[Qemu-ppc] [RFC PATCH v2.1 09/12] spapr: convert boot CPUs into CPU core devices

[Bharata B Rao]

Introduce sPAPRMachineClass.dr_cpu_enabled to indicate support for
CPU core hotplug. Initialize boot time CPUs as core deivces and prevent
topologies that result in partially filled cores. Both of these are done
only if CPU core hotplug is supported.

Note: An unrelated change in the call to xics_system_init() is done
in this patch as it makes sense to use the local variable smt introduced
in this patch instead of kvmppc_smt_threads() call here.

Signed-off-by: Bharata B Rao <address@hidden>
---
 hw/ppc/spapr.c                  | 73 +++++++++++++++++++++++++++++++++++------
 hw/ppc/spapr_cpu_core.c         | 45 +++++++++++++++++++++++++
 include/hw/ppc/spapr.h          |  2 ++
 include/hw/ppc/spapr_cpu_core.h |  3 ++
 4 files changed, 113 insertions(+), 10 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 45ac5dc..1ead043 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -64,6 +64,7 @@
 
 #include "hw/compat.h"
 #include "qemu-common.h"
+#include "hw/ppc/spapr_cpu_core.h"
 
 #include <libfdt.h>
 
@@ -1614,6 +1615,10 @@ static void spapr_boot_set(void *opaque, const char 
*boot_device,
     machine->boot_order = g_strdup(boot_device);
 }
 
+/*
+ * TODO: Check if some of these can be moved to rtas_start_cpu() where
+ * a few other things required for hotplugged CPUs are being done.
+ */
 void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp)
 {
     CPUPPCState *env = &cpu->env;
@@ -1644,6 +1649,7 @@ void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU 
*cpu, Error **errp)
     xics_cpu_setup(spapr->icp, cpu);
 
     qemu_register_reset(spapr_cpu_reset, cpu);
+    spapr_cpu_reset(cpu);
 }
 
 /*
@@ -1727,7 +1733,6 @@ static void ppc_spapr_init(MachineState *machine)
     const char *kernel_filename = machine->kernel_filename;
     const char *kernel_cmdline = machine->kernel_cmdline;
     const char *initrd_filename = machine->initrd_filename;
-    PowerPCCPU *cpu;
     PCIHostState *phb;
     int i;
     MemoryRegion *sysmem = get_system_memory();
@@ -1741,6 +1746,22 @@ static void ppc_spapr_init(MachineState *machine)
     long load_limit, fw_size;
     bool kernel_le = false;
     char *filename;
+    int smt = kvmppc_smt_threads();
+    int spapr_cores = smp_cpus / smp_threads;
+    int spapr_max_cores = max_cpus / smp_threads;
+
+    if (smc->dr_cpu_enabled) {
+        if (smp_cpus % smp_threads) {
+            error_report("smp_cpus (%u) must be multiple of threads (%u)",
+                         smp_cpus, smp_threads);
+            exit(1);
+        }
+        if (max_cpus % smp_threads) {
+            error_report("max_cpus (%u) must be multiple of threads (%u)",
+                         max_cpus, smp_threads);
+            exit(1);
+        }
+    }
 
     msi_supported = true;
 
@@ -1787,8 +1808,7 @@ static void ppc_spapr_init(MachineState *machine)
 
     /* Set up Interrupt Controller before we create the VCPUs */
     spapr->icp = xics_system_init(machine,
-                                  DIV_ROUND_UP(max_cpus * kvmppc_smt_threads(),
-                                               smp_threads),
+                                  DIV_ROUND_UP(max_cpus * smt, smp_threads),
                                   XICS_IRQS, &error_fatal);
 
     if (smc->dr_lmb_enabled) {
@@ -1799,13 +1819,34 @@ static void ppc_spapr_init(MachineState *machine)
     if (machine->cpu_model == NULL) {
         machine->cpu_model = kvm_enabled() ? "host" : "POWER7";
     }
-    for (i = 0; i < smp_cpus; i++) {
-        cpu = cpu_ppc_init(machine->cpu_model);
-        if (cpu == NULL) {
-            error_report("Unable to find PowerPC CPU definition");
-            exit(1);
+
+    if (smc->dr_cpu_enabled) {
+        spapr->cores = g_new0(Object *, spapr_max_cores);
+
+        for (i = 0; i < spapr_max_cores; i++) {
+            int core_dt_id = i * smt;
+
+            if (i < spapr_cores) {
+                char *type = spapr_get_cpu_core_type(machine->cpu_model);
+                Object *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);
+            }
         }
-        spapr_cpu_init(spapr, cpu, &error_fatal);
+    } else {
+        for (i = 0; i < smp_cpus; i++) {
+            PowerPCCPU *cpu = cpu_ppc_init(machine->cpu_model);
+            if (cpu == NULL) {
+                error_report("Unable to find PowerPC CPU definition");
+                exit(1);
+            }
+            spapr_cpu_init(spapr, cpu, &error_fatal);
+       }
     }
 
     if (kvm_enabled()) {
@@ -2257,10 +2298,19 @@ static void spapr_machine_device_unplug(HotplugHandler 
*hotplug_dev,
     }
 }
 
