Re: [Qemu-devel] [PATCH v4 3/8] hw/acpi: Add ACPI Generic Event Device Support

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

Hi Eric,

> -----Original Message-----
> From: Auger Eric [mailto:eric.auger@redhat.com]
> Sent: 30 April 2019 16:50
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> qemu-devel@nongnu.org; qemu-arm@nongnu.org; imammedo@redhat.com
> Cc: peter.maydell@linaro.org; shannon.zhaosl@gmail.com;
> sameo@linux.intel.com; sebastien.boeuf@intel.com; xuwei (O)
> <xuwei5@huawei.com>; lersek@redhat.com; ard.biesheuvel@linaro.org;
> Linuxarm <linuxarm@huawei.com>
> Subject: Re: [PATCH v4 3/8] hw/acpi: Add ACPI Generic Event Device Support
> 
> Hi Shameer,
> 
> On 4/9/19 12:29 PM, Shameer Kolothum wrote:
> > From: Samuel Ortiz <sameo@linux.intel.com>
> >
> > The ACPI Generic Event Device (GED) is a hardware-reduced specific
> > device[ACPI v6.1 Section 5.6.9] that handles all platform events,
> > including the hotplug ones.This patch generates the AML code that
> > defines GEDs.
> >
> > Platforms need to specify their own GedEvent array to describe what
> > kind of events they want to support through GED.  Also this uses a
> > a single interrupt for the  GED device, relying on IO memory region
> > to communicate the type of device affected by the interrupt. This
> > way, we can support up to 32 events with a unique interrupt.
> >
> > This supports only memory hotplug for now.
> >
> > Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
> > Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
> > Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> > ---
> >  hw/acpi/Kconfig                        |   4 +
> >  hw/acpi/Makefile.objs                  |   1 +
> >  hw/acpi/generic_event_device.c         | 311
> +++++++++++++++++++++++++++++++++
> >  include/hw/acpi/generic_event_device.h | 121 +++++++++++++
> >  4 files changed, 437 insertions(+)
> >  create mode 100644 hw/acpi/generic_event_device.c
> >  create mode 100644 include/hw/acpi/generic_event_device.h
> >
> > diff --git a/hw/acpi/Kconfig b/hw/acpi/Kconfig
> > index eca3bee..01a8b41 100644
> > --- a/hw/acpi/Kconfig
> > +++ b/hw/acpi/Kconfig
> > @@ -27,3 +27,7 @@ config ACPI_VMGENID
> >      bool
> >      default y
> >      depends on PC
> > +
> > +config ACPI_HW_REDUCED
> > +    bool
> > +    depends on ACPI
> > diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
> > index 2d46e37..b753232 100644
> > --- a/hw/acpi/Makefile.objs
> > +++ b/hw/acpi/Makefile.objs
> > @@ -6,6 +6,7 @@ common-obj-$(CONFIG_ACPI_MEMORY_HOTPLUG) +=
> memory_hotplug.o
> >  common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu.o
> >  common-obj-$(CONFIG_ACPI_NVDIMM) += nvdimm.o
> >  common-obj-$(CONFIG_ACPI_VMGENID) += vmgenid.o
> > +common-obj-$(CONFIG_ACPI_HW_REDUCED) += generic_event_device.o
> >  common-obj-$(call lnot,$(CONFIG_ACPI_X86)) += acpi-stub.o
> >
> >  common-obj-y += acpi_interface.o
> > diff --git a/hw/acpi/generic_event_device.c
> b/hw/acpi/generic_event_device.c
> > new file mode 100644
> > index 0000000..856ca04
> > --- /dev/null
> > +++ b/hw/acpi/generic_event_device.c
> > @@ -0,0 +1,311 @@
> > +/*
> > + *
> > + * Copyright (c) 2018 Intel Corporation
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2 or later, as published by the Free Software Foundation.
> I am not sure we need below statements: see hw/misc/armsse-mhu.c for a
> recent added file.

Ok. I will get rid of this.
 
