Re: [Qemu-devel] [PATCH v3 3/5] xics: setup cpu at realize time

[Cédric Le Goater]

On 06/07/2017 07:17 PM, Greg Kurz wrote:
> Until recently, spapr used to allocate ICPState objects for the lifetime
> of the machine. They would only be associated to vCPUs in xics_cpu_setup()
> when plugging a CPU core.
> 
> Now that ICPState objects have the same lifecycle as vCPUs, it is
> possible to associate them during realization.
> 
> This patch hence open-codes xics_cpu_setup() in icp_realize(). The vCPU
> is passed as a property. Note that vCPU now needs to be realized first
> for the IRQs to be allocated. It also needs to resetted before ICPState
> realization in order to synchronize with KVM.
> 
> Since ICPState objects are freed when unrealized, xics_cpu_destroy() isn't
> needed anymore and can be safely dropped.

I like the idea but I think the assignment of ->cs attribute should be 
moved under icp_kvm_cpu_setup(), as it is only used under xics_kvm by 
the kvm_vcpu_ioctl() calls. 

Ideally, we should also introduce :

        struct KvmState {
            ICPState parent_obj;
        
            CPUState *cs;
        };

That would be cleaner, but that might introduce some migration compat 
issues  again ...

Some minor comments below,

Thanks,

C. 

> Signed-off-by: Greg Kurz <address@hidden>
> ---
>  hw/intc/xics.c          |   76 
> ++++++++++++++++++++---------------------------
>  hw/ppc/pnv_core.c       |   16 ++++------
>  hw/ppc/spapr_cpu_core.c |   21 ++++++-------
>  include/hw/ppc/xics.h   |    2 -
>  4 files changed, 48 insertions(+), 67 deletions(-)
> 
> diff --git a/hw/intc/xics.c b/hw/intc/xics.c
> index ec73f02144c9..330441ff7fe8 100644
> --- a/hw/intc/xics.c
> +++ b/hw/intc/xics.c
> @@ -38,50 +38,6 @@
>  #include "monitor/monitor.h"
>  #include "hw/intc/intc.h"
>  
> -void xics_cpu_destroy(XICSFabric *xi, PowerPCCPU *cpu)
> -{
> -    CPUState *cs = CPU(cpu);
> -    ICPState *icp = ICP(cpu->intc);
> -
> -    assert(icp);
> -    assert(cs == icp->cs);
> -
> -    icp->output = NULL;
> -    icp->cs = NULL;
> -}
> -
> -void xics_cpu_setup(XICSFabric *xi, PowerPCCPU *cpu, ICPState *icp)
> -{
> -    CPUState *cs = CPU(cpu);
> -    CPUPPCState *env = &cpu->env;
> -    ICPStateClass *icpc;
> -
> -    assert(icp);
> -
> -    cpu->intc = OBJECT(icp);
> -    icp->cs = cs;
> -
> -    icpc = ICP_GET_CLASS(icp);
> -    if (icpc->cpu_setup) {
> -        icpc->cpu_setup(icp, cpu);
> -    }
> -
> -    switch (PPC_INPUT(env)) {
> -    case PPC_FLAGS_INPUT_POWER7:
> -        icp->output = env->irq_inputs[POWER7_INPUT_INT];
> -        break;
> -
> -    case PPC_FLAGS_INPUT_970:
> -        icp->output = env->irq_inputs[PPC970_INPUT_INT];
> -        break;
> -
> -    default:
> -        error_report("XICS interrupt controller does not support this CPU "
> -                     "bus model");
> -        abort();
> -    }
> -}
> -
>  void icp_pic_print_info(ICPState *icp, Monitor *mon)
>  {
>      int cpu_index = icp->cs ? icp->cs->cpu_index : -1;
> @@ -343,6 +299,8 @@ static void icp_realize(DeviceState *dev, Error **errp)
>  {
>      ICPState *icp = ICP(dev);
>      ICPStateClass *icpc = ICP_GET_CLASS(dev);
> +    PowerPCCPU *cpu;
> +    CPUPPCState *env;
>      Object *obj;
>      Error *err = NULL;
>  
> @@ -355,6 +313,36 @@ static void icp_realize(DeviceState *dev, Error **errp)
>  
>      icp->xics = XICS_FABRIC(obj);
>  
> +    obj = object_property_get_link(OBJECT(dev), "cs", &err);
> +    if (!obj) {
> +        error_setg(errp, "%s: required link 'xics' not found: %s",
> +                   __func__, error_get_pretty(err));
> +        return;
> +    }
> +
> +    cpu = POWERPC_CPU(obj);
> +    cpu->intc = OBJECT(icp);
> +    icp->cs = CPU(obj);

only xics_kvm needs ->cs. 

