Unmap KVM-created VMAs for KVM-internal memslots when the associated memslot is freed instead of unmapping via x86's internal API. This will allow deleting/freeing all memslots before kvm_arch_destroy_vm() without leaking VMAs, and in general is a net positive as it makes it far less likely that KVM will leak VMAs, e.g. in the unlikely scenario some other flow deletes KVM-internal memslots without going through __x86_set_memory_region().
Reviewed-by: James Houghton <[email protected]> Signed-off-by: Sean Christopherson <[email protected]> --- arch/x86/kvm/x86.c | 38 ++++++++++++++++---------------------- 1 file changed, 16 insertions(+), 22 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 32563a91fba9..0f3fa4571309 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10018,7 +10018,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) * @size > 0 to install a new slot, while @size == 0 to uninstall a * slot. The return code can be one of the following: * - * HVA: on success (uninstall will return a bogus HVA) + * HVA: on success (uninstall will return a NULL HVA) * -errno: on error * * The caller should always use IS_ERR() to check the return value @@ -10031,10 +10031,10 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size) { - int i, r; - unsigned long hva, old_npages; struct kvm_memslots *slots = kvm_memslots(kvm); struct kvm_memory_slot *slot; + unsigned long hva; + int i, r; lockdep_assert_held(&kvm->slots_lock); @@ -10058,8 +10058,7 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, if (!slot || !slot->npages) return NULL; - old_npages = slot->npages; - hva = slot->userspace_addr; + hva = 0; } for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { @@ -10075,9 +10074,6 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, return ERR_PTR_USR(r); } - if (!size) - vm_munmap(hva, old_npages * PAGE_SIZE); - return (void __user *)hva; } EXPORT_SYMBOL_FOR_KVM_INTERNAL(__x86_set_memory_region); @@ -10106,20 +10102,6 @@ void kvm_arch_pre_destroy_vm(struct kvm *kvm) void kvm_arch_destroy_vm(struct kvm *kvm) { - if (current->mm == kvm->mm) { - /* - * Free memory regions allocated on behalf of userspace, - * unless the memory map has changed due to process exit - * or fd copying. - */ - mutex_lock(&kvm->slots_lock); - __x86_set_memory_region(kvm, APIC_ACCESS_PAGE_PRIVATE_MEMSLOT, - 0, 0); - __x86_set_memory_region(kvm, IDENTITY_PAGETABLE_PRIVATE_MEMSLOT, - 0, 0); - __x86_set_memory_region(kvm, TSS_PRIVATE_MEMSLOT, 0, 0); - mutex_unlock(&kvm->slots_lock); - } if (kvm->arch.created_mediated_pmu) perf_release_mediated_pmu(); kvm_destroy_vcpus(kvm); @@ -10159,6 +10141,18 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot) } kvm_page_track_free_memslot(slot); + + /* + * Unmap VMAs allocated on behalf of userspace for internal memslots, + * unless the memory map has changed due to process exit or fd copying. + * Do the unmap only for the non-SMM slot, as the same VMA is used for + * both non-SMM and SMM memslots. Leak the mapping on failure, e.g. + * if the task is killed. Worst case scenario, the page(s) will be + * reclaimed when the process exits. + */ + if (current->mm == kvm->mm && slot->id >= KVM_USER_MEM_SLOTS && + !slot->as_id && !WARN_ON_ONCE(!slot->npages)) + vm_munmap(slot->userspace_addr, slot->npages * PAGE_SIZE); } int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages) -- 2.56.0.307.g5fe7bd680c-goog
