Re: [Xen-devel] [PATCH] x86/S3: add cache flush on secondary CPUs before going to sleep

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 24/09/2012 16:17, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:

> Secondary CPUs, between doing their final memory writes (particularly
> updating cpu_initialized) and getting a subsequent INIT, may not write
> back all modified data. The INIT itself then causes those modifications
> to be lost, so in the cpu_initialized case the CPU would find itself
> already initialized, (intentionally) entering an infinite loop instead
> of actually coming online.
> 
> Signed-off-by: Ben Guthro <ben@xxxxxxxxxx>
> 
> Make acpi_dead_idle() call default_dead_idle() rather than duplicating
> the logic there.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Add a comment in default_dead_idle() that the wbinvd is needed in case the
cpu is offline for s3 suspend. That may not otherwise be obvious! And it's a
different reason -- or at least there are other reasons why -- wbinvd is
needed in acpi_dead_idle().

Apart from that:

Acked-by: Keir Fraser <keir@xxxxxxx>

> --- a/xen/arch/x86/acpi/cpu_idle.c
> +++ b/xen/arch/x86/acpi/cpu_idle.c
> @@ -659,8 +659,7 @@ void acpi_dead_idle(void)
>      }
>  
>  default_halt:
> -    for ( ; ; )
> -        halt();
> +    default_dead_idle();
>  }
>  
>  int cpuidle_init_cpu(unsigned int cpu)
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -45,6 +45,7 @@
>  #include <asm/desc.h>
>  #include <asm/i387.h>
>  #include <asm/xstate.h>
> +#include <asm/cpuidle.h>
>  #include <asm/mpspec.h>
>  #include <asm/ldt.h>
>  #include <asm/fixmap.h>
> @@ -64,7 +65,6 @@ DEFINE_PER_CPU(struct vcpu *, curr_vcpu)
>  DEFINE_PER_CPU(unsigned long, cr4);
>  
>  static void default_idle(void);
> -static void default_dead_idle(void);
>  void (*pm_idle) (void) __read_mostly = default_idle;
>  void (*dead_idle) (void) __read_mostly = default_dead_idle;
>  
> @@ -82,8 +82,9 @@ static void default_idle(void)
>          local_irq_enable();
>  }
>  
> -static void default_dead_idle(void)
> +void default_dead_idle(void)
>  {
> +    wbinvd();
>      for ( ; ; )
>          halt();
>  }
> --- a/xen/include/asm-x86/cpuidle.h
> +++ b/xen/include/asm-x86/cpuidle.h
> @@ -18,6 +18,7 @@ extern uint64_t (*cpuidle_get_tick)(void
>  
>  int mwait_idle_init(struct notifier_block *);
>  int cpuidle_init_cpu(unsigned int cpu);
> +void default_dead_idle(void);
>  void acpi_dead_idle(void);
>  void trace_exit_reason(u32 *irq_traced);
>  void update_idle_stats(struct acpi_processor_power *,
> 
> 
> 
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> http://lists.xen.org/xen-devel



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