Re: [Xen-devel] [PATCH v2 2/3] x86/VPMU: Disable VPMU when NMI watchdog is on

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.01.15 at 18:58, <boris.ostrovsky@xxxxxxxxxx> wrote:
> @@ -219,6 +220,13 @@ void vpmu_initialise(struct vcpu *v)
>      uint8_t vendor = current_cpu_data.x86_vendor;
>      int ret;
>  
> +    /* NMI watchdog uses LVTPC and HW counter */
> +    if ( opt_watchdog && opt_vpmu_enabled )
> +    {
> +        printk(XENLOG_G_WARNING "NMI watchdog is enabled. Turning VPMU 
> off.\n");
> +        opt_vpmu_enabled = 0;
> +    }

I think this should be a boot time warning (and not guest level, so it
won't become suppressed due to rate limiting when default are in
effect), and I thought you said so on the previous version's thread
too. If there's no other suitable place, just add a small initcall.

> --- a/xen/arch/x86/nmi.c
> +++ b/xen/arch/x86/nmi.c
> @@ -42,7 +42,7 @@ static DEFINE_PER_CPU(struct timer, nmi_timer);
>  static DEFINE_PER_CPU(unsigned int, nmi_timer_ticks);
>  
>  /* opt_watchdog: If true, run a watchdog NMI on each processor. */
> -bool_t __initdata opt_watchdog = 0;
> +bool_t __read_mostly opt_watchdog = 0;

The above would eliminate the need for this change too.

Jan


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