Re: [PATCH 2/4 V13] Add functions to check if the host has stopped the vm

[Marcelo Tosatti <mtosatti@redhat.com>]

On Wed, Feb 08, 2012 at 10:07:44AM -0500, Eric B Munson wrote:
> When a host stops or suspends a VM it will set a flag to show this.  The
> watchdog will use these functions to determine if a softlockup is real, or the
> result of a suspended VM.
> 
> Signed-off-by: Eric B Munson <emunson@mgebm.net>
> asm-generic changes Acked-by: Arnd Bergmann <arnd@arndb.de>
> Cc: mingo@redhat.com
> Cc: hpa@zytor.com
> Cc: ryanh@linux.vnet.ibm.com
> Cc: aliguori@us.ibm.com
> Cc: mtosatti@redhat.com
> Cc: kvm@vger.kernel.org
> Cc: linux-arch@vger.kernel.org
> Cc: x86@kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
> Changes from V11:
>  Re-add the missing asm-generic stub for check_and_clear_guest_stopped()
> Changes from V6:
>  Use __this_cpu_and when clearing the PVCLOCK_GUEST_STOPPED flag
> Changes from V5:
>  Collapse generic stubs into this patch
>  check_and_clear_guest_stopped() takes no args and uses __get_cpu_var()
>  Include individual definitions in ia64, s390, and powerpc
> 
>  arch/ia64/include/asm/kvm_para.h    |    5 +++++
>  arch/powerpc/include/asm/kvm_para.h |    5 +++++
>  arch/s390/include/asm/kvm_para.h    |    5 +++++
>  arch/x86/include/asm/kvm_para.h     |    8 ++++++++
>  arch/x86/kernel/kvmclock.c          |   21 +++++++++++++++++++++
>  include/asm-generic/kvm_para.h      |   14 ++++++++++++++
>  6 files changed, 58 insertions(+), 0 deletions(-)
>  create mode 100644 include/asm-generic/kvm_para.h
> 
> diff --git a/arch/ia64/include/asm/kvm_para.h b/arch/ia64/include/asm/kvm_para.h
> index 1588aee..2019cb9 100644
> --- a/arch/ia64/include/asm/kvm_para.h
> +++ b/arch/ia64/include/asm/kvm_para.h
> @@ -26,6 +26,11 @@ static inline unsigned int kvm_arch_para_features(void)
>  	return 0;
>  }
>  
> +static inline bool kvm_check_and_clear_guest_paused(void)
> +{
> +	return false;
> +}
> +
>  #endif
>  
>  #endif
> diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
> index 50533f9..1f80293 100644
> --- a/arch/powerpc/include/asm/kvm_para.h
> +++ b/arch/powerpc/include/asm/kvm_para.h
> @@ -169,6 +169,11 @@ static inline unsigned int kvm_arch_para_features(void)
>  	return r;
>  }
>  
> +static inline bool kvm_check_and_clear_guest_paused(void)
> +{
> +	return false;
> +}
> +
>  #endif /* __KERNEL__ */
>  
>  #endif /* __POWERPC_KVM_PARA_H__ */
> diff --git a/arch/s390/include/asm/kvm_para.h b/arch/s390/include/asm/kvm_para.h
> index 6964db2..a988329 100644
> --- a/arch/s390/include/asm/kvm_para.h
> +++ b/arch/s390/include/asm/kvm_para.h
> @@ -149,6 +149,11 @@ static inline unsigned int kvm_arch_para_features(void)
>  	return 0;
>  }
>  
> +static inline bool kvm_check_and_clear_guest_paused(void)
> +{
> +	return false;
> +}
> +
>  #endif
>  
>  #endif /* __S390_KVM_PARA_H */
> diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
> index 734c376..99c4bbe 100644
> --- a/arch/x86/include/asm/kvm_para.h
> +++ b/arch/x86/include/asm/kvm_para.h
> @@ -95,6 +95,14 @@ struct kvm_vcpu_pv_apf_data {
>  extern void kvmclock_init(void);
>  extern int kvm_register_clock(char *txt);
>  
> +#ifdef CONFIG_KVM_CLOCK
> +bool kvm_check_and_clear_guest_paused(void);
> +#else
> +static inline bool kvm_check_and_clear_guest_paused(void)
> +{
> +	return false;
> +}
> +#endif /* CONFIG_KVMCLOCK */
>  
>  /* This instruction is vmcall.  On non-VT architectures, it will generate a
>   * trap that we will then rewrite to the appropriate instruction.
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index 44842d7..bdf6423 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -22,6 +22,7 @@
>  #include <asm/msr.h>
>  #include <asm/apic.h>
>  #include <linux/percpu.h>
> +#include <linux/hardirq.h>
>  
>  #include <asm/x86_init.h>
>  #include <asm/reboot.h>
> @@ -114,6 +115,26 @@ static void kvm_get_preset_lpj(void)
>  	preset_lpj = lpj;
>  }
>  
> +bool kvm_check_and_clear_guest_paused(void)
> +{
> +	bool ret = false;
> +	struct pvclock_vcpu_time_info *src;
> +
> +	/*
> +	 * per_cpu() is safe here because this function is only called from
> +	 * timer functions where preemption is already disabled.
> +	 */
> +	WARN_ON(!in_atomic());
> +	src = &__get_cpu_var(hv_clock);
> +	if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
> +		__this_cpu_and(hv_clock.flags, ~PVCLOCK_GUEST_STOPPED);
> +		ret = true;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(kvm_check_and_clear_guest_paused);
> +
>  static struct clocksource kvm_clock = {
>  	.name = "kvm-clock",
>  	.read = kvm_clock_get_cycles,
> diff --git a/include/asm-generic/kvm_para.h b/include/asm-generic/kvm_para.h
> new file mode 100644
> index 0000000..05ef7e7
> --- /dev/null
> +++ b/include/asm-generic/kvm_para.h
> @@ -0,0 +1,14 @@
> +#ifndef _ASM_GENERIC_KVM_PARA_H
> +#define _ASM_GENERIC_KVM_PARA_H
> +
> +
> +/*
> + * This function is used by architectures that support kvm to avoid issuing
> + * false soft lockup messages.
> + */
> +static inline bool kvm_check_and_clear_guest_paused(void)
> +{
> +	return false;
> +}
> +
> +#endif

How is the stub getting included for other architectures again?