Re: [PATCH] x86: kvmclock: Do not setup kvmclock vsyscall in the absence of that clock

[Gleb Natapov <gleb@redhat.com>]

On Sat, Feb 23, 2013 at 05:05:29PM +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This fixes boot lockups with "no-kvmclock", when the host is not
> exposing this particular feature (QEMU: -cpu ...,-kvmclock) or when
> the kvmclock initialization failed for whatever reason.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Applied, thanks.

> ---
> 
> Should go to 3.8 as well, I presume.
> 
>  arch/x86/kernel/kvmclock.c |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index 5bedbdd..b730efa 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -160,8 +160,12 @@ int kvm_register_clock(char *txt)
>  {
>  	int cpu = smp_processor_id();
>  	int low, high, ret;
> -	struct pvclock_vcpu_time_info *src = &hv_clock[cpu].pvti;
> +	struct pvclock_vcpu_time_info *src;
> +
> +	if (!hv_clock)
> +		return 0;
>  
> +	src = &hv_clock[cpu].pvti;
>  	low = (int)__pa(src) | 1;
>  	high = ((u64)__pa(src) >> 32);
>  	ret = native_write_msr_safe(msr_kvm_system_time, low, high);
> @@ -276,6 +280,9 @@ int __init kvm_setup_vsyscall_timeinfo(void)
>  	struct pvclock_vcpu_time_info *vcpu_time;
>  	unsigned int size;
>  
> +	if (!hv_clock)
> +		return 0;
> +
>  	size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
>  
>  	preempt_disable();
> -- 
> 1.7.3.4
> 



--
			Gleb.