[RFC PATCH v7 18/18] arm-qmp-cmds: introspection for ID register props

[Eric Auger <eric.auger@redhat.com>]

From: 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": 1,
"SYSREG_ID_AA64ISAR2_EL1_CLRBHB": 0, "SYSREG_CTR_EL0_L1Ip": 3,
"SYSREG_MIDR_EL1_PartNum": 3407, "SYSREG_CTR_EL0_DminLine": 4,
"SYSREG_ID_AA64MMFR0_EL1_PARange": 5, "SYSREG_ID_AA64MMFR1_EL1_ECBHB": 0
../..

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

It also allows to test some ID reg field values:
(QEMU) query-cpu-model-expansion type=full model={"name":"host","props":{"SYSREG_ID_AA64ISAR0_EL1_DP":0x13}}
{"error": {"class": "GenericError", "desc": "idreg SYSREG_ID_AA64ISAR0_EL1_DP set value (0x13) exceeds length of field (4)!"}}

(QEMU) query-cpu-model-expansion type=full model={"name":"host","props":{"SYSREG_ID_AA64ISAR0_EL1_DP":0x2}}
{"error": {"class": "GenericError", "desc": "idreg SYSREG_ID_AA64ISAR0_EL1_DP set value (0x2) does not match any arch valid enum value!"}}

The following checks are performed:
- the value does not exceed the field size
- if the field is associated to enum values, the set value must be one
  of those enum values
- the value is applied against a scratch vcpu making sure the setting is
  not rejected for this host

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

---

v5 -> v6:
- add the write capability
---
 target/arm/arm-qmp-cmds.c | 98 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)

diff --git a/target/arm/arm-qmp-cmds.c b/target/arm/arm-qmp-cmds.c
index 83ec95c290..41fefadcea 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 "qemu/target-info.h"
 #include "hw/core/boards.h"
 #include "kvm_arm.h"
@@ -30,7 +31,10 @@
 #include "qapi/qapi-commands-machine.h"
 #include "qapi/qapi-commands-misc-arm.h"
 #include "qobject/qdict.h"
+#include "qobject/qnum.h"
 #include "qom/qom-qobject.h"
+#include <linux/kvm.h>
+#include "system/kvm.h"
 #include "cpu.h"
 
 static GICCapability *gic_cap_new(int version)
@@ -84,11 +88,14 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
                                                      Error **errp)
 {
     CpuModelExpansionInfo *expansion_info;
+    ObjectPropertyIterator iter;
     const QDict *qdict_in;
+    ObjectProperty *idregprop;
     QDict *qdict_out;
     ObjectClass *oc;
     Object *obj;
     const char *name;
+    int fdarray[3];
     int i;
 
     if (type != CPU_MODEL_EXPANSION_TYPE_FULL) {
@@ -133,6 +140,38 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
 
     obj = object_new(object_class_get_name(oc));
 
+    if (kvm_enabled()) {
+        bool pmuv3_supported = kvm_check_extension(kvm_state, KVM_CAP_ARM_PMU_V3);
+        bool sve_supported = kvm_check_extension(kvm_state, KVM_CAP_ARM_SVE);
+        struct kvm_vcpu_init init = { .target = -1, };
+        bool el2_supported = kvm_arm_el2_supported();
+        bool pauth_supported;
+        int ret;
+
+        pauth_supported = kvm_check_extension(kvm_state, KVM_CAP_ARM_PTRAUTH_ADDRESS) &&
+                          kvm_check_extension(kvm_state, KVM_CAP_ARM_PTRAUTH_GENERIC);
+
+        if (sve_supported) {
+            init.features[0] |= 1 << KVM_ARM_VCPU_SVE;
+        }
+        if (el2_supported) {
+            init.features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
+        }
+        if (pauth_supported) {
+            init.features[0] |= (1 << KVM_ARM_VCPU_PTRAUTH_ADDRESS |
+                             1 << KVM_ARM_VCPU_PTRAUTH_GENERIC);
+        }
+        if (pmuv3_supported) {
+            init.features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
+        }
+
+        ret = kvm_arm_create_scratch_host_vcpu(fdarray, &init);
+        if (!ret) {
+            error_setg(errp, "failing creating a scratch vcpu");
+            return NULL;
+        }
+    }
+
     if (model->props) {
         Visitor *visitor;
         Error *err = NULL;
@@ -145,6 +184,49 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         }
 
         qdict_in = qobject_to(QDict, model->props);
+
+        for (const QDictEntry *entry = qdict_first(qdict_in);
+                 entry != NULL; entry = qdict_next(qdict_in, entry)) {
+            const char *key = qdict_entry_key(entry);
+            QObject *val_obj = qdict_entry_value(entry);
+            ObjectProperty *prop;
+            Visitor *v;
+            bool success;
+            uint64_t val;
+
+            prop = object_property_find(obj, key);
+            if (!prop) {
+                error_setg(errp, "%s does not exist!", key);
+                return NULL;
+            }
+
+            if (!g_str_has_prefix(key, "SYSREG_")) {
+                continue;
+            }
+
+            /* consume the prop to avoid unexpected parameter */
+            if (!visit_type_uint64(visitor, key, &val, errp)) {
+                return NULL;
+            }
+
+            v = qobject_input_visitor_new(val_obj);
+
+            if (!object_property_set(obj, key, v, &err)) {
+                error_propagate(errp, err);
+                visit_free(v);
+                return NULL;
+            }
+
+            success = kvm_idreg_write_scratch_vcpu(fdarray[2], v, key,
+                                                   prop->opaque, &err);
+            if (!success) {
+                error_propagate(errp, err);
+                visit_free(v);
+                return NULL;
+            }
+            visit_free(v);
+        }
+
         i = 0;
         while ((name = cpu_model_advertised_features[i++]) != NULL) {
             if (qdict_get(qdict_in, name)) {
@@ -160,6 +242,10 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         if (!err) {
             arm_cpu_finalize_features(ARM_CPU(obj), &err);
         }
+
+        if (kvm_enabled()) {
+            kvm_arm_destroy_scratch_host_vcpu(fdarray);
+        }
         visit_end_struct(visitor, NULL);
         visit_free(visitor);
         if (err) {
@@ -190,6 +276,18 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
         }
     }
 
+    object_property_iter_init(&iter, obj);
+
+    while ((idregprop = object_property_iter_next(&iter))) {
+        QObject *value;
+
+        if (!g_str_has_prefix(idregprop->name, "SYSREG_")) {
+            continue;
+        }
+        value = object_property_get_qobject(obj, idregprop->name, &error_abort);
+        qdict_put_obj(qdict_out, idregprop->name, value);
+    }
+
     if (!qdict_size(qdict_out)) {
         qobject_unref(qdict_out);
     } else {
-- 
2.53.0