Re: x86: kvmclock: abstract save/restore sched_clock_state

[Thomas Gleixner <tglx@linutronix.de>]

On Tue, 7 Feb 2012, Marcelo Tosatti wrote:
> 
> Upon resume from hibernation, CPU 0's hvclock area contains the old
> values for system_time and tsc_timestamp. It is necessary for the
> hypervisor to update these values with uptodate ones before the CPU uses
> them.
> 
> Abstract TSC's save/restore sched_clock_state functions and use
> restore_state to write to KVM_SYSTEM_TIME MSR, forcing an update.
> 
> Fixes suspend-to-disk with kvmclock.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
> diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
> index 15d9915..c91e8b9 100644
> --- a/arch/x86/include/asm/tsc.h
> +++ b/arch/x86/include/asm/tsc.h
> @@ -61,7 +61,7 @@ extern void check_tsc_sync_source(int cpu);
>  extern void check_tsc_sync_target(void);
>  
>  extern int notsc_setup(char *);
> -extern void save_sched_clock_state(void);
> -extern void restore_sched_clock_state(void);
> +extern void tsc_save_sched_clock_state(void);
> +extern void tsc_restore_sched_clock_state(void);
>  
>  #endif /* _ASM_X86_TSC_H */
> diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
> index 5d0afac..baaca8d 100644
> --- a/arch/x86/include/asm/x86_init.h
> +++ b/arch/x86/include/asm/x86_init.h
> @@ -162,6 +162,8 @@ struct x86_cpuinit_ops {
>   * @is_untracked_pat_range	exclude from PAT logic
>   * @nmi_init			enable NMI on cpus
>   * @i8042_detect		pre-detect if i8042 controller exists
> + * @save_sched_clock_state:	save state for sched_clock() on suspend
> + * @restore_sched_clock_state:	restore state for sched_clock() on resume
>   */
>  struct x86_platform_ops {
>  	unsigned long (*calibrate_tsc)(void);
> @@ -173,6 +175,8 @@ struct x86_platform_ops {
>  	void (*nmi_init)(void);
>  	unsigned char (*get_nmi_reason)(void);
>  	int (*i8042_detect)(void);
> +	void (*save_sched_clock_state)(void);
> +	void (*restore_sched_clock_state)(void);
>  };
>  
>  struct pci_dev;
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index ca4e735..57e6b78 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -136,6 +136,15 @@ int kvm_register_clock(char *txt)
>  	return ret;
>  }
>  
> +void kvm_save_sched_clock_state(void)

static ?

> +{
> +}
> +
> +void kvm_restore_sched_clock_state(void)

Ditto

> +{
> +	kvm_register_clock("primary cpu clock, resume");
> +}
> +

Otherwise: Reviewed-by: Thomas Gleixner <tglx@linutronix.de>