Per SDM,

80000000H EAX Maximum Input Value for Extended Function CPUID Information.
          EBX Reserved.
          ECX Reserved.
          EDX Reserved.

EBX/ECX/EDX in CPUID 0x80000000 leaf are reserved. Intel and Zhaoxin are
already using 0x0 leaf to encode vendor.

Reviewed-by: Tao Su <tao1.su@linux.intel.com>
Tested-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
Changes Since v1:
 * Consider Zhaoxin CPU. (Ewan)
---
 target/i386/cpu.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 8d67cadec2f2..37e4bf51d890 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8278,9 +8278,15 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         break;
     case 0x80000000:
         *eax = env->cpuid_xlevel;
-        *ebx = env->cpuid_vendor1;
-        *edx = env->cpuid_vendor2;
-        *ecx = env->cpuid_vendor3;
+
+        if (cpu->vendor_cpuid_only_v2 &&
+            (IS_INTEL_CPU(env) || IS_ZHAOXIN_CPU(env))) {
+            *ebx = *ecx = *edx = 0;
+        } else {
+            *ebx = env->cpuid_vendor1;
+            *edx = env->cpuid_vendor2;
+            *ecx = env->cpuid_vendor3;
+        }
         break;
     case 0x80000001:
         *eax = env->cpuid_version;
-- 
2.34.1

On 7/14/2025 4:08 PM, Zhao Liu wrote:
> Per SDM,
> 
> 80000000H EAX Maximum Input Value for Extended Function CPUID Information.
>            EBX Reserved.
>            ECX Reserved.
>            EDX Reserved.
> 
> EBX/ECX/EDX in CPUID 0x80000000 leaf are reserved. Intel and Zhaoxin are
> already using 0x0 leaf to encode vendor.
> 
> Reviewed-by: Tao Su <tao1.su@linux.intel.com>
> Tested-by: Yi Lai <yi1.lai@intel.com>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>