Re: [PATCH 3/3] target/loongarch: Add host CPU model in kvm mode

[lixianglai <lixianglai@loongson.cn>]

Hi Bibo Mao:
> Host CPU model is basically the same with max CPU model, except Product
> ID and CPU model name. With host CPU model, Product ID comes from
> cpucfg0 and CPU model comes from /proc/cpuinfo.
>
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
>   target/loongarch/cpu.c | 94 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 94 insertions(+)
>
> diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
> index 8b8723a343..c7f52adeb9 100644
> --- a/target/loongarch/cpu.c
> +++ b/target/loongarch/cpu.c
> @@ -429,6 +429,97 @@ static void loongarch_max_initfn(Object *obj)
>       }
>   }
>   
> +#if defined(CONFIG_KVM)
> +static int read_cpuinfo(const char *field, char *value, int len)
> +{
> +    FILE *f;
> +    int ret = -1;
> +    int field_len = strlen(field);
> +    char line[512];
> +
> +    f = fopen("/proc/cpuinfo", "r");
> +    if (!f) {
> +        return -1;
> +    }
> +
> +    do {
> +        if (!fgets(line, sizeof(line), f)) {
> +            break;
> +        }
> +        if (!strncmp(line, field, field_len)) {
> +            strncpy(value, line, len);
> +            ret = 0;
> +            break;
> +        }
> +    } while (*line);
> +
> +    fclose(f);
> +
> +    return ret;
> +}
> +
> +static uint64_t get_host_cpu_model(void)
> +{
> +    char line[512];
> +    char *ns;
> +    static uint64_t cpuid;
> +
> +    if (cpuid) {
> +        return cpuid;
> +    }
> +
> +    if (read_cpuinfo("Model Name", line, sizeof(line))) {
> +        return 0;
> +    }
> +
> +    ns = strchr(line, ':');
> +    if (!ns) {
> +        return 0;
> +    }
> +
> +    ns = strstr(ns, "Loongson-");
> +    if (!ns) {
> +        return 0;
> +    }
> +
> +    ns += strlen("Loongson-");
> +    memccpy((void *)&cpuid, ns, 0, 8);
> +    return cpuid;
> +}
> +
> +static uint32_t get_host_cpucfg(int number)
> +{
> +    unsigned int data = 0;
> +
> +#ifdef __loongarch__
> +    asm volatile("cpucfg %[val], %[reg]"
> +                 : [val] "=r" (data)
> +                 : [reg] "r" (number)
> +                 : "memory");
> +#endif
> +
> +    return data;
> +}
> +
> +static void loongarch_host_initfn(Object *obj)
> +{
> +    uint32_t data;
> +    uint64_t cpuid;
> +    LoongArchCPU *cpu = LOONGARCH_CPU(obj);
> +
> +    loongarch_max_initfn(obj);
> +    data = get_host_cpucfg(0);
> +    if (data) {
> +        cpu->env.cpucfg[0] = data;
> +    }
> +

Does the feature bit on cpucfg[2] also need to be consistent with the 
host feature bit?
Otherwise, some features might be lost.

Thanks!
Xianglai.


> +    cpuid = get_host_cpu_model();
> +    if (cpuid) {
> +        cpu->env.cpu_id = cpuid;
> +    }
> +}
> +#endif
> +
>   static void loongarch_cpu_reset_hold(Object *obj, ResetType type)
>   {
>       uint8_t tlb_ps;
> @@ -780,6 +871,9 @@ static const TypeInfo loongarch_cpu_type_infos[] = {
>       DEFINE_LOONGARCH_CPU_TYPE(64, "la464", loongarch_la464_initfn),
>       DEFINE_LOONGARCH_CPU_TYPE(32, "la132", loongarch_la132_initfn),
>       DEFINE_LOONGARCH_CPU_TYPE(64, "max", loongarch_max_initfn),
> +#if defined(CONFIG_KVM)
> +    DEFINE_LOONGARCH_CPU_TYPE(64, "host", loongarch_host_initfn),
> +#endif
>   };
>   
>   DEFINE_TYPES(loongarch_cpu_type_infos)