Re: [PATCH] target/loongarch: Set cpuid CSR register only once with kvm mode

[gaosong]

在 2024/1/15 下午4:51, Bibo Mao 写道:
> CSR cpuid register is used for routing irq to different vcpus, its
> value is kept unchanged since poweron. So it is not necessary to
> set CSR cpuid register after system resets, and it is only set at
> vm creation stage.
>
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
>   target/loongarch/kvm/kvm.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)

Reviewed-by: Song Gao <gaosong@loongson.cn>

Thanks.
Song Gao
> diff --git a/target/loongarch/kvm/kvm.c b/target/loongarch/kvm/kvm.c
> index 84bcdf5f86..2230f029d0 100644
> --- a/target/loongarch/kvm/kvm.c
> +++ b/target/loongarch/kvm/kvm.c
> @@ -250,7 +250,7 @@ static int kvm_loongarch_get_csr(CPUState *cs)
>       return ret;
>   }
>   
> -static int kvm_loongarch_put_csr(CPUState *cs)
> +static int kvm_loongarch_put_csr(CPUState *cs, int level)
>   {
>       int ret = 0;
>       LoongArchCPU *cpu = LOONGARCH_CPU(cs);
> @@ -322,8 +322,11 @@ static int kvm_loongarch_put_csr(CPUState *cs)
>       ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_RVACFG),
>                              &env->CSR_RVACFG);
>   
> -    ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_CPUID),
> +    /* CPUID is constant after poweron, it should be set only once */
> +    if (level >= KVM_PUT_FULL_STATE) {
> +        ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_CPUID),
>                              &env->CSR_CPUID);
> +    }
>   
>       ret |= kvm_set_one_reg(cs, KVM_IOC_CSRID(LOONGARCH_CSR_PRCFG1),
>                              &env->CSR_PRCFG1);
> @@ -598,7 +601,7 @@ int kvm_arch_put_registers(CPUState *cs, int level)
>           return ret;
>       }
>   
> -    ret = kvm_loongarch_put_csr(cs);
> +    ret = kvm_loongarch_put_csr(cs, level);
>       if (ret) {
>           return ret;
>       }
>
> base-commit: 977542ded7e6b28d2bc077bcda24568c716e393c