Re: [PATCH v7 9/9] KVM: guest_memfd: selftests: guest_memfd mmap() test when mapping is allowed

[Ackerley Tng <ackerleytng@google.com>]

Fuad Tabba <tabba@google.com> writes:

> Expand the guest_memfd selftests to include testing mapping guest
> memory for VM types that support it.
>
> Also, build the guest_memfd selftest for arm64.
>
> Signed-off-by: Fuad Tabba <tabba@google.com>
> ---
>  tools/testing/selftests/kvm/Makefile.kvm      |  1 +
>  .../testing/selftests/kvm/guest_memfd_test.c  | 75 +++++++++++++++++--
>  2 files changed, 70 insertions(+), 6 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index 4277b983cace..c9a3f30e28dd 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -160,6 +160,7 @@ TEST_GEN_PROGS_arm64 += coalesced_io_test
>  TEST_GEN_PROGS_arm64 += demand_paging_test
>  TEST_GEN_PROGS_arm64 += dirty_log_test
>  TEST_GEN_PROGS_arm64 += dirty_log_perf_test
> +TEST_GEN_PROGS_arm64 += guest_memfd_test
>  TEST_GEN_PROGS_arm64 += guest_print_test
>  TEST_GEN_PROGS_arm64 += get-reg-list
>  TEST_GEN_PROGS_arm64 += kvm_create_max_vcpus
> diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
> index ce687f8d248f..38c501e49e0e 100644
> --- a/tools/testing/selftests/kvm/guest_memfd_test.c
> +++ b/tools/testing/selftests/kvm/guest_memfd_test.c
> @@ -34,12 +34,48 @@ static void test_file_read_write(int fd)
>  		    "pwrite on a guest_mem fd should fail");
>  }
>  
> -static void test_mmap(int fd, size_t page_size)
> +static void test_mmap_allowed(int fd, size_t total_size)
>  {
> +	size_t page_size = getpagesize();
> +	const char val = 0xaa;
> +	char *mem;
> +	int ret;
> +	int i;

Was using this test with hugetlb patches - int i was overflowing and
causing test failures.  Perhaps use size_t i for this instead?

> +
> +	mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> +	TEST_ASSERT(mem != MAP_FAILED, "mmaping() guest memory should pass.");
> +
> +	memset(mem, val, total_size);
> +	for (i = 0; i < total_size; i++)
> +		TEST_ASSERT_EQ(mem[i], val);
> +
> +	ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0,
> +			page_size);
> +	TEST_ASSERT(!ret, "fallocate the first page should succeed");
> +
> +	for (i = 0; i < page_size; i++)
> +		TEST_ASSERT_EQ(mem[i], 0x00);
> +	for (; i < total_size; i++)
> +		TEST_ASSERT_EQ(mem[i], val);
> +
> +	memset(mem, val, total_size);
> +	for (i = 0; i < total_size; i++)
> +		TEST_ASSERT_EQ(mem[i], val);
> +
> +	ret = munmap(mem, total_size);
> +	TEST_ASSERT(!ret, "munmap should succeed");
> +}
> +
> +static void test_mmap_denied(int fd, size_t total_size)
> +{
> +	size_t page_size = getpagesize();
>  	char *mem;
>  
>  	mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
>  	TEST_ASSERT_EQ(mem, MAP_FAILED);
> +
> +	mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
> +	TEST_ASSERT_EQ(mem, MAP_FAILED);
>  }
>  
>  static void test_file_size(int fd, size_t page_size, size_t total_size)
> @@ -170,19 +206,27 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
>  	close(fd1);
>  }
>  
> -int main(int argc, char *argv[])
> +unsigned long get_shared_type(void)
>  {
> -	size_t page_size;
> +#ifdef __x86_64__
> +	return KVM_X86_SW_PROTECTED_VM;
> +#endif
> +	return 0;
> +}
> +
> +void test_vm_type(unsigned long type, bool is_shared)
> +{
> +	struct kvm_vm *vm;
>  	size_t total_size;
> +	size_t page_size;
>  	int fd;
> -	struct kvm_vm *vm;
>  
>  	TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD));
>  
>  	page_size = getpagesize();
>  	total_size = page_size * 4;
>  
> -	vm = vm_create_barebones();
> +	vm = vm_create_barebones_type(type);
>  
>  	test_create_guest_memfd_invalid(vm);
>  	test_create_guest_memfd_multiple(vm);
> @@ -190,10 +234,29 @@ int main(int argc, char *argv[])
>  	fd = vm_create_guest_memfd(vm, total_size, 0);
>  
>  	test_file_read_write(fd);
> -	test_mmap(fd, page_size);
> +
> +	if (is_shared)
> +		test_mmap_allowed(fd, total_size);
> +	else
> +		test_mmap_denied(fd, total_size);
> +
>  	test_file_size(fd, page_size, total_size);
>  	test_fallocate(fd, page_size, total_size);
>  	test_invalid_punch_hole(fd, page_size, total_size);
>  
>  	close(fd);
> +	kvm_vm_release(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +#ifndef __aarch64__
> +	/* For now, arm64 only supports shared guest memory. */
> +	test_vm_type(VM_TYPE_DEFAULT, false);
> +#endif
> +
> +	if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM))
> +		test_vm_type(get_shared_type(), true);
> +
> +	return 0;
>  }