Re: [PATCH v2 10/12] target/riscv: Add kvm_riscv_get/put_regs_timer

[Richard Henderson <richard.henderson@xxxxxxxxxx>]

On 12/12/21 9:05 PM, Anup Patel wrote:
> > +    ret = kvm_get_one_reg(cs, RISCV_TIMER_REG(env, state), &reg);
> > +    if (ret) {
> > +        abort();
> > +    }
> > +    env->kvm_timer_state = reg;
>
> Please read the timer frequency here.

Yep.

> > +
> > +    env->kvm_timer_dirty = true;
> > +}
> > +
> > +static void kvm_riscv_put_regs_timer(CPUState *cs)
> > +{
> > +    int ret;
> > +    uint64_t reg;
> > +    CPURISCVState *env = &RISCV_CPU(cs)->env;
> > +
> > +    if (!env->kvm_timer_dirty) {
> > +        return;
> > +    }
>
> Over here, we should get the timer frequency and abort() with an
> error message if it does not match env->kvm_timer_frequency
>
> For now, migration will not work between Hosts with different
> timer frequency.

You shouldn't have to do this every "put", only on migration, at which point you can 
actually signal a migration error rather than aborting directly.


r~