linux-kernel - Re: [Xen-devel] Stop the continuous flood of (XEN) traps.c:2432:d0 Domain attempted WRMSR ..

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Date:	Thu, 29 Mar 2012 00:19:47 +0300
From:	Pasi Kärkkäinen <pasik@....fi>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Konrad Rzeszutek Wilk <konrad@...nok.org>, mjg@...hat.com,
	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com
Subject: Re: [Xen-devel] Stop the continuous flood of (XEN) traps.c:2432:d0
	Domain attempted WRMSR ..

On Wed, Mar 28, 2012 at 04:29:07PM -0400, Konrad Rzeszutek Wilk wrote:
> > > 
> > > Jesse, and Matthew,
> > > 
> > > Is there a way to make the intel_ips.c driver be in a "low-power" state?
> > > 
> > > My first thought about fixing this was that we could allow the
> > > hypervisor to allow those RDMSR but the Linux kernel has no power to
> > > actually influence the power management (as the hypervisor is in charge
> > > of that) - so would the driver be capable of just sitting back and
> > > not influencing the CPU?
> > 
> > Yeah it's easy enough to turn off or disable.  But it doesn't currently
> > export any knobs for controlling behavior.  I don't have any issue with
> > exposing some though...
> 
> Pasi,
> 
> Could you test the two patches independetly of each other? Meaning
> test the Linux one without the Xen one, and vice-versa.
> 

Sure, I'll give it a try during the weekend when I'm able to access the box in question.

Thanks! 

-- Pasi




> diff --git a/drivers/platform/x86/intel_ips.c b/drivers/platform/x86/intel_ips.c
> index 88a98cf..7276831 100644
> --- a/drivers/platform/x86/intel_ips.c
> +++ b/drivers/platform/x86/intel_ips.c
> @@ -1407,6 +1407,10 @@ static struct ips_mcp_limits *ips_detect_cpu(struct ips_driver *ips)
>  	}
>  
>  	rdmsrl(TURBO_POWER_CURRENT_LIMIT, turbo_power);
> +	if (turbo_power == 0) {
> +		ips->turbo_toggle_allowed = false;
> +		return NULL;
> +	}
>  	tdp = turbo_power & TURBO_TDP_MASK;
>  
>  	/* Sanity check TDP against CPU */

> diff -r 8e2690dbec49 xen/arch/x86/traps.c
> --- a/xen/arch/x86/traps.c	Sat Mar 24 13:13:49 2012 -0400
> +++ b/xen/arch/x86/traps.c	Wed Mar 28 16:27:31 2012 -0400
> @@ -1746,7 +1746,8 @@ void (*pv_post_outb_hook)(unsigned int p
>  static inline uint64_t guest_misc_enable(uint64_t val)
>  {
>      val &= ~(MSR_IA32_MISC_ENABLE_PERF_AVAIL |
> -             MSR_IA32_MISC_ENABLE_MONITOR_ENABLE);
> +             MSR_IA32_MISC_ENABLE_MONITOR_ENABLE |
> +             MSR_IA32_MISC_ENABLE_TURBO);
>      val |= MSR_IA32_MISC_ENABLE_BTS_UNAVAIL |
>             MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL |
>             MSR_IA32_MISC_ENABLE_XTPR_DISABLE;
> diff -r 8e2690dbec49 xen/include/asm-x86/msr-index.h
> --- a/xen/include/asm-x86/msr-index.h	Sat Mar 24 13:13:49 2012 -0400
> +++ b/xen/include/asm-x86/msr-index.h	Wed Mar 28 16:27:31 2012 -0400
> @@ -327,6 +327,7 @@
>  #define MSR_IA32_MISC_ENABLE_MONITOR_ENABLE (1<<18)
>  #define MSR_IA32_MISC_ENABLE_LIMIT_CPUID  (1<<22)
>  #define MSR_IA32_MISC_ENABLE_XTPR_DISABLE (1<<23)
> +#define MSR_IA32_MISC_ENABLE_TURBO        (1<<38)
>  
>  #define MSR_IA32_TSC_DEADLINE		0x000006E0
>  #define MSR_IA32_ENERGY_PERF_BIAS	0x000001b0

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