Re: [Qemu-devel] [PATCH v4 4/5] s390x/cpu: Add functions to register CPU state

[Igor Mammedov]

On Wed, 17 Feb 2016 15:12:34 -0500
Matthew Rosato <address@hidden> wrote:

> Introduce s390_register_cpustate, which will set the
> machine/cpu[n] link with the current CPU state.  Additionally,
> maintain an array of state pointers indexed by CPU id for fast lookup
> during interrupt handling.
> 
cosmetic nit,
you call qdev_get_machine() several time withing single function
or when function already has machine argument. You probably shouldn't
do it or do it once and use return value throughout function.

> Signed-off-by: Matthew Rosato <address@hidden>
> ---
>  hw/s390x/s390-virtio.c | 45 ++++++++++++++++++++++++++++++++++++---------
>  target-s390x/cpu.c     | 14 +++++++++++++-
>  target-s390x/cpu.h     |  1 +
>  3 files changed, 50 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/s390x/s390-virtio.c b/hw/s390x/s390-virtio.c
> index b3707f4..6a1e3f6 100644
> --- a/hw/s390x/s390-virtio.c
> +++ b/hw/s390x/s390-virtio.c
> @@ -60,15 +60,35 @@
>  #define S390_TOD_CLOCK_VALUE_MISSING    0x00
>  #define S390_TOD_CLOCK_VALUE_PRESENT    0x01
>  
> -static S390CPU **ipi_states;
> +static S390CPU **cpu_states;
>  
>  S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
>  {
> -    if (cpu_addr >= smp_cpus) {
> +    if (cpu_addr >= max_cpus) {
>          return NULL;
>      }
>  
> -    return ipi_states[cpu_addr];
> +    /* Fast lookup via CPU ID */
> +    return cpu_states[cpu_addr];
> +}
> +
> +int s390_register_cpustate(uint16_t cpu_addr, S390CPU *state)
isn't it the board responsibility to link CPU somewhere?
I'd suggest to use for it generic device hotplug hooks
see how get_hotplug_handler() and pc_machine_device_plug_cb() are used,
it's executed after CPU's realize is successfully completed.

> +{
> +    gchar *name;
> +    int r = 0;
> +
> +    name = g_strdup_printf("cpu[%i]", cpu_addr);
> +    if (object_property_get_link(qdev_get_machine(), name, NULL)) {
> +        r = -EEXIST;
> +        goto out;
> +    }
> +
> +    object_property_set_link(qdev_get_machine(), OBJECT(state), name,\
> +                             &error_abort);
> +
> +out:
> +    g_free(name);
> +    return r;
>  }
>  
>  void s390_init_ipl_dev(const char *kernel_filename,
> @@ -98,19 +118,26 @@ void s390_init_ipl_dev(const char *kernel_filename,
>  void s390_init_cpus(MachineState *machine)
>  {
>      int i;
> +    gchar *name;
>  
>      if (machine->cpu_model == NULL) {
>          machine->cpu_model = "host";
>      }
>  
> -    ipi_states = g_malloc(sizeof(S390CPU *) * smp_cpus);
> -
> -    for (i = 0; i < smp_cpus; i++) {
> -        S390CPU *cpu;
> +    cpu_states = g_malloc0(sizeof(S390CPU *) * max_cpus);
>  
> -        cpu = cpu_s390x_init(machine->cpu_model);
> +    for (i = 0; i < max_cpus; i++) {
> +        name = g_strdup_printf("cpu[%i]", i);
> +        object_property_add_link(qdev_get_machine(), name, TYPE_S390_CPU,
> +                                 (Object **) &cpu_states[i],
> +                                 object_property_allow_set_link,
> +                                 OBJ_PROP_LINK_UNREF_ON_RELEASE,
> +                                 &error_abort);
> +        g_free(name);
> +    }
>  
> -        ipi_states[i] = cpu;
> +    for (i = 0; i < smp_cpus; i++) {
> +        cpu_s390x_init(machine->cpu_model);
>      }
>  }
>  
> diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
> index 5f6411f..620b2e3 100644
> --- a/target-s390x/cpu.c
> +++ b/target-s390x/cpu.c
> @@ -32,6 +32,7 @@
>  #include "trace.h"
>  #ifndef CONFIG_USER_ONLY
>  #include "sysemu/arch_init.h"
> +#include "sysemu/sysemu.h"
>  #endif
>  
>  #define CR0_RESET       0xE0UL
> @@ -202,9 +203,20 @@ static void s390_cpu_realizefn(DeviceState *dev, Error 
> **errp)
>      CPUS390XState *env = &cpu->env;
>  
>  #if !defined(CONFIG_USER_ONLY)
> +    if (s390_register_cpustate(next_cpu_id, cpu) < 0) {
> +        error_setg(errp, "Cannot have more than %d CPUs", max_cpus);
> +        return;
> +    }
>      qemu_register_reset(s390_cpu_machine_reset_cb, cpu);
> -#endif
> +    env->cpu_num = next_cpu_id;
> +    while (next_cpu_id < max_cpus - 1) {
> +        if (!cpu_exists(++next_cpu_id)) {
> +            break;
> +        }
> +    }
maybe it's possible to reuse cpu_get_free_index() here?


> +#else
>      env->cpu_num = next_cpu_id++;
> +#endif
>      s390_cpu_gdb_init(cs);
>      qemu_init_vcpu(cs);
>  #if !defined(CONFIG_USER_ONLY)
> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
> index 06ca60b..429bf90 100644
> --- a/target-s390x/cpu.h
> +++ b/target-s390x/cpu.h
> @@ -531,6 +531,7 @@ static inline int s390_set_clock(uint8_t *tod_high, 
> uint64_t *tod_low)
>  }
>  
>  S390CPU *s390_cpu_addr2state(uint16_t cpu_addr);
> +int s390_register_cpustate(uint16_t cpu_addr, S390CPU *state);
>  unsigned int s390_cpu_halt(S390CPU *cpu);
>  void s390_cpu_unhalt(S390CPU *cpu);
>  unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);