target/riscv: move 128-bit check to TCG realize

Besides removing non-declarative code in instance_init, this also fixes
an issue with query-cpu-model-expansion.  Just invoking it for the
x-rv128 CPU model causes QEMU to exit immediately.  With this patch it
is possible to do

  {'execute': 'query-cpu-model-expansion',
   'arguments':{'type': 'full', 'model': {'name': 'x-rv128'}}}

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 9 insertions, 7 deletions

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 0dcde54..d7ecf72 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -700,13 +700,6 @@ static void rv128_base_cpu_init(Object *obj)
     RISCVCPU *cpu = RISCV_CPU(obj);
     CPURISCVState *env = &cpu->env;
 
-    if (qemu_tcg_mttcg_enabled()) {
-        /* Missing 128-bit aligned atomics */
-        error_report("128-bit RISC-V currently does not work with Multi "
-                     "Threaded TCG. Please use: -accel tcg,thread=single");
-        exit(EXIT_FAILURE);
-    }
-
     cpu->cfg.mmu = true;
     cpu->cfg.pmp = true;
 
diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index 0a13728..d7e694f 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -1014,6 +1014,7 @@ static bool riscv_cpu_is_generic(Object *cpu_obj)
 static bool riscv_tcg_cpu_realize(CPUState *cs, Error **errp)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
+    RISCVCPUClass *mcc = RISCV_CPU_GET_CLASS(cpu);
 
     if (!riscv_cpu_tcg_compatible(cpu)) {
         g_autofree char *name = riscv_cpu_get_name(cpu);
@@ -1022,6 +1023,14 @@ static bool riscv_tcg_cpu_realize(CPUState *cs, Error **errp)
         return false;
     }
 
+    if (mcc->misa_mxl_max >= MXL_RV128 && qemu_tcg_mttcg_enabled()) {
+        /* Missing 128-bit aligned atomics */
+        error_setg(errp,
+                   "128-bit RISC-V currently does not work with Multi "
+                   "Threaded TCG. Please use: -accel tcg,thread=single");
+        return false;
+    }
+
 #ifndef CONFIG_USER_ONLY
     CPURISCVState *env = &cpu->env;