diff mbox

[for-2.7,v3,09/15] spapr: CPU hotplug support

Message ID 1463024905-28401-10-git-send-email-bharata@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Bharata B Rao May 12, 2016, 3:48 a.m. UTC 
Set up device tree entries for the hotplugged CPU core and use the
exising RTAS event logging infrastructure to send CPU hotplug notification
to the guest.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c                  | 91 ++++++++++++++++++++++++++++++++++-------
 hw/ppc/spapr_cpu_core.c         | 69 +++++++++++++++++++++++++++++++
 hw/ppc/spapr_events.c           |  3 ++
 hw/ppc/spapr_rtas.c             | 24 +++++++++++
 include/hw/ppc/spapr.h          |  2 +
 include/hw/ppc/spapr_cpu_core.h |  2 +
 6 files changed, 176 insertions(+), 15 deletions(-)

Comments

David Gibson June 3, 2016, 6:10 a.m. UTC | #1 
On Thu, May 12, 2016 at 09:18:19AM +0530, Bharata B Rao wrote:
> Set up device tree entries for the hotplugged CPU core and use the
> exising RTAS event logging infrastructure to send CPU hotplug notification
> to the guest.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/ppc/spapr.c                  | 91 ++++++++++++++++++++++++++++++++++-------
>  hw/ppc/spapr_cpu_core.c         | 69 +++++++++++++++++++++++++++++++
>  hw/ppc/spapr_events.c           |  3 ++
>  hw/ppc/spapr_rtas.c             | 24 +++++++++++
>  include/hw/ppc/spapr.h          |  2 +
>  include/hw/ppc/spapr_cpu_core.h |  2 +
>  6 files changed, 176 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0f64218..8c3100d 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -605,6 +605,16 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset,
>      size_t page_sizes_prop_size;
>      uint32_t vcpus_per_socket = smp_threads * smp_cores;
>      uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)};
> +    sPAPRDRConnector *drc;
> +    sPAPRDRConnectorClass *drck;
> +    int drc_index;
> +
> +    drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index);
> +    if (drc) {
> +        drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +        drc_index = drck->get_index(drc);
> +        _FDT((fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index)));
> +    }
>  
>      /* Note: we keep CI large pages off for now because a 64K capable guest
>       * provisioned with large pages might otherwise try to map a qemu
> @@ -988,6 +998,16 @@ static void spapr_finalize_fdt(sPAPRMachineState *spapr,
>          _FDT(spapr_drc_populate_dt(fdt, 0, NULL, SPAPR_DR_CONNECTOR_TYPE_LMB));
>      }
>  
> +    if (smc->dr_cpu_enabled) {
> +        int offset = fdt_path_offset(fdt, "/cpus");
> +        ret = spapr_drc_populate_dt(fdt, offset, NULL,
> +                                    SPAPR_DR_CONNECTOR_TYPE_CPU);
> +        if (ret < 0) {
> +            error_report("Couldn't set up CPU DR device tree properties");
> +            exit(1);
> +        }
> +    }
> +
>      _FDT((fdt_pack(fdt)));
>  
>      if (fdt_totalsize(fdt) > FDT_MAX_SIZE) {
> @@ -1613,6 +1633,8 @@ static void spapr_boot_set(void *opaque, const char *boot_device,
>  void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
>  {
>      CPUPPCState *env = &cpu->env;
> +    CPUState *cs = CPU(cpu);
> +    int i;
>  
>      /* Set time-base frequency to 512 MHz */
>      cpu_ppc_tb_init(env, TIMEBASE_FREQ);
> @@ -1630,6 +1652,14 @@ void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
>          }
>      }
>  
> +    /* Set NUMA node for the added CPUs  */
> +    for (i = 0; i < nb_numa_nodes; i++) {
> +        if (test_bit(cs->cpu_index, numa_info[i].node_cpu)) {
> +            cs->numa_node = i;
> +            break;
> +        }
> +    }
> +
>      xics_cpu_setup(spapr->icp, cpu);
>  
>      qemu_register_reset(spapr_cpu_reset, cpu);
> @@ -1807,23 +1837,31 @@ static void ppc_spapr_init(MachineState *machine)
>      if (smc->dr_cpu_enabled) {
>          spapr->cores = g_new0(Object *, spapr_max_cores);
>  
> -        for (i = 0; i < spapr_cores; i++) {
> +        for (i = 0; i < spapr_max_cores; i++) {
>              int core_dt_id = i * smt;
> -            char *type = spapr_get_cpu_core_type(machine->cpu_model);
> -            Object *core;
> -
> -            if (!object_class_by_name(type)) {
> -                error_report("Unable to find sPAPR CPU Core definition");
> -                exit(1);
> +            sPAPRDRConnector *drc =
> +                spapr_dr_connector_new(OBJECT(spapr),
