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RE: [RFC v1] arm/virt: Add memory hot remove support
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From: |
Shameerali Kolothum Thodi |
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Subject: |
RE: [RFC v1] arm/virt: Add memory hot remove support |
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Date: |
Thu, 26 Mar 2020 11:14:53 +0000 |
Hi Eric,
> -----Original Message-----
> From: Auger Eric [mailto:address@hidden]
> Sent: 26 March 2020 11:01
> To: Shameerali Kolothum Thodi <address@hidden>;
> address@hidden; address@hidden
> Cc: address@hidden; address@hidden; address@hidden;
> xuwei (O) <address@hidden>; Zengtao (B) <address@hidden>;
> Linuxarm <address@hidden>; Anshuman Khandual
> <address@hidden>
> Subject: Re: [RFC v1] arm/virt: Add memory hot remove support
>
> Hi Shameer,
>
> On 3/18/20 1:37 PM, Shameer Kolothum wrote:
> > This adds support for memory hot remove on arm/virt that
> > uses acpi ged device.
>
> I gave this a try and it works fine if the PCDIMM slot was initially
> hotplugged:
> (QEMU) object-add qom-type=memory-backend-ram id=mem1
> props.size=4294967296
> {"return": {}}
> (QEMU) device_add driver=pc-dimm id=pcdimm1 memdev=mem1
> (QEMU) device_del id=pcdimm1
> {"return": {}}
>
> on guest I can see:
> [ 82.466321] Offlined Pages 262144
> [ 82.541712] Offlined Pages 262144
> [ 82.589236] Offlined Pages 262144
> [ 82.969166] Offlined Pages 262144
>
> However I noticed that if qemu is launched directly with
>
> -m 16G,maxmem=32G,slots=2 \
> -object memory-backend-ram,id=mem1,size=4G \
> -device pc-dimm,memdev=mem1,id=dimm1,driver=pc-dimm -device
>
> and then in the qmp shell:
> (QEMU) device_del id=dimm1
>
> the hot-unplug fails in guest:
>
> [ 78.897407] Offlined Pages 262144
> [ 79.260811] Offlined Pages 262144
> [ 79.308105] Offlined Pages 262144
> [ 79.333675] page:fffffe00137d1f40 refcount:1 mapcount:0
> mapping:ffff0004ea9f20b1 index:0xaaab11c6e
> [ 79.335927] anon flags: 0x17ffff8000080024(uptodate|active|swapbacked)
> [ 79.337571] raw: 17ffff8000080024 dead000000000100
> dead000000000122
> ffff0004ea9f20b1
> [ 79.339502] raw: 0000000aaab11c6e 0000000000000000 00000001ffffffff
> ffff0004fd4e3000
> [ 79.341701] page dumped because: unmovable page
> [ 79.342887] page->mem_cgroup:ffff0004fd4e3000
> [ 79.354729] page:fffffe00137d1f40 refcount:1 mapcount:0
> mapping:ffff0004ea9f20b1 index:0xaaab11c6e
> [ 79.357012] anon flags: 0x17ffff8000080024(uptodate|active|swapbacked)
> [ 79.358658] raw: 17ffff8000080024 dead000000000100
> dead000000000122
> ffff0004ea9f20b1
> [ 79.360611] raw: 0000000aaab11c6e 0000000000000000 00000001ffffffff
> ffff0004fd4e3000
> [ 79.362560] page dumped because: unmovable page
> [ 79.363742] page->mem_cgroup:ffff0004fd4e3000
> [ 79.368636] memory memory20: Offline failed.
>
> I did not expect this. The PCDIMM slot in that case does not seem to be
> interpreted as a hot-unpluggable one (?). I added Anshuman in cc.
Could you please try adding "movable_node" to qemu guest kernel command line
params.
This will prevent any kernel allocation from hotplugable memory nodes which I
think is
causing the behavior you are seeing.
Thanks,
Shameer
> Thanks
>
> Eric
>
>
>
> >
> > Signed-off-by: Shameer Kolothum <address@hidden>
> > ---
> > -RFC because linux kernel support for mem hot remove is just queued
> > for 5.7[1].
