Re: [Qemu-devel] [PATCH-for-4.2 v7 03/10] hw/acpi: Add ACPI Generic Event Device Support

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 18 Jul 2019 10:52:10 +0000
Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com> wrote:

> Hi Igor,
> 
> > -----Original Message-----
> > From: Qemu-devel
> > [mailto:qemu-devel-bounces+shameerali.kolothum.thodi=huawei.com@nongn
> > u.org] On Behalf Of Igor Mammedov
> > Sent: 17 July 2019 15:33
> > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> > Cc: peter.maydell@linaro.org; sameo@linux.intel.com;
> > shannon.zhaosl@gmail.com; ard.biesheuvel@linaro.org;
> > qemu-devel@nongnu.org; xuwei (O) <xuwei5@huawei.com>; Linuxarm
> > <linuxarm@huawei.com>; eric.auger@redhat.com; qemu-arm@nongnu.org;
> > sebastien.boeuf@intel.com; lersek@redhat.com
> > Subject: Re: [Qemu-devel] [PATCH-for-4.2 v7 03/10] hw/acpi: Add ACPI Generic
> > Event Device Support
> > 
> > On Tue, 16 Jul 2019 16:38:09 +0100
> > Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> wrote:  
> 
> [...]
> 
> > > +static void acpi_ged_event(AcpiGedState *s, uint32_t sel)
> > > +{
> > > +    GEDState *ged_st = &s->ged_state;
> > > +    /*
> > > +     * 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.  
> > comment isn't correct anymore, pls fix it  
> 
> True.
> 
> >   
> > > +     */
> > > +    qemu_mutex_lock(&ged_st->lock);  
> > Is this lock really necessary?
> > (I thought that MMIO and monitor access is guarded by BQL)  
> 
> Hmm..I am not sure. This is to synchronize with the ged_st->sel update inside
> ged_read(). And also acpi_ged_event() gets called through _power_down_notifier()
> as well. BQL guard is in place for all the paths here? 
power down command originates from HMP or QMP monitor, so you don't really
need a lock here.

> 
> >   
> > > +    ged_st->sel |= sel;
> > > +    qemu_mutex_unlock(&ged_st->lock);
> > > +
> > > +    /* Trigger the event by sending an interrupt to the guest. */
> > > +    qemu_irq_pulse(s->irq);
> > > +}
> > > +
> > > +static void acpi_ged_init(MemoryRegion *as, DeviceState *dev, GEDState  
> > *ged_st)  
> > > +{
> > > +    AcpiGedState *s = ACPI_GED(dev);
> > > +
> > > +    assert(s->ged_base);
> > > +
> > > +    qemu_mutex_init(&ged_st->lock);
> > > +    memory_region_init_io(&ged_st->io, OBJECT(dev), &ged_ops, ged_st,
> > > +                          TYPE_ACPI_GED, ACPI_GED_REG_LEN);
> > > +    memory_region_add_subregion(as, s->ged_base, &ged_st->io);
> > > +    qdev_init_gpio_out_named(DEVICE(s), &s->irq, "ged-irq", 1);
> > > +}
> > > +
> > > +static void acpi_ged_device_plug_cb(HotplugHandler *hotplug_dev,
> > > +                                    DeviceState *dev, Error **errp)
> > > +{
> > > +    AcpiGedState *s = ACPI_GED(hotplug_dev);
> > > +
> > > +    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
> > > +        if (s->memhp_state.is_enabled) {
> > > +            acpi_memory_plug_cb(hotplug_dev, &s->memhp_state, dev,  
> > errp);  
> > > +        } else {
> > > +            error_setg(errp,
> > > +                 "memory hotplug is not  
> > enabled: %s.memory-hotplug-support "  
> > > +                 "is not set", object_get_typename(OBJECT(s)));
> > > +        }
> > > +    } 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_MEM_HOTPLUG_EVT;
> > > +    } else {
> > > +        /* Unknown event. Return without generating interrupt. */
> > > +        warn_report("GED: Unsupported event %d. No irq injected", ev);
> > > +        return;
> > > +    }
> > > +
> > > +    /*
> > > +     * We inject the hotplug interrupt. The IRQ selector will make
> > > +     * the difference from the ACPI table.  
> > I don't get comment at all, pls rephrase/  
> 
> Ok. I think better to get rid of this comment here and update the one in acpi_ged_event()
> appropriately.
> 
> >   
> > > +     */
> > > +    acpi_ged_event(s, sel);  
> > it seems to used only once and only here, suggest to drop acpi_ged_event()
> > and move it's code here.  
> 
> But patch #10 makes use of it from acpi_ged_pm_powerdown_req().
it looks like a valid shortcut but I'd make it follow AcpiInterface->send_event()
path for consistency so only one call chain would exist.