> +                                       SPAPR_DR_CONNECTOR_TYPE_CPU, core_dt_id);
> +
> +            qemu_register_reset(spapr_drc_reset, drc);
> +
> +            if (i < spapr_cores) {
> +                char *type = spapr_get_cpu_core_type(machine->cpu_model);
> +                Object *core;
> +
> +                if (!object_class_by_name(type)) {
> +                    error_report("Unable to find sPAPR CPU Core definition");
> +                    exit(1);
> +                }
> +
> +                core  = object_new(type);
> +                g_free(type);
> +                object_property_set_int(core, smp_threads, "threads",
> +                                        &error_fatal);
> +                object_property_set_int(core, core_dt_id, CPU_CORE_PROP_CORE,
> +                                        &error_fatal);
> +                object_property_set_bool(core, true, "realized", &error_fatal);
>              }
> -
> -            core  = object_new(type);
> -            g_free(type);
> -            object_property_set_int(core, smp_threads, "threads",
> -                                    &error_fatal);
> -            object_property_set_int(core, core_dt_id, CPU_CORE_PROP_CORE,
> -                                    &error_fatal);
> -            object_property_set_bool(core, true, "realized", &error_fatal);
>          }
>      } else {
>          for (i = 0; i < smp_cpus; i++) {
> @@ -2234,6 +2272,27 @@ out:
>      error_propagate(errp, local_err);
>  }
>  
> +void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
> +                                    sPAPRMachineState *spapr)
> +{
> +    PowerPCCPU *cpu = POWERPC_CPU(cs);
> +    DeviceClass *dc = DEVICE_GET_CLASS(cs);
> +    int id = ppc_get_vcpu_dt_id(cpu);
> +    void *fdt;
> +    int offset, fdt_size;
> +    char *nodename;
> +
> +    fdt = create_device_tree(&fdt_size);
> +    nodename = g_strdup_printf("%s@%x", dc->fw_name, id);
> +    offset = fdt_add_subnode(fdt, 0, nodename);
> +
> +    spapr_populate_cpu_dt(cs, fdt, offset, spapr);
> +    g_free(nodename);
> +
> +    *fdt_offset = offset;
> +    return fdt;
> +}
> +
>  static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
>                                        DeviceState *dev, Error **errp)
>  {
> @@ -2278,6 +2337,8 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
>          }
>  
>          spapr_memory_plug(hotplug_dev, dev, node, errp);
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
> +        spapr_core_plug(hotplug_dev, dev, errp);
>      }
>  }
>  
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 4450362..ed36beb 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -28,10 +28,74 @@ char *spapr_get_cpu_core_type(const char *model)
>      return g_strdup(core_type);
>  }
>  
> +void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> +                     Error **errp)
> +{
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(OBJECT(hotplug_dev));
> +    sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
> +    sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> +    CPUCore *cc = CPU_CORE(dev);
> +    CPUState *cs = CPU(&core->threads[0]);
> +    sPAPRDRConnector *drc;
> +    sPAPRDRConnectorClass *drck;
> +    Error *local_err = NULL;
> +    void *fdt = NULL;
> +    int fdt_offset = 0;
> +    int index;
> +    int smt = kvmppc_smt_threads();
> +
> +    drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core);
> +    index = cc->core / smt;
> +    spapr->cores[index] = OBJECT(dev);
> +
> +    if (!smc->dr_cpu_enabled) {
> +        /*
> +         * This is a cold plugged CPU core but the machine doesn't support
> +         * DR. So skip the hotplug path ensuring that the core is brought
> +         * up online with out an associated DR connector.
> +         */
> +        return;
> +    }
> +
> +    g_assert(drc);
> +
> +    /*
> +     * Setup CPU DT entries only for hotplugged CPUs. For boot time or
> +     * coldplugged CPUs DT entries are setup in spapr_finalize_fdt().
> +     */
> +    if (dev->hotplugged) {
> +        fdt = spapr_populate_hotplug_cpu_dt(cs, &fdt_offset, spapr);
> +    }
> +
> +    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, &local_err);
> +    if (local_err) {
> +        g_free(fdt);
> +        spapr->cores[index] = NULL;
> +        error_propagate(errp, local_err);
> +        return;
> +    }
> +
> +    if (dev->hotplugged) {
> +        /*
> +         * Send hotplug notification interrupt to the guest only in case
