Re: [Xen-devel] [PATCH] x86: fix MWAIT-based idle driver for CPUs without ARAT

[Keir Fraser <keir@xxxxxxx>]

On 24/09/2012 12:02, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> lapic_timer_{on,off} need to get initialized in this case. This in turn
> requires getting HPET broadcast setup to be carried out earlier (and
> hence preventing double initialization there).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Keir Fraser <keir@xxxxxxx>

> ---
> Note that I don't have a respective system available to test these
> adjustments (which is also why I didn't notice the omission from the
> original patch), so I can only hope that this works and takes care of
> the observed boot failure.
> 
> --- a/xen/arch/x86/acpi/cpu_idle.c
> +++ b/xen/arch/x86/acpi/cpu_idle.c
> @@ -74,6 +74,29 @@ static void lapic_timer_nop(void) { }
>  void (*__read_mostly lapic_timer_off)(void);
>  void (*__read_mostly lapic_timer_on)(void);
>  
> +bool_t lapic_timer_init(void)
> +{
> +    if ( boot_cpu_has(X86_FEATURE_ARAT) )
> +    {
> +        lapic_timer_off = lapic_timer_nop;
> +        lapic_timer_on = lapic_timer_nop;
> +    }
> +    else if ( hpet_broadcast_is_available() )
> +    {
> +        lapic_timer_off = hpet_broadcast_enter;
> +        lapic_timer_on = hpet_broadcast_exit;
> +    }
> +    else if ( pit_broadcast_is_available() )
> +    {
> +        lapic_timer_off = pit_broadcast_enter;
> +        lapic_timer_on = pit_broadcast_exit;
> +    }
> +    else
> +        return 0;
> +
> +    return 1;
> +}
> +
>  static uint64_t (*__read_mostly tick_to_ns)(uint64_t) = acpi_pm_tick_to_ns;
>  
>  void (*__read_mostly pm_idle_save)(void);
> @@ -789,25 +812,8 @@ static int check_cx(struct acpi_processo
>          if ( local_apic_timer_c2_ok )
>              break;
>      case ACPI_STATE_C3:
> -        if ( boot_cpu_has(X86_FEATURE_ARAT) )
> -        {
> -            lapic_timer_off = lapic_timer_nop;
> -            lapic_timer_on = lapic_timer_nop;
> -        }
> -        else if ( hpet_broadcast_is_available() )
> -        {
> -            lapic_timer_off = hpet_broadcast_enter;
> -            lapic_timer_on = hpet_broadcast_exit;
> -        }
> -        else if ( pit_broadcast_is_available() )
> -        {
> -            lapic_timer_off = pit_broadcast_enter;
> -            lapic_timer_on = pit_broadcast_exit;
> -        }
> -        else
> -        {
> +        if ( !lapic_timer_init() )
>              return -EINVAL;
> -        }
>  
>          /* All the logic here assumes flags.bm_check is same across all CPUs
> */
>          if ( bm_check_flag == -1 )
> --- a/xen/arch/x86/cpu/mwait-idle.c
> +++ b/xen/arch/x86/cpu/mwait-idle.c
> @@ -56,6 +56,7 @@
>  #include <xen/softirq.h>
>  #include <xen/trace.h>
>  #include <asm/cpuidle.h>
> +#include <asm/hpet.h>
>  #include <asm/mwait.h>
>  #include <asm/msr.h>
>  #include <acpi/cpufreq/cpufreq.h>
> @@ -501,6 +502,12 @@ int __init mwait_idle_init(struct notifi
>  
> err = mwait_idle_probe();
> if (!err) {
> +  if (!boot_cpu_has(X86_FEATURE_ARAT))
> +   hpet_broadcast_init();
> +  if (!lapic_timer_init())
> +   err = -EINVAL;
> + }
> + if (!err) {
> nfb->notifier_call = mwait_idle_cpu_init;
> mwait_idle_cpu_init(nfb, CPU_UP_PREPARE, NULL);
>  
> --- a/xen/arch/x86/hpet.c
> +++ b/xen/arch/x86/hpet.c
> @@ -495,7 +495,7 @@ void __init hpet_broadcast_init(void)
>      u32 hpet_id, cfg;
>      unsigned int i, n;
>  
> -    if ( hpet_rate == 0 )
> +    if ( hpet_rate == 0 || hpet_broadcast_is_available() )
>          return;
>  
>      cfg = hpet_read32(HPET_CFG);
> --- a/xen/include/asm-x86/cpuidle.h
> +++ b/xen/include/asm-x86/cpuidle.h
> @@ -10,6 +10,7 @@ extern struct acpi_processor_power *proc
>  
>  extern void (*pm_idle_save)(void);
>  
> +bool_t lapic_timer_init(void);
>  extern void (*lapic_timer_off)(void);
>  extern void (*lapic_timer_on)(void);
>  
> 
> 
> 
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