Re: [Qemu-devel] [PATCH for-2.13 2/4] platform-bus-device: use device plug callback instead of machine_done notifier

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Apr 12, 2018 at 06:40:19PM +0200, Igor Mammedov wrote:
> platform-bus were using machine_done notifier to get and map
> (assign irq/mmio resources) dynamically added sysbus devices
> after all '-device' options had been processed.
> That however creates non obvious dependencies on ordering of
> machine_done notifiers and requires carefull line juggling
> to keep it working. For example see comment above
> create_platform_bus() and 'straitforward' arm_load_kernel()
> had to converted to machine_done notifier and that lead to
> yet another machine_done notifier to keep it working
> arm_register_platform_bus_fdt_creator().
> 
> Instead of hiding resource assignment in platform-bus-device
> to magically initialize sysbus devices, use device plug
> callback and assign resources explicitly at board level
> at the moment each -device option is being processed.
> 
> That adds a bunch of machine declaration boiler plate to
> e500plat board, similar to ARM/x86 but gets rid of hidden
> machine_done notifier and would allow to remove the dependent
> notifiers in ARM code simplifying it and making code flow
> easier to follow.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> CC: agraf@suse.de
> CC: david@gibson.dropbear.id.au
> CC: qemu-ppc@nongnu.org
> ---
>  hw/ppc/e500.h             |  3 +++
>  include/hw/arm/virt.h     |  3 +++
>  include/hw/platform-bus.h |  4 ++--
>  hw/arm/sysbus-fdt.c       |  3 ---
>  hw/arm/virt.c             | 36 ++++++++++++++++++++++++++++
>  hw/core/platform-bus.c    | 29 ++++-------------------
>  hw/ppc/e500.c             | 37 +++++++++++++++++------------
>  hw/ppc/e500plat.c         | 60 +++++++++++++++++++++++++++++++++++++++++++++--
>  8 files changed, 129 insertions(+), 46 deletions(-)
> 
> diff --git a/hw/ppc/e500.h b/hw/ppc/e500.h
> index 70ba1d8..d0f8ddd 100644
> --- a/hw/ppc/e500.h
> +++ b/hw/ppc/e500.h
> @@ -2,6 +2,7 @@
>  #define PPCE500_H
>  
>  #include "hw/boards.h"
> +#include "hw/sysbus.h"
>  
>  typedef struct PPCE500Params {
>      int pci_first_slot;
> @@ -26,6 +27,8 @@ typedef struct PPCE500Params {
>  
>  void ppce500_init(MachineState *machine, PPCE500Params *params);
>  
> +void ppce500_plug_dynamic_sysbus_device(SysBusDevice *sbdev);
> +
>  hwaddr booke206_page_size_to_tlb(uint64_t size);
>  
>  #endif
> diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> index ba0c1a4..5535760 100644
> --- a/include/hw/arm/virt.h
> +++ b/include/hw/arm/virt.h
> @@ -86,11 +86,14 @@ typedef struct {
>      bool no_pmu;
>      bool claim_edge_triggered_timers;
>      bool smbios_old_sys_ver;
> +    HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
> +                                           DeviceState *dev);
>  } VirtMachineClass;
>  
>  typedef struct {
>      MachineState parent;
>      Notifier machine_done;
> +    DeviceState *platform_bus_dev;
>      FWCfgState *fw_cfg;
>      bool secure;
>      bool highmem;
> diff --git a/include/hw/platform-bus.h b/include/hw/platform-bus.h
> index a00775c..19e20c5 100644
> --- a/include/hw/platform-bus.h
> +++ b/include/hw/platform-bus.h
> @@ -37,8 +37,6 @@ typedef struct PlatformBusDevice PlatformBusDevice;
>  struct PlatformBusDevice {
>      /*< private >*/
>      SysBusDevice parent_obj;
> -    Notifier notifier;
> -    bool done_gathering;
>  
>      /*< public >*/
>      uint32_t mmio_size;
> @@ -54,4 +52,6 @@ int platform_bus_get_irqn(PlatformBusDevice *platform_bus, SysBusDevice *sbdev,
>  hwaddr platform_bus_get_mmio_addr(PlatformBusDevice *pbus, SysBusDevice *sbdev,
>                                    int n);
>  
> +void platform_bus_link_device(PlatformBusDevice *pbus, SysBusDevice *sbdev);
> +
>  #endif /* HW_PLATFORM_BUS_H */
> diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
> index d68e3dc..80ff70e 100644
> --- a/hw/arm/sysbus-fdt.c
