[v2] target/loongarch/kvm: Enable LSX/LASX extension

The kernel had already support LSX and LASX [1],
but QEMU is disable LSX/LASX for kvm. This patch adds
kvm_check_cpucfg2() to check CPUCFG2.

[1]: https://lore.kernel.org/all/CABgObfZHRf7E_7Jk4uPRmSyxTy3EiuuYwHC35jQncNL9s-zTDA@mail.gmail.com/

Signed-off-by: Song Gao <gaosong@loongson.cn>
---
 linux-headers/asm-loongarch/kvm.h |  1 +
 target/loongarch/kvm/kvm.c        | 45 ++++++++++++++++++++++++++-----
 2 files changed, 39 insertions(+), 7 deletions(-)

On 2024/1/22 下午5:02, Song Gao wrote:
> The kernel had already support LSX and LASX [1],
> but QEMU is disable LSX/LASX for kvm. This patch adds
> kvm_check_cpucfg2() to check CPUCFG2.
> 
> [1]: https://lore.kernel.org/all/CABgObfZHRf7E_7Jk4uPRmSyxTy3EiuuYwHC35jQncNL9s-zTDA@mail.gmail.com/
> 
> Signed-off-by: Song Gao <gaosong@loongson.cn>
> ---
>   linux-headers/asm-loongarch/kvm.h |  1 +
>   target/loongarch/kvm/kvm.c        | 45 ++++++++++++++++++++++++++-----
>   2 files changed, 39 insertions(+), 7 deletions(-)
> 
> diff --git a/linux-headers/asm-loongarch/kvm.h b/linux-headers/asm-loongarch/kvm.h
> index c6ad2ee610..923d0bd382 100644
> --- a/linux-headers/asm-loongarch/kvm.h
> +++ b/linux-headers/asm-loongarch/kvm.h
> @@ -79,6 +79,7 @@ struct kvm_fpu {
>   #define LOONGARCH_REG_64(TYPE, REG)	(TYPE | KVM_REG_SIZE_U64 | (REG << LOONGARCH_REG_SHIFT))
>   #define KVM_IOC_CSRID(REG)		LOONGARCH_REG_64(KVM_REG_LOONGARCH_CSR, REG)
>   #define KVM_IOC_CPUCFG(REG)		LOONGARCH_REG_64(KVM_REG_LOONGARCH_CPUCFG, REG)
> +#define KVM_LOONGARCH_VCPU_CPUCFG	0
>   
>   struct kvm_debug_exit_arch {
>   };
> diff --git a/target/loongarch/kvm/kvm.c b/target/loongarch/kvm/kvm.c
> index 84bcdf5f86..2712bb7ab6 100644
> --- a/target/loongarch/kvm/kvm.c
> +++ b/target/loongarch/kvm/kvm.c
> @@ -537,6 +537,38 @@ static int kvm_loongarch_get_cpucfg(CPUState *cs)
>       return ret;
>   }
>   
> +static int kvm_check_cpucfg2(CPUState *cs)
> +{
> +    int ret;
> +    uint64_t val;
> +    struct kvm_device_attr attr = {
> +        .group = KVM_LOONGARCH_VCPU_CPUCFG,
> +        .attr = 2,
> +        .addr = (uint64_t)&val,
> +    };
> +    LoongArchCPU *cpu = LOONGARCH_CPU(cs);
> +    CPULoongArchState *env = &cpu->env;
> +
> +    ret = kvm_vcpu_ioctl(cs, KVM_HAS_DEVICE_ATTR, &attr);
> +
> +    if (!ret) {
> +        kvm_vcpu_ioctl(cs, KVM_GET_DEVICE_ATTR, &attr);
> +        env->cpucfg[2] &= val;
> +
> +        if (FIELD_EX32(env->cpucfg[2], CPUCFG2, FP)) {
> +            /* The FP minimal version is 1. */
> +            env->cpucfg[2] = FIELD_DP32(env->cpucfg[2], CPUCFG2, FP_VER, 1);
> +        }
> +
> +        if (FIELD_EX32(env->cpucfg[2], CPUCFG2, LLFTP)) {
> +            /* The LLFTP minimal version is 1. */
> +            env->cpucfg[2] = FIELD_DP32(env->cpucfg[2], CPUCFG2, LLFTP_VER, 1);
> +        }
> +    }
> +
> +    return ret;
> +}
> +
>   static int kvm_loongarch_put_cpucfg(CPUState *cs)
>   {
>       int i, ret = 0;
> @@ -545,14 +577,13 @@ static int kvm_loongarch_put_cpucfg(CPUState *cs)
>       uint64_t val;
>   
>       for (i = 0; i < 21; i++) {
> +	if (i == 2) {
> +            ret = kvm_check_cpucfg2(cs);
> +            if (ret) {
> +                return ret;
> +            }
> +	}
>           val = env->cpucfg[i];
> -        /* LSX and LASX and LBT are not supported in kvm now */
> -        if (i == 2) {
> -            val &= ~(BIT(R_CPUCFG2_LSX_SHIFT) | BIT(R_CPUCFG2_LASX_SHIFT));
> -            val &= ~(BIT(R_CPUCFG2_LBT_X86_SHIFT) |
> -                     BIT(R_CPUCFG2_LBT_ARM_SHIFT) |
> -                     BIT(R_CPUCFG2_LBT_MIPS_SHIFT));
> -        }
>           ret = kvm_set_one_reg(cs, KVM_IOC_CPUCFG(i), &val);
>           if (ret < 0) {
>               trace_kvm_failed_put_cpucfg(strerror(errno));
> 
Reviewed-by: Bibo Mao <maobibo@loongson.cn>