Re: [Qemu-devel] [RFC v2 3/6] hw/arm/virt: Add pc-dimm mem hotplug framework

[Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>]

Hi Eric,

> -----Original Message-----
> From: Auger Eric [mailto:eric.auger@redhat.com]
> Sent: Monday, May 28, 2018 3:22 PM
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> qemu-devel@nongnu.org; qemu-arm@nongnu.org
> Cc: drjones@redhat.com; imammedo@redhat.com; peter.maydell@linaro.org;
> alex.williamson@redhat.com; Zhaoshenglong <zhaoshenglong@huawei.com>;
> Jonathan Cameron <jonathan.cameron@huawei.com>; Linuxarm
> <linuxarm@huawei.com>
> Subject: Re: [RFC v2 3/6] hw/arm/virt: Add pc-dimm mem hotplug framework
> 
> Hi Shameer,
> 
> On 05/16/2018 05:20 PM, Shameer Kolothum wrote:
> > This will be used in subsequent patches to model a chunk of
> > memory as pc-dimm(cold plug) if the valid iova regions are
> > non-contiguous. This is not yet a full hotplug support.
> Please can you give more details about this restriction?
> >
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > ---
> >  default-configs/aarch64-softmmu.mak |  1 +
> >  hw/arm/virt.c                       | 82
> +++++++++++++++++++++++++++++++++++++
> >  include/hw/arm/virt.h               |  2 +
> >  3 files changed, 85 insertions(+)
> >
> > diff --git a/default-configs/aarch64-softmmu.mak b/default-configs/aarch64-
> softmmu.mak
> > index 9ddccf8..7a82ed8 100644
> > --- a/default-configs/aarch64-softmmu.mak
> > +++ b/default-configs/aarch64-softmmu.mak
> > @@ -8,3 +8,4 @@ CONFIG_DDC=y
> >  CONFIG_DPCD=y
> >  CONFIG_XLNX_ZYNQMP=y
> >  CONFIG_XLNX_ZYNQMP_ARM=y
> > +CONFIG_MEM_HOTPLUG=y
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index 05fcb62..be3ad14 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -1552,9 +1552,82 @@ static const CPUArchIdList
> *virt_possible_cpu_arch_ids(MachineState *ms)
> >      return ms->possible_cpus;
> >  }
> >
> > +static void virt_dimm_plug(HotplugHandler *hotplug_dev,
> > +                         DeviceState *dev, Error **errp)
> > +{
> > +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> > +    PCDIMMDevice *dimm = PC_DIMM(dev);
> > +    PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> > +    MemoryRegion *mr;
> > +    uint64_t align;
> > +    Error *local_err = NULL;
> > +
> > +    mr = ddc->get_memory_region(dimm, &local_err);
> > +    if (local_err) {
> > +        goto out;
> > +    }
> > +
> > +    align = memory_region_get_alignment(mr);
> I see that on PC machine class they have an "enforce_aligned_dimm"
> option. Also looks memory_region_get_alignment(mr) can return 0.
> 
> if (memory_region_get_alignment(mr) && pcmc->enforce_aligned_dimm) {

Ok.
 
> 
> > +    pc_dimm_memory_plug(dev, &vms->hotplug_memory, mr, align,
> &local_err);
> > +    if (local_err) {
> > +        goto out;
> > +    }
> useless block and error_propagate does nothing if local_err is NULL so
> we are fine.

Ok. I will remove this from this patch.

> > +
> > +out:
> > +    error_propagate(errp, local_err);
> > +}
> > +
> > +static void virt_dimm_unplug(HotplugHandler *hotplug_dev,
> > +                           DeviceState *dev, Error **errp)
> > +{
> > +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> > +    PCDIMMDevice *dimm = PC_DIMM(dev);
> > +    PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> > +    MemoryRegion *mr;
> > +    Error *local_err = NULL;
> > +
> > +    mr = ddc->get_memory_region(dimm, &local_err);
> don't you want to avoid executing the following if local_err?