> +++ b/hw/arm/sysbus-fdt.c
> @@ -506,9 +506,6 @@ static void add_all_platform_bus_fdt_nodes(ARMPlatformBusFDTParams *fdt_params)
>      dev = qdev_find_recursive(sysbus_get_default(), TYPE_PLATFORM_BUS_DEVICE);
>      pbus = PLATFORM_BUS_DEVICE(dev);
>  
> -    /* We can only create dt nodes for dynamic devices when they're ready */
> -    assert(pbus->done_gathering);
> -
>      PlatformBusFDTData data = {
>          .fdt = fdt,
>          .irq_start = irq_start,
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 94dcb12..2e10d8b 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1087,6 +1087,7 @@ static void create_platform_bus(VirtMachineState *vms, qemu_irq *pic)
>      qdev_prop_set_uint32(dev, "mmio_size",
>          platform_bus_params.platform_bus_size);
>      qdev_init_nofail(dev);
> +    vms->platform_bus_dev = dev;
>      s = SYS_BUS_DEVICE(dev);
>  
>      for (i = 0; i < platform_bus_params.platform_bus_num_irqs; i++) {
> @@ -1536,9 +1537,37 @@ static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
>      return ms->possible_cpus;
>  }
>  
> +static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
> +                                        DeviceState *dev, Error **errp)
> +{
> +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> +
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +        if (vms->platform_bus_dev) {
> +            platform_bus_link_device(PLATFORM_BUS_DEVICE(vms->platform_bus_dev),
> +                                     SYS_BUS_DEVICE(dev));
> +        }
> +    }
> +}
> +
> +static HotplugHandler *virt_machine_get_hotpug_handler(MachineState *machine,
> +                                                       DeviceState *dev)
> +{
> +    VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(machine);
> +
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +        return HOTPLUG_HANDLER(machine);
> +    }
> +
> +    return vmc->get_hotplug_handler ?
> +        vmc->get_hotplug_handler(machine, dev) : NULL;
> +}
> +
>  static void virt_machine_class_init(ObjectClass *oc, void *data)
>  {
>      MachineClass *mc = MACHINE_CLASS(oc);
> +    VirtMachineClass *vmc = VIRT_MACHINE_CLASS(oc);
> +    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
>  
>      mc->init = machvirt_init;
>      /* Start max_cpus at the maximum QEMU supports. We'll further restrict
> @@ -1557,6 +1586,9 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
>      mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
>      mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
>      mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
> +    vmc->get_hotplug_handler = mc->get_hotplug_handler;
> +    mc->get_hotplug_handler = virt_machine_get_hotpug_handler;
> +    hc->plug = virt_machine_device_plug_cb;
>  }
>  
>  static const TypeInfo virt_machine_info = {
> @@ -1566,6 +1598,10 @@ static const TypeInfo virt_machine_info = {
>      .instance_size = sizeof(VirtMachineState),
>      .class_size    = sizeof(VirtMachineClass),
>      .class_init    = virt_machine_class_init,
> +    .interfaces = (InterfaceInfo[]) {
> +         { TYPE_HOTPLUG_HANDLER },
> +         { }
> +    },
>  };
>  
>  static void machvirt_machine_init(void)
> diff --git a/hw/core/platform-bus.c b/hw/core/platform-bus.c
> index 33d32fb..807cb5c 100644
> --- a/hw/core/platform-bus.c
> +++ b/hw/core/platform-bus.c
> @@ -103,7 +103,6 @@ static void plaform_bus_refresh_irqs(PlatformBusDevice *pbus)
>  {
>      bitmap_zero(pbus->used_irqs, pbus->num_irqs);
>      foreach_dynamic_sysbus_device(platform_bus_count_irqs, pbus);
> -    pbus->done_gathering = true;
>  }
>  
>  static void platform_bus_map_irq(PlatformBusDevice *pbus, SysBusDevice *sbdev,
> @@ -163,12 +162,11 @@ static void platform_bus_map_mmio(PlatformBusDevice *pbus, SysBusDevice *sbdev,
>  }
>  
>  /*
> - * For each sysbus device, look for unassigned IRQ lines as well as
> - * unassociated MMIO regions. Connect them to the platform bus if available.
