rust/vmstate: Add unit test for vmstate_{of|struct} macro

Add a unit test to cover some patterns accepted by vmstate_of and
vmstate_struct macros, which correspond to the following C version
macros:

 * VMSTATE_BOOL_V
 * VMSTATE_U64
 * VMSTATE_STRUCT_VARRAY_UINT8
 * (no C version) MULTIPLY variant of VMSTATE_STRUCT_VARRAY_UINT32
 * VMSTATE_ARRAY

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250318130219.1799170-13-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/qemu-api/tests/vmstate_tests.rs

@@ -5,10 +5,14 @@
 use std::{ffi::CStr, mem::size_of, slice};
 
 use qemu_api::{
-    bindings::{vmstate_info_int8, vmstate_info_uint8, vmstate_info_unused_buffer, VMStateFlags},
+    bindings::{
+        vmstate_info_bool, vmstate_info_int64, vmstate_info_int8, vmstate_info_uint64,
+        vmstate_info_uint8, vmstate_info_unused_buffer, VMStateFlags,
+    },
     c_str,
+    cell::BqlCell,
     vmstate::{VMStateDescription, VMStateField},
-    vmstate_fields, vmstate_of, vmstate_unused,
+    vmstate_fields, vmstate_of, vmstate_struct, vmstate_unused,
     zeroable::Zeroable,
 };
 
