i386/cpu: Mark CPUID 0x80000007[EBX] as reserved for Intel

Per SDM,

80000007H EAX Reserved = 0.
          EBX Reserved = 0.
          ECX Reserved = 0.
          EDX Bits 07-00: Reserved = 0.
              Bit 08: Invariant TSC available if 1.
              Bits 31-09: Reserved = 0.

EAX/EBX/ECX in CPUID 0x80000007 leaf are reserved for Intel.

At present, EAX is reserved for AMD, too. And AMD hasn't used ECX in
QEMU. So these 2 registers are both left as 0.

Therefore, only fix the EBX and excode it as 0 for Intel.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Tao Su <tao1.su@linux.intel.com>
Link: https://lore.kernel.org/r/20250627035129.2755537-3-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index ae508fa962dbee1e9810ac69404efad19a5146ed..533c9d9abc769f98e8b48d54e7d583590e65b5d0 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8376,7 +8376,11 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
     }
     case 0x80000007:
         *eax = 0;
-        *ebx = env->features[FEAT_8000_0007_EBX];
+        if (cpu->vendor_cpuid_only_v2 && IS_INTEL_CPU(env)) {
+            *ebx = 0;
+        } else {
+            *ebx = env->features[FEAT_8000_0007_EBX];
+        }
         *ecx = 0;
         *edx = env->features[FEAT_8000_0007_EDX];
         break;