[Qemu-devel] [RFC PATCH v2 12/23] spapr: CPU hotplug support

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

Support CPU hotplug via device-add command. Set up device tree
entries for the hotplugged CPU core and use the exising EPOW event
infrastructure to send CPU hotplug notification to the guest.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 hw/ppc/spapr.c        | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/ppc/spapr_events.c |  8 +++---
 hw/ppc/spapr_rtas.c   | 11 ++++++++
 3 files changed, 91 insertions(+), 3 deletions(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index f52d38f..b48994b 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -33,6 +33,7 @@
 #include "sysemu/block-backend.h"
 #include "sysemu/cpus.h"
 #include "sysemu/kvm.h"
+#include "sysemu/device_tree.h"
 #include "kvm_ppc.h"
 #include "mmu-hash64.h"
 #include "qom/cpu.h"
@@ -660,6 +661,10 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset)
     QemuOpts *opts = qemu_opts_find(qemu_find_opts("smp-opts"), NULL);
     unsigned sockets = opts ? qemu_opt_get_number(opts, "sockets", 0) : 0;
     uint32_t cpus_per_socket = sockets ? (smp_cpus / sockets) : 1;
+    sPAPRDRConnector *drc =
+        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, index);
+    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
+    int drc_index = drck->get_index(drc);
 
     _FDT((fdt_setprop_cell(fdt, offset, "reg", index)));
     _FDT((fdt_setprop_string(fdt, offset, "device_type", "cpu")));
@@ -728,6 +733,8 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, int offset)
 
     _FDT((fdt_setprop_cell(fdt, offset, "ibm,chip-id",
                             cs->cpu_index / cpus_per_socket)));
+    _FDT((fdt_setprop_cell(fdt, offset, "ibm,my-drc-index", drc_index)));
+
 
     _FDT(spapr_fixup_cpu_numa_smt_dt(fdt, offset, cs, spapr));
 }
@@ -1840,6 +1847,70 @@ static void spapr_nmi(NMIState *n, int cpu_index, Error **errp)
     }
 }
 
+static void spapr_cpu_hotplug_add(DeviceState *dev, CPUState *cs, Error **errp)
+{
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
+    DeviceClass *dc = DEVICE_GET_CLASS(cs);
+    int id = ppc_get_vcpu_dt_id(cpu);
+    sPAPRDRConnector *drc =
+        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
+    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
+    void *fdt;
+    int offset, i, 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);
+
+    /* Set NUMA node for the added CPU core */
+    for (i = 0; i < nb_numa_nodes; i++) {
+        if (test_bit(cs->cpu_index, numa_info[i].node_cpu)) {
+            cs->numa_node = i;
+            break;
+        }
+    }
+
+    spapr_populate_cpu_dt(cs, fdt, offset);
+    g_free(nodename);
+
+    drck->attach(drc, dev, fdt, offset, !dev->hotplugged, errp);
+    if (*errp) {
+        g_free(fdt);
+    }
+}
+
+static void spapr_cpu_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                            Error **errp)
+{
+    CPUState *cs = CPU(dev);
+    PowerPCCPU *cpu = POWERPC_CPU(cs);
+    int id = ppc_get_vcpu_dt_id(cpu);
+    sPAPRDRConnector *drc =
+        spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
+    int smt = kvmppc_smt_threads();
+    Error *local_err = NULL;
+
+    /*
+     * SMT threads return from here, only main thread (core) will
+     * continue and signal hotplug event to the guest.
+     */
+    if ((id % smt) != 0) {
+        return;
+    }
+
+    g_assert(drc);
+
+    spapr_cpu_hotplug_add(dev, cs, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+    spapr_hotplug_req_add_event(drc);
+
+    return;
+}
+
 static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
                                       DeviceState *dev, Error **errp)
 {
@@ -1848,6 +1919,10 @@ static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
         PowerPCCPU *cpu = POWERPC_CPU(cs);
 
         spapr_cpu_init(cpu);
+        spapr_cpu_reset(cpu);
+        if (dev->hotplugged && spapr->dr_cpu_enabled) {
+            spapr_cpu_plug(hotplug_dev, dev, errp);
+        }
     }
 }
 
diff --git a/hw/ppc/spapr_events.c b/hw/ppc/spapr_events.c
index be82815..4ae818a 100644
--- a/hw/ppc/spapr_events.c
+++ b/hw/ppc/spapr_events.c
@@ -421,14 +421,16 @@ static void spapr_hotplug_req_event(sPAPRDRConnector *drc, uint8_t hp_action)
     hp->hdr.section_length = cpu_to_be16(sizeof(*hp));
     hp->hdr.section_version = 1; /* includes extended modifier */
     hp->hotplug_action = hp_action;
-
+    hp->drc.index = cpu_to_be32(drck->get_index(drc));
+    hp->hotplug_identifier = RTAS_LOG_V6_HP_ID_DRC_INDEX;
 
     switch (drc_type) {
     case SPAPR_DR_CONNECTOR_TYPE_PCI:
-        hp->drc.index = cpu_to_be32(drck->get_index(drc));
-        hp->hotplug_identifier = RTAS_LOG_V6_HP_ID_DRC_INDEX;
         hp->hotplug_type = RTAS_LOG_V6_HP_TYPE_PCI;
         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 57ec97a..48aeb86 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -121,6 +121,16 @@ static void rtas_query_cpu_stopped_state(PowerPCCPU *cpu_,
     rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
 }
 
+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_, sPAPREnvironment *spapr,
                            uint32_t token, uint32_t nargs,
                            target_ulong args,
@@ -157,6 +167,7 @@ static void rtas_start_cpu(PowerPCCPU *cpu_, sPAPREnvironment *spapr,
         env->nip = start;
         env->gpr[3] = r3;
         cs->halted = 0;
+        spapr_cpu_set_endianness(cpu);
 
         qemu_cpu_kick(cs);
 
-- 
2.1.0