Add a guest_memfd testcase to verify that faulting in private memory gets a SIGBUS. For now, test only the case where memory is private by default since KVM doesn't yet support in-place conversion. Deliberately run the CoW test with and without INIT_SHARED set as KVM should disallow MAP_PRIVATE regardless of whether the memory itself is private from a CoCo perspective. Cc: Ackerley Tng Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Reviewed-by: David Hildenbrand Reviewed-by: Ackerley Tng Signed-off-by: Sean Christopherson --- .../testing/selftests/kvm/guest_memfd_test.c | 26 +++++++++++++++---- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c index 73c2e54e7297..f5372fdf096d 100644 --- a/tools/testing/selftests/kvm/guest_memfd_test.c +++ b/tools/testing/selftests/kvm/guest_memfd_test.c @@ -75,9 +75,8 @@ static void test_mmap_supported(int fd, size_t total_size) kvm_munmap(mem, total_size); } -static void test_fault_overflow(int fd, size_t total_size) +static void test_fault_sigbus(int fd, size_t accessible_size, size_t map_size) { - size_t map_size = total_size * 4; const char val = 0xaa; char *mem; size_t i; @@ -86,12 +85,22 @@ static void test_fault_overflow(int fd, size_t total_size) TEST_EXPECT_SIGBUS(memset(mem, val, map_size)); - for (i = 0; i < total_size; i++) + for (i = 0; i < accessible_size; i++) TEST_ASSERT_EQ(READ_ONCE(mem[i]), val); kvm_munmap(mem, map_size); } +static void test_fault_overflow(int fd, size_t total_size) +{ + test_fault_sigbus(fd, total_size, total_size * 4); +} + +static void test_fault_private(int fd, size_t total_size) +{ + test_fault_sigbus(fd, 0, total_size); +} + static void test_mmap_not_supported(int fd, size_t total_size) { char *mem; @@ -260,9 +269,14 @@ static void __test_guest_memfd(struct kvm_vm *vm, uint64_t flags) gmem_test(file_read_write, vm, flags); if (flags & GUEST_MEMFD_FLAG_MMAP) { - gmem_test(mmap_supported, vm, flags); + if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) { + gmem_test(mmap_supported, vm, flags); + gmem_test(fault_overflow, vm, flags); + } else { + gmem_test(fault_private, vm, flags); + } + gmem_test(mmap_cow, vm, flags); - gmem_test(fault_overflow, vm, flags); } else { gmem_test(mmap_not_supported, vm, flags); } @@ -282,6 +296,8 @@ static void test_guest_memfd(unsigned long vm_type) __test_guest_memfd(vm, 0); flags = vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_FLAGS); + if (flags & GUEST_MEMFD_FLAG_MMAP) + __test_guest_memfd(vm, GUEST_MEMFD_FLAG_MMAP); /* MMAP should always be supported if INIT_SHARED is supported. */ if (flags & GUEST_MEMFD_FLAG_INIT_SHARED) -- 2.51.0.618.g983fd99d29-goog