On Wed, Jan 29, 2025 at 11:58:14AM +0100, Paolo Bonzini wrote:
> Date: Wed, 29 Jan 2025 11:58:14 +0100
> From: Paolo Bonzini <pbonz...@redhat.com>
> Subject: Re: [PATCH 09/10] rust/timer/hpet: add qom and qdev APIs support
>
>
>
> On Sat, Jan 25, 2025 at 1:32 PM Zhao Liu <zhao1....@intel.com> wrote:
> > fn read(&mut self, addr: hwaddr, _size: u32) -> u64 {
>
> This can be &self.
Done.
> > let shift: u64 = (addr & 4) * 8;
> >
> > + match addr {
> > + HPET_TN_CFG_REG => self.config >> shift, // including
> > interrupt capabilities
>
> This needs to be "match addr & !4".
I understand it's not necessary:
In timer_and_addr(), I've masked the address with 0x18.
fn timer_and_addr(&self, addr: hwaddr) -> Option<(&BqlRefCell<HPETTimer>,
hwaddr)> {
let timer_id: usize = ((addr - 0x100) / 0x20) as usize;
if timer_id > self.num_timers.get() {
None
} else {
Some((&self.timers[timer_id], addr & 0x18))
}
}
And in HPETState::read(), I pass the masked address to
HPETTimer::read():
fn read(&self, addr: hwaddr, size: u32) -> u64 {
let shift: u64 = (addr & 4) * 8;
if (0x100..=0x3ff).contains(&addr) {
match self.timer_and_addr(addr) {
None => 0, // Reserved,
Some((timer, addr)) => timer.borrow_mut().read(addr, size),
}
}
Ah, the `addr` variable in Some() is misleading, and I should use
anothor name like `tn_addr`.
0x18 is a subset of !0x4, so the bitwise & operation with !0x4 can be
omitted (I understand that this is why you also omitted this in the C
side in the commit c2366567378dd :-) ).
But `match addr & !4` is also reasonable, which explicitly emphasize
`& !4` makes the code clearer. I would do this.
> > + HPET_TN_CMP_REG => self.cmp >> shift, // comparator register
> > + HPET_TN_FSB_ROUTE_REG => self.fsb >> shift,
> > + _ => {
> > + // TODO: Add trace point - trace_hpet_ram_read_invalid()
> > + // Reserved.
> > + 0
> > + }
> > + }
> > + }
> > +
> > + fn write(&mut self, addr: hwaddr, value: u64, size: u32) {
> > + let shift = ((addr & 4) * 8) as u32;
> > + let len = std::cmp::min(size * 8, 64 - shift);
> > +
> > + match addr {
> > + HPET_TN_CFG_REG => self.set_tn_cfg_reg(shift, len, value),
>
> Likewise.
Done. Thanks!
> > + fn write(&self, addr: hwaddr, value: u64, size: u32) {
> > + let shift = ((addr & 4) * 8) as u32;
> > + let len = std::cmp::min(size * 8, 64 - shift);
> > +
> > + // TODO: Add trace point - trace_hpet_ram_write(addr, value)
> > + if (0x100..=0x3ff).contains(&addr
> ) {
> > + match self.timer_and_addr(addr) {
> > + None => return, // Reserved.
>
> Clippy complains about an unnecessary return, just replace it with "()".
Fixed.
> > + Some((timer, addr)) => timer.borrow_mut().write(addr,
> > value, size),
> > + }
>
> > +
> > + fn reset_hold(&self, _type: ResetType) {
> > + let sbd = self.upcast::<SysBusDevice>();
> > +
> > + for timer in self.timers.iter().take(self.num_timers.get()) {
> > + timer.borrow_mut().reset();
> > + }
> > +
> > + self.counter.set(0);
> > + self.config.set(0);
> > + self.pit_enabled.set(true);
> > + self.hpet_offset.set(0);
> > +
> > + HPETFwConfig::update_hpet_cfg(
> > + self.hpet_id.get(),
> > + Some(self.capability.get() as u32),
> > + Some((*sbd).mmio[0].addr),
> > + );
>
> This can be simply sbd.mmio[0].addr, without the (*...).
>
> Also, you can change update_hpet_cfg to take arguments without the Option<>
> around them.
Good idea! Done.
> > +// TODO: add OBJECT_DECLARE_SIMPLE_TYPE.
> > +#[repr(C)]
> > +pub struct HPETClass {
> > + parent_class: <SysBusDevice as ObjectType>::Class,
> > +}
> > +
> > +unsafe impl ObjectType for HPETState {
> > + type Class = HPETClass;
> > + const TYPE_NAME: &'static CStr = crate::TYPE_HPET;
> > +}
>
> No need for HPETClass (and for ClassInitImpl<HPETClass>), just do
>
> unsafe impl ObjectType for HPETState {
Pls let me add a comment here:
// No need for HPETClass. Just like OBJECT_DECLARE_SIMPLE_TYPE in C.
Then this can be "grep", as a reference.
> type Class = <SysBusDevice as ObjectType>::Class;
> const TYPE_NAME: &'static CStr = crate::TYPE_HPET;
> }
>
> which is indeed more similar to OBJECT_DECLARE_SIMPLE_TYPE().
Awesome! Thanks.
Regards,
Zhao
