Re: [Qemu-devel] [RFC PATCH v2 2/2] spapr: Memory hot-unplug support

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Mar 15, 2016 at 10:08:56AM +0530, Bharata B Rao wrote:
> Add support to hot remove pc-dimm memory devices.
> 
> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Looks correct, but again, needs to wait on the PAPR change.

Have you thought any further on the idea of sending an index message,
then a count message as an interim approach to fixing this without
requiring a PAPR change?

> ---
>  hw/ppc/spapr.c     | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  hw/ppc/spapr_drc.c | 18 +++++++++++
>  2 files changed, 110 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 43708a2..cdf268a 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2197,6 +2197,88 @@ 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;
> +
> +    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, 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));
> +    uint32_t start_index;
> +
> +    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);
> +        if (!i) {
> +            start_index = drck->get_index(drc);
> +        }
> +        addr += SPAPR_MEMORY_BLOCK_SIZE;
> +    }
> +    spapr_hotplug_req_remove_by_count_indexed(SPAPR_DR_CONNECTOR_TYPE_LMB,
> +                                              nr_lmbs, start_index);
> +}
> +
> +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);
> +}
> +
>  static void spapr_machine_device_plug(HotplugHandler *hotplug_dev,
>                                        DeviceState *dev, Error **errp)
>  {
> @@ -2244,7 +2326,15 @@ static void spapr_machine_device_unplug(HotplugHandler *hotplug_dev,
>                                        DeviceState *dev, Error **errp)
>  {
>      if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> -        error_setg(errp, "Memory hot unplug not supported by sPAPR");
> +        spapr_memory_unplug(hotplug_dev, dev, errp);
> +    }
> +}
> +
> +static void spapr_machine_device_unplug_request(HotplugHandler *hotplug_dev,
> +                                                DeviceState *dev, Error **errp)
> +{
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> +        spapr_memory_unplug_request(hotplug_dev, dev, errp);
>      }
>  }
>  
> @@ -2293,6 +2383,7 @@ 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;
>      fwc->get_dev_path = spapr_get_fw_dev_path;
> diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
> index ef063c0..740b9d4 100644
> --- a/hw/ppc/spapr_drc.c
> +++ b/hw/ppc/spapr_drc.c
> @@ -12,6 +12,7 @@
>  
>  #include "qemu/osdep.h"
>  #include "hw/ppc/spapr_drc.h"
> +#include "hw/ppc/spapr.h"
>  #include "qom/object.h"
>  #include "hw/qdev.h"
>  #include "qapi/visitor.h"
> @@ -78,6 +79,23 @@ 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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