[PATCH RFCv2 19/20] arm-qmp-cmds: introspection for ID register props

[Cornelia Huck <cohuck@redhat.com>]

Implement the capability to query available ID register values by
adding SYSREG_* options and values to the cpu model expansion for the
host model, if available.

Excerpt:
(QEMU) query-cpu-model-expansion type=full model={"name":"host"}
{"return": {"model": {"name": "host", "props":
{"SYSREG_ID_AA64PFR0_EL1_EL3": 1224979098931106066,
"SYSREG_ID_AA64ISAR2_EL1_CLRBHB": 0,
../..

So this allows the upper stack to detect available writable ID
regs and the "host passthrough model" values.

[CH: moved SYSREG_* values to host model]
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

---

TODO: Add the moment there is no way to test changing a given
ID reg field value. ie:

(QEMU) query-cpu-model-expansion type=full model={"name":"host", "prop":{"SYSREG_ID_AA64ISAR0_EL1_DP":0x13}}
---
 target/arm/arm-qmp-cmds.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/target/arm/arm-qmp-cmds.c b/target/arm/arm-qmp-cmds.c
index 3cc8cc738bb0..44d7bf4c80ce 100644
--- a/target/arm/arm-qmp-cmds.c
+++ b/target/arm/arm-qmp-cmds.c
@@ -21,6 +21,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 #include "hw/boards.h"
 #include "kvm_arm.h"
 #include "qapi/error.h"
@@ -209,6 +210,24 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         }
     }
 
+    /* If writable ID regs are supported, add them as well */
+    if (ARM_CPU(obj)->writable_id_regs == WRITABLE_ID_REGS_AVAIL) {
+        ObjectProperty *prop;
+        ObjectPropertyIterator iter;
+
+        object_property_iter_init(&iter, obj);
+
+        while ((prop = object_property_iter_next(&iter))) {
+            QObject *value;
+
+            if (!g_str_has_prefix(prop->name, "SYSREG_")) {
+                continue;
+            }
+            value = object_property_get_qobject(obj, prop->name, &error_abort);
+            qdict_put_obj(qdict_out, prop->name, value);
+        }
+    }
+
     if (!qdict_size(qdict_out)) {
         qobject_unref(qdict_out);
     } else {
-- 
2.47.0