True.

> > +    pc_dimm_memory_unplug(dev, &vms->hotplug_memory, mr);
> needs a rebase on top of "pc-dimm: no need to pass the memory region"
> in master pc_dimm_memory_unplug we now have
>  MemoryRegion *mr = ddc->get_memory_region(dimm, &error_abort);

Right. I will follow that then.

> Thanks
> 
> Eric
> > +    object_unparent(OBJECT(dev));
> > +
> > +    error_propagate(errp, local_err);
> > +}
> > +
> > +static void virt_machinedevice_plug_cb(HotplugHandler *hotplug_dev,
> > +                                      DeviceState *dev, Error **errp)
> > +{
> > +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > +        virt_dimm_plug(hotplug_dev, dev, errp);
> > +    } else {
> > +        error_setg(errp, "device plug request for not supported device"
> > +                   " type: %s", object_get_typename(OBJECT(dev)));
> > +    }
> > +}
> > +
> > +static void virt_machinedevice_unplug_cb(HotplugHandler *hotplug_dev,
> > +                                        DeviceState *dev, Error **errp)
> > +{
> > +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > +        virt_dimm_unplug(hotplug_dev, dev, errp);
> > +    } else {
> > +        error_setg(errp, "device unplug for not supported device"
> > +                   " type: %s", object_get_typename(OBJECT(dev)));
> > +    }
> > +}
> > +
> > +static HotplugHandler *virt_get_hotplug_handler(MachineState *machine,
> > +                                             DeviceState *dev)
> > +{
> > +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > +        return HOTPLUG_HANDLER(machine);
> > +    }
> > +    return NULL;
> > +}
> > +
> >  static void virt_machine_class_init(ObjectClass *oc, void *data)
> >  {
> >      MachineClass *mc = MACHINE_CLASS(oc);
> > +    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
> >
> >      mc->init = machvirt_init;
> >      /* Start max_cpus at the maximum QEMU supports. We'll further restrict
> > @@ -1573,6 +1646,11 @@ static void virt_machine_class_init(ObjectClass
> *oc, void *data)
> >      mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
> >      mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
> >      mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
> > +
> > +    mc->get_hotplug_handler = virt_get_hotplug_handler;
> This requires a rebase on top of Igor's  and David's series.
> 
Sure.

Thanks,
Shameer

> Thanks
> 
> Eric
> > +    hc->plug = virt_machinedevice_plug_cb;
> > +    hc->unplug = virt_machinedevice_unplug_cb;
> > +
> >  }
> >
> >  static const TypeInfo virt_machine_info = {
> > @@ -1582,6 +1660,10 @@ static const TypeInfo virt_machine_info = {
> >      .instance_size = sizeof(VirtMachineState),
> >      .class_size    = sizeof(VirtMachineClass),
> >      .class_init    = virt_machine_class_init,
> > +    .interfaces = (InterfaceInfo[]) {
> > +         { TYPE_HOTPLUG_HANDLER },
> > +         { }
> > +    },
> >  };
> >
> >  static void machvirt_machine_init(void)
> > diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> > index fc24f3a..a39f29e 100644
> > --- a/include/hw/arm/virt.h
> > +++ b/include/hw/arm/virt.h
> > @@ -35,6 +35,7 @@
> >  #include "qemu/notify.h"
> >  #include "hw/boards.h"
> >  #include "hw/arm/arm.h"
> > +#include "hw/mem/pc-dimm.h"
> >
> >  #define NUM_GICV2M_SPIS       64
> >  #define NUM_VIRTIO_TRANSPORTS 32
> > @@ -108,6 +109,7 @@ typedef struct {
> >      uint32_t gic_phandle;
> >      uint32_t msi_phandle;
> >      int psci_conduit;
> > +    MemoryHotplugState hotplug_memory;
> >  } VirtMachineState;
> >
> >  #define TYPE_VIRT_MACHINE   MACHINE_TYPE_NAME("virt")
> >