linux-kernel - Re: [PATCH v2] perf/x86: Fix HO/GO counting with SVM disabled

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Date:	Wed, 29 Feb 2012 19:00:09 +0200
From:	Avi Kivity <avi@...hat.com>
To:	Joerg Roedel <joerg.roedel@....com>
CC:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org, joro@...tes.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Stephane Eranian <eranian@...gle.com>,
	David Ahern <dsahern@...il.com>,
	Gleb Natapov <gleb@...hat.com>,
	Robert Richter <robert.richter@....com>
Subject: Re: [PATCH v2] perf/x86: Fix HO/GO counting with SVM disabled

On 02/29/2012 03:57 PM, Joerg Roedel wrote:
> It turned out that a performance counter on AMD does not
> count at all when the GO or HO bit is set in the control
> register and SVM is disabled in EFER.
>
> This patch works around this issue by masking out the HO bit
> in the performance counter control register when SVM is not
> enabled.
>
> The GO bit is not touched because it is only set when the
> user wants to count in guest-mode only. So when SVM is
> disabled the counter should not run at all and the
> not-counting is the intended behaviour.
>
> diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
> index 0397b23..67250a5 100644
> --- a/arch/x86/kernel/cpu/perf_event_amd.c
> +++ b/arch/x86/kernel/cpu/perf_event_amd.c
> @@ -1,4 +1,5 @@
>  #include <linux/perf_event.h>
> +#include <linux/export.h>
>  #include <linux/types.h>
>  #include <linux/init.h>
>  #include <linux/slab.h>
> @@ -357,7 +358,9 @@ static void amd_pmu_cpu_starting(int cpu)
>  	struct amd_nb *nb;
>  	int i, nb_id;
>  
> -	if (boot_cpu_data.x86_max_cores < 2)
> +	cpuc->perf_ctr_virt_mask = AMD_PERFMON_EVENTSEL_HOSTONLY;
> +
> +	if (boot_cpu_data.x86_max_cores < 2 || boot_cpu_data.x86 == 0x15)
>  		return;

Why this (boot_cpu_data.x86 == 0x15) change?



-- 
error compiling committee.c: too many arguments to function

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