linux-kernel - Re: [PATCH v4 10/15] target-s390x: Prepare accelerator during cpu object realization

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Message-ID: <20150330193351.GC7031@thinpad.lan.raisama.net>
Date:	Mon, 30 Mar 2015 16:33:51 -0300
From:	Eduardo Habkost <ehabkost@...hat.com>
To:	Michael Mueller <mimu@...ux.vnet.ibm.com>
Cc:	qemu-devel@...gnu.org, kvm@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
	Gleb Natapov <gleb@...nel.org>, Alexander Graf <agraf@...e.de>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	"Jason J. Herne" <jjherne@...ux.vnet.ibm.com>,
	Cornelia Huck <cornelia.huck@...ibm.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Andreas Faerber <afaerber@...e.de>,
	Richard Henderson <rth@...ddle.net>,
	Daniel Hansel <daniel.hansel@...ux.vnet.ibm.com>
Subject: Re: [PATCH v4 10/15] target-s390x: Prepare accelerator during cpu
 object realization

On Mon, Mar 30, 2015 at 04:28:23PM +0200, Michael Mueller wrote:
> This patch implements routine s390_cpu_model_init(). It is called by the
> realize function during instantiation of an cpu object. Its task is to
> initialize the current accelerator with the properties of the selected
> processor model.
> 
> Signed-off-by: Michael Mueller <mimu@...ux.vnet.ibm.com>
> ---
>  target-s390x/cpu-models.c | 37 +++++++++++++++++++++++++++++++++++++
>  target-s390x/cpu-models.h |  4 ++++
>  target-s390x/cpu.c        |  1 +
>  3 files changed, 42 insertions(+)
> 
> diff --git a/target-s390x/cpu-models.c b/target-s390x/cpu-models.c
> index 8a877d3..ba873ea 100644
> --- a/target-s390x/cpu-models.c
> +++ b/target-s390x/cpu-models.c
> @@ -111,6 +111,7 @@ typedef struct ParmAddrAddrModeMask {
>  } ParmAddrAddrModeMask;
>  
>  static GSList *s390_cpu_aliases;
> +static bool cpu_models_used;
>  
>  /* compare order of two cpu classes for ascending sort */
>  gint s390_cpu_class_asc_order_compare(gconstpointer a, gconstpointer b)
> @@ -670,3 +671,39 @@ uint64_t *s390_current_fac_list_mask(void)
>      return s390_fac_list_mask_by_machine(mc->name);
>  }
>  #endif
> +
> +/**
> + * s390_cpu_model_init:
> + * @cc: S390 CPU class
> + *
> + * This function intitializes the current accelerator with processor
> + * related properties.
> + *
> + * Since: 2.4
> + */
> +void s390_cpu_model_init(S390CPUClass *cc)
> +{
> +    S390ProcessorProps proc;
> +
> +    /* none cpu model case */
> +    if (!strcmp(object_class_get_name(OBJECT_CLASS(cc)), TYPE_S390_CPU)) {
> +        return;
> +    }

Instead of checking the class name, can't you just check a S390CPUClass
field that may indicate that s390_cpu_model_init() doesn't need to do
anything for the class? Maybe (cpuid(cc->proc) == 0)?


> +
> +    /* accelerator already prepared */
> +    if (cpu_models_used) {
> +        return;
> +    }

I'm still trying to understand the need for this global. But I will ask
for more details in the following patches that actually use
s390_cpu_models_used()?

> +
> +    proc.cpuid = cpuid(cc->proc);
> +    proc.ibc = cc->proc.ibc;
> +    bitmap_zero(proc.fac_list, FAC_LIST_ARCH_S390_SIZE_UINT1);
> +    bitmap_copy(proc.fac_list, cc->fac_list[ACCEL_CURRENT],
> +                FAC_LIST_CPU_S390_SIZE_UINT1);
> +
> +    if (kvm_enabled()) {
> +        if (!kvm_s390_set_processor_props(&proc)) {
> +            cpu_models_used = true;
> +        }
> +    }
> +}
> diff --git a/target-s390x/cpu-models.h b/target-s390x/cpu-models.h
> index 9562088..fe3997f 100644
> --- a/target-s390x/cpu-models.h
> +++ b/target-s390x/cpu-models.h
> @@ -45,6 +45,9 @@
>  #define type_cpuid(x)     ((uint64_t)((x) & 0xffff) << 16)
>  #define id_cpuid(x)       ((uint64_t)((x) & 0xffffff) << 32)
>  #define ver_cpuid(x)      ((uint64_t)((x) & 0xff) << 56)
> +#define cpuid(x)          (ver_cpuid(x.ver) |  \
> +                           id_cpuid(x.id) |    \
> +                           type_cpuid(x.type))
>  
>  #define oldest_ibc(x)     (((uint32_t)(x) >> 16) & 0xfff)
>  #define newest_ibc(x)     ((uint32_t)(x) & 0xfff)
> @@ -108,6 +111,7 @@ void s390_cpu_list_entry(gpointer data, gpointer user_data);
>  bool s390_cpu_classes_initialized(void);
>  uint64_t *s390_fac_list_mask_by_machine(const char *name);
>  uint64_t *s390_current_fac_list_mask(void);
> +void s390_cpu_model_init(S390CPUClass *cc);
>  
>  extern uint64_t qemu_s390_fac_list_mask[];
>  
> diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
> index c33f05e..829945d 100644
> --- a/target-s390x/cpu.c
> +++ b/target-s390x/cpu.c
> @@ -180,6 +180,7 @@ static void s390_cpu_realizefn(DeviceState *dev, Error **errp)
>      CPUState *cs = CPU(dev);
>      S390CPUClass *scc = S390_CPU_GET_CLASS(dev);
>  
> +    s390_cpu_model_init(scc);
>      s390_cpu_gdb_init(cs);
>      qemu_init_vcpu(cs);
>  #if !defined(CONFIG_USER_ONLY)
> -- 
> 1.8.3.1
> 

-- 
Eduardo
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