Hi Igor,
Thanks for the feedback.
> From: qemu-arm-bounces+salil.mehta=huawei....@nongnu.org <qemu-
> arm-bounces+salil.mehta=huawei....@nongnu.org> On Behalf Of Igor
> Mammedov
> Sent: Monday, July 15, 2024 2:12 PM
> To: Salil Mehta <salil.me...@huawei.com>
>
> On Sat, 13 Jul 2024 19:25:12 +0100
> Salil Mehta <salil.me...@huawei.com> wrote:
>
> > ACPI GED (as described in the ACPI 6.4 spec) uses an interrupt listed
> > in the _CRS object of GED to intimate OSPM about an event. Later then
> > demultiplexes the notified event by evaluating ACPI _EVT method to
> > know the type of event. Use ACPI GED to also notify the guest kernel
> about any CPU hot(un)plug events.
> >
> > Note, GED interface is used by many hotplug events like memory
> > hotplug, NVDIMM hotplug and non-hotplug events like system power
> down
> > event. Each of these can be selected using a bit in the 32 bit GED IO
> > interface. A bit has been reserved for the CPU hotplug event.
>
> > ACPI CPU hotplug related initialization should only happen if
> > ACPI_CPU_HOTPLUG support has been enabled for particular
> architecture.
> > Add cpu_hotplug_hw_init() stub to avoid compilation break.
>
> so any target (and machines in it) that has ACPI_CPU_HOTPLUG enabled will
> use have all CPU hotplug machinery builtin which is fine.
>
> However any machine that uses GED but do not opt-in into CPU hotplug, will
> still have CPU hotplug registers/memory regions enabled/mapped.
>
> It's not much concern for upstream as migration from new to older QEMU is
> not supported, however it will break migration downstream (arm/virt) as
> new QEMU will try to migrate memory regions/state that do not exists in
> older QEMU. Se below for suggestion.
Sorry. I missed this one. Yes. agreed.
> > Co-developed-by: Keqian Zhu <zhukeqi...@huawei.com>
> > Signed-off-by: Keqian Zhu <zhukeqi...@huawei.com>
> > Signed-off-by: Salil Mehta <salil.me...@huawei.com>
> > Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
> > Reviewed-by: Gavin Shan <gs...@redhat.com>
> > Reviewed-by: David Hildenbrand <da...@redhat.com>
> > Reviewed-by: Shaoqin Huang <shahu...@redhat.com>
> > Tested-by: Vishnu Pajjuri <vis...@os.amperecomputing.com>
> > Tested-by: Xianglai Li <lixiang...@loongson.cn>
> > Tested-by: Miguel Luis <miguel.l...@oracle.com>
> > Reviewed-by: Vishnu Pajjuri <vis...@os.amperecomputing.com>
> > Tested-by: Zhao Liu <zhao1....@intel.com>
> > Reviewed-by: Zhao Liu <zhao1....@intel.com>
> > ---
> > docs/specs/acpi_hw_reduced_hotplug.rst | 3 ++-
> > hw/acpi/acpi-cpu-hotplug-stub.c | 6 ++++++
> > hw/acpi/generic_event_device.c | 24 ++++++++++++++++++++++++
> > include/hw/acpi/generic_event_device.h | 4 ++++
> > 4 files changed, 36 insertions(+), 1 deletion(-)
> >
> > diff --git a/docs/specs/acpi_hw_reduced_hotplug.rst
> > b/docs/specs/acpi_hw_reduced_hotplug.rst
> > index 0bd3f9399f..3acd6fcd8b 100644
> > --- a/docs/specs/acpi_hw_reduced_hotplug.rst
> > +++ b/docs/specs/acpi_hw_reduced_hotplug.rst
> > @@ -64,7 +64,8 @@ GED IO interface (4 byte access)
