[Qemu-devel] [PATCH v2 4/6] cpu: use CPUClass->parse_features() as convertor to global properties

[Igor Mammedov <imammedo@redhat.com>]

Currently CPUClass->parse_features() is used to parse
-cpu features string and set properties on created CPU
instances.

But considering that features specified by -cpu apply to
every created CPU instance, it doesn't make sence to
parse the same features string for every CPU created.
It also makes every target that cares about parsing
features string explicitly call CPUClass->parse_features()
parser, which gets in a way if we consider using
generic device_add for CPU hotplug as device_add
has not a clue about CPU specific hooks.

Turns out we can use global properties mechanism to set
properties on every created CPU instance for a given
type. That way it's possible to convert CPU features
into a set of global properties for CPU type specified
by -cpu cpu_model and common Device.device_post_init()
will apply them to CPU of given type automatically
regardless whether it's manually created CPU or CPU
created with help of device_add.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
This patch only make CPUClass->parse_features()
a global properties convertor and follow up patches
will switch individual users to new behaviour

v2:
  - add todo comments in cpu_generic_init/cpu_common_parse_features
  - set cpu_globals_initialized = true early
---
 hw/arm/virt.c     |  7 ++++---
 include/qom/cpu.h |  2 +-
 qom/cpu.c         | 40 ++++++++++++++++++++++++++++------------
 target-i386/cpu.c | 25 +++++++++++++++++++------
 4 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 73113cf..3519c9f 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1198,6 +1198,7 @@ static void machvirt_init(MachineState *machine)
 
     for (n = 0; n < smp_cpus; n++) {
         ObjectClass *oc = cpu_class_by_name(TYPE_ARM_CPU, cpustr[0]);
+        const char *typename = object_class_get_name(oc);
         CPUClass *cc = CPU_CLASS(oc);
         Object *cpuobj;
         Error *err = NULL;
@@ -1207,10 +1208,10 @@ static void machvirt_init(MachineState *machine)
             error_report("Unable to find CPU definition");
             exit(1);
         }
-        cpuobj = object_new(object_class_get_name(oc));
+        /* convert -smp CPU options specified by the user into global props */
+        cc->parse_features(typename, cpuopts, &err);
+        cpuobj = object_new(typename);
 
-        /* Handle any CPU options specified by the user */
-        cc->parse_features(CPU(cpuobj), cpuopts, &err);
         g_free(cpuopts);
         if (err) {
             error_report_err(err);
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 32f3af3..cacb100 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -134,7 +134,7 @@ typedef struct CPUClass {
     /*< public >*/
 
     ObjectClass *(*class_by_name)(const char *cpu_model);
-    void (*parse_features)(CPUState *cpu, char *str, Error **errp);
+    void (*parse_features)(const char *typename, char *str, Error **errp);
 
     void (*reset)(CPUState *cpu);
     int reset_dump_flags;
diff --git a/qom/cpu.c b/qom/cpu.c
index 751e992..eee23db 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -28,6 +28,7 @@
 #include "exec/log.h"
 #include "qemu/error-report.h"
 #include "sysemu/sysemu.h"
+#include "hw/qdev-properties.h"
 
 bool cpu_exists(int64_t id)
 {
@@ -46,7 +47,7 @@ bool cpu_exists(int64_t id)
 CPUState *cpu_generic_init(const char *typename, const char *cpu_model)
 {
     char *str, *name, *featurestr;
-    CPUState *cpu;
+    CPUState *cpu = NULL;
     ObjectClass *oc;
     CPUClass *cc;
     Error *err = NULL;
@@ -60,16 +61,18 @@ CPUState *cpu_generic_init(const char *typename, const char *cpu_model)
         return NULL;
     }
 
-    cpu = CPU(object_new(object_class_get_name(oc)));
-    cc = CPU_GET_CLASS(cpu);
-
+    cc = CPU_CLASS(oc);
     featurestr = strtok(NULL, ",");
-    cc->parse_features(cpu, featurestr, &err);
+    /* TODO: all callers of cpu_generic_init() need to be converted to
+     * call parse_features() only once, before calling cpu_generic_init().
+     */
+    cc->parse_features(object_class_get_name(oc), featurestr, &err);
     g_free(str);
     if (err != NULL) {
         goto out;
     }
 
