Hi,
This series is in preparation for HPET migration support (in particular,
to support varray and vmstate_validate), and it also cleans up and fixes
the current vmstate! However, there is still the gap from being a ‘stable’
vmstate.
Patch Summary
=============
Patch 1-11: Clean up & fix for vmstate_of & vmstate_struct, where the
issues are catched by unit tests.
Patch 12,13: Add versioned vmstate and vmstate_validate support, and
vmstate_validate can accept safe "test" callback.
Patch 13-17: Add unit test to cover as much as possible cases to be
compatible with C version macros.
* Note while in principle Rust's vmstate pattern doesn't
have to match the C version, the C vmstate macros are
rich enough to cover as much logic as possible. So
checking against the C version is the most effective way
to detect the error.
With unit tests, the 2 vmstate gaps that come to mind right now are:
* `test` parameter in vmstate_of/vmstate_struct. I think there's not
too much difficulty, since referring to vmstate_validate makes it
straightforward...
* pointer to `struct`. assert_field_type() can't aware a inner type of
the pointer. We may need another trait (different from
impl_vmstate_pointer). Or, we may need to use the new
vmstate_struct_ptr macro. But I haven't tried it in details yet.
Thoughts about 'stable' vmstate
===============================
To make vmstate 'stable', I think one key point is to make vmstate
related things accept "safe" callbacks.
vmstate_validate (and future `test` parameters) has achieved this. But
VMStateDescription hasn't and it has the following callbacks:
int (*pre_load)(void *opaque);
int (*post_load)(void *opaque, int version_id);
int (*pre_save)(void *opaque);
int (*post_save)(void *opaque);
bool (*needed)(void *opaque);
bool (*dev_unplug_pending)(void *opaque);
I find there would be 2 options to address this:
1. introduce macros (like vmstate_validate) to accept "safe" callback.
For example,
static VMSTATE_HPET: VMStateDescription = VMStateDescription {
name: c_str!("hpet").as_ptr(),
version_id: 2,
minimum_version_id: 1,
pre_save: pre_save!(hpet_pre_save), // the pre_save macro will convert
"safe" hpet_pre_save() to C style callback.
post_load: post_load!(hpet_post_load), // ditto
fields: vmstate_fields! {
vmstate_of!(HPETState, config),
vmstate_of!(HPETState, int_status),
vmstate_of!(HPETState, counter),
vmstate_of!(HPETState, num_timers, version = 2),
vmstate_validate!(HPETState, VALIDATE_TIMERS_NAME,
HPETState::validate_num_timers),
vmstate_struct!(HPETState, timers, [0 .. num_timers],
VMSTATE_HPET_TIMER, BqlRefCell<HPETTimer>, version = 0),
},
subsections: vmstate_subsections! {
VMSTATE_HPET_RTC_IRQ_LEVEL,
VMSTATE_HPET_OFFSET,
},
..Zeroable::ZERO
};
2. introduce VMStateDescriptionBuilder (like MemoryRegionOpsBuilder) and
use the call chain to accept callbacks and initialize VMStateField.
About these 2 options, which one do you like?
Best Regards,
Zhao
---
Zhao Liu (17):
rust/vmstate: Remove unnecessary unsafe
rust/vmstate: Fix num_offset in vmstate macros
rust/vmstate: Add a prefix separator ", " for the array field in
vmstate macros
rust/vmstate: Use ident instead of expr to parse vmsd in
vmstate_struct macro
rust/vmstate: Fix num field when varray flags are set
rust/vmstate: Fix size field of VMStateField with VMS_ARRAY_OF_POINTER
flag
rust/vmstate: Fix type check for varray in vmstate_struct
rust/vmstate: Fix "cannot infer type" error in vmstate_struct
rust/vmstate: Fix unnecessary VMState bound of with_varray_flag()
rust/vmstate: Relax array check when build varray in vmstate_struct
rust/vmstate: Re-implement VMState trait for timer binding
rust/vmstate: Support version field in vmstate macros
rust/vmstate: Support vmstate_validate
rust/vmstate: Add unit test for vmstate_of macro
rust/vmstate: Add unit test for vmstate_{of|struct} macro
rust/vmstate: Add unit test for pointer case
rust/vmstate: Add unit test for vmstate_validate
rust/hw/char/pl011/src/device_class.rs | 2 +-
rust/qemu-api/meson.build | 5 +-
rust/qemu-api/src/assertions.rs | 15 +
rust/qemu-api/src/vmstate.rs | 110 ++++--
rust/qemu-api/tests/tests.rs | 2 +
rust/qemu-api/tests/vmstate_tests.rs | 467 +++++++++++++++++++++++++
6 files changed, 575 insertions(+), 26 deletions(-)
create mode 100644 rust/qemu-api/tests/vmstate_tests.rs
--
2.34.1
