| Message ID | 20230821194411.2165757-1-ackerleytng@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: selftests: Add tests - invalid inputs for KVM_CREATE_GUEST_MEMFD | expand |
On Mon, Aug 21, 2023, Ackerley Tng wrote: > Test that invalid inputs for KVM_CREATE_GUEST_MEMFD, such as > non-page-aligned page size and invalid flags, are rejected by the > KVM_CREATE_GUEST_MEMFD with EINVAL > > Signed-off-by: Ackerley Tng <ackerleytng@google.com> > --- > .../testing/selftests/kvm/guest_memfd_test.c | 33 +++++++++++++++++++ > .../selftests/kvm/include/kvm_util_base.h | 11 +++++-- > 2 files changed, 42 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c > index eb93c608a7e0..a8e37f001297 100644 > --- a/tools/testing/selftests/kvm/guest_memfd_test.c > +++ b/tools/testing/selftests/kvm/guest_memfd_test.c > @@ -90,6 +90,37 @@ static void test_fallocate(int fd, size_t page_size, size_t total_size) > TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed"); > } > > +static void test_create_guest_memfd_invalid(struct kvm_vm *vm, size_t page_size) > +{ > + int fd; > + uint64_t size; This should be size_t. > + uint64_t flags; > + uint64_t valid_flags = 0; Revert fir/xmas-tree please. > + > + for (size = 1; size < page_size; size++) { > + fd = __vm_create_guest_memfd(vm, size, 0); > + TEST_ASSERT( No, bad Google3, bad. Never immediately wrap after an opening parenthesis. > + fd == -1, > + "Creating guest memfds with non-page-aligned page sizes should fail"); > + TEST_ASSERT(errno == EINVAL, "... and errno should be set to EINVAL"); Don't split/delay "errno" checks, it's all too easy for errno to get clobbered. And there's absolutely zero reason to split these, the ret+errno get printed so the odds of what went wrong not being super duper obvious are very low. What _is_ worth printing is the size. > + } > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > + valid_flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE; > +#endif Ugh, this is annoying. But HPAGE_PMD_SIZE wrapping with CONFIG_TRANSPARENT_HUGEPAGE and so guest_memfd() can't (easily) enforce the alignment check if THP is disabled, i.e. always letting userspace specify KVM_GUEST_MEMFD_ALLOW_HUGEPAGE would be messy. Oh! And we should also test for unaligned huge pages, i.e. multiples of page_size that aren't PMD-aligned. At that point, I would say don't pass in @page_size to this particular testcase, e.g. have main() be something like this: vm = vm_create_barebones(); test_create_guest_memfd_invalid(vm); page_size = getpagesize(); total_size = page_size * 4; fd = vm_create_guest_memfd(vm, total_size, 0); test_file_read_write(fd); test_mmap(fd, page_size); test_file_size(fd, page_size, total_size); test_fallocate(fd, page_size, total_size); And then in here, use get_trans_hugepagesz() to do negative testing of KVM_GUEST_MEMFD_ALLOW_HUGEPAGE. > + > + for (flags = 1; flags; flags <<= 1) { > + if (flags & valid_flags) This only ever tests one flag in isolation, e.g. if it would detect if KVM did something ridiculous like if (flags && !(flags & KVM_GUEST_MEMFD_ALLOW_HUGEPAGE)) return -EINVAL; Iterating over all possible values doesn't make sense, and giving "lower" flags preference is likewise a bit silly, so what if we do (note the s/flags/flag) for (flag = 1; flag; flag <<= 1) { if (flag & valid_flags) continue; fd = __vm_create_guest_memfd(vm, page_size, flag); TEST_ASSERT(fd == -1 && errno == EINVAL, "guest_memfd() with flags '0x%llx' should fail with EINVAL", flag); for_each_set_bit(bit, &valid_flags, 64) { fd = __vm_create_guest_memfd(vm, page_size, flag | BIT_ULL(bit)); TEST_ASSERT(fd == -1 && errno == EINVAL, "guest_memfd() with flags '0x%llx' should fail with EINVAL", flag | BIT_ULL(bit)); } } i.e. test the invalid flag in isolation, and then also test it in combination with each valid flag. It's from from exhaustive, but it'll at least ensure we have *some* coverage if/when new flags come along.
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index eb93c608a7e0..a8e37f001297 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -90,6 +90,37 @@ static void test_fallocate(int fd, size_t page_size, size_t total_size) TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed"); } +static void test_create_guest_memfd_invalid(struct kvm_vm *vm, size_t page_size) +{ + int fd; + uint64_t size; + uint64_t flags; + uint64_t valid_flags = 0; + + for (size = 1; size < page_size; size++) { + fd = __vm_create_guest_memfd(vm, size, 0); + TEST_ASSERT( + fd == -1, + "Creating guest memfds with non-page-aligned page sizes should fail"); + TEST_ASSERT(errno == EINVAL, "... and errno should be set to EINVAL"); + } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + valid_flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE; +#endif + + for (flags = 1; flags; flags <<= 1) { + if (flags & valid_flags) + continue; + + fd = __vm_create_guest_memfd(vm, page_size, flags); + TEST_ASSERT( + fd == -1, + "Creating guest memfds with invalid flags should fail"); + TEST_ASSERT(errno == EINVAL, "... and errno should be set to EINVAL"); + } +} + int main(int argc, char *argv[]) { @@ -103,6 +134,8 @@ int main(int argc, char *argv[]) vm = vm_create_barebones(); + test_create_guest_memfd_invalid(vm, page_size); + fd = vm_create_guest_memfd(vm, total_size, 0); test_file_read_write(fd); diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h index 39b38c75b99c..8bdfadd72349 100644 --- a/tools/testing/selftests/kvm/include/kvm_util_base.h +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h @@ -474,7 +474,8 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name) } void vm_create_irqchip(struct kvm_vm *vm); -static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size, + +static inline int __vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size, uint64_t flags) { struct kvm_create_guest_memfd gmem = { @@ -482,7 +483,13 @@ static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size, .flags = flags, }; - int fd = __vm_ioctl(vm, KVM_CREATE_GUEST_MEMFD, &gmem); + return __vm_ioctl(vm, KVM_CREATE_GUEST_MEMFD, &gmem); +} + +static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size, + uint64_t flags) +{ + int fd = __vm_create_guest_memfd(vm, size, flags); TEST_ASSERT(fd >= 0, KVM_IOCTL_ERROR(KVM_CREATE_GUEST_MEMFD, fd)); return fd;
Test that invalid inputs for KVM_CREATE_GUEST_MEMFD, such as non-page-aligned page size and invalid flags, are rejected by the KVM_CREATE_GUEST_MEMFD with EINVAL Signed-off-by: Ackerley Tng <ackerleytng@google.com> --- .../testing/selftests/kvm/guest_memfd_test.c | 33 +++++++++++++++++++ .../selftests/kvm/include/kvm_util_base.h | 11 +++++-- 2 files changed, 42 insertions(+), 2 deletions(-)