target/riscv: add query-cpy-definitions support

This command is used by tooling like libvirt to retrieve a list of
supported CPUs. Each entry returns a CpuDefinitionInfo object that
contains more information about each CPU.

This initial support includes only the name of the CPU and its typename.
Here's what the command produces for the riscv64 target:

$ ./build/qemu-system-riscv64 -S -M virt -display none -qmp stdio
{"QMP": {"version": (...)}
{"execute": "qmp_capabilities", "arguments": {"enable": ["oob"]}}
{"return": {}}
{"execute": "query-cpu-definitions"}
{"return": [
{"name": "rv64", "typename": "rv64-riscv-cpu", "static": false, "deprecated": false},
{"name": "sifive-e51", "typename": "sifive-e51-riscv-cpu", "static": false, "deprecated": false},
{"name": "any", "typename": "any-riscv-cpu", "static": false, "deprecated": false},
{"name": "x-rv128", "typename": "x-rv128-riscv-cpu", "static": false, "deprecated": false},
{"name": "shakti-c", "typename": "shakti-c-riscv-cpu", "static": false, "deprecated": false},
{"name": "thead-c906", "typename": "thead-c906-riscv-cpu", "static": false, "deprecated": false},
{"name": "sifive-u54", "typename": "sifive-u54-riscv-cpu", "static": false, "deprecated": false}]
}

Next patch will introduce a way to tell whether a given CPU is static or
not.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230411183511.189632-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

qapi/machine-target.json

@@ -324,7 +324,8 @@
                    'TARGET_I386',
                    'TARGET_S390X',
                    'TARGET_MIPS',
-                   'TARGET_LOONGARCH64' ] } }
+                   'TARGET_LOONGARCH64',
+                   'TARGET_RISCV' ] } }
 
 ##
 # @query-cpu-definitions:
@@ -341,4 +342,5 @@
                    'TARGET_I386',
                    'TARGET_S390X',
                    'TARGET_MIPS',
-                   'TARGET_LOONGARCH64' ] } }
+                   'TARGET_LOONGARCH64',
+                   'TARGET_RISCV' ] } }

target/riscv/meson.build

@@ -32,7 +32,8 @@ riscv_softmmu_ss.add(files(
   'monitor.c',
   'machine.c',
   'pmu.c',
-  'time_helper.c'
+  'time_helper.c',
+  'riscv-qmp-cmds.c',
 ))
 
 target_arch += {'riscv': riscv_ss}

target/riscv/riscv-qmp-cmds.c

@@ -0,0 +1,53 @@
+/*
+ * QEMU CPU QMP commands for RISC-V
+ *
+ * Copyright (c) 2023 Ventana Micro Systems Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+
+#include "qapi/qapi-commands-machine-target.h"
+#include "cpu-qom.h"
+
+static void riscv_cpu_add_definition(gpointer data, gpointer user_data)
+{
+    ObjectClass *oc = data;
+    CpuDefinitionInfoList **cpu_list = user_data;
+    CpuDefinitionInfo *info = g_malloc0(sizeof(*info));
+    const char *typename = object_class_get_name(oc);
+
+    info->name = g_strndup(typename,
+                           strlen(typename) - strlen("-" TYPE_RISCV_CPU));
+    info->q_typename = g_strdup(typename);
+
+    QAPI_LIST_PREPEND(*cpu_list, info);
+}
+
+CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
+{
+    CpuDefinitionInfoList *cpu_list = NULL;
+    GSList *list = object_class_get_list(TYPE_RISCV_CPU, false);
+
+    g_slist_foreach(list, riscv_cpu_add_definition, &cpu_list);
+    g_slist_free(list);
+
+    return cpu_list;
+}