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Re: [Qemu-devel] [for-2.7 PATCH v3 12/15] spapr: CPU hot unplug support
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [for-2.7 PATCH v3 12/15] spapr: CPU hot unplug support |
Date: |
Fri, 3 Jun 2016 16:27:48 +1000 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Thu, May 12, 2016 at 09:18:22AM +0530, Bharata B Rao wrote:
> Remove the CPU core device by removing the underlying CPU thread devices.
> Hot removal of CPU for sPAPR guests is achieved by sending the hot unplug
> notification to the guest. Release the vCPU object after CPU hot unplug so
> that vCPU fd can be parked and reused.
>
> Signed-off-by: Bharata B Rao <address@hidden>
Reviewed-by: David Gibson <address@hidden>
Couple of suggestions for minor improvements below, though.
> ---
> hw/ppc/spapr.c | 16 ++++++++
> hw/ppc/spapr_cpu_core.c | 81
> +++++++++++++++++++++++++++++++++++++++++
> include/hw/ppc/spapr.h | 1 +
> include/hw/ppc/spapr_cpu_core.h | 11 ++++++
> 4 files changed, 109 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 8c3100d..a8cd74d 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2342,11 +2342,27 @@ static void spapr_machine_device_plug(HotplugHandler
> *hotplug_dev,
> }
> }
>
> +void spapr_cpu_destroy(PowerPCCPU *cpu)
I think this would make more sense in spapr_cpu_core.c (where it could
be static).
> +{
> + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> +
> + xics_cpu_destroy(spapr->icp, cpu);
> + qemu_unregister_reset(spapr_cpu_reset, cpu);
> +}
> +
> static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
> DeviceState *dev, Error **errp)
> {
> + sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(qdev_get_machine());
> +
> if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> error_setg(errp, "Memory hot unplug not supported by sPAPR");
> + } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
> + if (!smc->dr_cpu_enabled) {
> + error_setg(errp, "CPU hot unplug not supported on this machine");
> + return;
> + }
> + spapr_core_unplug(hotplug_dev, dev, errp);
> }
> }
>
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index ed36beb..0b62456 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -28,6 +28,87 @@ char *spapr_get_cpu_core_type(const char *model)
> return g_strdup(core_type);
> }
>
> +static void spapr_cpu_core_cleanup(struct sPAPRCPUUnplugList *unplug_list)
> +{
> + sPAPRCPUUnplug *unplug, *next;
> + Object *cpu;
> +
> + QLIST_FOREACH_SAFE(unplug, unplug_list, node, next) {
> + cpu = unplug->cpu;
> + object_unparent(cpu);
> + QLIST_REMOVE(unplug, node);
> + g_free(unplug);
> + }
> +}
> +
> +static void spapr_add_cpu_to_unplug_list(Object *cpu,
> + struct sPAPRCPUUnplugList
> *unplug_list)
> +{
> + sPAPRCPUUnplug *unplug = g_malloc(sizeof(*unplug));
> +
> + unplug->cpu = cpu;
> + QLIST_INSERT_HEAD(unplug_list, unplug, node);
> +}
> +
> +static int spapr_cpu_release(Object *obj, void *opaque)
> +{
> + DeviceState *dev = DEVICE(obj);
> + CPUState *cs = CPU(dev);
> + PowerPCCPU *cpu = POWERPC_CPU(cs);
> + struct sPAPRCPUUnplugList *unplug_list = opaque;
> +
> + spapr_cpu_destroy(cpu);
> + cpu_remove_sync(cs);
> +
> + /*
> + * We are still walking the core object's children list, and
> + * hence can't cleanup this CPU thread object just yet. Put
> + * it on a list for later removal.
> + */
> + spapr_add_cpu_to_unplug_list(obj, unplug_list);
> + return 0;
> +}
> +
> +static void spapr_core_release(DeviceState *dev, void *opaque)
> +{
> + struct sPAPRCPUUnplugList unplug_list;
> + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> + CPUCore *cc = CPU_CORE(dev);
> + int smt = kvmppc_smt_threads();
> +
> + QLIST_INIT(&unplug_list);
> + object_child_foreach(OBJECT(dev), spapr_cpu_release, &unplug_list);
> + spapr_cpu_core_cleanup(&unplug_list);
> + spapr->cores[cc->core / smt] = NULL;
Could you avoid the awkwardness with the two phase release by stepping
through the cc->threads array instead of using object_child_foreach()?
> +
> + g_free(core->threads);
> + object_unparent(OBJECT(dev));
> +}
> +
> +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
> + Error **errp)
> +{
> + sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> + PowerPCCPU *cpu = &core->threads[0];
> + int id = ppc_get_vcpu_dt_id(cpu);
> + sPAPRDRConnector *drc =
> + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> + sPAPRDRConnectorClass *drck;
> + Error *local_err = NULL;
> +
> + g_assert(drc);
> +
> + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> + drck->detach(drc, dev, spapr_core_release, NULL, &local_err);
> + if (local_err) {
> + error_propagate(errp, local_err);
> + return;
> + }
> +
> + spapr_hotplug_req_remove_by_index(drc);
> +}
> +
> void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> Error **errp)
> {
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index ca4ae3e..a443693 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -585,6 +585,7 @@ void
> spapr_hotplug_req_remove_by_count(sPAPRDRConnectorType drc_type,
> void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu, Error **errp);
> void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
> sPAPRMachineState *spapr);
> +void spapr_cpu_destroy(PowerPCCPU *cpu);
>
> /* 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 4cd837e..3d8d6ac 100644
> --- a/include/hw/ppc/spapr_cpu_core.h
> +++ b/include/hw/ppc/spapr_cpu_core.h
> @@ -30,4 +30,15 @@ void spapr_core_pre_plug(HotplugHandler *hotplug_dev,
> DeviceState *dev,
> char *spapr_get_cpu_core_type(const char *model);
> void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> Error **errp);
> +void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
> + Error **errp);
> +
> +/* List to store unplugged CPU objects for cleanup during unplug */
> +typedef struct sPAPRCPUUnplug {
> + Object *cpu;
> + QLIST_ENTRY(sPAPRCPUUnplug) node;
> +} sPAPRCPUUnplug;
> +
> +QLIST_HEAD(sPAPRCPUUnplugList, sPAPRCPUUnplug);
> +
> #endif
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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