Re: [Qemu-devel] [PATCH v4 5/5] s390x/cpu: Allow hotplug of CPUs

[Igor Mammedov]

On Wed, 17 Feb 2016 15:12:35 -0500
Matthew Rosato <address@hidden> wrote:

> Implement cpu hotplug routine and add the machine hook.
> 
> Signed-off-by: Matthew Rosato <address@hidden>
> ---
>  hw/s390x/s390-virtio-ccw.c |  1 +
>  target-s390x/cpu.c         | 40 ++++++++++++++++++++++++++++++++++++++++
>  target-s390x/cpu.h         |  1 +
>  3 files changed, 42 insertions(+)
> 
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index b05ed8b..a15904d 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -163,6 +163,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void 
> *data)
>  
>      mc->init = ccw_init;
>      mc->reset = s390_machine_reset;
> +    mc->hot_add_cpu = s390_hot_add_cpu;
>      mc->block_default_type = IF_VIRTIO;
>      mc->no_cdrom = 1;
>      mc->no_floppy = 1;
> diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
> index 620b2e3..b4c59c9 100644
> --- a/target-s390x/cpu.c
> +++ b/target-s390x/cpu.c
> @@ -33,6 +33,8 @@
>  #ifndef CONFIG_USER_ONLY
>  #include "sysemu/arch_init.h"
>  #include "sysemu/sysemu.h"
> +#include "hw/boards.h"
> +#include "hw/s390x/sclp.h"
>  #endif
>  
>  #define CR0_RESET       0xE0UL
> @@ -226,6 +228,12 @@ static void s390_cpu_realizefn(DeviceState *dev, Error 
> **errp)
>  #endif
>  
>      scc->parent_realize(dev, errp);
> +
> +#if !defined(CONFIG_USER_ONLY)
> +    if (dev->hotplugged) {
> +        raise_irq_cpu_hotplug();
> +    }
> +#endif
>  }
>  
>  static void s390_cpu_initfn(Object *obj)
> @@ -269,6 +277,38 @@ static void s390_cpu_finalize(Object *obj)
>  }
>  
>  #if !defined(CONFIG_USER_ONLY)
> +void s390_hot_add_cpu(const int64_t id, Error **errp)
> +{
to make it future-proof wrt migration it could be better to
enforce here that 'id' grows in +1 steps so user
won't be able create cpus with gaps.


> +    MachineState *machine = MACHINE(qdev_get_machine());
> +
> +    if (id < 0) {
> +        error_setg(errp, "Invalid CPU id: %" PRIi64, id);
> +        return;
> +    }
> +
> +    if (cpu_exists(id)) {
> +        error_setg(errp, "Unable to add CPU: %" PRIi64
> +                   ", it already exists", id);
> +        return;
> +    }
> +
> +    if (id >= max_cpus) {
> +        error_setg(errp, "Unable to add CPU: %" PRIi64
> +                   ", max allowed: %d", id, max_cpus - 1);
> +        return;
> +    }
> +
> +    if (id != next_cpu_id) {
> +        error_setg(errp, "Unable to add CPU: %" PRIi64
> +                   ", The next available id is %d", id, next_cpu_id);
> +        return;
> +    }
> +
> +    cpu_s390x_init(machine->cpu_model);
> +}
> +#endif
> +
> +#if !defined(CONFIG_USER_ONLY)
>  static bool disabled_wait(CPUState *cpu)
>  {
>      return cpu->halted && !(S390_CPU(cpu)->env.psw.mask &
> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
> index 429bf90..3752932 100644
> --- a/target-s390x/cpu.h
> +++ b/target-s390x/cpu.h
> @@ -542,6 +542,7 @@ static inline uint8_t s390_cpu_get_state(S390CPU *cpu)
>  
>  void gtod_save(QEMUFile *f, void *opaque);
>  int gtod_load(QEMUFile *f, void *opaque, int version_id);
> +void s390_hot_add_cpu(const int64_t id, Error **errp);
>  
>  /* service interrupts are floating therefore we must not pass an cpustate */
>  void s390_sclp_extint(uint32_t parm);