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of
> MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
> License for
> > + * more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> with
> > + * this program.  If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "qapi/error.h"
> > +#include "exec/address-spaces.h"
> > +#include "hw/sysbus.h"
> > +#include "hw/acpi/acpi.h"
> > +#include "hw/acpi/generic_event_device.h"
> > +#include "hw/mem/pc-dimm.h"
> > +
> > +static Aml *ged_event_aml(const GedEvent *event)
> > +{
> > +
> > +    if (!event) {
> > +        return NULL;
> > +    }
> > +
> > +    switch (event->event) {
> > +    case GED_MEMORY_HOTPLUG:
> > +        /* We run a complete memory SCAN when getting a memory
> hotplug event */
> > +        return aml_call0(MEMORY_DEVICES_CONTAINER "."
> MEMORY_SLOT_SCAN_METHOD);
> > +    default:
> > +        break;
> > +    }
> > +
> > +    return NULL;
> > +}
> > +
> > +/*
> > + * The ACPI Generic Event Device (GED) is a hardware-reduced specific
> > + * device[ACPI v6.1 Section 5.6.9] that handles all platform events,
> > + * including the hotplug ones. Platforms need to specify their own
> > + * GedEvent array to describe what kind of events they want to support
> > + * through GED. This routine uses a single interrupt for the GED device,
> > + * relying on IO memory region to communicate the type of device
> > + * affected by the interrupt. This way, we can support up to 32 events
> > + * with a unique interrupt.
> > + */
> > +void build_ged_aml(Aml *table, const char *name, HotplugHandler
> *hotplug_dev,
> > +                   uint32_t ged_irq, AmlRegionSpace rs)
> > +{
> > +    AcpiGedState *s = ACPI_GED(hotplug_dev);
> > +    GedEvent *ged_events = s->ged_events;
> > +    Aml *crs = aml_resource_template();
> > +    Aml *evt, *field;
> > +    Aml *dev = aml_device("%s", name);
> > +    Aml *irq_sel = aml_local(0);
> > +    Aml *isel = aml_name(AML_GED_IRQ_SEL);
> > +    uint32_t i;
> > +
> > +    if (!s->ged_base || !ged_events || !s->ged_events_size) {
> > +        return;
> > +    }
> > +
> > +    /* _CRS interrupt */
> > +    aml_append(crs, aml_interrupt(AML_CONSUMER, AML_EDGE,
> AML_ACTIVE_HIGH,
> > +                                  AML_EXCLUSIVE, &ged_irq, 1));
> > +    /*
> > +     * For each GED event we:
> > +     * - Add an interrupt to the CRS section.
> > +     * - Add a conditional block for each event, inside a while loop.
> > +     *   This is semantically equivalent to a switch/case implementation.
> > +     */
> > +    evt = aml_method("_EVT", 1, AML_SERIALIZED);
> > +    {
> > +        Aml *ged_aml;
> > +        Aml *if_ctx;
> > +
> > +        /* Local0 = ISEL */
> > +        aml_append(evt, aml_store(isel, irq_sel));
> > +
> > +        /*
> > +         * Here we want to call a method for each supported GED event
> type.
> > +         * The resulting ASL code looks like:
> > +         *
> > +         * Local0 = ISEL
> > +         * If ((Local0 & irq0) == irq0)
> > +         * {
> > +         *     MethodEvent0()
> > +         * }
> > +         *
> > +         * If ((Local0 & irq1) == irq1)
> > +         * {
> > +         *     MethodEvent1()
> > +         * }
> > +         * ...
> > +         */
> > +
> > +        for (i = 0; i < s->ged_events_size; i++) {
> > +            ged_aml = ged_event_aml(&ged_events[i]);
> > +            if (!ged_aml) {
> > +                continue;
> > +            }
> > +
> > +            /* If ((Local1 == irq))*/
> > +            if_ctx = aml_if(aml_equal(aml_and(irq_sel,
> > +
> aml_int(ged_events[i].selector), NULL),
> > +
> aml_int(ged_events[i].selector)));
> > +            {
> > +                /* AML for this specific type of event */
> > +                aml_append(if_ctx, ged_aml);
> > +            }
> > +
> > +            /*
> > +             * We append the first "if" to the "while" context.
> > +             * Other "if"s will be "elseif"s.
> Are we sure about that:
> in hw/acpi/nvdimm.c nvdimm_build_common_dsm() I can see an aml_else() is
> added inbetween aml_if's?

Right. I think the comment here is misleading. This will be as mentioned in the
comment block above,

 If ((Local0 & irq0) == irq0)
 {
     MethodEvent0()
 }

 If ((Local0 & irq1) == irq1)
 {
     MethodEvent1()
 }

 And this should do the job. Do we really need ElseIf block here?

