Re: [Qemu-ppc] [PATCH 10/10] spapr: Memory hot-unplug support

[David Gibson]

On Mon, Oct 24, 2016 at 11:47:36PM -0500, Michael Roth wrote:
> From: Bharata B Rao <address@hidden>
> 
> Add support to hot remove pc-dimm memory devices.
> 
> Since we're introducing a machine-level unplug_request hook, we also
> had handling for CPU unplug there as well to ensure CPU unplug
> continues to work as it did before.
> 
> Signed-off-by: Bharata B Rao <address@hidden>
> * add hooks to CAS/cmdline enablement of hotplug ACR support
> * add hook for CPU unplug
> Signed-off-by: Michael Roth <address@hidden>
> ---
>  hw/ppc/spapr.c     | 119 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  hw/ppc/spapr_drc.c |  17 ++++++++
>  2 files changed, 135 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 0b3aa2f..a4a6058 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2281,6 +2281,90 @@ out:
>      error_propagate(errp, local_err);
>  }
>  
> +typedef struct sPAPRDIMMState {
> +    uint32_t nr_lmbs;
> +} sPAPRDIMMState;
> +
> +static void spapr_lmb_release(DeviceState *dev, void *opaque)
> +{
> +    sPAPRDIMMState *ds = (sPAPRDIMMState *)opaque;
> +    HotplugHandler *hotplug_ctrl = NULL;

No reason for the NULL initializer here - you set the variable
unconditionally below.

