diff --git a/qemu/target/i386/cpu.c b/qemu/target/i386/cpu.c
index 024a9222..76247538 100644
--- a/qemu/target/i386/cpu.c
+++ b/qemu/target/i386/cpu.c
@@ -2418,28 +2418,26 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
     X86CPU *cpu = x86_env_get_cpu(env);
     CPUState *cs = CPU(cpu);
     uint32_t pkg_offset;
+    uint32_t limit;
+    uint32_t signature[3];
 
-    /* test if maximum index reached */
-    if (index & 0x80000000) {
-        if (index > env->cpuid_xlevel) {
-            if (env->cpuid_xlevel2 > 0) {
-                /* Handle the Centaur's CPUID instruction. */
-                if (index > env->cpuid_xlevel2) {
-                    index = env->cpuid_xlevel2;
-                } else if (index < 0xC0000000) {
-                    index = env->cpuid_xlevel;
-                }
-            } else {
-                /* Intel documentation states that invalid EAX input will
-                 * return the same information as EAX=cpuid_level
-                 * (Intel SDM Vol. 2A - Instruction Set Reference - CPUID)
-                 */
-                index =  env->cpuid_level;
-            }
-        }
+    /* Calculate & apply limits for different index ranges */
+    if (index >= 0xC0000000) {
+        limit = env->cpuid_xlevel2;
+    } else if (index >= 0x80000000) {
+        limit = env->cpuid_xlevel;
+    } else if (index >= 0x40000000) {
+        limit = 0x40000001;
     } else {
-        if (index > env->cpuid_level)
-            index = env->cpuid_level;
+        limit = env->cpuid_level;
+    }
+
+    if (index > limit) {
+        /* Intel documentation states that invalid EAX input will
+         * return the same information as EAX=cpuid_level
+         * (Intel SDM Vol. 2A - Instruction Set Reference - CPUID)
+         */
+        index = env->cpuid_level;
     }
 
     switch(index) {
@@ -2655,6 +2653,30 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         }
         break;
     }
+    case 0x40000000:
+        /*
+         * CPUID code in kvm_arch_init_vcpu() ignores stuff
+         * set here, but we restrict to TCG none the less.
+         */
+        if (tcg_enabled(env->uc) && cpu->expose_tcg) {
+            memcpy(signature, "TCGTCGTCGTCG", 12);
+            *eax = 0x40000001;
+            *ebx = signature[0];
+            *ecx = signature[1];
+            *edx = signature[2];
+        } else {
+            *eax = 0;
+            *ebx = 0;
+            *ecx = 0;
+            *edx = 0;
+        }
+        break;
+    case 0x40000001:
+        *eax = 0;
+        *ebx = 0;
+        *ecx = 0;
+        *edx = 0;
+        break;
     case 0x80000000:
         *eax = env->cpuid_xlevel;
         *ebx = env->cpuid_vendor1;
diff --git a/qemu/target/i386/cpu.h b/qemu/target/i386/cpu.h
index 9fdf0eb1..6662ebbb 100644
--- a/qemu/target/i386/cpu.h
+++ b/qemu/target/i386/cpu.h
@@ -1199,6 +1199,7 @@ typedef struct X86CPU {
     bool check_cpuid;
     bool enforce_cpuid;
     bool expose_kvm;
+    bool expose_tcg;
     bool migratable;
     bool max_features; /* Enable all supported features automatically */
     uint32_t apic_id;