qapi,risc-v: add query-cpu-model-expansion

This API is used to inspect the characteristics of a given CPU model. It
also allows users to validate a CPU model with a certain configuration,
e.g. if "-cpu X,a=true,b=false" is a valid setup for a given QEMU
binary. We'll start implementing the first part. The second requires
more changes in RISC-V CPU boot flow.

The implementation is inspired by the existing ARM
query-cpu-model-expansion impl in target/arm/arm-qmp-cmds.c. We'll
create a RISCVCPU object with the required model, fetch its existing
properties, add a couple of relevant boolean options (pmp and mmu) and
display it to users.

Here's an usage example:

./build/qemu-system-riscv64 -S -M virt -display none \
  -qmp  tcp:localhost:1234,server,wait=off

./scripts/qmp/qmp-shell localhost:1234
Welcome to the QMP low-level shell!
Connected to QEMU 8.1.50

(QEMU)  query-cpu-model-expansion type=full model={"name":"rv64"}
{"return": {"model": {"name": "rv64", "props": {"zicond": false, "x-zvfh": false, "mmu": true, "x-zvfbfwma": false, "x-zvfbfmin": false, "xtheadbs": false, "xtheadbb": false, "xtheadba": false, "xtheadmemidx": false, "smstateen": false, "zfinx": false, "Zve64f": false, "Zve32f": false, "x-zvfhmin": false, "xventanacondops": false, "xtheadcondmov": false, "svpbmt": false, "zbs": true, "zbc": true, "zbb": true, "zba": true, "zicboz": true, "xtheadmac": false, "Zfh": false, "Zfa": true, "zbkx": false, "zbkc": false, "zbkb": false, "Zve64d": false, "x-zfbfmin": false, "zk": false, "x-epmp": false, "xtheadmempair": false, "zkt": false, "zks": false, "zkr": false, "zkn": false, "Zfhmin": false, "zksh": false, "zknh": false, "zkne": false, "zknd": false, "zhinx": false, "Zicsr": true, "sscofpmf": false, "Zihintntl": true, "sstc": true, "xtheadcmo": false, "x-zvbb": false, "zksed": false, "x-zvkned": false, "xtheadsync": false, "x-zvkg": false, "zhinxmin": false, "svadu": true, "xtheadfmv": false, "x-zvksed": false, "svnapot": false, "pmp": true, "x-zvknhb": false, "x-zvknha": false, "xtheadfmemidx": false, "x-zvksh": false, "zdinx": false, "zicbom": true, "Zihintpause": true, "svinval": false, "zcf": false, "zce": false, "zcd": false, "zcb": false, "zca": false, "x-ssaia": false, "x-smaia": false, "zmmul": false, "x-zvbc": false, "Zifencei": true, "zcmt": false, "zcmp": false, "Zawrs": true}}}}

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231018195638.211151-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

qapi/machine-target.json

@@ -231,7 +231,8 @@
   'if': { 'any': [ 'TARGET_S390X',
                    'TARGET_I386',
                    'TARGET_ARM',
-                   'TARGET_LOONGARCH64' ] } }
+                   'TARGET_LOONGARCH64',
+                   'TARGET_RISCV' ] } }
 
 ##
 # @query-cpu-model-expansion:
@@ -277,7 +278,8 @@
   'if': { 'any': [ 'TARGET_S390X',
                    'TARGET_I386',
                    'TARGET_ARM',
-                   'TARGET_LOONGARCH64' ] } }
+                   'TARGET_LOONGARCH64',
+                   'TARGET_RISCV' ] } }
 
 ##
 # @CpuDefinitionInfo:

target/riscv/riscv-qmp-cmds.c

@@ -24,8 +24,12 @@
 
 #include "qemu/osdep.h"
 
+#include "qapi/error.h"
 #include "qapi/qapi-commands-machine-target.h"
+#include "qapi/qmp/qdict.h"
+#include "qom/qom-qobject.h"
 #include "cpu-qom.h"
+#include "cpu.h"
 
 static void riscv_cpu_add_definition(gpointer data, gpointer user_data)
 {
@@ -55,3 +59,74 @@ CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
 
     return cpu_list;
 }
+
+static void riscv_obj_add_qdict_prop(Object *obj, QDict *qdict_out,
+                                     const char *name)
+{
+    ObjectProperty *prop = object_property_find(obj, name);
+
+    if (prop) {
+        QObject *value;
+
+        assert(prop->get);
+        value = object_property_get_qobject(obj, name, &error_abort);
+
+        qdict_put_obj(qdict_out, name, value);
+    }
+}
+
+static void riscv_obj_add_multiext_props(Object *obj, QDict *qdict_out,
+                                         const RISCVCPUMultiExtConfig *arr)
+{
+    for (int i = 0; arr[i].name != NULL; i++) {
+        riscv_obj_add_qdict_prop(obj, qdict_out, arr[i].name);
+    }
+}
+
+CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
+                                                     CpuModelInfo *model,
+                                                     Error **errp)
+{
+    CpuModelExpansionInfo *expansion_info;
+    QDict *qdict_out;
+    ObjectClass *oc;
+    Object *obj;
+
+    if (type != CPU_MODEL_EXPANSION_TYPE_FULL) {
+        error_setg(errp, "The requested expansion type is not supported");
+        return NULL;
+    }
+
+    oc = cpu_class_by_name(TYPE_RISCV_CPU, model->name);
+    if (!oc) {
+        error_setg(errp, "The CPU type '%s' is not a known RISC-V CPU type",
+                   model->name);
+        return NULL;
+    }
+
+    obj = object_new(object_class_get_name(oc));
+
+    expansion_info = g_new0(CpuModelExpansionInfo, 1);
+    expansion_info->model = g_malloc0(sizeof(*expansion_info->model));
+    expansion_info->model->name = g_strdup(model->name);
+
+    qdict_out = qdict_new();
+
+    riscv_obj_add_multiext_props(obj, qdict_out, riscv_cpu_extensions);
+    riscv_obj_add_multiext_props(obj, qdict_out, riscv_cpu_experimental_exts);
+    riscv_obj_add_multiext_props(obj, qdict_out, riscv_cpu_vendor_exts);
+
+    /* Add our CPU boolean options too */
+    riscv_obj_add_qdict_prop(obj, qdict_out, "mmu");
+    riscv_obj_add_qdict_prop(obj, qdict_out, "pmp");
+
+    if (!qdict_size(qdict_out)) {
+        qobject_unref(qdict_out);
+    } else {
+        expansion_info->model->props = QOBJECT(qdict_out);
+    }
+
+    object_unref(obj);
+
+    return expansion_info;
+}