> + * Look for unassigned IRQ lines as well as unassociated MMIO regions.
> + * Connect them to the platform bus if available.
>   */
> -static void link_sysbus_device(SysBusDevice *sbdev, void *opaque)
> +void platform_bus_link_device(PlatformBusDevice *pbus, SysBusDevice *sbdev)
>  {
> -    PlatformBusDevice *pbus = opaque;
>      int i;
>  
>      for (i = 0; sysbus_has_irq(sbdev, i); i++) {
> @@ -180,19 +178,6 @@ static void link_sysbus_device(SysBusDevice *sbdev, void *opaque)
>      }
>  }
>  
> -static void platform_bus_init_notify(Notifier *notifier, void *data)
> -{
> -    PlatformBusDevice *pb = container_of(notifier, PlatformBusDevice, notifier);
> -
> -    /*
> -     * Generate a bitmap of used IRQ lines, as the user might have specified
> -     * them on the command line.
> -     */
> -    plaform_bus_refresh_irqs(pb);
> -
> -    foreach_dynamic_sysbus_device(link_sysbus_device, pb);
> -}
> -
>  static void platform_bus_realize(DeviceState *dev, Error **errp)
>  {
>      PlatformBusDevice *pbus;
> @@ -211,12 +196,8 @@ static void platform_bus_realize(DeviceState *dev, Error **errp)
>          sysbus_init_irq(d, &pbus->irqs[i]);
>      }
>  
> -    /*
> -     * Register notifier that allows us to gather dangling devices once the
> -     * machine is completely assembled
> -     */
> -    pbus->notifier.notify = platform_bus_init_notify;
> -    qemu_add_machine_init_done_notifier(&pbus->notifier);
> +    /* some devices might be initialized before so update used IRQs map */
> +    plaform_bus_refresh_irqs(pbus);
>  }
>  
>  static Property platform_bus_properties[] = {
> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
> index 9a85a41..e2829db 100644
> --- a/hw/ppc/e500.c
> +++ b/hw/ppc/e500.c
> @@ -64,6 +64,8 @@
>  #define MPC8XXX_GPIO_OFFSET        0x000FF000ULL
>  #define MPC8XXX_GPIO_IRQ           47
>  
> +static SysBusDevice *pbus_dev;

I'm not thrilled about adding a new global for information that really
belongs in the machine state.  Although I do recognize that adding an
actual MachineState subtype that didn't previously exist is a bit of a pain.

>  struct boot_info
>  {
>      uint32_t dt_base;
> @@ -248,23 +250,28 @@ static void platform_bus_create_devtree(PPCE500Params *params, void *fdt,
>      dev = qdev_find_recursive(sysbus_get_default(), TYPE_PLATFORM_BUS_DEVICE);
>      pbus = PLATFORM_BUS_DEVICE(dev);
>  
> -    /* We can only create dt nodes for dynamic devices when they're ready */
> -    if (pbus->done_gathering) {
> -        PlatformDevtreeData data = {
> -            .fdt = fdt,
> -            .mpic = mpic,
> -            .irq_start = irq_start,
> -            .node = node,
> -            .pbus = pbus,
> -        };
> +    /* Create dt nodes for dynamic devices */
> +    PlatformDevtreeData data = {
> +        .fdt = fdt,
> +        .mpic = mpic,
> +        .irq_start = irq_start,
> +        .node = node,
> +        .pbus = pbus,
> +    };
>  
> -        /* Loop through all dynamic sysbus devices and create nodes for them */
> -        foreach_dynamic_sysbus_device(sysbus_device_create_devtree, &data);
> -    }
> +    /* Loop through all dynamic sysbus devices and create nodes for them */
> +    foreach_dynamic_sysbus_device(sysbus_device_create_devtree, &data);
>  
>      g_free(node);
>  }
>  
> +void ppce500_plug_dynamic_sysbus_device(SysBusDevice *sbdev)
> +{
> +    if (pbus_dev) {
> +        platform_bus_link_device(PLATFORM_BUS_DEVICE(pbus_dev), sbdev);
> +    }
> +}
> +
>  static int ppce500_load_device_tree(MachineState *machine,
>                                      PPCE500Params *params,
>                                      hwaddr addr,
> @@ -945,16 +952,16 @@ void ppce500_init(MachineState *machine, PPCE500Params *params)
>          qdev_prop_set_uint32(dev, "num_irqs", params->platform_bus_num_irqs);