> +         * of hotplugged CPUs.
> +         */
> +        spapr_hotplug_req_add_by_index(drc);
> +    } else {
> +        /*
> +         * Set the right DRC states for cold plugged CPU.
> +         */
> +        drck->set_allocation_state(drc, SPAPR_DR_ALLOCATION_STATE_USABLE);
> +        drck->set_isolation_state(drc, SPAPR_DR_ISOLATION_STATE_UNISOLATED);
> +    }
> +}
> +
>  void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>                           Error **errp)
>  {
>      MachineState *machine = MACHINE(OBJECT(hotplug_dev));
> +    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(OBJECT(hotplug_dev));
>      sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
>      int spapr_max_cores = max_cpus / smp_threads;
>      int index;
> @@ -46,6 +110,11 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>          goto out;
>      }
>  
> +    if (!smc->dr_cpu_enabled && dev->hotplugged) {
> +        error_setg(&local_err, "CPU hotplug not supported for this machine");
> +        goto out;
> +    }
> +
>      if (cc->threads != smp_threads) {
>          error_setg(&local_err, "threads must be %d", smp_threads);
>          goto out;
> diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
> index 049fb1b..af80992 100644
> --- a/hw/ppc/spapr_events.c
> +++ b/hw/ppc/spapr_events.c
> @@ -449,6 +449,9 @@ static void spapr_hotplug_req_event(uint8_t hp_id, uint8_t hp_action,
>      case SPAPR_DR_CONNECTOR_TYPE_LMB:
>          hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_MEMORY;
>          break;
> +    case SPAPR_DR_CONNECTOR_TYPE_CPU:
> +        hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_CPU;
> +        break;
>      default:
>          /* we shouldn't be signaling hotplug events for resources
>           * that don't support them
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index f073258..e53ecc0 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -34,6 +34,7 @@
>  
>  #include "hw/ppc/spapr.h"
>  #include "hw/ppc/spapr_vio.h"
> +#include "hw/ppc/ppc.h"
>  #include "qapi-event.h"
>  #include "hw/boards.h"
>  
> @@ -162,6 +163,27 @@ static void rtas_query_cpu_stopped_state(PowerPCCPU *cpu_,
>      rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>  }
>  
> +/*
> + * Set the timebase offset of the CPU to that of first CPU.
> + * This helps hotplugged CPU to have the correct timebase offset.
> + */
> +static void spapr_cpu_update_tb_offset(PowerPCCPU *cpu)
> +{
> +    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> +
> +    cpu->env.tb_env->tb_offset = fcpu->env.tb_env->tb_offset;
> +}
> +
> +static void spapr_cpu_set_endianness(PowerPCCPU *cpu)
> +{
> +    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(fcpu);
> +
> +    if (!pcc->interrupts_big_endian(fcpu)) {
> +        cpu->env.spr[SPR_LPCR] |= LPCR_ILE;
> +    }
> +}
> +
>  static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPRMachineState *spapr,
>                             uint32_t token, uint32_t nargs,
>                             target_ulong args,
> @@ -198,6 +220,8 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPRMachineState *spapr,
>          env->nip = start;
>          env->gpr[3] = r3;
>          cs->halted = 0;
> +        spapr_cpu_set_endianness(cpu);
> +        spapr_cpu_update_tb_offset(cpu);
>  
>          qemu_cpu_kick(cs);
>  
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 1b3eeee..ca4ae3e 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -583,6 +583,8 @@ void spapr_hotplug_req_add_by_count(sPAPRDRConnectorType drc_type,
>  void spapr_hotplug_req_remove_by_count(sPAPRDRConnectorType drc_type,
>                                            uint32_t count);
>  void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp);
> +void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
> +                                    sPAPRMachineState *spapr);
>  
>  /* rtas-configure-connector state */
>  struct sPAPRConfigureConnectorState {
> diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
> index f1ebd85..4cd837e 100644
> --- a/include/hw/ppc/spapr_cpu_core.h
> +++ b/include/hw/ppc/spapr_cpu_core.h
> @@ -28,4 +28,6 @@ typedef struct sPAPRCPUCore {
>  void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>                           Error **errp);
>  char *spapr_get_cpu_core_type(const char *model);
> +void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> +                     Error **errp);
>  #endif
diff mbox