> > -Tested with guest kernel 5.6-rc5 + [1]
> >
> > 1. https://patchwork.kernel.org/cover/11419301/
> > ---
> > hw/acpi/generic_event_device.c | 28 +++++++++++++++++
> > hw/arm/virt.c | 56
> ++++++++++++++++++++++++++++++++--
> > 2 files changed, 82 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/acpi/generic_event_device.c
> b/hw/acpi/generic_event_device.c
> > index 021ed2bf23..3e28c110fa 100644
> > --- a/hw/acpi/generic_event_device.c
> > +++ b/hw/acpi/generic_event_device.c
> > @@ -182,6 +182,32 @@ static void
> acpi_ged_device_plug_cb(HotplugHandler *hotplug_dev,
> > }
> > }
> >
> > +static void acpi_ged_unplug_request_cb(HotplugHandler *hotplug_dev,
> > + DeviceState *dev, Error
> **errp)
> > +{
> > + AcpiGedState *s = ACPI_GED(hotplug_dev);
> > +
> > + if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > + acpi_memory_unplug_request_cb(hotplug_dev,
> &s->memhp_state, dev, errp);
> > + } else {
> > + error_setg(errp, "acpi: device unplug request for unsupported
> device"
> > + " type: %s", object_get_typename(OBJECT(dev)));
> > + }
> > +}
> > +
> > +static void acpi_ged_unplug_cb(HotplugHandler *hotplug_dev,
> > + DeviceState *dev, Error **errp)
> > +{
> > + AcpiGedState *s = ACPI_GED(hotplug_dev);
> > +
> > + if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > + acpi_memory_unplug_cb(&s->memhp_state, dev, errp);
> > + } else {
> > + error_setg(errp, "acpi: device unplug for unsupported device"
> > + " type: %s", object_get_typename(OBJECT(dev)));
> > + }
> > +}
> > +
> > static void acpi_ged_send_event(AcpiDeviceIf *adev, AcpiEventStatusBits
> ev)
> > {
> > AcpiGedState *s = ACPI_GED(adev);
> > @@ -286,6 +312,8 @@ static void acpi_ged_class_init(ObjectClass *class,
> void *data)
> > dc->vmsd = &vmstate_acpi_ged;
> >
> > hc->plug = acpi_ged_device_plug_cb;
> > + hc->unplug_request = acpi_ged_unplug_request_cb;
> > + hc->unplug = acpi_ged_unplug_cb;
> >
> > adevc->send_event = acpi_ged_send_event;
> > }
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index 94f93dda54..91974e4e80 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -2096,11 +2096,62 @@ static void
> virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
> > }
> > }
> >
> > +static void virt_dimm_unplug_request(HotplugHandler *hotplug_dev,
> > + DeviceState *dev, Error
> **errp)
> > +{
> > + VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> > + Error *local_err = NULL;
> > +
> > + if (!vms->acpi_dev) {
> > + error_setg(errp,
> > + "memory hotplug is not enabled: missing acpi-ged
> device");
> > + goto out;
> > + }
> > +
> > + hotplug_handler_unplug_request(HOTPLUG_HANDLER(vms->acpi_dev),
> dev,
> > + &local_err);
> > +out:
> > + error_propagate(errp, local_err);
> > +}
> > +
> > +static void virt_dimm_unplug(HotplugHandler *hotplug_dev,
> > + DeviceState *dev, Error **errp)
> > +{
> > + VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> > + Error *local_err = NULL;
> > +
> > + hotplug_handler_unplug(HOTPLUG_HANDLER(vms->acpi_dev), dev,
> &local_err);
> > + if (local_err) {
> > + goto out;
> > + }
> > +
> > + pc_dimm_unplug(PC_DIMM(dev), MACHINE(vms));
> > + object_property_set_bool(OBJECT(dev), false, "realized", NULL);
> > +
> > + out:
> > + error_propagate(errp, local_err);
> > +}
> > +
> > static void virt_machine_device_unplug_request_cb(HotplugHandler
> *hotplug_dev,
> > DeviceState *dev, Error
> **errp)
> > {
> > - error_setg(errp, "device unplug request for unsupported device"
> > - " type: %s", object_get_typename(OBJECT(dev)));
> > + if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > + virt_dimm_unplug_request(hotplug_dev, dev, errp);
> > + } else {
> > + error_setg(errp, "device unplug request for unsupported device"
> > + " type: %s", object_get_typename(OBJECT(dev)));
> > + }
> > +}
> > +
> > +static void virt_machine_device_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, "virt: device unplug for unsupported device"
> > + " type: %s", object_get_typename(OBJECT(dev)));
> > + }
> > }
> >
> > static HotplugHandler *virt_machine_get_hotplug_handler(MachineState
> *machine,
> > @@ -2181,6 +2232,7 @@ static void virt_machine_class_init(ObjectClass
> *oc, void *data)
> > hc->pre_plug = virt_machine_device_pre_plug_cb;
> > hc->plug = virt_machine_device_plug_cb;
> > hc->unplug_request = virt_machine_device_unplug_request_cb;
> > + hc->unplug = virt_machine_device_unplug_cb;
> > mc->numa_mem_supported = true;
> > mc->auto_enable_numa_with_memhp = true;
> > mc->default_ram_id = "mach-virt.ram";
> >