> > +             */
> > +            aml_append(evt, if_ctx);
> > +        }
> > +    }
> > +
> > +    aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0013")));
> > +    aml_append(dev, aml_name_decl("_UID", aml_string(GED_DEVICE)));
> > +    aml_append(dev, aml_name_decl("_CRS", crs));
> > +
> > +    /* Append IO region */
> > +    aml_append(dev, aml_operation_region(AML_GED_IRQ_REG, rs,
> > +               aml_int(s->ged_base + ACPI_GED_IRQ_SEL_OFFSET),
> > +               ACPI_GED_IRQ_SEL_LEN));
> > +    field = aml_field(AML_GED_IRQ_REG, AML_DWORD_ACC,
> AML_NOLOCK,
> > +                      AML_WRITE_AS_ZEROS);
> > +    aml_append(field, aml_named_field(AML_GED_IRQ_SEL,
> > +                                      ACPI_GED_IRQ_SEL_LEN *
> 8));
> nit s/8/BITS_PER_BYTE as done in nvdimm.c.

Ok.

> > +    aml_append(dev, field);
> > +
> > +    /* Append _EVT method */
> > +    aml_append(dev, evt);
> > +
> > +    aml_append(table, dev);
> > +}
> > +
> > +/* Memory read by the GED _EVT AML dynamic method */
> > +static uint64_t ged_read(void *opaque, hwaddr addr, unsigned size)
> > +{
> > +    uint64_t val = 0;
> > +    GEDState *ged_st = opaque;
> > +
> > +    switch (addr) {
> > +    case ACPI_GED_IRQ_SEL_OFFSET:
> > +        /* Read the selector value and reset it */
> > +        qemu_mutex_lock(&ged_st->lock);
> > +        val = ged_st->sel;
> > +        ged_st->sel = 0;
> > +        qemu_mutex_unlock(&ged_st->lock);
> > +        break;
> > +    default:
> > +        break;
> > +    }
> > +
> > +    return val;
> > +}
> > +
> > +/* Nothing is expected to be written to the GED memory region */
> > +static void ged_write(void *opaque, hwaddr addr, uint64_t data,
> > +                      unsigned int size)
> > +{
> > +}
> > +
> > +static const MemoryRegionOps ged_ops = {
> > +    .read = ged_read,
> > +    .write = ged_write,
> > +    .endianness = DEVICE_LITTLE_ENDIAN,
> > +    .valid = {
> > +        .min_access_size = 4,
> > +        .max_access_size = 4,
> > +    },
> > +};
> > +
> > +static void acpi_ged_event(GEDState *ged_st, uint32_t ged_irq_sel)
> > +{
> > +    /*
> I would personally inline that code in void acpi_ged_send_event()

Ok.

> > +     * Set the GED IRQ selector to the expected device type value. This
> > +     * way, the ACPI method will be able to trigger the right code based
> > +     * on a unique IRQ.
> > +     */
> > +    qemu_mutex_lock(&ged_st->lock);
> > +    ged_st->sel = ged_irq_sel;
> > +    qemu_mutex_unlock(&ged_st->lock);
> > +
> > +    /* Trigger the event by sending an interrupt to the guest. */
> > +    qemu_irq_pulse(ged_st->gsi[ged_st->irq]);
> I don't really understand why we need this array. Doesn't The GED use a
> single IRQ. So why can't you store the precise qemu_irq pointer directly
> through the propery (DEFINE_PROP_PTR("gsi", AcpiGedState, gsi))?

Yes. You have raised this point previously as well. Sorry, I missed it when I
reworked the GED type from SYS_BUS_DEVICE to TYPE_DEVICE. I think
we can get rid of this array and the GED/gsi routing done in virt.c.