Patch

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 0f64218..8c3100d 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -605,6 +605,16 @@  static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset,
     size_t page_sizes_prop_size;
     uint32_t vcpus_per_socket = smp_threads * smp_cores;
     uint32_t pft_size_prop[] = {0, cpu_to_be32(spapr->htab_shift)};
+    sPAPRDRConnector *drc;
+    sPAPRDRConnectorClass *drck;
+    int drc_index;
+
+    drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index);
+    if (drc) {
+        drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
+        drc_index = drck->get_index(drc);
+        _FDT((fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index)));
+    }
 
     /* Note: we keep CI large pages off for now because a 64K capable guest
      * provisioned with large pages might otherwise try to map a qemu
@@ -988,6 +998,16 @@  static void spapr_finalize_fdt(sPAPRMachineState *spapr,
         _FDT(spapr_drc_populate_dt(fdt, 0, NULL, SPAPR_DR_CONNECTOR_TYPE_LMB));
     }
 
+    if (smc->dr_cpu_enabled) {
+        int offset = fdt_path_offset(fdt, "/cpus");
+        ret = spapr_drc_populate_dt(fdt, offset, NULL,
+                                    SPAPR_DR_CONNECTOR_TYPE_CPU);
+        if (ret < 0) {
+            error_report("Couldn't set up CPU DR device tree properties");
+            exit(1);
+        }
+    }
+
     _FDT((fdt_pack(fdt)));
 
     if (fdt_totalsize(fdt) > FDT_MAX_SIZE) {
@@ -1613,6 +1633,8 @@  static void spapr_boot_set(void *opaque, const char *boot_device,
 void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
 {
     CPUPPCState *env = &cpu->env;
+    CPUState *cs = CPU(cpu);
+    int i;
 
     /* Set time-base frequency to 512 MHz */
     cpu_ppc_tb_init(env, TIMEBASE_FREQ);
@@ -1630,6 +1652,14 @@  void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
         }
     }
 
+    /* Set NUMA node for the added CPUs  */
+    for (i = 0; i < nb_numa_nodes; i++) {
+        if (test_bit(cs->cpu_index, numa_info[i].node_cpu)) {
+            cs->numa_node = i;
+            break;
+        }
+    }
+
     xics_cpu_setup(spapr->icp, cpu);
 
     qemu_register_reset(spapr_cpu_reset, cpu);
@@ -1807,23 +1837,31 @@  static void ppc_spapr_init(MachineState *machine)
     if (smc->dr_cpu_enabled) {
         spapr->cores = g_new0(Object *, spapr_max_cores);
 
