linux-kernel - Re: [PATCH 2/7] x86/msr: Add PerfCntrGlobal* registers

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Date:   Thu, 17 Mar 2022 12:25:47 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Sandipan Das <sandipan.das@....com>
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        x86@...nel.org, bp@...en8.de, dave.hansen@...ux.intel.com,
        acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, namhyung@...nel.org,
        jolsa@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        pbonzini@...hat.com, jmattson@...gle.com, like.xu.linux@...il.com,
        eranian@...gle.com, ananth.narayan@....com, ravi.bangoria@....com,
        santosh.shukla@....com
Subject: Re: [PATCH 2/7] x86/msr: Add PerfCntrGlobal* registers

On Thu, Mar 17, 2022 at 11:58:31AM +0530, Sandipan Das wrote:
> Add MSR definitions that will be used to enable the new AMD
> Performance Monitoring Version 2 (PerfMonV2) features. These
> include:
> 
>   * Performance Counter Global Control (PerfCntrGlobalCtl)
>   * Performance Counter Global Status (PerfCntrGlobalStatus)
>   * Performance Counter Global Status Clear (PerfCntrGlobalStatusClr)
> 
> The new Performance Counter Global Control and Status MSRs
> provide an interface for enabling or disabling multiple
> counters at the same time and for testing overflow without
> probing the individual registers for each PMC.
> 
> The availability of these registers is indicated through the
> PerfMonV2 feature bit of CPUID Fn80000022[EAX].
> 
> Signed-off-by: Sandipan Das <sandipan.das@....com>
> ---
>  arch/x86/include/asm/msr-index.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
> index a4a39c3e0f19..61d1a55e15b8 100644
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -504,6 +504,11 @@
>  #define AMD_CPPC_DES_PERF(x)		(((x) & 0xff) << 16)
>  #define AMD_CPPC_ENERGY_PERF_PREF(x)	(((x) & 0xff) << 24)
>  
> +/* AMD Performance Counter Global Status and Control MSRs */
> +#define MSR_AMD64_PERF_CNTR_GLOBAL_STATUS	0xc0000300
> +#define MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR	0xc0000302
> +#define MSR_AMD64_PERF_CNTR_GLOBAL_CTL		0xc0000301

My OCD would suggest ordering them by number :-)