> +
> +    if (icpc->cpu_setup) {
> +        icpc->cpu_setup(icp, cpu);
> +    }
> +
> +    env = &cpu->env;
> +    switch (PPC_INPUT(env)) {
> +    case PPC_FLAGS_INPUT_POWER7:
> +        icp->output = env->irq_inputs[POWER7_INPUT_INT];
> +        break;
> +
> +    case PPC_FLAGS_INPUT_970:
> +        icp->output = env->irq_inputs[PPC970_INPUT_INT];
> +        break;
> +
> +    default:
> +        error_setg(errp, "XICS interrupt controller does not support this 
> CPU bus model");
> +        return;
> +    }
> +
>      if (icpc->realize) {
>          icpc->realize(dev, errp);
>      }
> diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c
> index e8a9a94d5a24..1393005e76f3 100644
> --- a/hw/ppc/pnv_core.c
> +++ b/hw/ppc/pnv_core.c
> @@ -118,19 +118,19 @@ static void pnv_core_realize_child(Object *child, 
> XICSFabric *xi, Error **errp)
>      PowerPCCPU *cpu = POWERPC_CPU(cs);
>      Object *obj;
>  
> -    obj = object_new(TYPE_PNV_ICP);
> -    object_property_add_child(OBJECT(cpu), "icp", obj, &error_abort);
> -    object_unref(obj);
> -    object_property_add_const_link(obj, "xics", OBJECT(xi), &error_abort);
> -    object_property_set_bool(obj, true, "realized", &local_err);
> +    object_property_set_bool(child, true, "realized", &local_err);
>      if (local_err) {
>          error_propagate(errp, local_err);
>          return;
>      }
>  
> -    object_property_set_bool(child, true, "realized", &local_err);
> +    obj = object_new(TYPE_PNV_ICP);
> +    object_property_add_child(child, "icp", obj, NULL);
> +    object_unref(obj);
> +    object_property_add_const_link(obj, "xics", OBJECT(xi), &error_abort);
> +    object_property_add_const_link(obj, "cs", child, &error_abort);

may be link the cpu object instead ? 

> +    object_property_set_bool(obj, true, "realized", &local_err);
>      if (local_err) {
> -        object_unparent(obj);
>          error_propagate(errp, local_err);
>          return;
>      }
> @@ -141,8 +141,6 @@ static void pnv_core_realize_child(Object *child, 
> XICSFabric *xi, Error **errp)
>          error_propagate(errp, local_err);
>          return;
>      }
> -
> -    xics_cpu_setup(xi, cpu, ICP(obj));
>  }
>  
>  static void pnv_core_realize(DeviceState *dev, Error **errp)
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 029a14120edd..9a6259525953 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -53,9 +53,6 @@ static void spapr_cpu_reset(void *opaque)
>  
>  static void spapr_cpu_destroy(PowerPCCPU *cpu)
>  {
> -    sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> -
> -    xics_cpu_destroy(XICS_FABRIC(spapr), cpu);
>      qemu_unregister_reset(spapr_cpu_reset, cpu);
>  }
>  
> @@ -140,28 +137,28 @@ static void spapr_cpu_core_realize_child(Object *child, 
> Error **errp)
>      sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
>      CPUState *cs = CPU(child);
>      PowerPCCPU *cpu = POWERPC_CPU(cs);
> -    Object *obj;
> +    Object *obj = NULL;
>  
> -    obj = object_new(spapr->icp_type);
> -    object_property_add_child(OBJECT(cpu), "icp", obj, &error_abort);
> -    object_unref(obj);
> -    object_property_add_const_link(obj, "xics", OBJECT(spapr), &error_abort);
> -    object_property_set_bool(obj, true, "realized", &local_err);
> +    object_property_set_bool(child, true, "realized", &local_err);
>      if (local_err) {
>          goto error;
>      }
>  
> -    object_property_set_bool(child, true, "realized", &local_err);
> +    spapr_cpu_init(spapr, cpu, &local_err);
>      if (local_err) {
>          goto error;
>      }
>  
> -    spapr_cpu_init(spapr, cpu, &local_err);
> +    obj = object_new(spapr->icp_type);
> +    object_property_add_child(child, "icp", obj, &error_abort);
> +    object_unref(obj);
> +    object_property_add_const_link(obj, "xics", OBJECT(spapr), &error_abort);
> +    object_property_add_const_link(obj, "cs", child, &error_abort);

same here.

> +    object_property_set_bool(obj, true, "realized", &local_err);
>      if (local_err) {
>          goto error;
>      }
>  
> -    xics_cpu_setup(XICS_FABRIC(spapr), cpu, ICP(obj));
>      return;
>  
>  error:
> diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
> index 40a506eacfb4..05767a15be9a 100644
> --- a/include/hw/ppc/xics.h
> +++ b/include/hw/ppc/xics.h
> @@ -183,8 +183,6 @@ void spapr_dt_xics(int nr_servers, void *fdt, uint32_t 
> phandle);
>  
>  qemu_irq xics_get_qirq(XICSFabric *xi, int irq);
>  ICPState *xics_icp_get(XICSFabric *xi, int server);
> -void xics_cpu_setup(XICSFabric *xi, PowerPCCPU *cpu, ICPState *icp);
> -void xics_cpu_destroy(XICSFabric *xi, PowerPCCPU *cpu);
>  
>  /* Internal XICS interfaces */
>  void icp_set_cppr(ICPState *icp, uint8_t cppr);
>