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[PATCH 7/9] i386/cpu: Suppress CPUID values not defined by Intel


From: Xiaoyao Li
Subject: [PATCH 7/9] i386/cpu: Suppress CPUID values not defined by Intel
Date: Wed, 14 Aug 2024 03:54:29 -0400

Some CPUID leaves are defined by AMD while it also gets exposed to Intel
VMs by QEMU. It causes no issue with current VMs however it will not work
with Intel TDX because these CPUID leaves are enforced by TDX module as
reserved.

Stop to advertise them to Intel VMs when vendor_cpuid_only is true.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
---
 target/i386/cpu.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 7a4835289760..fed805e04aeb 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6863,12 +6863,16 @@ 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 && IS_INTEL_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;
+        *eax = (cpu->vendor_cpuid_only && IS_INTEL_CPU(env)) ? 0 : 
env->cpuid_version;
         *ebx = 0;
         *ecx = env->features[FEAT_8000_0001_ECX];
         *edx = env->features[FEAT_8000_0001_EDX];
-- 
2.34.1




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