On Fri, Jan 08, 2016 at 12:25:19PM +0530, Bharata B Rao wrote:
> Remove the CPU core device by removing the underlying CPU thread devices.
> Support hot removal of CPU for sPAPR guests by sending the hot unplug
> notification to the guest via EPOW interrupt. Release the vCPU object
> after CPU hot unplug so that vCPU fd can be parked and reused.
>
> Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> ---
> hw/ppc/spapr.c | 113
> +++++++++++++++++++++++++++++++++++++++++++++++++
> include/hw/ppc/spapr.h | 6 +++
> 2 files changed, 119 insertions(+)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index c2af9ca..43cb726 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -93,6 +93,9 @@
>
> #define HTAB_SIZE(spapr) (1ULL << ((spapr)->htab_shift))
>
> +static QLIST_HEAD(cpu_unplug_list, sPAPRCPUUnplug) cpu_unplug_list
> + = QLIST_HEAD_INITIALIZER(cpu_unplug_list);
> +
> static XICSState *try_create_xics(const char *type, int nr_servers,
> int nr_irqs, Error **errp)
> {
> @@ -2432,11 +2435,121 @@ static void spapr_machine_device_plug(HotplugHandler
> *hotplug_dev,
> }
> }
>
> +static void spapr_cpu_destroy(PowerPCCPU *cpu)
> +{
> + sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> +
> + xics_cpu_destroy(spapr->icp, cpu);
> + qemu_unregister_reset(spapr_cpu_reset, cpu);
> +}
> +
> +static void spapr_cpu_core_cleanup(void)
> +{
> + sPAPRCPUUnplug *unplug, *next;
> + Object *cpu;
> +
> + QLIST_FOREACH_SAFE(unplug, &cpu_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)
> +{
> + sPAPRCPUUnplug *unplug = g_malloc(sizeof(*unplug));
> +
> + unplug->cpu = cpu;
> + QLIST_INSERT_HEAD(&cpu_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);
> +
> + 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);
> + return 0;
> +}
> +
> +static void spapr_core_release(DeviceState *dev, void *opaque)
> +{
> + object_child_foreach(OBJECT(dev), spapr_cpu_release, opaque);
> + spapr_cpu_core_cleanup();
> + object_unparent(OBJECT(dev));
I'd prefer to see the unplug_list as a local to this function (passed
to spapr_cpu_release via opaque) rather than using a new global.
> +}
> +
> +static int spapr_core_detach(Object *obj, void *opaque)
> +{
> + sPAPRCoreState *core = opaque;
> + DeviceState *dev = DEVICE(obj);
> + CPUState *cs = CPU(dev);
> + PowerPCCPU *cpu = POWERPC_CPU(cs);
> + int id = ppc_get_vcpu_dt_id(cpu);
> + int smt = kvmppc_smt_threads();
> + sPAPRDRConnector *drc =
> + spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_CPU, id);
> + sPAPRDRConnectorClass *drck;
> + Error *local_err = NULL;
> +
> + /*
> + * SMT threads return from here, only main thread (thread 0) will
> + * continue and signal hot unplug event to the guest.
> + */
This seems silly. spapr_core_unplug() iterates through all the
children only to have all of them except thread 0 ignore the call..
Can't you just grab the first thread and do this logic directly from
spapr_core_unplug()?
Same question for the plug side, though I didn't think of it when I
was looking at that.
> + if ((id % smt) != 0) {
> + return 0;
> + }
> + g_assert(drc);
> +
> + drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> + drck->detach(drc, core->dev, spapr_core_release, NULL, &local_err);
> + if (local_err) {
> + error_propagate(core->errp, local_err);
> + return 1;
> + }
> +
> + /*
> + * In addition to hotplugged CPUs, send the hot-unplug notification
> + * interrupt to the guest for coldplugged CPUs started via -device
> + * option too.
> + */
> + spapr_hotplug_req_remove_by_index(drc);
> + return 0;
> +}
> +
> +static void spapr_core_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
> + Error **errp)
> +{
> + sPAPRCoreState core;
> +
> + core.dev = dev;
> + core.errp = errp;
> + object_child_foreach(OBJECT(dev), spapr_core_detach, &core);
> +}
> +
> 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_POWERPC_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/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index 68d51d6..4d89016 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -88,6 +88,12 @@ typedef struct sPAPRCoreState {
> Error **errp;
> } sPAPRCoreState;
>
> +/* List to store unplugged CPU objects for cleanup during unplug */
> +typedef struct sPAPRCPUUnplug {
> + Object *cpu;
> + QLIST_ENTRY(sPAPRCPUUnplug) node;
> +} sPAPRCPUUnplug;
> +
> #define H_SUCCESS 0
> #define H_BUSY 1 /* Hardware busy -- retry later */
> #define H_CLOSED 2 /* Resource closed */
--
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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