Re: [PATCH 15/16] target/riscv: update multi-letter extension KVM properties

From: Andrew Jones <ajones@ventanamicro.com>
To: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Cc: qemu-devel@nongnu.org, qemu-riscv@nongnu.org,
	alistair.francis@wdc.com,  bmeng@tinylab.org,
	liweiwei@iscas.ac.cn, zhiwei_liu@linux.alibaba.com,
	 palmer@rivosinc.com
Subject: Re: [PATCH 15/16] target/riscv: update multi-letter extension KVM properties
Date: Wed, 7 Jun 2023 14:30:44 +0200	[thread overview]
Message-ID: <20230607-9a3e536ad70720dd791c7e83@orel> (raw)
In-Reply-To: <20230530194623.272652-16-dbarboza@ventanamicro.com>

On Tue, May 30, 2023 at 04:46:22PM -0300, Daniel Henrique Barboza 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>
> ---
>  target/riscv/kvm.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c
> index 675e18df3b..92b99fe261 100644
> --- a/target/riscv/kvm.c
> +++ b/target/riscv/kvm.c
> @@ -295,6 +295,32 @@ 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++) {
> +        RISCVCPUMultiExtConfig *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;
> @@ -829,6 +855,7 @@ 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;
>  }
> -- 
> 2.40.1
> 
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>