> > 0: Memory hotplug event
> > 1: System power down event
> > 2: NVDIMM hotplug event
> > - 3-31: Reserved
> > + 3: CPU hotplug event
> > + 4-31: Reserved
> >
> > **write_access:**
> >
> > diff --git a/hw/acpi/acpi-cpu-hotplug-stub.c
> > b/hw/acpi/acpi-cpu-hotplug-stub.c index 3fc4b14c26..c6c61bb9cd 100644
> > --- a/hw/acpi/acpi-cpu-hotplug-stub.c
> > +++ b/hw/acpi/acpi-cpu-hotplug-stub.c
> > @@ -19,6 +19,12 @@ void legacy_acpi_cpu_hotplug_init(MemoryRegion
> *parent, Object *owner,
> > return;
> > }
> >
> > +void cpu_hotplug_hw_init(MemoryRegion *as, Object *owner,
> > + CPUHotplugState *state, hwaddr base_addr) {
> > + return;
> > +}
> > +
> > void acpi_cpu_ospm_status(CPUHotplugState *cpu_st, ACPIOSTInfoList
> > ***list) {
> > return;
> > diff --git a/hw/acpi/generic_event_device.c
> > b/hw/acpi/generic_event_device.c index 2d6e91b124..1b31d633ba
> 100644
> > --- a/hw/acpi/generic_event_device.c
> > +++ b/hw/acpi/generic_event_device.c
> > @@ -25,6 +25,7 @@ static const uint32_t ged_supported_events[] = {
> > ACPI_GED_MEM_HOTPLUG_EVT,
> > ACPI_GED_PWR_DOWN_EVT,
> > ACPI_GED_NVDIMM_HOTPLUG_EVT,
> > + ACPI_GED_CPU_HOTPLUG_EVT,
> > };
> >
> > /*
> > @@ -234,6 +235,8 @@ static void
> acpi_ged_device_plug_cb(HotplugHandler *hotplug_dev,
> > } else {
> > acpi_memory_plug_cb(hotplug_dev, &s->memhp_state, dev,
> errp);
> > }
> > + } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
> > + acpi_cpu_plug_cb(hotplug_dev, &s->cpuhp_state, dev, errp);
> > } else {
> > error_setg(errp, "virt: device plug request for unsupported
> device"
> > " type: %s", object_get_typename(OBJECT(dev)));
> > @@ -248,6 +251,8 @@ static void
> acpi_ged_unplug_request_cb(HotplugHandler *hotplug_dev,
> > if ((object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
> > !(object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM))))
> {
> > acpi_memory_unplug_request_cb(hotplug_dev, &s->memhp_state,
> > dev, errp);
> > + } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
> > + acpi_cpu_unplug_request_cb(hotplug_dev, &s->cpuhp_state, dev,
> > + errp);
> > } else {
> > error_setg(errp, "acpi: device unplug request for unsupported
> device"
> > " type: %s", object_get_typename(OBJECT(dev)));
> > @@ -261,6 +266,8 @@ static void acpi_ged_unplug_cb(HotplugHandler
> > *hotplug_dev,
> >
> > if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > acpi_memory_unplug_cb(&s->memhp_state, dev, errp);
> > + } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
> > + acpi_cpu_unplug_cb(&s->cpuhp_state, dev, errp);
> > } else {
> > error_setg(errp, "acpi: device unplug for unsupported device"
> > " type: %s", object_get_typename(OBJECT(dev)));
> > @@ -272,6 +279,7 @@ static void acpi_ged_ospm_status(AcpiDeviceIf
> *adev, ACPIOSTInfoList ***list)
> > AcpiGedState *s = ACPI_GED(adev);
> >
> > acpi_memory_ospm_status(&s->memhp_state, list);
> > + acpi_cpu_ospm_status(&s->cpuhp_state, list);
> > }
> >
> > static void acpi_ged_send_event(AcpiDeviceIf *adev,
> > AcpiEventStatusBits ev) @@ -286,6 +294,8 @@ static void