> 
> > > +}
> > > +
> > > +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 acpi-mem-hotplug
> > > +     * memory region 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_UINT64("ged-base", AcpiGedState, ged_base, 0),  
> > 
> > I'd add checks to realize() to ensure that both foo_base are not left
> > uninitialized (i.e. at default values)  
> 
> Ok. ged_base has a check in acpi_ged_init(). I will add check for memhp_base
> and move the ged_base one to realize().
> 
> >   
> > > +    DEFINE_PROP_UINT32("ged-event", AcpiGedState, ged_event_bitmap,  
> > 0),  
> > > +    DEFINE_PROP_END_OF_LIST(),
> > > +};
> > > +
> > > +static bool vmstate_test_use_memhp(void *opaque)
> > > +{
> > > +    AcpiGedState *s = opaque;
> > > +    return s->memhp_state.is_enabled;
> > > +}
> > > +
> > > +static const VMStateDescription vmstate_memhp_state = {
> > > +    .name = "acpi-ged/memhp",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .needed = vmstate_test_use_memhp,
> > > +    .fields      = (VMStateField[]) {
> > > +        VMSTATE_MEMORY_HOTPLUG(memhp_state, AcpiGedState),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > > +static const VMStateDescription vmstate_ged_state = {
> > > +    .name = "acpi-ged-state",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields      = (VMStateField[]) {
> > > +        VMSTATE_UINT32(sel, GEDState),
> > > +        VMSTATE_END_OF_LIST()
> > > +    }
> > > +};
> > > +
> > > +static const VMStateDescription vmstate_acpi_ged = {
> > > +    .name = "acpi-ged",
> > > +    .version_id = 1,
> > > +    .minimum_version_id = 1,
> > > +    .fields = (VMStateField[]) {
> > > +        VMSTATE_STRUCT(ged_state, AcpiGedState, 1,  
> > vmstate_ged_state, GEDState),  
> > > +        VMSTATE_END_OF_LIST(),
> > > +    },
> > > +    .subsections = (const VMStateDescription * []) {
> > > +        &vmstate_memhp_state,
> > > +        NULL
> > > +    }
> > > +};
> > > +
> > > +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 Generic Event Device";
> > > +    dc->props = acpi_ged_properties;
> > > +    dc->realize = acpi_ged_device_realize;
> > > +    dc->vmsd = &vmstate_acpi_ged;
> > > +
> > > +    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 0000000000..f69d084c89
> > > --- /dev/null
> > > +++ b/include/hw/acpi/generic_event_device.h
> > > @@ -0,0 +1,102 @@
> > > +/*
> > > + *
> > > + * Copyright (c) 2018 Intel Corporation
> > > + * Copyright (c) 2019 Huawei Technologies R & D (UK) Ltd
> > > + * Written by Samuel Ortiz, Shameer Kolothum
> > > + *
> > > + * 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.
> > > + *
> > > + * 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 (EREG, SystemMemory, 0x09080000, 0x04)
> > > + *     Field (EREG, DWordAcc, NoLock, WriteAsZeros)
> > > + *     {
> > > + *         ESEL,   32
> > > + *     }
> > > + *
> > > + *     Method (_EVT, 1, Serialized)  // _EVT: Event
> > > + *     {
> > > + *         Local0 = ESEL // ESEL = IO memory region which specifies the
> > > + *                       // device type.
> > > + *         If (((Local0 & One) == One))
> > > + *         {
> > > + *             MethodEvent1()
> > > + *         }
> > > + *         If ((Local0 & 0x2) == 0x2)
> > > + *         {
> > > + *             MethodEvent2()
> > > + *         }
> > > + *         ...
> > > + *     }
> > > + * }
> > > + *
> > > + */
> > > +
> > > +#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_EVT_SEL_OFFSET    0x0  
> >   
> > > +#define ACPI_GED_EVT_SEL_LEN       0x4
> > > +#define ACPI_GED_REG_LEN           0x4  
> > Didn't both macros refer to the same thing?
> > Why not use the same one in AML and in QEMU MMIO handler?  
> 
> Ok.
> 
> Thanks,
> Shameer
> 
> >   
> > > +
> > > +#define GED_DEVICE      "GED"
> > > +#define AML_GED_EVT_REG "EREG"
> > > +#define AML_GED_EVT_SEL "ESEL"
> > > +
> > > +/*
> > > + * Platforms need to specify the GED event bitmap
> > > + * to describe what kind of events they want to support
> > > + * through GED.
> > > + */
> > > +#define ACPI_GED_MEM_HOTPLUG_EVT   0x1
> > > +
> > > +typedef struct GEDState {
> > > +    MemoryRegion io;
> > > +    uint32_t     sel;
> > > +    QemuMutex    lock;
> > > +} GEDState;
> > > +
> > > +typedef struct AcpiGedState {
> > > +    DeviceClass parent_obj;
> > > +    MemHotplugState memhp_state;
> > > +    hwaddr memhp_base;
> > > +    hwaddr ged_base;
> > > +    GEDState ged_state;
> > > +    uint32_t ged_event_bitmap;
> > > +    qemu_irq irq;
> > > +} AcpiGedState;
> > > +
> > > +void build_ged_aml(Aml *table, const char* name, HotplugHandler  
> > *hotplug_dev,  
> > > +                   uint32_t ged_irq, AmlRegionSpace rs);
> > > +
> > > +#endif  
> >   
>