diff --git a/target-i386/helper.c b/target-i386/helper.c
index cb9113e8c80d5240e6a8be7e5480cfb0d69d39f7..d7563f7bbd6dd789ac205a65f030ba5de78016e3 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -273,9 +273,9 @@ static x86_def_t x86_defs[] = {
     {
         .name = "athlon",
         .level = 2,
-        .vendor1 = 0x68747541, /* "Auth" */
-        .vendor2 = 0x69746e65, /* "enti" */
-        .vendor3 = 0x444d4163, /* "cAMD" */
+        .vendor1 = CPUID_VENDOR_AMD_1,
+        .vendor2 = CPUID_VENDOR_AMD_2,
+        .vendor3 = CPUID_VENDOR_AMD_3,
         .family = 6,
         .model = 2,
         .stepping = 3,
@@ -308,6 +308,54 @@ static x86_def_t x86_defs[] = {
     },
 };
 
+static void host_cpuid(uint32_t function, uint32_t count, uint32_t *eax,
+                               uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
+
+static int cpu_x86_fill_model_id(char *str)
+{
+    uint32_t eax, ebx, ecx, edx;
+    int i;
+
+    for (i = 0; i < 3; i++) {
+        host_cpuid(0x80000002 + i, 0, &eax, &ebx, &ecx, &edx);
+        memcpy(str + i * 16 +  0, &eax, 4);
+        memcpy(str + i * 16 +  4, &ebx, 4);
+        memcpy(str + i * 16 +  8, &ecx, 4);
+        memcpy(str + i * 16 + 12, &edx, 4);
+    }
+    return 0;
+}
+
+static int cpu_x86_fill_host(x86_def_t *x86_cpu_def)
+{
+    uint32_t eax, ebx, ecx, edx;
+
+    x86_cpu_def->name = "host";
+    host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
+    x86_cpu_def->level = eax;
+    x86_cpu_def->vendor1 = ebx;
+    x86_cpu_def->vendor2 = edx;
+    x86_cpu_def->vendor3 = ecx;
+
+    host_cpuid(0x1, 0, &eax, &ebx, &ecx, &edx);
+    x86_cpu_def->family = ((eax >> 8) & 0x0F) + ((eax >> 20) & 0xFF);
+    x86_cpu_def->model = ((eax >> 4) & 0x0F) | ((eax & 0xF0000) >> 12);
+    x86_cpu_def->stepping = eax & 0x0F;
+    x86_cpu_def->ext_features = ecx;
+    x86_cpu_def->features = edx;
+
+    host_cpuid(0x80000000, 0, &eax, &ebx, &ecx, &edx);
+    x86_cpu_def->xlevel = eax;
+
+    host_cpuid(0x80000001, 0, &eax, &ebx, &ecx, &edx);
+    x86_cpu_def->ext2_features = edx;
+    x86_cpu_def->ext3_features = ecx;
+    cpu_x86_fill_model_id(x86_cpu_def->model_id);
+    x86_cpu_def->vendor_override = 0;
+
+    return 0;
+}
+
 static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
 {
     unsigned int i;
@@ -326,9 +374,14 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
             break;
         }
     }
-    if (!def)
-        goto error;
-    memcpy(x86_cpu_def, def, sizeof(*def));
+    if (!def) {
+        if (strcmp(name, "host") != 0) {
+            goto error;
+        }
+        cpu_x86_fill_host(x86_cpu_def);
+    } else {
+        memcpy(x86_cpu_def, def, sizeof(*def));
+    }
 
     add_flagname_to_bitmaps("hypervisor", &plus_features,
         &plus_ext_features, &plus_ext2_features, &plus_ext3_features);