> acpi_ged_send_event(AcpiDeviceIf *adev, AcpiEventStatusBits ev)
> > sel = ACPI_GED_PWR_DOWN_EVT;
> > } else if (ev & ACPI_NVDIMM_HOTPLUG_STATUS) {
> > sel = ACPI_GED_NVDIMM_HOTPLUG_EVT;
> > + } else if (ev & ACPI_CPU_HOTPLUG_STATUS) {
> > + sel = ACPI_GED_CPU_HOTPLUG_EVT;
> > } else {
> > /* Unknown event. Return without generating interrupt. */
> > warn_report("GED: Unsupported event %d. No irq injected",
> > ev); @@ -371,6 +381,19 @@ static const VMStateDescription
> vmstate_acpi_ged = {
> > }
> > };
> >
> > +static void acpi_ged_realize(DeviceState *dev, Error **errp) {
> > + AcpiGedState *s = ACPI_GED(dev);
> > + SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
> > +
>
> > + /* initialize CPU Hotplug related regions */
> > + memory_region_init(&s->container_cpuhp, OBJECT(dev), "cpuhp
> container",
> > + ACPI_CPU_HOTPLUG_REG_LEN);
> > + sysbus_init_mmio(sbd, &s->container_cpuhp);
> > + cpu_hotplug_hw_init(&s->container_cpuhp, OBJECT(dev),
> > + &s->cpuhp_state, 0);
>
> how about making it conditional on supported events see hw/arm/virt.c:
> create_acpi_ged()
> if (ms->ram_slots) {
> event |= ACPI_GED_MEM_HOTPLUG_EVT;
> }
>
> if (ms->nvdimms_state->is_enabled) {
> event |= ACPI_GED_NVDIMM_HOTPLUG_EVT;
> }
>
> so cpu hotplug would have similar section and ged realize could use ged-
> event to enable/disable cpuhp feature registers and hwinit.
Got it, thanks for pointing out. I will fix this and share V16 by COB today
itself.
Best regards
Salil.
>
> > +}
> > +
> > static void acpi_ged_initfn(Object *obj) {
> > DeviceState *dev = DEVICE(obj);
> > @@ -411,6 +434,7 @@ static void acpi_ged_class_init(ObjectClass *class,
> void *data)
> > dc->desc = "ACPI Generic Event Device";
> > device_class_set_props(dc, acpi_ged_properties);
> > dc->vmsd = &vmstate_acpi_ged;
> > + dc->realize = acpi_ged_realize;
> >
> > hc->plug = acpi_ged_device_plug_cb;
> > hc->unplug_request = acpi_ged_unplug_request_cb; diff --git
> > a/include/hw/acpi/generic_event_device.h
> > b/include/hw/acpi/generic_event_device.h
> > index ba84ce0214..e091ac2108 100644
> > --- a/include/hw/acpi/generic_event_device.h
> > +++ b/include/hw/acpi/generic_event_device.h
> > @@ -62,6 +62,7 @@
> > #include "hw/sysbus.h"
> > #include "hw/acpi/memory_hotplug.h"
> > #include "hw/acpi/ghes.h"
> > +#include "hw/acpi/cpu.h"
> > #include "qom/object.h"
> >
> > #define ACPI_POWER_BUTTON_DEVICE "PWRB"
> > @@ -95,6 +96,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(AcpiGedState,
> ACPI_GED)
> > #define ACPI_GED_MEM_HOTPLUG_EVT 0x1
> > #define ACPI_GED_PWR_DOWN_EVT 0x2
> > #define ACPI_GED_NVDIMM_HOTPLUG_EVT 0x4
> > +#define ACPI_GED_CPU_HOTPLUG_EVT 0x8
> >
> > typedef struct GEDState {
> > MemoryRegion evt;
> > @@ -106,6 +108,8 @@ struct AcpiGedState {
> > SysBusDevice parent_obj;
> > MemHotplugState memhp_state;
> > MemoryRegion container_memhp;
> > + CPUHotplugState cpuhp_state;
> > + MemoryRegion container_cpuhp;
> > GEDState ged_state;
> > uint32_t ged_event_bitmap;
> > qemu_irq irq;
>
