Hi Fuad,
On 5/28/25 4:02 AM, Fuad Tabba wrote:
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.
Co-developed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
---
tools/testing/selftests/kvm/Makefile.kvm | 1 +
.../testing/selftests/kvm/guest_memfd_test.c | 162 +++++++++++++++---
2 files changed, 142 insertions(+), 21 deletions(-)
The test case fails on 64KB host, and the file size in test_create_guest_memfd_multiple()
would be page_size and (2 * page_size). The fixed size 4096 and 8192 aren't aligned to 64KB.
# ./guest_memfd_test
Random seed: 0x6b8b4567
==== Test Assertion Failure ====
guest_memfd_test.c:178: fd1 != -1
pid=7565 tid=7565 errno=22 - Invalid argument
1 0x000000000040252f: test_create_guest_memfd_multiple at guest_memfd_test.c:178
2 (inlined by) test_with_type at guest_memfd_test.c:231
3 0x00000000004020c7: main at guest_memfd_test.c:306
4 0x0000ffff8cec733f: ?? ??:0
5 0x0000ffff8cec7417: ?? ??:0
6 0x00000000004021ef: _start at ??:?
memfd creation should succeed
diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
index f62b0a5aba35..ccf95ed037c3 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -163,6 +163,7 @@ TEST_GEN_PROGS_arm64 += access_tracking_perf_test
TEST_GEN_PROGS_arm64 += arch_timer
TEST_GEN_PROGS_arm64 += coalesced_io_test
TEST_GEN_PROGS_arm64 += dirty_log_perf_test
+TEST_GEN_PROGS_arm64 += guest_memfd_test
TEST_GEN_PROGS_arm64 += get-reg-list
TEST_GEN_PROGS_arm64 += memslot_modification_stress_test
TEST_GEN_PROGS_arm64 += memslot_perf_test
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index ce687f8d248f..3d6765bc1f28 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -34,12 +34,46 @@ 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 page_size, size_t total_size)
+{
+ const char val = 0xaa;
+ char *mem;
+ size_t i;
+ int ret;
+
+ mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ TEST_ASSERT(mem != MAP_FAILED, "mmaping() guest memory should pass.");
+
If you agree, I think it would be nice to ensure guest-memfd doesn't support
copy-on-write, more details are provided below.
+ 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, page_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 page_size, size_t total_size)
{
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);
}
Add one more argument to test_mmap_denied as the flags passed to mmap().
static void test_mmap_denied(int fd, size_t page_size, size_t total_size, int mmap_flags)
{
mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, mmap_flags, fd, 0);
}
static void test_file_size(int fd, size_t page_size, size_t total_size)
@@ -120,26 +154,19 @@ static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size)
}
}
-static void test_create_guest_memfd_invalid(struct kvm_vm *vm)
+static void test_create_guest_memfd_invalid_sizes(struct kvm_vm *vm,
+ uint64_t guest_memfd_flags,
+ size_t page_size)
{
- size_t page_size = getpagesize();
- uint64_t flag;
size_t size;
int fd;
for (size = 1; size < page_size; size++) {
- fd = __vm_create_guest_memfd(vm, size, 0);
- TEST_ASSERT(fd == -1 && errno == EINVAL,
+ fd = __vm_create_guest_memfd(vm, size, guest_memfd_flags);
+ TEST_ASSERT(fd < 0 && errno == EINVAL,
"guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL",
size);
}
-
- for (flag = BIT(0); flag; flag <<= 1) {
- fd = __vm_create_guest_memfd(vm, page_size, flag);
- TEST_ASSERT(fd == -1 && errno == EINVAL,
- "guest_memfd() with flag '0x%lx' should fail with EINVAL",
- flag);
- }
}
static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
@@ -170,30 +197,123 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
close(fd1);
}
-int main(int argc, char *argv[])
+#define GUEST_MEMFD_TEST_SLOT 10
+#define GUEST_MEMFD_TEST_GPA 0x100000000
+
+static bool check_vm_type(unsigned long vm_type)
{
- size_t page_size;
+ /*
+ * Not all architectures support KVM_CAP_VM_TYPES. However, those that
+ * support guest_memfd have that support for the default VM type.
