Re: [PATCH v2 1/1] target/riscv/kvm: fix timebase-frequency when using KVM acceleration

[Michael Tokarev]

27.04.2024 09:23, Andrew Jones wrote:
> On April 27, 2024 1:44:42 AM GMT+02:00, Michael Tokarev <mjt@tls.msk.ru> wrote:
> > 14.03.2024 09:15, Yong-Xuan Wang:
> > > The timebase-frequency of guest OS should be the same with host
> > > machine. The timebase-frequency value in DTS should be got from
> > > hypervisor when using KVM acceleration.
> >
> > This change ended up in stable-8.2 (v8.2.3).  Interestingly, this thing
> > compiled not even once, or else it would be obvious it fails to compile.
> > Somehow I was too used to CI, forgetting that we don't have riscv *host*
> > in CI (and I don't have one locally either).  So 8.2.3 is broken on
> > riscv64 *host*.
>
> It's possible to cross-compile qemu, so it'd be good to add that to the CI for 
> riscv until we can add native compiling.

Yes, definitely.  Qemu is already being cross-compiled on all "other"
architectures during CI.  But it is also being *run*, not just compiled.
And this is what's broken on riscv64 for almost a year now, and this
job has been disabled.  Instead, the *run* part of this job needs to
be disabled, but *build* part should be kept.

> > In 8.2, KVM_RISCV_GET_TIMER macro accepts 4 arguments, because it does
> > not have 10f86d1b845087d1 "target/riscv/kvm: change timer regs size to u64".
> >
> > What do you think, should I revert this change for stable-8.2, or pick
> > 10f86d1b845087d1 too, or change this commit (fix timebase-frequency) to
> > provide the missing argument for this macro?
>
> Changing the timer regs to u64 is an rv32 fix, so it's reasonable to also pick 
> it up. I suggest we keep this patch one way or another, though.

Okay, so I need help choosing which patches to pick.

10f86d1b845087d1 isn't sufficient, since it relies on 450bd6618fda3d
"target/riscv/kvm: change KVM_REG_RISCV_FP_D to u64".  In the same series
there also was 49c211ffca00fdf7c "target/riscv/kvm: change KVM_REG_RISCV_FP_F
to u32" - is it also needed?

Please tell me the set of things I need for stable-8.2 here.  I'd
love to makes 8.2.4 release really soon, to fix this breakage.

Also, right now I don't know how to even compile-test it.  So meanwhile I'll
try to fix that and push this change to qemu master (to re-enable riscv64
CI job but only build part of it).  I don't have riscv hardware handy :)

Thanks,

/mjt