Re: [PATCH v3 12/19] target/riscv: add KVM specific MISA properties

[Daniel Henrique Barboza]

On 6/23/23 06:38, Andrew Jones wrote:
> On Thu, Jun 22, 2023 at 10:56:53AM -0300, Daniel Henrique Barboza wrote:
> ...
> > +#define KVM_MISA_CFG(_bit, _reg_id) \
> > +    {.offset = _bit, .kvm_reg_id = _reg_id}
> > +
> > +/* KVM ISA extensions */
> > +static KVMCPUConfig kvm_misa_ext_cfgs[] = {
> > +    KVM_MISA_CFG(RVA, KVM_RISCV_ISA_EXT_A),
> > +    KVM_MISA_CFG(RVC, KVM_RISCV_ISA_EXT_C),
> > +    KVM_MISA_CFG(RVD, KVM_RISCV_ISA_EXT_D),
> > +    KVM_MISA_CFG(RVF, KVM_RISCV_ISA_EXT_F),
> > +    KVM_MISA_CFG(RVH, KVM_RISCV_ISA_EXT_H),
> > +    KVM_MISA_CFG(RVI, KVM_RISCV_ISA_EXT_I),
> > +    KVM_MISA_CFG(RVM, KVM_RISCV_ISA_EXT_M),
> > +};
> > +
> ...
> > +static void kvm_riscv_add_cpu_user_properties(Object *cpu_obj)
> > +{
> > +    int i;
> > +
> > +    for (i = 0; i < ARRAY_SIZE(kvm_misa_ext_cfgs); i++) {
> > +        KVMCPUConfig *misa_cfg = &kvm_misa_ext_cfgs[i];
> > +        int bit = misa_cfg->offset;
> > +
> > +        misa_cfg->name = misa_ext_info_arr[bit].name;
> > +        misa_cfg->description = misa_ext_info_arr[bit].description;
>
> I'd prefer these be set by KVM_MISA_CFG(), since we can. No need to wait
> until runtime if we can do it at compile-time.

The compiler will complain about "error: initializer element is not constant" 
and
the build will fail. This happens because, apparently, the compiler doesn't see 
the
imported array as a constant, regardless of the 'const' type.

If there's a trick that allow us to set these inside that macro I'm all ears. I 
tried
a bit, failed, and ended up adding these 2 extra lines. Thanks,


Daniel



> Thanks,
> drew
>
> > +
> > +        object_property_add(cpu_obj, misa_cfg->name, "bool",
> > +                            NULL,
> > +                            kvm_cpu_set_misa_ext_cfg,
> > +                            NULL, misa_cfg);
> > +        object_property_set_description(cpu_obj, misa_cfg->name,
> > +                                        misa_cfg->description);
> > +    }
> > +}
> > +
> >   static int kvm_riscv_get_regs_core(CPUState *cs)
> >   {
> >       int ret = 0;
> > @@ -427,6 +504,7 @@ void kvm_riscv_init_user_properties(Object *cpu_obj)
> >           return;
> >       }
> >   
> > +    kvm_riscv_add_cpu_user_properties(cpu_obj);
> >       kvm_riscv_init_machine_ids(cpu, &kvmcpu);
> >       kvm_riscv_init_misa_ext_mask(cpu, &kvmcpu);
> >   
> > --
> > 2.41.0