+ */
+ if (vm_type == VM_TYPE_DEFAULT)
+ return true;
+
+ return kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type);
+}
+
+static void test_with_type(unsigned long vm_type, uint64_t guest_memfd_flags,
+ bool expect_mmap_allowed)
+{
+ 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 (!check_vm_type(vm_type))
+ return;
page_size = getpagesize();
total_size = page_size * 4;
- vm = vm_create_barebones();
+ vm = vm_create_barebones_type(vm_type);
- test_create_guest_memfd_invalid(vm);
test_create_guest_memfd_multiple(vm);
+ test_create_guest_memfd_invalid_sizes(vm, guest_memfd_flags, page_size);
- fd = vm_create_guest_memfd(vm, total_size, 0);
+ fd = vm_create_guest_memfd(vm, total_size, guest_memfd_flags);
test_file_read_write(fd);
- test_mmap(fd, page_size);
+
+ if (expect_mmap_allowed)
+ test_mmap_allowed(fd, page_size, total_size);
+ else
+ test_mmap_denied(fd, page_size, total_size);
+
if (expect_mmap_allowed) {
test_mmap_denied(fd, page_size, total_size, MAP_PRIVATE);
test_mmap_allowed(fd, page_size, total_size);
} else {
test_mmap_denied(fd, page_size, total_size, MAP_SHARED);
}
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);
+}
+
+static void test_vm_type_gmem_flag_validity(unsigned long vm_type,
+ uint64_t expected_valid_flags)
+{
+ size_t page_size = getpagesize();
+ struct kvm_vm *vm;
+ uint64_t flag = 0;
+ int fd;
+
+ if (!check_vm_type(vm_type))
+ return;
+
+ vm = vm_create_barebones_type(vm_type);
+
+ for (flag = BIT(0); flag; flag <<= 1) {
+ fd = __vm_create_guest_memfd(vm, page_size, flag);
+
+ if (flag & expected_valid_flags) {
+ TEST_ASSERT(fd >= 0,
+ "guest_memfd() with flag '0x%lx' should be valid",
+ flag);
+ close(fd);
+ } else {
+ TEST_ASSERT(fd < 0 && errno == EINVAL,
+ "guest_memfd() with flag '0x%lx' should fail with EINVAL",
+ flag);
+ }
+ }
+
+ kvm_vm_release(vm);
+}
+
+static void test_gmem_flag_validity(void)
+{
+ uint64_t non_coco_vm_valid_flags = 0;
+
+ if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM))
+ non_coco_vm_valid_flags = GUEST_MEMFD_FLAG_SUPPORT_SHARED;
+
+ test_vm_type_gmem_flag_validity(VM_TYPE_DEFAULT, non_coco_vm_valid_flags);
+
+#ifdef __x86_64__
+ test_vm_type_gmem_flag_validity(KVM_X86_SW_PROTECTED_VM, non_coco_vm_valid_flags);
+ test_vm_type_gmem_flag_validity(KVM_X86_SEV_VM, 0);
+ test_vm_type_gmem_flag_validity(KVM_X86_SEV_ES_VM, 0);
+ test_vm_type_gmem_flag_validity(KVM_X86_SNP_VM, 0);
+ test_vm_type_gmem_flag_validity(KVM_X86_TDX_VM, 0);
+#endif
+}
+
+int main(int argc, char *argv[])
+{
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD));
+
+ test_gmem_flag_validity();
+
+ test_with_type(VM_TYPE_DEFAULT, 0, false);
+ if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) {
+ test_with_type(VM_TYPE_DEFAULT, GUEST_MEMFD_FLAG_SUPPORT_SHARED,
+ true);
+ }
+
+#ifdef __x86_64__
+ test_with_type(KVM_X86_SW_PROTECTED_VM, 0, false);
+ if (kvm_has_cap(KVM_CAP_GMEM_SHARED_MEM)) {
+ test_with_type(KVM_X86_SW_PROTECTED_VM,
+ GUEST_MEMFD_FLAG_SUPPORT_SHARED, true);
+ }
+#endif
}
Thanks,
Gavin
