Re: [PATCH v2 4/4] target/i386: Update CMPLegacy handling for Zhaoxin CPUs

[Zhao Liu]

Hi EwanHai,

On Thu, Jul 04, 2024 at 07:25:11AM -0400, EwanHai wrote:
> Date: Thu, 4 Jul 2024 07:25:11 -0400
> From: EwanHai <ewanhai-oc@zhaoxin.com>
> Subject: [PATCH v2 4/4] target/i386: Update CMPLegacy handling for Zhaoxin
>  CPUs
> X-Mailer: git-send-email 2.34.1
> 
> Zhaoxin CPUs handle the CMPLegacy bit in the same way
> as Intel CPUs. This patch simplifies the existing logic by
> using the IS_XXX_CPU macro and includes checks for Zhaoxin
> vendor to align their behavior with Intel.
> 
> Signed-off-by: EwanHai <ewanhai-oc@zhaoxin.com>
> ---
>  target/i386/cpu.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index a3747fc487..c52a4cf3ba 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -6945,9 +6945,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
> uint32_t count,
>           * So don't set it here for Intel to make Linux guests happy.
>           */
>          if (threads_per_pkg > 1) {
> -            if (env->cpuid_vendor1 != CPUID_VENDOR_INTEL_1 ||
> -                env->cpuid_vendor2 != CPUID_VENDOR_INTEL_2 ||
> -                env->cpuid_vendor3 != CPUID_VENDOR_INTEL_3) {
> +            if (!IS_INTEL_CPU(env) && !IS_ZHAOXIN_CPU(env)) {

This change implicitly changes the behavior of existing VIA CPU.

Is this a bug for the original VIA? If so, I suggest a separate patch to
fix it and explain the effect on the VIA (Zhaoxin1) CPU.

Regards,
Zhao

>                  *ecx |= 1 << 1;    /* CmpLegacy bit */
>              }
>          }
> -- 
> 2.34.1
>