Otherwise,

Reviewed-by: David Gibson <address@hidden>

> +    if (--ds->nr_lmbs) {
> +        return;
> +    }
> +
> +    g_free(ds);
> +
> +    /*
> +     * Now that all the LMBs have been removed by the guest, call the
> +     * pc-dimm unplug handler to cleanup up the pc-dimm device.
> +     */
> +    hotplug_ctrl = qdev_get_hotplug_handler(dev);
> +    hotplug_handler_unplug(hotplug_ctrl, dev, &error_abort);
> +}
> +
> +static void spapr_del_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t 
> size,
> +                           Error **errp)
> +{
> +    sPAPRDRConnector *drc;
> +    sPAPRDRConnectorClass *drck;
> +    uint32_t nr_lmbs = size / SPAPR_MEMORY_BLOCK_SIZE;
> +    int i;
> +    sPAPRDIMMState *ds = g_malloc0(sizeof(sPAPRDIMMState));
> +    uint64_t addr = addr_start;
> +
> +    ds->nr_lmbs = nr_lmbs;
> +    for (i = 0; i < nr_lmbs; i++) {
> +        drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
> +                addr / SPAPR_MEMORY_BLOCK_SIZE);
> +        g_assert(drc);
> +
> +        drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +        drck->detach(drc, dev, spapr_lmb_release, ds, errp);
> +        addr += SPAPR_MEMORY_BLOCK_SIZE;
> +    }
> +
> +    drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
> +                                   addr_start / SPAPR_MEMORY_BLOCK_SIZE);
> +    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    spapr_hotplug_req_remove_by_count_indexed(SPAPR_DR_CONNECTOR_TYPE_LMB,
> +                                              nr_lmbs,
> +                                              drck->get_index(drc));
> +}
> +
> +static void spapr_memory_unplug(HotplugHandler *hotplug_dev, DeviceState 
> *dev,
> +                                Error **errp)
> +{
> +    sPAPRMachineState *ms = SPAPR_MACHINE(hotplug_dev);
> +    PCDIMMDevice *dimm = PC_DIMM(dev);
> +    PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> +    MemoryRegion *mr = ddc->get_memory_region(dimm);
> +
> +    pc_dimm_memory_unplug(dev, &ms->hotplug_memory, mr);
> +    object_unparent(OBJECT(dev));
> +}
> +
> +static void spapr_memory_unplug_request(HotplugHandler *hotplug_dev,
> +                                        DeviceState *dev, Error **errp)
> +{
> +    Error *local_err = NULL;
> +    PCDIMMDevice *dimm = PC_DIMM(dev);
> +    PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> +    MemoryRegion *mr = ddc->get_memory_region(dimm);
> +    uint64_t size = memory_region_size(mr);
> +    uint64_t addr;
> +
> +    addr = object_property_get_int(OBJECT(dimm), PC_DIMM_ADDR_PROP, 
> &local_err);
> +    if (local_err) {
> +        goto out;
> +    }
> +
> +    spapr_del_lmbs(dev, addr, size, &error_abort);
> +out:
> +    error_propagate(errp, local_err);
> +}
> +
>  void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
>                                      sPAPRMachineState *spapr)
>  {
> @@ -2354,10 +2438,42 @@ static void spapr_machine_device_plug(HotplugHandler 
> *hotplug_dev,
>  static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
>                                        DeviceState *dev, Error **errp)
>  {
> +    sPAPRMachineState *sms = SPAPR_MACHINE(qdev_get_machine());
>      MachineClass *mc = 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");
> +        if (spapr_ovec_test(sms->ov5_cas, OV5_HP_EVT)) {
> +            spapr_memory_unplug(hotplug_dev, dev, errp);
> +        } else {
> +            error_setg(errp, "Memory hot unplug not supported for this 
> guest");
> +        }
> +    } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
> +        if (!mc->query_hotpluggable_cpus) {
> +            error_setg(errp, "CPU hot unplug not supported on this machine");
> +            return;
> +        }
> +        spapr_core_unplug(hotplug_dev, dev, errp);
> +    }
> +}
> +
> +static void spapr_machine_device_unplug_request(HotplugHandler *hotplug_dev,
> +                                                DeviceState *dev, Error 
> **errp)
> +{
> +    sPAPRMachineState *sms = SPAPR_MACHINE(qdev_get_machine());
> +    MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
> +
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        if (spapr_ovec_test(sms->ov5_cas, OV5_HP_EVT)) {
> +            spapr_memory_unplug_request(hotplug_dev, dev, errp);
> +        } else {
> +            /* NOTE: this means there is a window after guest reset, prior to
> +             * CAS negotiation, where unplug requests will fail due to the
> +             * capability not being detected yet. This is a bit different 
> than
> +             * the case with PCI unplug, where the events will be queued and
> +             * eventually handled by the guest after boot
> +             */
> +            error_setg(errp, "Memory hot unplug not supported for this 
> guest");
> +        }
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_SPAPR_CPU_CORE)) {
>          if (!mc->query_hotpluggable_cpus) {
>              error_setg(errp, "CPU hot unplug not supported on this machine");
> @@ -2503,6 +2619,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> void *data)
>      hc->plug = spapr_machine_device_plug;
>      hc->unplug = spapr_machine_device_unplug;
>      mc->cpu_index_to_socket_id = spapr_cpu_index_to_socket_id;
> +    hc->unplug_request = spapr_machine_device_unplug_request;
>  
>      smc->dr_lmb_enabled = true;
>      smc->tcg_default_cpu = "POWER8";
> diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
> index 6e54fd4..a0c44ee 100644
> --- a/hw/ppc/spapr_drc.c
> +++ b/hw/ppc/spapr_drc.c
> @@ -68,6 +68,23 @@ static uint32_t set_isolation_state(sPAPRDRConnector *drc,
>          }
>      }
>  
> +    /*
> +     * Fail any requests to ISOLATE the LMB DRC if this LMB doesn't
> +     * belong to a DIMM device that is marked for removal.
> +     *
> +     * Currently the guest userspace tool drmgr that drives the memory
> +     * hotplug/unplug will just try to remove a set of 'removable' LMBs
> +     * in response to a hot unplug request that is based on drc-count.
> +     * If the LMB being removed doesn't belong to a DIMM device that is
> +     * actually being unplugged, fail the isolation request here.
> +     */
> +    if (drc->type == SPAPR_DR_CONNECTOR_TYPE_LMB) {
> +        if ((state == SPAPR_DR_ISOLATION_STATE_ISOLATED) &&
> +             !drc->awaiting_release) {
> +            return RTAS_OUT_HW_ERROR;
> +        }
> +    }
> +
>      drc->isolation_state = state;
>  
>      if (drc->isolation_state == SPAPR_DR_ISOLATION_STATE_ISOLATED) {

-- 
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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