[RFC PATCH v4 11/14] KVM: guest_memfd: selftests: guest_memfd mmap() test when mapping is allowed

Fuad Tabba
2024-12-13T16:48:38Z

Expand the guest_memfd selftests to include testing mapping guest
memory if the capability is supported, and that still checks that
memory is not mappable if the capability isn't supported.

Also, build the guest_memfd selftest for aarch64.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../testing/selftests/kvm/guest_memfd_test.c | 57 +++++++++++++++++--
2 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 41593d2e7de9..c998eb3c3b77 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -174,6 +174,7 @@ TEST_GEN_PROGS_aarch64 += coalesced_io_test
TEST_GEN_PROGS_aarch64 += demand_paging_test
TEST_GEN_PROGS_aarch64 += dirty_log_test
TEST_GEN_PROGS_aarch64 += dirty_log_perf_test
+TEST_GEN_PROGS_aarch64 += guest_memfd_test
TEST_GEN_PROGS_aarch64 += guest_print_test
TEST_GEN_PROGS_aarch64 += get-reg-list
TEST_GEN_PROGS_aarch64 += 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 04b4111b7190..12b5777c2eb5 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -34,12 +34,55 @@ 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();
+ char *mem;
+ int ret;
+ int i;
+
+ 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, 0xaa, total_size);
+ for (i = 0; i < total_size; i++)
+ TEST_ASSERT_EQ(mem[i], 0xaa);
+
+ 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], 0xaa);
+
+ memset(mem, 0xaa, total_size);
+ for (i = 0; i < total_size; i++)
+ TEST_ASSERT_EQ(mem[i], 0xaa);
+
+ 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_mmap(int fd, size_t total_size)
+{
+ if (kvm_has_cap(KVM_CAP_GUEST_MEMFD_MAPPABLE))
+ test_mmap_allowed(fd, total_size);
+ else
+ test_mmap_denied(fd, total_size);
}

static void test_file_size(int fd, size_t page_size, size_t total_size)
@@ -175,13 +218,17 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm)

int main(int argc, char *argv[])
{
- size_t page_size;
+ uint64_t flags = 0;
+ 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));

+ if (kvm_has_cap(KVM_CAP_GUEST_MEMFD_MAPPABLE))
+ flags |= GUEST_MEMFD_FLAG_INIT_MAPPABLE;
+
page_size = getpagesize();
total_size = page_size * 4;

@@ -190,10 +237,10 @@ int main(int argc, char *argv[])
test_create_guest_memfd_invalid(vm);
test_create_guest_memfd_multiple(vm);

- fd = vm_create_guest_memfd(vm, total_size, 0);
+ fd = vm_create_guest_memfd(vm, total_size, flags);

test_file_read_write(fd);
- test_mmap(fd, page_size);
+ test_mmap(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);
--
2.47.1.613.gc27f4b7a9f-goog