[Qemu-devel] [PATCH 4/4] s390x/cpu: Allow hotplug of CPUs

[Matthew Rosato <mjrosato@linux.vnet.ibm.com>]

Implement cpu hotplug routine and add the machine hook.

Signed-off-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
---
 hw/s390x/s390-virtio-ccw.c |  1 +
 target-s390x/cpu.c         | 45 +++++++++++++++++++++++++++++++++++++++++++--
 target-s390x/cpu.h         |  1 +
 3 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index 7561e18..cfcde8d 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -163,6 +163,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
 
     mc->init = ccw_init;
     mc->reset = s390_machine_reset;
+    mc->hot_add_cpu = s390_hot_add_cpu;
     mc->block_default_type = IF_VIRTIO;
     mc->no_cdrom = 1;
     mc->no_floppy = 1;
diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
index 3228c3b..48ecd34 100644
--- a/target-s390x/cpu.c
+++ b/target-s390x/cpu.c
@@ -31,11 +31,17 @@
 #include "trace.h"
 #ifndef CONFIG_USER_ONLY
 #include "sysemu/arch_init.h"
+#include "hw/boards.h"
+#include "hw/s390x/sclp.h"
+#include "sysemu/sysemu.h"
 #endif
 
 #define CR0_RESET       0xE0UL
 #define CR14_RESET      0xC2000000UL;
 
+/* Older kernels require CPUs to be added sequentially by id */
+int next_cpu_id;
+
 /* generate CPU information for cpu -? */
 void s390_cpu_list(FILE *f, fprintf_function cpu_fprintf)
 {
@@ -204,6 +210,12 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
 #endif
 
     scc->parent_realize(dev, errp);
+
+#if !defined(CONFIG_USER_ONLY)
+    if (dev->hotplugged) {
+        raise_irq_cpu_hotplug();
+    }
+#endif
 }
 
 static void s390_cpu_initfn(Object *obj)
@@ -212,7 +224,6 @@ static void s390_cpu_initfn(Object *obj)
     S390CPU *cpu = S390_CPU(obj);
     CPUS390XState *env = &cpu->env;
     static bool inited;
-    static int cpu_num = 0;
 #if !defined(CONFIG_USER_ONLY)
     struct tm tm;
 #endif
@@ -221,7 +232,7 @@ static void s390_cpu_initfn(Object *obj)
     cs->halted = 1;
     cs->exception_index = EXCP_HLT;
     cpu_exec_init(cs, &error_abort);
-    env->cpu_num = cpu_num++;
+    env->cpu_num = next_cpu_id++;
 #if !defined(CONFIG_USER_ONLY)
     qemu_register_reset(s390_cpu_machine_reset_cb, cpu);
     qemu_get_timedate(&tm, 0);
@@ -251,6 +262,36 @@ static void s390_cpu_finalize(Object *obj)
 }
 
 #if !defined(CONFIG_USER_ONLY)
+void s390_hot_add_cpu(const int64_t id, Error **errp)
+{
+    MachineState *machine = MACHINE(qdev_get_machine());
+
+    if (id < 0) {
+        error_setg(errp, "Invalid CPU id: %" PRIi64, id);
+        return;
+    }
+
+    if (cpu_exists(id)) {
+        error_setg(errp, "Unable to add CPU: %" PRIi64
+                   ", it already exists", id);
+        return;
+    }
+
+    if (id >= max_cpus) {
+        error_setg(errp, "Unable to add CPU: %" PRIi64
+                   ", max allowed: %d", id, max_cpus - 1);
+        return;
+    }
+
+    if (id != next_cpu_id) {
+        error_setg(errp, "Unable to add CPU: %" PRIi64
+                   ", The next available id is %d", id, next_cpu_id);
+        return;
+    }
+
+    cpu_s390x_init(machine->cpu_model);
+}
+
 static bool disabled_wait(CPUState *cpu)
 {
     return cpu->halted && !(S390_CPU(cpu)->env.psw.mask &
diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 803841b..99daf79 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -542,6 +542,7 @@ static inline uint8_t s390_cpu_get_state(S390CPU *cpu)
 
 void gtod_save(QEMUFile *f, void *opaque);
 int gtod_load(QEMUFile *f, void *opaque, int version_id);
+void s390_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);
-- 
1.9.1