[Qemu-devel] [PATCH v4 18/21] s390x: implement query-hotpluggable-cpus

[David Hildenbrand <david@redhat.com>]

CPU hotplug is only possible on a per core basis on s390x.

As we now have ms->possible_cpus, we can get rid of the global variable
cpu_states.

While rewriting s390_cpu_addr2state() completely to be based on
possible_cpus, move it to cpu.c, as it is independent of the virtio-ccw
machine.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/s390x/s390-virtio-ccw.c | 87 +++++++++++++++++++++++++++++-----------------
 qapi-schema.json           | 16 +++++++++
 target/s390x/cpu.c         | 17 +++++++++
 target/s390x/cpu.h         |  5 +--
 4 files changed, 89 insertions(+), 36 deletions(-)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 120f82e339..0e10a4c73a 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -36,24 +36,12 @@
 #include "qapi/qmp/qerror.h"
 #include "hw/nmi.h"
 
-static S390CPU **cpu_states;
-
-S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
-{
-    if (cpu_addr >= max_cpus) {
-        return NULL;
-    }
-
-    /* Fast lookup via CPU ID */
-    return cpu_states[cpu_addr];
-}
-
 /* #define S390_TCG_SMP_SUPPORT */
 
 static void s390_init_cpus(MachineState *machine)
 {
+    MachineClass *mc = MACHINE_GET_CLASS(machine);
     int i;
-    gchar *name;
 
     if (machine->cpu_model == NULL) {
         machine->cpu_model = s390_default_cpu_model_name();
@@ -66,17 +54,8 @@ static void s390_init_cpus(MachineState *machine)
     }
 #endif
 
-    cpu_states = g_new0(S390CPU *, max_cpus);
-
-    for (i = 0; i < max_cpus; i++) {
-        name = g_strdup_printf("cpu[%i]", i);
-        object_property_add_link(OBJECT(machine), name, TYPE_S390_CPU,
-                                 (Object **) &cpu_states[i],
-                                 object_property_allow_set_link,
-                                 OBJ_PROP_LINK_UNREF_ON_RELEASE,
-                                 &error_abort);
-        g_free(name);
-    }
+    /* initialize possible_cpus */
+    mc->possible_cpu_arch_ids(machine);
 
     for (i = 0; i < smp_cpus; i++) {
         s390x_new_cpu(machine->cpu_model, i, &error_fatal);
@@ -307,17 +286,14 @@ static void ccw_init(MachineState *machine)
     register_savevm_live(NULL, "todclock", 0, 1, &savevm_gtod, NULL);
 }
 
-static void s390_cpu_plug(HotplugHandler *hotplug_dev,
-                        DeviceState *dev, Error **errp)
+static void s390_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                          Error **errp)
 {
-    gchar *name;
+    MachineState *ms = MACHINE(hotplug_dev);
     S390CPU *cpu = S390_CPU(dev);
-    CPUState *cs = CPU(dev);
 
-    name = g_strdup_printf("cpu[%i]", cpu->env.core_id);
-    object_property_set_link(OBJECT(hotplug_dev), OBJECT(cs), name,
-                             errp);
-    g_free(name);
+    g_assert(!ms->possible_cpus->cpus[cpu->env.core_id].cpu);
+    ms->possible_cpus->cpus[cpu->env.core_id].cpu = OBJECT(dev);
 }
 
 static void s390_machine_reset(void)
@@ -350,6 +326,50 @@ static void s390_machine_device_unplug_request(HotplugHandler *hotplug_dev,
     }
 }
 
