target/riscv/cpu.c: add riscv_bare_cpu_init()

Next patch will add more bare CPUs. Their cpu_init() functions would be
glorified copy/pastes of rv64i_bare_cpu_init(), differing only by a
riscv_cpu_set_misa() call.

Add a new .instance_init for the TYPE_RISCV_BARE_CPU typ to avoid this
code repetition. While we're at it, add a better explanation on why
we're disabling the timing extensions for bare CPUs.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240122123348.973288-2-dbarboza@ventanamicro.com>
[ Changes by AF:
 - Rebase on latest changes
]
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.c

@@ -605,22 +605,6 @@ static void rv64i_bare_cpu_init(Object *obj)
 {
     CPURISCVState *env = &RISCV_CPU(obj)->env;
     riscv_cpu_set_misa_ext(env, RVI);
-
-    /* Remove the defaults from the parent class */
-    RISCV_CPU(obj)->cfg.ext_zicntr = false;
-    RISCV_CPU(obj)->cfg.ext_zihpm = false;
-
-    /* Set to QEMU's first supported priv version */
-    env->priv_ver = PRIV_VERSION_1_10_0;
-
-    /*
-     * Support all available satp_mode settings. The default
-     * value will be set to MBARE if the user doesn't set
-     * satp_mode manually (see set_satp_mode_default()).
-     */
-#ifndef CONFIG_USER_ONLY
-    set_satp_mode_max_supported(RISCV_CPU(obj), VM_1_10_SV64);
-#endif
 }
 #else
 static void rv32_base_cpu_init(Object *obj)
@@ -1329,6 +1313,34 @@ static void riscv_cpu_init(Object *obj)
     cpu->env.vext_ver = VEXT_VERSION_1_00_0;
 }
 
+static void riscv_bare_cpu_init(Object *obj)
+{
+    RISCVCPU *cpu = RISCV_CPU(obj);
+
+    /*
+     * Bare CPUs do not inherit the timer and performance
+     * counters from the parent class (see riscv_cpu_init()
+     * for info on why the parent enables them).
+     *
+     * Users have to explicitly enable these counters for
+     * bare CPUs.
+     */
+    cpu->cfg.ext_zicntr = false;
+    cpu->cfg.ext_zihpm = false;
+
+    /* Set to QEMU's first supported priv version */
+    cpu->env.priv_ver = PRIV_VERSION_1_10_0;
+
+    /*
+     * Support all available satp_mode settings. The default
+     * value will be set to MBARE if the user doesn't set
+     * satp_mode manually (see set_satp_mode_default()).
+     */
+#ifndef CONFIG_USER_ONLY
+    set_satp_mode_max_supported(cpu, VM_1_10_SV64);
+#endif
+}
+
 typedef struct misa_ext_info {
     const char *name;
     const char *description;
@@ -2505,6 +2517,7 @@ static const TypeInfo riscv_cpu_type_infos[] = {
     {
         .name = TYPE_RISCV_BARE_CPU,
         .parent = TYPE_RISCV_CPU,
+        .instance_init = riscv_bare_cpu_init,
         .abstract = true,
     },
 #if defined(TARGET_RISCV32)