@@ -132,3 +136,153 @@ fn test_vmstate_varray_multiply() {
     // The last VMStateField in VMSTATE_FOOA.
     assert_eq!(foo_fields[4].flags, VMStateFlags::VMS_END);
 }
+
+// =========================== Test VMSTATE_FOOB ===========================
+// Test the use cases of the vmstate macro, corresponding to the following C
+// macro variants:
+//   * VMSTATE_FOOB:
+//     - VMSTATE_BOOL_V
+//     - VMSTATE_U64
+//     - VMSTATE_STRUCT_VARRAY_UINT8
+//     - (no C version) MULTIPLY variant of VMSTATE_STRUCT_VARRAY_UINT32
+//     - VMSTATE_ARRAY
+#[repr(C)]
+#[derive(qemu_api_macros::offsets)]
+struct FooB {
+    arr_a: [FooA; FOO_ARRAY_MAX],
+    num_a: u8,
+    arr_a_mul: [FooA; FOO_ARRAY_MAX],
+    num_a_mul: u32,
+    wrap: BqlCell<u64>,
+    val: bool,
+    // FIXME: Use Timer array. Now we can't since it's hard to link savevm.c to test.
+    arr_i64: [i64; FOO_ARRAY_MAX],
+}
+
+static VMSTATE_FOOB: VMStateDescription = VMStateDescription {
+    name: c_str!("foo_b").as_ptr(),
+    version_id: 2,
+    minimum_version_id: 1,
+    fields: vmstate_fields! {
+        vmstate_of!(FooB, val).with_version_id(2),
+        vmstate_of!(FooB, wrap),
+        vmstate_struct!(FooB, arr_a[0 .. num_a], &VMSTATE_FOOA, FooA).with_version_id(1),
+        vmstate_struct!(FooB, arr_a_mul[0 .. num_a_mul * 32], &VMSTATE_FOOA, FooA).with_version_id(2),
+        vmstate_of!(FooB, arr_i64),
+    },
+    ..Zeroable::ZERO
+};
+
+#[test]
+fn test_vmstate_bool_v() {
+    let foo_fields: &[VMStateField] = unsafe { slice::from_raw_parts(VMSTATE_FOOB.fields, 6) };
+
+    // 1st VMStateField ("val") in VMSTATE_FOOB (corresponding to VMSTATE_BOOL_V)
+    assert_eq!(
+        unsafe { CStr::from_ptr(foo_fields[0].name) }.to_bytes_with_nul(),
+        b"val\0"
+    );
+    assert_eq!(foo_fields[0].offset, 136);
+    assert_eq!(foo_fields[0].num_offset, 0);
+    assert_eq!(foo_fields[0].info, unsafe { &vmstate_info_bool });
+    assert_eq!(foo_fields[0].version_id, 2);
+    assert_eq!(foo_fields[0].size, 1);
+    assert_eq!(foo_fields[0].num, 0);
+    assert_eq!(foo_fields[0].flags, VMStateFlags::VMS_SINGLE);
+    assert!(foo_fields[0].vmsd.is_null());
+    assert!(foo_fields[0].field_exists.is_none());
+}
+
+#[test]
+fn test_vmstate_uint64() {
+    let foo_fields: &[VMStateField] = unsafe { slice::from_raw_parts(VMSTATE_FOOB.fields, 6) };
+
+    // 2nd VMStateField ("wrap") in VMSTATE_FOOB (corresponding to VMSTATE_U64)
+    assert_eq!(
+        unsafe { CStr::from_ptr(foo_fields[1].name) }.to_bytes_with_nul(),
+        b"wrap\0"
+    );
+    assert_eq!(foo_fields[1].offset, 128);
+    assert_eq!(foo_fields[1].num_offset, 0);
+    assert_eq!(foo_fields[1].info, unsafe { &vmstate_info_uint64 });
+    assert_eq!(foo_fields[1].version_id, 0);
+    assert_eq!(foo_fields[1].size, 8);
+    assert_eq!(foo_fields[1].num, 0);
+    assert_eq!(foo_fields[1].flags, VMStateFlags::VMS_SINGLE);
+    assert!(foo_fields[1].vmsd.is_null());
+    assert!(foo_fields[1].field_exists.is_none());
+}
+
+#[test]
+fn test_vmstate_struct_varray_uint8() {
+    let foo_fields: &[VMStateField] = unsafe { slice::from_raw_parts(VMSTATE_FOOB.fields, 6) };
+
+    // 3rd VMStateField ("arr_a") in VMSTATE_FOOB (corresponding to
+    // VMSTATE_STRUCT_VARRAY_UINT8)
+    assert_eq!(
+        unsafe { CStr::from_ptr(foo_fields[2].name) }.to_bytes_with_nul(),
+        b"arr_a\0"
+    );
+    assert_eq!(foo_fields[2].offset, 0);
+    assert_eq!(foo_fields[2].num_offset, 60);
+    assert!(foo_fields[2].info.is_null()); // VMSTATE_STRUCT_VARRAY_UINT8 doesn't set info field.
+    assert_eq!(foo_fields[2].version_id, 1);
+    assert_eq!(foo_fields[2].size, 20);
+    assert_eq!(foo_fields[2].num, 0);
+    assert_eq!(
+        foo_fields[2].flags.0,
+        VMStateFlags::VMS_STRUCT.0 | VMStateFlags::VMS_VARRAY_UINT8.0
+    );
+    assert_eq!(foo_fields[2].vmsd, &VMSTATE_FOOA);
+    assert!(foo_fields[2].field_exists.is_none());
+}
+
+#[test]
+fn test_vmstate_struct_varray_uint32_multiply() {
+    let foo_fields: &[VMStateField] = unsafe { slice::from_raw_parts(VMSTATE_FOOB.fields, 6) };
+
+    // 4th VMStateField ("arr_a_mul") in VMSTATE_FOOB (corresponding to
+    // (no C version) MULTIPLY variant of VMSTATE_STRUCT_VARRAY_UINT32)
+    assert_eq!(
+        unsafe { CStr::from_ptr(foo_fields[3].name) }.to_bytes_with_nul(),
+        b"arr_a_mul\0"
+    );
+    assert_eq!(foo_fields[3].offset, 64);
+    assert_eq!(foo_fields[3].num_offset, 124);
+    assert!(foo_fields[3].info.is_null()); // VMSTATE_STRUCT_VARRAY_UINT8 doesn't set info field.
+    assert_eq!(foo_fields[3].version_id, 2);
+    assert_eq!(foo_fields[3].size, 20);
+    assert_eq!(foo_fields[3].num, 32);
+    assert_eq!(
+        foo_fields[3].flags.0,
+        VMStateFlags::VMS_STRUCT.0
+            | VMStateFlags::VMS_VARRAY_UINT32.0
+            | VMStateFlags::VMS_MULTIPLY_ELEMENTS.0
+    );
+    assert_eq!(foo_fields[3].vmsd, &VMSTATE_FOOA);
+    assert!(foo_fields[3].field_exists.is_none());
+}
+
+#[test]
+fn test_vmstate_macro_array() {
+    let foo_fields: &[VMStateField] = unsafe { slice::from_raw_parts(VMSTATE_FOOB.fields, 6) };
+
+    // 5th VMStateField ("arr_i64") in VMSTATE_FOOB (corresponding to
+    // VMSTATE_ARRAY)
+    assert_eq!(
+        unsafe { CStr::from_ptr(foo_fields[4].name) }.to_bytes_with_nul(),
+        b"arr_i64\0"
+    );
+    assert_eq!(foo_fields[4].offset, 144);
+    assert_eq!(foo_fields[4].num_offset, 0);
+    assert_eq!(foo_fields[4].info, unsafe { &vmstate_info_int64 });
+    assert_eq!(foo_fields[4].version_id, 0);
+    assert_eq!(foo_fields[4].size, 8);
+    assert_eq!(foo_fields[4].num, FOO_ARRAY_MAX as i32);
+    assert_eq!(foo_fields[4].flags, VMStateFlags::VMS_ARRAY);
+    assert!(foo_fields[4].vmsd.is_null());
+    assert!(foo_fields[4].field_exists.is_none());
+
+    // The last VMStateField in VMSTATE_FOOB.
+    assert_eq!(foo_fields[5].flags, VMStateFlags::VMS_END);
+}