Re: [PATCH v9 18/20] target/riscv: update multi-letter extension KVM properties

[Alistair Francis]

On Thu, Jul 6, 2023 at 8:19 PM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> We're now ready to update the multi-letter extensions status for KVM.
>
> kvm_riscv_update_cpu_cfg_isa_ext() is called called during vcpu creation
> time to verify which user options changes host defaults (via the 'user_set'
> flag) and tries to write them back to KVM.
>
> Failure to commit a change to KVM is only ignored in case KVM doesn't
> know about the extension (-EINVAL error code) and the user wanted to
> disable the given extension. Otherwise we're going to abort the boot
> process.
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/kvm.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
>
> diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c
> index 2d39ec154f..ba940e570e 100644
> --- a/target/riscv/kvm.c
> +++ b/target/riscv/kvm.c
> @@ -273,6 +273,32 @@ static void kvm_cpu_set_multi_ext_cfg(Object *obj, 
> Visitor *v,
>      kvm_cpu_cfg_set(cpu, multi_ext_cfg, value);
>  }
>
> +static void kvm_riscv_update_cpu_cfg_isa_ext(RISCVCPU *cpu, CPUState *cs)
> +{
> +    CPURISCVState *env = &cpu->env;
> +    uint64_t id, reg;
> +    int i, ret;
> +
> +    for (i = 0; i < ARRAY_SIZE(kvm_multi_ext_cfgs); i++) {
> +        KVMCPUConfig *multi_ext_cfg = &kvm_multi_ext_cfgs[i];
> +
> +        if (!multi_ext_cfg->user_set) {
> +            continue;
> +        }
> +
> +        id = kvm_riscv_reg_id(env, KVM_REG_RISCV_ISA_EXT,
> +                              multi_ext_cfg->kvm_reg_id);
> +        reg = kvm_cpu_cfg_get(cpu, multi_ext_cfg);
> +        ret = kvm_set_one_reg(cs, id, &reg);
> +        if (ret != 0) {
> +            error_report("Unable to %s extension %s in KVM, error %d",
> +                         reg ? "enable" : "disable",
> +                         multi_ext_cfg->name, ret);
> +            exit(EXIT_FAILURE);
> +        }
> +    }
> +}
> +
>  static void kvm_riscv_add_cpu_user_properties(Object *cpu_obj)
>  {
>      int i;
> @@ -792,6 +818,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
>      }
>
>      kvm_riscv_update_cpu_misa_ext(cpu, cs);
> +    kvm_riscv_update_cpu_cfg_isa_ext(cpu, cs);
>
>      return ret;
>  }
> --
> 2.41.0
>
>