x86, mce: ignore SRAO only when MCG_SER_P is available

And restruct this block to call kvm_mce_in_exception() only when it is
required.
Signed-off-by: NHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

target-i386/kvm.c

@@ -239,12 +239,16 @@ static void kvm_do_inject_x86_mce(void *_data)
     struct kvm_x86_mce_data *data = _data;
     int r;
 
-    /* If there is an MCE excpetion being processed, ignore this SRAO MCE */
-    r = kvm_mce_in_exception(data->env);
-    if (r == -1)
-        fprintf(stderr, "Failed to get MCE status\n");
-    else if (r && !(data->mce->status & MCI_STATUS_AR))
-        return;
+    /* If there is an MCE exception being processed, ignore this SRAO MCE */
+    if ((data->env->mcg_cap & MCG_SER_P) &&
+        !(data->mce->status & MCI_STATUS_AR)) {
+        r = kvm_mce_in_exception(data->env);
+        if (r == -1) {
+            fprintf(stderr, "Failed to get MCE status\n");
+        } else if (r) {
+            return;
+        }
+    }
 
     r = kvm_set_mce(data->env, data->mce);
     if (r < 0) {