> > +}
> > +
> > +static void acpi_ged_init(MemoryRegion *as, DeviceState *dev, GEDState
> *ged_st)
> > +{
> > +    AcpiGedState *s = ACPI_GED(dev);
> > +
> > +    assert(s->ged_base);
> > +
> > +    ged_st->irq = s->ged_irq;
> > +    ged_st->gsi = s->gsi;
> > +    qemu_mutex_init(&ged_st->lock);
> > +    memory_region_init_io(&ged_st->io, OBJECT(dev), &ged_ops, ged_st,
> > +                          "acpi-ged-event", ACPI_GED_REG_LEN);
> > +    memory_region_add_subregion(as, s->ged_base, &ged_st->io);
> > +}
> > +
> > +static void acpi_ged_device_plug_cb(HotplugHandler *hotplug_dev,
> > +                                    DeviceState *dev, Error **errp)
> > +{
> > +    AcpiGedState *s = ACPI_GED(hotplug_dev);
> > +
> > +    if (s->memhp_state.is_enabled &&
> > +        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > +            acpi_memory_plug_cb(hotplug_dev, &s->memhp_state,
> > +                                dev, errp);
> > +    } else {
> > +        error_setg(errp, "virt: device plug request 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);
> > +    uint32_t sel;
> > +
> > +    if (ev & ACPI_MEMORY_HOTPLUG_STATUS) {
> > +        sel = ACPI_GED_IRQ_SEL_MEM;
> > +    } else {
> > +        /* Unknown event. Return without generating interrupt. */
> > +        return;
> > +    }
> > +
> > +    /*
> > +     * We inject the hotplug interrupt. The IRQ selector will make
> > +     * the difference from the ACPI table.
> > +     */
> > +    acpi_ged_event(&s->ged_state, sel);
> > +}
> > +
> > +static void acpi_ged_device_realize(DeviceState *dev, Error **errp)
> > +{
> > +    AcpiGedState *s = ACPI_GED(dev);
> > +
> > +    if (s->memhp_state.is_enabled) {
> > +        acpi_memory_hotplug_init(get_system_memory(), OBJECT(dev),
> > +                                 &s->memhp_state,
> > +                                 s->memhp_base);
> > +        acpi_ged_init(get_system_memory(), dev, &s->ged_state);
> > +    }
> > +}
> > +
> > +static Property acpi_ged_properties[] = {
> > +    /*
> > +     * Memory hotplug base address is a property of GED here,
> > +     * because GED handles memory hotplug event and
> MEMORY_HOTPLUG_DEVICE
> > +     * gets initialized when GED device is realized.
> > +     */
> > +    DEFINE_PROP_UINT64("memhp-base", AcpiGedState, memhp_base,
> 0),
> > +    DEFINE_PROP_BOOL("memory-hotplug-support", AcpiGedState,
> > +                     memhp_state.is_enabled, true),
> > +    DEFINE_PROP_PTR("gsi", AcpiGedState, gsi),
> > +    DEFINE_PROP_UINT64("ged-base", AcpiGedState, ged_base, 0),
> > +    DEFINE_PROP_UINT32("ged-irq", AcpiGedState, ged_irq, 0),
> > +    DEFINE_PROP_PTR("ged-events", AcpiGedState, ged_events),
> > +    DEFINE_PROP_UINT32("ged-events-size", AcpiGedState,
> ged_events_size, 0),
> > +    DEFINE_PROP_END_OF_LIST(),
> > +};
> > +
> > +static void acpi_ged_class_init(ObjectClass *class, void *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(class);
> > +    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(class);
> > +    AcpiDeviceIfClass *adevc = ACPI_DEVICE_IF_CLASS(class);
> > +
> > +    dc->desc = "ACPI";
> > +    dc->props = acpi_ged_properties;
> > +    dc->realize = acpi_ged_device_realize;
> > +
> > +    /* Reason: pointer properties "gsi" and "ged_events" */
> > +    dc->user_creatable = false;
> > +
> > +    hc->plug = acpi_ged_device_plug_cb;
> > +
> > +    adevc->send_event = acpi_ged_send_event;
> > +}
> > +
> > +static const TypeInfo acpi_ged_info = {
> > +    .name          = TYPE_ACPI_GED,
> > +    .parent        = TYPE_DEVICE,
> > +    .instance_size = sizeof(AcpiGedState),
> > +    .class_init    = acpi_ged_class_init,
> > +    .interfaces = (InterfaceInfo[]) {
> > +        { TYPE_HOTPLUG_HANDLER },
> > +        { TYPE_ACPI_DEVICE_IF },
> > +        { }
> > +    }
> > +};
> > +
> > +static void acpi_ged_register_types(void)
> > +{
> > +    type_register_static(&acpi_ged_info);
> > +}
> > +
> > +type_init(acpi_ged_register_types)
> > diff --git a/include/hw/acpi/generic_event_device.h