+    cpu = CPU(object_new(object_class_get_name(oc)));
     object_property_set_bool(OBJECT(cpu), true, "realized", &err);
 
 out:
@@ -282,25 +285,38 @@ static ObjectClass *cpu_common_class_by_name(const char *cpu_model)
     return NULL;
 }
 
-static void cpu_common_parse_features(CPUState *cpu, char *features,
+static void cpu_common_parse_features(const char *typename, char *features,
                                       Error **errp)
 {
     char *featurestr; /* Single "key=value" string being parsed */
     char *val;
-    Error *err = NULL;
+    static bool cpu_globals_initialized;
+
+    /* TODO: all callers of ->parse_features() need to be changed to
+     * call it only once, so we can remove this check (or change it
+     * to assert(!cpu_globals_initialized).
+     * Current callers of ->parse_features() are:
+     * - machvirt_init()
+     * - cpu_generic_init()
+     * - cpu_x86_create()
+     */
+    if (cpu_globals_initialized) {
+        return;
+    }
+    cpu_globals_initialized = true;
 
     featurestr = features ? strtok(features, ",") : NULL;
 
     while (featurestr) {
         val = strchr(featurestr, '=');
         if (val) {
+            GlobalProperty *prop = g_new0(typeof(*prop), 1);
             *val = 0;
             val++;
-            object_property_parse(OBJECT(cpu), val, featurestr, &err);
-            if (err) {
-                error_propagate(errp, err);
-                return;
-            }
+            prop->driver = typename;
+            prop->property = g_strdup(featurestr);
+            prop->value = g_strdup(val);
+            qdev_prop_register_global(prop);
         } else {
             error_setg(errp, "Expected key=value format, found %s.",
                        featurestr);
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 3f886a5..279f656 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1958,12 +1958,17 @@ static FeatureWordArray minus_features = { 0 };
 
 /* Parse "+feature,-feature,feature=foo" CPU feature string
  */
-static void x86_cpu_parse_featurestr(CPUState *cs, char *features,
+static void x86_cpu_parse_featurestr(const char *typename, char *features,
                                      Error **errp)
 {
-    X86CPU *cpu = X86_CPU(cs);
     char *featurestr; /* Single 'key=value" string being parsed */
     Error *local_err = NULL;
+    static bool cpu_globals_initialized;
+
+    if (cpu_globals_initialized) {
+        return;
+    }
+    cpu_globals_initialized = true;
 
     if (!features) {
         return;
@@ -1975,6 +1980,7 @@ static void x86_cpu_parse_featurestr(CPUState *cs, char *features,
         const char *name;
         const char *val = NULL;
         char *eq = NULL;
+        GlobalProperty *prop;
 
         /* Compatibility syntax: */
         if (featurestr[0] == '+') {
@@ -2019,7 +2025,11 @@ static void x86_cpu_parse_featurestr(CPUState *cs, char *features,
             name = "tsc-frequency";
         }
 
-        object_property_parse(OBJECT(cpu), val, name, &local_err);
+        prop = g_new0(typeof(*prop), 1);
+        prop->driver = typename;
+        prop->property = g_strdup(name);
+        prop->value = g_strdup(val);
+        qdev_prop_register_global(prop);
     }
 
     if (local_err) {
@@ -2208,9 +2218,11 @@ X86CPU *cpu_x86_create(const char *cpu_model, Error **errp)
 {
     X86CPU *cpu = NULL;
     ObjectClass *oc;
+    CPUClass *cc;
     gchar **model_pieces;
     char *name, *features;
     Error *error = NULL;
+    const char *typename;
 
     model_pieces = g_strsplit(cpu_model, ",", 2);
     if (!model_pieces[0]) {
@@ -2225,10 +2237,11 @@ X86CPU *cpu_x86_create(const char *cpu_model, Error **errp)
         error_setg(&error, "Unable to find CPU definition: %s", name);
         goto out;
     }
+    cc = CPU_CLASS(oc);
+    typename = object_class_get_name(oc);
 
-    cpu = X86_CPU(object_new(object_class_get_name(oc)));
-
-    x86_cpu_parse_featurestr(CPU(cpu), features, &error);
+    cc->parse_features(typename, features, &error);
+    cpu = X86_CPU(object_new(typename));
     if (error) {
         goto out;
     }
-- 
2.7.0