[Qemu-devel] [PATCH 7/8] [PATCH RFC v3] s390-qemu: cpu hotplug - Implement hot_add_cpu hook

["Jason J. Herne" <jjherne@us.ibm.com>]

From: "Jason J. Herne" <jjherne@us.ibm.com>

Implement hot_add_cpu for S390 to allow hot plugging of cpus.

Signed-off-by: Jason J. Herne <jjherne@us.ibm.com>
---
 hw/s390x/s390-virtio-ccw.c |    3 +++
 target-s390x/cpu.c         |   32 ++++++++++++++++++++++++++++++++
 target-s390x/cpu.h         |    2 ++
 3 files changed, 37 insertions(+)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index b469960..30b6a48 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -117,6 +117,9 @@ static QEMUMachine ccw_machine = {
     .alias = "s390-ccw",
     .desc = "VirtIO-ccw based S390 machine",
     .init = ccw_init,
+#if !defined(CONFIG_USER_ONLY)
+    .hot_add_cpu = ccw_hot_add_cpu,
+#endif
     .block_default_type = IF_VIRTIO,
     .no_cdrom = 1,
     .no_floppy = 1,
diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
index c90a91c..60029d9 100644
--- a/target-s390x/cpu.c
+++ b/target-s390x/cpu.c
@@ -27,6 +27,8 @@
 #include "qemu-common.h"
 #include "qemu/timer.h"
 #include "hw/hw.h"
+#include "hw/s390x/sclp.h"
+#include "sysemu/sysemu.h"
 #ifndef CONFIG_USER_ONLY
 #include "sysemu/arch_init.h"
 #endif
@@ -154,6 +156,36 @@ static void s390_cpu_finalize(Object *obj)
 #endif
 }
 
+#if !defined(CONFIG_USER_ONLY)
+void ccw_hot_add_cpu(const int64_t id, Error **errp)
+{
+    S390CPU *new_cpu;
+    CPUState *cpu;
+    const char *model_str;
+    int cpu_count = 0;
+
+    for (cpu = first_cpu; cpu != NULL; cpu = cpu->next_cpu) {
+        cpu_count++;
+    }
+
+    if (cpu_count == max_cpus) {
+        error_setg(errp, "Maximum number of cpus already defined");
+        return;
+    }
+
+    if (id != cpu_count) {
+        error_setg(errp, "Unable to add CPU: %" PRIi64
+                   ", The next available id is %d", id, cpu_count);
+        return;
+    }
+
+    model_str = s390_cpu_addr2state(0)->env.cpu_model_str;
+    new_cpu = s390_new_cpu(model_str, id);
+    object_property_set_bool(OBJECT(new_cpu), true, "realized", NULL);
+    raise_irq_cpu_hotplug();
+}
+#endif
+
 static const VMStateDescription vmstate_s390_cpu = {
     .name = "cpu",
     .unmigratable = 1,
diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 0f68dd0..711aad4 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -383,6 +383,8 @@ S390CPU *s390_cpu_addr2state(uint16_t cpu_addr);
 void s390_add_running_cpu(S390CPU *cpu);
 unsigned s390_del_running_cpu(S390CPU *cpu);
 
+void ccw_hot_add_cpu(const int64_t id, Error **errp);
+
 /* service interrupts are floating therefore we must not pass an cpustate */
 void s390_sclp_extint(uint32_t parm);
 
-- 
1.7.10.4