Re: [PATCH 1/4] x86: skip further initialization for idle domains

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 28/01/15 08:10, Jan Beulich wrote:
> While in the end not really found necessary, early versions of the
> patches to follow pointed out that we needlessly set up paging for idle
> domains. Arranging for that to be skipped made me notice that we can at
> once skip vMCE setup for them. Leverage to adjustment to further
> re-arrange the way FPU setup gets skipped.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -427,12 +427,15 @@ int vcpu_initialise(struct vcpu *v)
>      if ( rc )
>          return rc;
>  
> -    paging_vcpu_init(v);
> +    if ( !is_idle_domain(d) )
> +    {
> +        paging_vcpu_init(v);
>  
> -    if ( (rc = vcpu_init_fpu(v)) != 0 )
> -        return rc;
> +        if ( (rc = vcpu_init_fpu(v)) != 0 )
> +            return rc;
>  
> -    vmce_init_vcpu(v);
> +        vmce_init_vcpu(v);
> +    }
>  
>      if ( has_hvm_container_domain(d) )
>      {
> @@ -559,12 +562,12 @@ int arch_domain_create(struct domain *d,
>      HYPERVISOR_COMPAT_VIRT_START(d) =
>          is_pv_domain(d) ? __HYPERVISOR_COMPAT_VIRT_START : ~0u;
>  
> -    if ( (rc = paging_domain_init(d, domcr_flags)) != 0 )
> -        goto fail;
> -    paging_initialised = 1;
> -
>      if ( !is_idle_domain(d) )
>      {
> +        if ( (rc = paging_domain_init(d, domcr_flags)) != 0 )
> +            goto fail;
> +        paging_initialised = 1;
> +
>          d->arch.cpuids = xmalloc_array(cpuid_input_t, MAX_CPUID_INPUT);
>          rc = -ENOMEM;
>          if ( d->arch.cpuids == NULL )
> --- a/xen/arch/x86/i387.c
> +++ b/xen/arch/x86/i387.c
> @@ -303,12 +303,8 @@ void save_fpu_enable(void)
>  /* Initialize FPU's context save area */
>  int vcpu_init_fpu(struct vcpu *v)
>  {
> -    int rc = 0;
> +    int rc;
>      
> -    /* Idle domain doesn't have FPU state allocated */
> -    if ( is_idle_vcpu(v) )
> -        goto done;
> -
>      if ( (rc = xstate_alloc_save_area(v)) != 0 )
>          return rc;
>  
> @@ -318,13 +314,9 @@ int vcpu_init_fpu(struct vcpu *v)
>      {
>          v->arch.fpu_ctxt = _xzalloc(sizeof(v->arch.xsave_area->fpu_sse), 16);
>          if ( !v->arch.fpu_ctxt )
> -        {
>              rc = -ENOMEM;
> -            goto done;
> -        }
>      }
>  
> -done:
>      return rc;
>  }
>  
>
>
>