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Re: [RFC v1] arm/virt: Add memory hot remove support
From: |
Auger Eric |
Subject: |
Re: [RFC v1] arm/virt: Add memory hot remove support |
Date: |
Thu, 26 Mar 2020 12:00:53 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
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.
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";
>