct kvm *kvm); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 24f46dce192e..ccbec4796e4b 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2516,7 +2516,7 @@ static bool kvm_range_memory_attributes_need_sync(struct kvm *kvm, return kvm_range_has_any_memory_attributes(kvm, start, end, mask); } -static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, +static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm, struct kvm_mmu_notifier_range *range) { struct kvm_gfn_range gfn_range; @@ -2566,6 +2566,8 @@ static __always_inline void kvm_handle_gfn_range(struct kvm *kvm, if (found_memslot) KVM_MMU_UNLOCK(kvm); + + return found_memslot; } static bool kvm_pre_set_memory_attributes(struct kvm *kvm, @@ -2652,7 +2654,8 @@ static int kvm_vm_set_mem_attributes(struct kvm *kvm, gfn_t start, gfn_t end, smp_store_release(&kvm->mem_attrs.generation, kvm->mem_attrs.generation + 1); - kvm_handle_gfn_range(kvm, &post_set_range); + if (kvm_handle_gfn_range(kvm, &post_set_range)) + kvm_arch_post_set_memory_attributes_unlocked(kvm); out_unlock: mutex_unlock(&kvm->slots_lock); -- 2.52.0