[PATCH v9 14/26] target/arm/kvm: Implement SYSREG property setter and getter

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

When the setter is called, the final vcpu is not created yet.
Applying the override on vcpu.isar initialized with the max scratch
vcpu would not be correct because the final vcpu may have some features
turned off (for instance virtualization) while the scratch vcpu
features it. So we need to postpone the actual override until the
final vcpu has been initialized.

In terms of input value validation what can be done now is checking
against field length and arch enum value if any.

If this succeeds, the field value is added in the hash table to be
written later on once the final vcpu has been created

With regards to the getter, if the sysreg prop was set, we return the
set value, otherwise, we return the value in cpu->isar.idregs[].

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 target/arm/cpu.h |  2 ++
 target/arm/cpu.c |  5 ++--
 target/arm/kvm.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 68 insertions(+), 4 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index e3f931dba2..9bbd42dd2b 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -952,6 +952,8 @@ struct ArchCPU {
     uint64_t *cpreg_vmstate_values;
     int32_t cpreg_vmstate_array_len;
 
+    GHashTable *sysreg_props;
+
     DynamicGDBFeatureInfo dyn_sysreg_feature;
     DynamicGDBFeatureInfo dyn_svereg_feature;
     DynamicGDBFeatureInfo dyn_smereg_feature;
diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index 77aa78f00e..917f709cb4 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -1236,8 +1236,8 @@ static void arm_cpu_initfn(Object *obj)
 {
     ARMCPU *cpu = ARM_CPU(obj);
 
-    cpu->cp_regs = g_hash_table_new_full(g_direct_hash, g_direct_equal,
-                                         NULL, g_free);
+    cpu->cp_regs = g_hash_table_new(g_direct_hash, g_direct_equal);
+    cpu->sysreg_props = g_hash_table_new(g_direct_hash, g_direct_equal);
 
     QLIST_INIT(&cpu->pre_el_change_hooks);
     QLIST_INIT(&cpu->el_change_hooks);
@@ -1725,6 +1725,7 @@ static void arm_cpu_finalizefn(Object *obj)
     ARMCPRegMigTolerance *t, *n;
 
     g_hash_table_destroy(cpu->cp_regs);
+    g_hash_table_destroy(cpu->sysreg_props);
 
     QLIST_FOREACH_SAFE(hook, &cpu->pre_el_change_hooks, node, next) {
         QLIST_REMOVE(hook, node);
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 341542279d..cdc3779321 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -340,18 +340,79 @@ static ARM64SysRegField *get_field(int i, ARM64SysReg *reg)
     return NULL;
 }
 
+#define MAKE_IDREG_KEY(reg_idx, field_shift) \
+    (((uint64_t)(reg_idx) << 8) | ((uint64_t)(field_shift) & 0xFF))
+
 static void set_sysreg_prop(Object *obj, Visitor *v,
                             const char *name, void *opaque,
                             Error **errp)
 {
-    error_setg(errp, "%s setter not yet implemented", name);
+    ARM64SysRegField *field = (ARM64SysRegField *)opaque;
+    ARMCPU *cpu = ARM_CPU(obj);
+    int index = field->index;
+    int lower = field->shift;
+    int length = field->length;
+    uint64_t key, value;
+
+    if (!visit_type_uint64(v, name, &value, errp)) {
+        return;
+    }
+
+    if (length < 64 && value > ((1 << length) - 1)) {
+        error_setg(errp,
+                   "idreg %s set value (0x%lx) exceeds length of field (%d)!",
+                   name, value, length);
+        return;
+    }
+
+    if (field->arch_vals) {
+        /* this field has some enum values */
+        for (int i = 0; i < field->arch_vals_count; i++) {
+            if (value == field->arch_vals[i]) {
+                goto valid;
+            }
+        }
+        error_setg(errp,
+                   "idreg %s set value (0x%lx) does not match any "
+                   "arch valid enum value", name, value);
+        return;
+    }
+
+valid:
+
+    key = MAKE_IDREG_KEY(index, lower);
+    g_hash_table_insert(cpu->sysreg_props, GUINT_TO_POINTER(key),
+                       GUINT_TO_POINTER(value));
 }
 
 static void get_sysreg_prop(Object *obj, Visitor *v,
                             const char *name, void *opaque,
                             Error **errp)
 {
-    error_setg(errp, "%s getter not yet implemented", name);
+    ARM64SysRegField *field = (ARM64SysRegField *)opaque;
+    ARMCPU *cpu = ARM_CPU(obj);
+    int index = field->index;
+    int lower = field->shift;
+    int length = field->length;
+    gpointer value_ptr;
+    uint64_t value;
+    uint64_t key = MAKE_IDREG_KEY(index, lower);
+    gboolean exists;
+
+    exists = g_hash_table_lookup_extended(cpu->sysreg_props,
+                                          GUINT_TO_POINTER(key), NULL,
+                                          &value_ptr);
+    if (exists) {
+        value = GPOINTER_TO_UINT(value_ptr);
+    } else {
+        uint64_t mask = MAKE_64BIT_MASK(lower, length);
+        uint64_t *idregs = cpu->isar.idregs;
+
+        value = (idregs[index] & mask) >> lower;
+    }
+
+    visit_type_uint64(v, name, &value, errp);
+    trace_get_sysreg_prop(name, value);
 }
 
 /*
-- 
2.53.0