+static void spapr_machine_device_pre_plug(HotplugHandler *hotplug_dev,
+                                          DeviceState *dev, Error **errp)
+{
+    if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
+        spapr_core_pre_plug(hotplug_dev, dev, errp);
+    }
+}
+
 static HotplugHandler *spapr_get_hotpug_handler(MachineState *machine,
                                              DeviceState *dev)
 {
-    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
+    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) ||
+        object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
         return HOTPLUG_HANDLER(machine);
     }
     return NULL;
@@ -2299,11 +2349,13 @@ static void spapr_machine_class_init(ObjectClass *oc, 
void *data)
     mc->has_dynamic_sysbus = true;
     mc->pci_allow_0_address = true;
     mc->get_hotplug_handler = spapr_get_hotpug_handler;
+    hc->pre_plug = spapr_machine_device_pre_plug;
     hc->plug = spapr_machine_device_plug;
     hc->unplug = spapr_machine_device_unplug;
     mc->cpu_index_to_socket_id = spapr_cpu_index_to_socket_id;
 
     smc->dr_lmb_enabled = true;
+    smc->dr_cpu_enabled = true;
     fwc->get_dev_path = spapr_get_fw_dev_path;
     nc->nmi_monitor_handler = spapr_nmi;
 }
@@ -2383,6 +2435,7 @@ static void spapr_machine_2_5_class_options(MachineClass 
*mc)
 
     spapr_machine_2_6_class_options(mc);
     smc->use_ohci_by_default = true;
+    smc->dr_cpu_enabled = false;
     SET_MACHINE_COMPAT(mc, SPAPR_COMPAT_2_5);
 }
 
diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 3751a54..640d143 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -15,6 +15,40 @@
 #include <sysemu/cpus.h>
 #include "target-ppc/kvm_ppc.h"
 
+void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                         Error **errp)
+{
+    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+    int spapr_max_cores = max_cpus / smp_threads;
+    int index;
+    int smt = kvmppc_smt_threads();
+    Error *local_err = NULL;
+    CPUCore *cc = CPU_CORE(dev);
+
+    if (cc->threads != smp_threads) {
+        error_setg(&local_err, "threads must be %d", smp_threads);
+        goto out;
+    }
+
+    if (cc->core % smt) {
+        error_setg(&local_err, "invalid core id %d\n", cc->core);
+        goto out;
+    }
+
+    index = cc->core / smt;
+    if (index < 0 || index >= spapr_max_cores) {
+        error_setg(&local_err, "core id %d out of range", cc->core);
+        goto out;
+    }
+
+    if (spapr->cores[index]) {
+        error_setg(&local_err, "core %d already populated", cc->core);
+    }
+
+out:
+    error_propagate(errp, local_err);
+}
+
 static const TypeInfo spapr_cpu_core_type_info = {
     .name = TYPE_SPAPR_CPU_CORE,
     .parent = TYPE_CPU_CORE,
@@ -146,3 +180,14 @@ static void spapr_cpu_core_register_types(void)
 }
 
 type_init(spapr_cpu_core_register_types)
+
+/*
+ * TODO: Looks fragile :(
+ */
+char *spapr_get_cpu_core_type(const char *model)
+{
+    char core_type[32];
+
+    snprintf(core_type, 32, "%s-%s", model, TYPE_SPAPR_CPU_CORE);
+    return g_strdup(core_type);
+}
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index 0fdf448..a6956c0 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -36,6 +36,7 @@ struct sPAPRMachineClass {
 
     /*< public >*/
     bool dr_lmb_enabled;       /* enable dynamic-reconfig/hotplug of LMBs */
+    bool dr_cpu_enabled;       /* enable dynamic-reconfig/hotplug of CPUs */
     bool use_ohci_by_default;  /* use USB-OHCI instead of XHCI */
 };
 
@@ -79,6 +80,7 @@ struct sPAPRMachineState {
     /*< public >*/
     char *kvm_type;
     MemoryHotplugState hotplug_memory;
+    Object **cores;
 };
 
 #define H_SUCCESS         0
diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
index 71e69c0..f08f291 100644
--- a/include/hw/ppc/spapr_cpu_core.h
+++ b/include/hw/ppc/spapr_cpu_core.h
@@ -60,4 +60,7 @@ typedef struct POWER8sPAPRCPUCore {
     ObjectClass *cpu;
 } POWER8sPAPRCPUCore;
 
+void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                         Error **errp);
+char *spapr_get_cpu_core_type(const char *model);
 #endif
-- 
2.1.0