+static CPUArchId *s390_find_cpu_slot(MachineState *ms, uint32_t core_id,
+                                     int *idx)
+{
+    if (core_id >= ms->possible_cpus->len) {
+        return NULL;
+    }
+    /* core_id corresponds to the index */
+    if (idx) {
+        *idx = core_id;
+    }
+    return &ms->possible_cpus->cpus[core_id];
+}
+
+static CpuInstanceProperties s390_cpu_index_to_props(MachineState *machine,
+                                                     unsigned cpu_index)
+{
+    CPUArchId *slot = s390_find_cpu_slot(machine, cpu_index, NULL);
+
+    assert(slot);
+    return slot->props;
+}
+
+static const CPUArchIdList *s390_possible_cpu_arch_ids(MachineState *ms)
+{
+    int i;
+
+    if (ms->possible_cpus) {
+        g_assert(ms->possible_cpus && ms->possible_cpus->len == max_cpus);
+        return ms->possible_cpus;
+    }
+
+    ms->possible_cpus = g_malloc0(sizeof(CPUArchIdList) +
+                                  sizeof(CPUArchId) * max_cpus);
+    ms->possible_cpus->len = max_cpus;
+    for (i = 0; i < ms->possible_cpus->len; i++) {
+        ms->possible_cpus->cpus[i].vcpus_count = 1;
+        ms->possible_cpus->cpus[i].arch_id = i;
+        ms->possible_cpus->cpus[i].props.has_core_id = true;
+        ms->possible_cpus->cpus[i].props.core_id = i;
+    }
+
+    return ms->possible_cpus;
+}
+
 static HotplugHandler *s390_get_hotplug_handler(MachineState *machine,
                                                 DeviceState *dev)
 {
@@ -397,7 +417,10 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
     mc->no_sdcard = 1;
     mc->use_sclp = 1;
     mc->max_cpus = 248;
+    mc->has_hotpluggable_cpus = true;
     mc->get_hotplug_handler = s390_get_hotplug_handler;
+    mc->cpu_index_to_instance_props = s390_cpu_index_to_props;
+    mc->possible_cpu_arch_ids = s390_possible_cpu_arch_ids;
     hc->plug = s390_machine_device_plug;
     hc->unplug_request = s390_machine_device_unplug_request;
     nc->nmi_monitor_handler = s390_nmi;
diff --git a/qapi-schema.json b/qapi-schema.json
index f3af2cb851..79e9f85404 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -3121,6 +3121,22 @@
 #      }
 #    ]}
 #
+# For s390x-virtio-ccw machine type started with -smp 1,maxcpus=2 -cpu qemu
+# (Since: 2.11):
+#
+# -> { "execute": "query-hotpluggable-cpus" }
+# <- {"return": [
+#      {
+#         "type": "qemu-s390-cpu", "vcpus-count": 1,
+#         "props": { "core-id": 1 }
+#      },
+#      {
+#         "qom-path": "/machine/unattached/device[0]",
+#         "type": "qemu-s390-cpu", "vcpus-count": 1,
+#         "props": { "core-id": 0 }
+#      }
+#    ]}
+#
 ##
 { 'command': 'query-hotpluggable-cpus', 'returns': ['HotpluggableCPU'] }
 
diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
index 5724dffb88..7f174f90a4 100644
--- a/target/s390x/cpu.c
+++ b/target/s390x/cpu.c
@@ -38,6 +38,7 @@
 #include "exec/exec-all.h"
 #include "hw/qdev-properties.h"
 #ifndef CONFIG_USER_ONLY
+#include "hw/boards.h"
 #include "hw/hw.h"
 #include "sysemu/arch_init.h"
 #include "sysemu/sysemu.h"
@@ -446,6 +447,22 @@ void s390_enable_css_support(S390CPU *cpu)
         kvm_s390_enable_css_support(cpu);
     }
 }
+
+S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
+{
+    static MachineState *ms;
+
+    if (!ms) {
+        ms = MACHINE(qdev_get_machine());
+        g_assert(ms->possible_cpus);
+    }
+
+    /* CPU address corresponds to the core_id and the index */
+    if (cpu_addr >= ms->possible_cpus->len) {
+        return NULL;
+    }
+    return S390_CPU(ms->possible_cpus->cpus[cpu_addr].cpu);
+}
 #endif
 
 static gchar *s390_gdb_arch_name(CPUState *cs)
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 1c8456fa57..5810079f48 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -671,6 +671,7 @@ int s390_cpu_restart(S390CPU *cpu);
 void s390_enable_css_support(S390CPU *cpu);
 int s390_assign_subch_ioeventfd(EventNotifier *notifier, uint32_t sch_id,
                                 int vq, bool assign);
+S390CPU *s390_cpu_addr2state(uint16_t cpu_addr);
 #ifndef CONFIG_USER_ONLY
 unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);
 #else
@@ -718,8 +719,4 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, uint8_t ar, void *hostbuf,
 #define s390_cpu_virt_mem_check_write(cpu, laddr, ar, len)   \
         s390_cpu_virt_mem_rw(cpu, laddr, ar, NULL, len, true)
 
-
-/* outside of target/s390x/ */
-S390CPU *s390_cpu_addr2state(uint16_t cpu_addr);
-
 #endif
-- 
2.13.5