tcg: Emit barriers with parallel_cpus

Reviewed-by: NEmilio G. Cota <cota@braap.org>
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NRichard Henderson <rth@twiddle.net>

tcg/tcg-op.c

@@ -150,17 +150,7 @@ void tcg_gen_op6(TCGContext *ctx, TCGOpcode opc, TCGArg a1, TCGArg a2,
 
 void tcg_gen_mb(TCGBar mb_type)
 {
-    bool emit_barriers = true;
-
-#ifndef CONFIG_USER_ONLY
-    /* TODO: When MTTCG is available for system mode, we will check
-     * the following condition and enable emit_barriers
-     * (qemu_tcg_mttcg_enabled() && smp_cpus > 1)
-     */
-    emit_barriers = false;
-#endif
-
-    if (emit_barriers) {
+    if (parallel_cpus) {
         tcg_gen_op1(&tcg_ctx, INDEX_op_mb, mb_type);
     }
 }