>          qdev_prop_set_uint32(dev, "mmio_size", params->platform_bus_size);
>          qdev_init_nofail(dev);
> -        s = SYS_BUS_DEVICE(dev);
> +        pbus_dev = SYS_BUS_DEVICE(dev);
>  
>          for (i = 0; i < params->platform_bus_num_irqs; i++) {
>              int irqn = params->platform_bus_first_irq + i;
> -            sysbus_connect_irq(s, i, qdev_get_gpio_in(mpicdev, irqn));
> +            sysbus_connect_irq(pbus_dev, i, qdev_get_gpio_in(mpicdev, irqn));
>          }
>  
>          memory_region_add_subregion(address_space_mem,
>                                      params->platform_bus_base,
> -                                    sysbus_mmio_get_region(s, 0));
> +                                    sysbus_mmio_get_region(pbus_dev, 0));
>      }
>  
>      /*
> diff --git a/hw/ppc/e500plat.c b/hw/ppc/e500plat.c
> index 81d03e1..2f014cc 100644
> --- a/hw/ppc/e500plat.c
> +++ b/hw/ppc/e500plat.c
> @@ -60,8 +60,49 @@ static void e500plat_init(MachineState *machine)
>      ppce500_init(machine, &params);
>  }
>  
> -static void e500plat_machine_init(MachineClass *mc)
> +typedef struct {
> +    MachineClass parent;
> +    HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
> +                                           DeviceState *dev);
> +} E500PlatMachineClass;
> +
> +#define TYPE_E500PLAT_MACHINE  MACHINE_TYPE_NAME("ppce500")
> +#define E500PLAT_MACHINE_GET_CLASS(obj) \
> +    OBJECT_GET_CLASS(E500PlatMachineClass, obj, TYPE_E500PLAT_MACHINE)
> +#define E500PLAT_MACHINE_CLASS(klass) \
> +    OBJECT_CLASS_CHECK(E500PlatMachineClass, klass, TYPE_E500PLAT_MACHINE)
> +
> +static void e500plat_machine_device_plug_cb(HotplugHandler *hotplug_dev,
> +                                            DeviceState *dev, Error **errp)
>  {
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +        ppce500_plug_dynamic_sysbus_device(SYS_BUS_DEVICE(dev));
> +    }
> +}
> +
> +static
> +HotplugHandler *e500plat_machine_get_hotpug_handler(MachineState *machine,
> +                                                    DeviceState *dev)
> +{
> +    E500PlatMachineClass *emc = E500PLAT_MACHINE_GET_CLASS(machine);
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +        return HOTPLUG_HANDLER(machine);
> +    }
> +
> +    return emc->get_hotplug_handler ?
> +        emc->get_hotplug_handler(machine, dev) : NULL;
> +}
> +
> +static void e500plat_machine_class_init(ObjectClass *oc, void *data)
> +{
> +    E500PlatMachineClass *emc = E500PLAT_MACHINE_CLASS(oc);
> +    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
> +    MachineClass *mc = MACHINE_CLASS(oc);
> +
> +    emc->get_hotplug_handler = mc->get_hotplug_handler;
> +    mc->get_hotplug_handler = e500plat_machine_get_hotpug_handler;

I'm pretty sure the parent type will never have a handler, so I'm not
sure this is really necessary.

> +    hc->plug = e500plat_machine_device_plug_cb;
> +
>      mc->desc = "generic paravirt e500 platform";
>      mc->init = e500plat_init;
>      mc->max_cpus = 32;
> @@ -69,4 +110,19 @@ static void e500plat_machine_init(MachineClass *mc)
>      mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("e500v2_v30");
>  }
>  
> -DEFINE_MACHINE("ppce500", e500plat_machine_init)
> +static const TypeInfo e500plat_info = {
> +    .name          = TYPE_E500PLAT_MACHINE,
> +    .parent        = TYPE_MACHINE,
> +    .class_size    = sizeof(E500PlatMachineClass),
> +    .class_init    = e500plat_machine_class_init,
> +    .interfaces    = (InterfaceInfo[]) {
> +         { TYPE_HOTPLUG_HANDLER },
> +         { }
> +    }
> +};
> +
> +static void e500plat_register_types(void)
> +{
> +    type_register_static(&e500plat_info);
> +}
> +type_init(e500plat_register_types)

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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