linux-kernel - Re: [PATCH v2] perf: CXL: fix CPMU filter value mask length

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Message-ID: <20240215092712.000048cd@Huawei.com>
Date: Thu, 15 Feb 2024 09:27:12 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Hojin Nam <hj96.nam@...sung.com>
CC: "linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>, Wonjae Lee
	<wj28.lee@...sung.com>, KyungSan Kim <ks0204.kim@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "will@...nel.org" <will@...nel.org>,
	"mark.rutland@....com" <mark.rutland@....com>
Subject: Re: [PATCH v2] perf: CXL: fix CPMU filter value mask length

On Thu, 15 Feb 2024 17:09:06 +0900
Hojin Nam <hj96.nam@...sung.com> wrote:

> CPMU filter value is described as 4B length in CXL r3.0 8.2.7.2.2.
> However, it is used as 2B length in code and comments.
> 
> Signed-off-by: Hojin Nam <hj96.nam@...sung.com>

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

Thanks for tidying this up.

> ---
> 
> Hi Jonathan,
> as you said, I didn't actually hit this. I just found it by simply
> comparing the code to the CXL Spec. I removed Fixes tag and 
> repaired broken sign off, Thank you!
> 
> Changes since v1:
> - Remove Fixes tag (Jonathan)
> - Repair broken sign off (Jonathan)
> 
>  drivers/perf/cxl_pmu.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c
> index 365d964b0f6a..ca5e92f28b4a 100644
> --- a/drivers/perf/cxl_pmu.c
> +++ b/drivers/perf/cxl_pmu.c
> @@ -59,7 +59,7 @@
>  #define   CXL_PMU_COUNTER_CFG_EVENT_GRP_ID_IDX_MSK     GENMASK_ULL(63, 59)
> 
>  #define CXL_PMU_FILTER_CFG_REG(n, f)   (0x400 + 4 * ((f) + (n) * 8))
> -#define   CXL_PMU_FILTER_CFG_VALUE_MSK                 GENMASK(15, 0)
> +#define   CXL_PMU_FILTER_CFG_VALUE_MSK                 GENMASK(31, 0)
> 
>  #define CXL_PMU_COUNTER_REG(n)         (0xc00 + 8 * (n))
> 
> @@ -314,9 +314,9 @@ static bool cxl_pmu_config1_get_edge(struct perf_event *event)
>  }
> 
>  /*
> - * CPMU specification allows for 8 filters, each with a 16 bit value...
> - * So we need to find 8x16bits to store it in.
> - * As the value used for disable is 0xffff, a separate enable switch
> + * CPMU specification allows for 8 filters, each with a 32 bit value...
> + * So we need to find 8x32bits to store it in.
> + * As the value used for disable is 0xffff_ffff, a separate enable switch
>   * is needed.
>   */
> 
> @@ -642,7 +642,7 @@ static void cxl_pmu_event_start(struct perf_event *event, int flags)
>                 if (cxl_pmu_config1_hdm_filter_en(event))
>                         cfg = cxl_pmu_config2_get_hdm_decoder(event);
>                 else
> -                       cfg = GENMASK(15, 0); /* No filtering if 0xFFFF_FFFF */
> +                       cfg = GENMASK(31, 0); /* No filtering if 0xFFFF_FFFF */
>                 writeq(cfg, base + CXL_PMU_FILTER_CFG_REG(hwc->idx, 0));
>         }
> 
> --
> 2.34.1