Re: [PATCH 1/6] spapr: Add an "spapr" property to sPAPR CPU core

[Philippe Mathieu-Daudé]

On 12/9/20 6:00 PM, Greg Kurz wrote:
> The sPAPR CPU core device can only work with pseries machine types.
> This is currently checked in the realize function with a dynamic
> cast of qdev_get_machine(). Some other places also need to reach
> out to the machine using qdev_get_machine().
> 
> Make this dependency explicit by introducing an "spapr" link
> property which officialy points to the machine. This link is
> set by pseries machine types only in the pre-plug handler. This
> allows to drop some users of qdev_get_machine().
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
>  include/hw/ppc/spapr_cpu_core.h |  2 ++
>  hw/ppc/spapr.c                  |  4 ++++
>  hw/ppc/spapr_cpu_core.c         | 17 +++++++----------
>  3 files changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/include/hw/ppc/spapr_cpu_core.h b/include/hw/ppc/spapr_cpu_core.h
> index dab3dfc76c0a..0969b29fd96c 100644
> --- a/include/hw/ppc/spapr_cpu_core.h
> +++ b/include/hw/ppc/spapr_cpu_core.h
> @@ -10,6 +10,7 @@
>  #define HW_SPAPR_CPU_CORE_H
>  
>  #include "hw/cpu/core.h"
> +#include "hw/ppc/spapr.h"
>  #include "hw/qdev-core.h"
>  #include "target/ppc/cpu-qom.h"
>  #include "target/ppc/cpu.h"
> @@ -24,6 +25,7 @@ OBJECT_DECLARE_TYPE(SpaprCpuCore, SpaprCpuCoreClass,
>  struct SpaprCpuCore {
>      /*< private >*/
>      CPUCore parent_obj;
> +    SpaprMachineState *spapr;
>  
>      /*< public >*/
>      PowerPCCPU **threads;
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index d1dcf3ab2c94..4cc51723c62e 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -3816,6 +3816,10 @@ static void spapr_core_pre_plug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>      int index;
>      unsigned int smp_threads = machine->smp.threads;
>  
> +    /* Required by spapr_cpu_core_realize() */
> +    object_property_set_link(OBJECT(dev), "spapr", OBJECT(hotplug_dev),
> +                             &error_abort);
> +
>      if (dev->hotplugged && !mc->has_hotpluggable_cpus) {
>          error_setg(errp, "CPU hotplug not supported for this machine");
>          return;
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 2f7dc3c23ded..dec09367e4a0 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -25,14 +25,13 @@
>  #include "sysemu/hw_accel.h"
>  #include "qemu/error-report.h"
>  
> -static void spapr_reset_vcpu(PowerPCCPU *cpu)
> +static void spapr_reset_vcpu(PowerPCCPU *cpu, SpaprMachineState *spapr)
>  {
>      CPUState *cs = CPU(cpu);
>      CPUPPCState *env = &cpu->env;
>      PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
>      SpaprCpuState *spapr_cpu = spapr_cpu_state(cpu);
>      target_ulong lpcr;
> -    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
>  
>      cpu_reset(cs);
>  
> @@ -186,7 +185,7 @@ static void spapr_unrealize_vcpu(PowerPCCPU *cpu, 
> SpaprCpuCore *sc)
>      if (!sc->pre_3_0_migration) {
>          vmstate_unregister(NULL, &vmstate_spapr_cpu_state, 
> cpu->machine_data);
>      }
> -    spapr_irq_cpu_intc_destroy(SPAPR_MACHINE(qdev_get_machine()), cpu);
> +    spapr_irq_cpu_intc_destroy(sc->spapr, cpu);
>      qdev_unrealize(DEVICE(cpu));
>  }
>  
> @@ -200,7 +199,7 @@ static void spapr_cpu_core_reset(DeviceState *dev)
>      int i;
>  
>      for (i = 0; i < cc->nr_threads; i++) {
> -        spapr_reset_vcpu(sc->threads[i]);
> +        spapr_reset_vcpu(sc->threads[i], sc->spapr);

Why reset() needs access to the machine state, don't
you have it in realize()?

>      }
>  }
>  
> @@ -314,16 +313,12 @@ err:
>  
>  static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
>  {
> -    /* We don't use SPAPR_MACHINE() in order to exit gracefully if the user
> -     * tries to add a sPAPR CPU core to a non-pseries machine.
> -     */
> -    SpaprMachineState *spapr =
> -        (SpaprMachineState *) object_dynamic_cast(qdev_get_machine(),
> -                                                  TYPE_SPAPR_MACHINE);
>      SpaprCpuCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> +    SpaprMachineState *spapr = sc->spapr;
>      CPUCore *cc = CPU_CORE(OBJECT(dev));
>      int i;
>  
> +    /* Set in spapr_core_pre_plug() */
>      if (!spapr) {
>          error_setg(errp, TYPE_SPAPR_CPU_CORE " needs a pseries machine");
>          return;
> @@ -345,6 +340,8 @@ static Property spapr_cpu_core_properties[] = {
>      DEFINE_PROP_INT32("node-id", SpaprCpuCore, node_id, 
> CPU_UNSET_NUMA_NODE_ID),
>      DEFINE_PROP_BOOL("pre-3.0-migration", SpaprCpuCore, pre_3_0_migration,
>                       false),
> +    DEFINE_PROP_LINK("spapr", SpaprCpuCore, spapr, TYPE_SPAPR_MACHINE,
> +                     SpaprMachineState *),
>      DEFINE_PROP_END_OF_LIST()
>  };
>  
>