> b/include/hw/acpi/generic_event_device.h
> > new file mode 100644
> > index 0000000..9c840d8
> > --- /dev/null
> > +++ b/include/hw/acpi/generic_event_device.h
> > @@ -0,0 +1,121 @@
> > +/*
> > + *
> > + * Copyright (c) 2018 Intel Corporation
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2 or later, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of
> MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
> License for
> > + * more details.
> > + *
> > + * You should have received a copy of the GNU General Public License along
> with
> > + * this program.  If not, see <http://www.gnu.org/licenses/>.
> > + *
> > + * The ACPI Generic Event Device (GED) is a hardware-reduced specific
> > + * device[ACPI v6.1 Section 5.6.9] that handles all platform events,
> > + * including the hotplug ones. Generic Event Device allows platforms
> > + * to handle interrupts in ACPI ASL statements. It follows a very
> > + * similar approach like the _EVT method from GPIO events. All
> > + * interrupts are listed in  _CRS and the handler is written in _EVT> + *
> method. Here, we use a single interrupt for the GED device, relying
> > + * on IO memory region to communicate the type of device affected by
> > + * the interrupt. This way, we can support up to 32 events with a
> > + * unique interrupt.
> > + *
> > + * Here is an example.
> > + *
> > + * Device (\_SB.GED)
> > + * {
> > + *     Name (_HID, "ACPI0013")
> > + *     Name (_UID, Zero)
> > + *     Name (_CRS, ResourceTemplate ()
> > + *     {
> > + *         Interrupt (ResourceConsumer, Edge, ActiveHigh, Exclusive, ,, )
> > + *         {
> > + *              0x00000029,
> > + *         }
> > + *     })
> > + *     OperationRegion (IREG, SystemMemory, 0x09080000, 0x04)
> > + *     Field (IREG, DWordAcc, NoLock, WriteAsZeros)
> > + *     {
> > + *         ISEL,   32
> > + *     }
> > + *
> > + *     Method (_EVT, 1, Serialized)  // _EVT: Event
> > + *     {
> > + *         Local0 = ISEL // ISEL = IO memory region which specifies the
> > + *                       // device type.
> > + *         If (((Local0 & irq0) == irq0))
> > + *         {
> > + *             MethodEvent0()
> > + *         }
> > + *         ElseIf ((Local0 & irq1) == irq1)
> > + *         {
> > + *             MethodEvent1()
> > + *         }
> > + *         ...
> > + *     }
> > + * }
> > + *
> > + */
> > +
> > +#ifndef HW_ACPI_GED_H
> > +#define HW_ACPI_GED_H
> > +
> > +#include "hw/acpi/memory_hotplug.h"
> > +
> > +#define TYPE_ACPI_GED "acpi-ged"
> > +#define ACPI_GED(obj) \
> > +    OBJECT_CHECK(AcpiGedState, (obj), TYPE_ACPI_GED)
> > +
> > +#define ACPI_GED_IRQ_SEL_OFFSET 0x0
> > +#define ACPI_GED_IRQ_SEL_LEN    0x4
> > +#define ACPI_GED_IRQ_SEL_MEM    0x1
> > +#define ACPI_GED_REG_LEN        0x4
> > +
> > +#define GED_DEVICE      "GED"
> > +#define AML_GED_IRQ_REG "IREG"
> > +#define AML_GED_IRQ_SEL "ISEL"
> > +
> > +typedef enum {
> > +    GED_MEMORY_HOTPLUG = 1,
> > +} GedEventType;
> > +
> > +/*
> > + * Platforms need to specify their own GedEvent array
> > + * to describe what kind of events they want to support
> > + * through GED.
> > + */
> > +typedef struct GedEvent {
> > +    uint32_t     selector;
> > +    GedEventType event;
> > +} GedEvent;
> > +
> > +typedef struct GEDState {
> > +    MemoryRegion io;
> > +    uint32_t     sel;
> > +    uint32_t     irq;
> > +    qemu_irq     *gsi;
> so I am not sure why with need gsi + irq.
> > +    QemuMutex    lock;
> > +} GEDState;
> > +
> > +
> > +typedef struct AcpiGedState {
> > +    DeviceClass parent_obj;
> > +    MemHotplugState memhp_state;
> > +    hwaddr memhp_base;
> > +    void *gsi;
> > +    hwaddr ged_base;
> > +    GEDState ged_state;
> > +    uint32_t ged_irq;
> > +    void *ged_events;
> > +    uint32_t ged_events_size;
> > +} AcpiGedState;
> > +
> > +void build_ged_aml(Aml *table, const char* name, HotplugHandler
> *hotplug_dev,
> > +                   uint32_t ged_irq, AmlRegionSpace rs);
> > +
> > +#endif
> >
> Besides, this looks good to me.
> 

Thanks,
Shameer