[Qemu-devel] [for-2.7 PATCH v3 08/15] spapr: convert boot CPUs into CPU core devices

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

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.

TODO: We derive sPAPR core type by looking at -cpu <model>. However
we don't take care of "compat=" feature yet for boot time as well
as hotplug CPUs.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c                  | 76 +++++++++++++++++++++++++++++++++++------
 hw/ppc/spapr_cpu_core.c         | 58 +++++++++++++++++++++++++++++++
 include/hw/ppc/spapr.h          |  2 ++
 include/hw/ppc/spapr_cpu_core.h |  3 ++
 4 files changed, 129 insertions(+), 10 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 95db047..0f64218 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -65,6 +65,7 @@
 
 #include "hw/compat.h"
 #include "qemu/cutils.h"
+#include "hw/ppc/spapr_cpu_core.h"
 
 #include <libfdt.h>
 
@@ -1605,6 +1606,10 @@ 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;
@@ -1628,6 +1633,7 @@ 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);
 }
 
 /*
@@ -1711,7 +1717,6 @@ 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();
@@ -1725,6 +1730,22 @@ 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_nonbroken = true;
 
@@ -1771,8 +1792,7 @@ 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) {
@@ -1783,13 +1803,37 @@ 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_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);
+            }
+
+            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()) {
@@ -2245,10 +2289,19 @@ 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;
@@ -2287,11 +2340,13 @@ 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;
 }
@@ -2376,6 +2431,7 @@ 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 af63ed9..4450362 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -14,6 +14,64 @@
 #include <sysemu/cpus.h>
 #include "target-ppc/kvm_ppc.h"
 
+/*
+ * Return the sPAPR CPU core type for @model which essentially is the CPU
+ * model specified with -cpu cmdline option.
+ */
+char *spapr_get_cpu_core_type(const char *model)
+{
+    char core_type[32];
+    gchar **model_pieces = g_strsplit(model, ",", 2);
+
+    snprintf(core_type, 32, "%s-%s", model_pieces[0], TYPE_SPAPR_CPU_CORE);
+    g_strfreev(model_pieces);
+    return g_strdup(core_type);
+}
+
+void spapr_core_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                         Error **errp)
+{
+    MachineState *machine = MACHINE(OBJECT(hotplug_dev));
+    sPAPRMachineState *spapr = SPAPR_MACHINE(OBJECT(hotplug_dev));
+    int spapr_max_cores = max_cpus / smp_threads;
+    int index;
+    int smt = kvmppc_smt_threads();
+    Error *local_err = NULL;
+    CPUCore *cc = CPU_CORE(dev);
+    char *base_core_type = spapr_get_cpu_core_type(machine->cpu_model);
+    const char *type = object_get_typename(OBJECT(dev));
+
+    if (strcmp(base_core_type, type)) {
+        error_setg(&local_err, "CPU core type should be %s", base_core_type);
+        goto out;
+    }
+
+    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);
+        goto out;
+    }
+
+out:
+    g_free(base_core_type);
+    error_propagate(errp, local_err);
+}
+
 static void spapr_cpu_core_create_threads(DeviceState *dev, int threads,
                                           Error **errp)
 {
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index bcd9de6..1b3eeee 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 b6aa39e..f1ebd85 100644
--- a/include/hw/ppc/spapr_cpu_core.h
+++ b/include/hw/ppc/spapr_cpu_core.h
@@ -25,4 +25,7 @@ typedef struct sPAPRCPUCore {
     ObjectClass *cpu;
 } sPAPRCPUCore;
 
+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