-        for (i = 0; i < spapr_cores; i++) {
+        for (i = 0; i < spapr_max_cores; i++) {
             int core_dt_id = i * smt;
-            char *type = spapr_get_cpu_core_type(machine->cpu_model);
-            Object *core;
-
-            if (!object_class_by_name(type)) {
-                error_report("Unable to find sPAPR CPU Core definition");
-                exit(1);
+            sPAPRDRConnector *drc =
+                spapr_dr_connector_new(OBJECT(spapr),
+                                       SPAPR_DR_CONNECTOR_TYPE_CPU, core_dt_id);
+
+            qemu_register_reset(spapr_drc_reset, drc);
+
+            if (i < spapr_cores) {
+                char *type = spapr_get_cpu_core_type(machine->cpu_model);
+                Object *core;
+
+                if (!object_class_by_name(type)) {
+                    error_report("Unable to find sPAPR CPU Core definition");
+                    exit(1);
+                }
+
+                core  = object_new(type);
+                g_free(type);
+                object_property_set_int(core, smp_threads, "threads",
+                                        &error_fatal);
+                object_property_set_int(core, core_dt_id, CPU_CORE_PROP_CORE,
+                                        &error_fatal);
+                object_property_set_bool(core, true, "realized", &error_fatal);
             }
-
-            core  = object_new(type);
-            g_free(type);
-            object_property_set_int(core, smp_threads, "threads",
-                                    &error_fatal);
-            object_property_set_int(core, core_dt_id, CPU_CORE_PROP_CORE,
-                                    &error_fatal);
-            object_property_set_bool(core, true, "realized", &error_fatal);
         }
     } else {
         for (i = 0; i < smp_cpus; i++) {
@@ -2234,6 +2272,27 @@  out:
     error_propagate(errp, local_err);
 }
 
+void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
+                                    sPAPRMachineState *spapr)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
+    DeviceClass *dc = DEVICE_GET_CLASS(cs);
+    int id = ppc_get_vcpu_dt_id(cpu);
+    void *fdt;
+    int offset, fdt_size;
+    char *nodename;
+
+    fdt = create_device_tree(&fdt_size);
+    nodename = g_strdup_printf("%s@%x", dc->fw_name, id);
+    offset = fdt_add_subnode(fdt, 0, nodename);
+
+    spapr_populate_cpu_dt(cs, fdt, offset, spapr);
+    g_free(nodename);
+
+    *fdt_offset = offset;
+    return fdt;
+}
+
 static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
                                       DeviceState *dev, Error **errp)
 {
@@ -2278,6 +2337,8 @@  static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
         }
 
         spapr_memory_plug(hotplug_dev, dev, node, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
+        spapr_core_plug(hotplug_dev, dev, errp);
     }
 }
 
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 4450362..ed36beb 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -28,10 +28,74 @@  char *spapr_get_cpu_core_type(const char *model)
     return g_strdup(core_type);
 }
 
+void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                     Error **errp)
+{
+    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(OBJECT(hotplug_dev));
+    sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
+    sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
+    CPUCore *cc = CPU_CORE(dev);
+    CPUState *cs = CPU(&core->threads[0]);
+    sPAPRDRConnector *drc;
+    sPAPRDRConnectorClass *drck;
+    Error *local_err = NULL;
+    void *fdt = NULL;
+    int fdt_offset = 0;
+    int index;
+    int smt = kvmppc_smt_threads();
+
+    drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, cc->core);
+    index = cc->core / smt;
+    spapr->cores[index] = OBJECT(dev);
+
+    if (!smc->dr_cpu_enabled) {
+        /*
+         * This is a cold plugged CPU core but the machine doesn't support
+         * DR. So skip the hotplug path ensuring that the core is brought
+         * up online with out an associated DR connector.
+         */
+        return;
+    }
+
+    g_assert(drc);
+
+    /*
+     * Setup CPU DT entries only for hotplugged CPUs. For boot time or
+     * coldplugged CPUs DT entries are setup in spapr_finalize_fdt().
+     */
+    if (dev->hotplugged) {
+        fdt = spapr_populate_hotplug_cpu_dt(cs, &fdt_offset, spapr);
+    }
+
+    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
+    drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, &local_err);
+    if (local_err) {
+        g_free(fdt);
+        spapr->cores[index] = NULL;
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    if (dev->hotplugged) {
+        /*
+         * Send hotplug notification interrupt to the guest only in case
+         * of hotplugged CPUs.
+         */
+        spapr_hotplug_req_add_by_index(drc);
+    } else {
+        /*
+         * Set the right DRC states for cold plugged CPU.
+         */
+        drck->set_allocation_state(drc, SPAPR_DR_ALLOCATION_STATE_USABLE);
+        drck->set_isolation_state(drc, SPAPR_DR_ISOLATION_STATE_UNISOLATED);
+    }
+}
+
 void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
                          Error **errp)
 {
     MachineState *machine = MACHINE(OBJECT(hotplug_dev));
+    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(OBJECT(hotplug_dev));
     sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
     int spapr_max_cores = max_cpus / smp_threads;
     int index;
@@ -46,6 +110,11 @@  void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
         goto out;
     }
 
+    if (!smc->dr_cpu_enabled && dev->hotplugged) {
+        error_setg(&local_err, "CPU hotplug not supported for this machine");
+        goto out;
+    }
+
     if (cc->threads != smp_threads) {
         error_setg(&local_err, "threads must be %d", smp_threads);
         goto out;
diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index 049fb1b..af80992 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -449,6 +449,9 @@  static void spapr_hotplug_req_event(uint8_t hp_id, uint8_t hp_action,
     case SPAPR_DR_CONNECTOR_TYPE_LMB:
         hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_MEMORY;
         break;
+    case SPAPR_DR_CONNECTOR_TYPE_CPU:
+        hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_CPU;
+        break;
     default:
         /* we shouldn't be signaling hotplug events for resources
          * that don't support them
diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index f073258..e53ecc0 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -34,6 +34,7 @@ 
 
 #include "hw/ppc/spapr.h"
 #include "hw/ppc/spapr_vio.h"
+#include "hw/ppc/ppc.h"
 #include "qapi-event.h"
 #include "hw/boards.h"
 
@@ -162,6 +163,27 @@  static void rtas_query_cpu_stopped_state(PowerPCCPU *cpu_,
     rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 }
 
+/*
+ * Set the timebase offset of the CPU to that of first CPU.
+ * This helps hotplugged CPU to have the correct timebase offset.
+ */
+static void spapr_cpu_update_tb_offset(PowerPCCPU *cpu)
+{
+    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
+
+    cpu->env.tb_env->tb_offset = fcpu->env.tb_env->tb_offset;
+}
+
+static void spapr_cpu_set_endianness(PowerPCCPU *cpu)
+{
+    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
+    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(fcpu);
+
+    if (!pcc->interrupts_big_endian(fcpu)) {
+        cpu->env.spr[SPR_LPCR] |= LPCR_ILE;
+    }
+}
+
 static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPRMachineState *spapr,
                            uint32_t token, uint32_t nargs,
                            target_ulong args,
@@ -198,6 +220,8 @@  static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPRMachineState *spapr,
         env->nip = start;
         env->gpr[3] = r3;
         cs->halted = 0;
+        spapr_cpu_set_endianness(cpu);
+        spapr_cpu_update_tb_offset(cpu);
 
         qemu_cpu_kick(cs);
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 1b3eeee..ca4ae3e 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -583,6 +583,8 @@  void spapr_hotplug_req_add_by_count(sPAPRDRConnectorType drc_type,
 void spapr_hotplug_req_remove_by_count(sPAPRDRConnectorType drc_type,
                                           uint32_t count);
 void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp);
+void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
+                                    sPAPRMachineState *spapr);
 
 /* rtas-configure-connector state */
 struct sPAPRConfigureConnectorState {
diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
index f1ebd85..4cd837e 100644
--- a/include/hw/ppc/spapr_cpu_core.h
+++ b/include/hw/ppc/spapr_cpu_core.h
@@ -28,4 +28,6 @@  typedef struct sPAPRCPUCore {
 void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
                          Error **errp);
 char *spapr_get_cpu_core_type(const char *model);
+void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                     Error **errp);
 #endif