linux-kernel - Re: [PATCH v2] perf: CXL: fix mismatched cpmu event opcode

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Date: Wed, 7 Feb 2024 12:27:43 +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 mismatched cpmu event opcode

On Wed, 07 Feb 2024 13:22:35 +0900
Hojin Nam <hj96.nam@...sung.com> wrote:

> S2M NDR BI-ConflictAck opcode is described as 4 in the CXL
> r3.1 3.3.9 Table 3.50. However, it is defined as 3 in macro definition. Also
> adds s2m_ndr_cmpm for bit 3 that was added in CXL r3.1.
> 
> Fixes: 5d7107c72796 ("perf: CXL Performance Monitoring Unit driver")
> Signed-off-by: Hojin Nam <hj96.nam@...sung.com>

Ah. Sorry I've mislead you. I lazily assumed this was in the 3.0 spec as well
without checking.

As a fix, we should not add the cmpm or update the reference comment.

So should be the v1 patch with a reference to table 3-43 in r3.0
and the fixes tag.

A follow up patch to add the 3.1 definitions would be excellent but we shouldn't
be looking to backport that so it doesn't belong in the fix :(


Jonathan


> ---
> 
> Hi Jonathan,
> I've modified the commit messsge and code to reflect you mentioned. Thank you!
> 
> Changes since v1:
> - Add s2m_ndr_cmpm event attribute (Jonathan)
> 
> 
>  drivers/perf/cxl_pmu.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c
> index 365d964b0f6a..d85d53d907a6 100644
> --- a/drivers/perf/cxl_pmu.c
> +++ b/drivers/perf/cxl_pmu.c
> @@ -415,11 +415,12 @@ static struct attribute *cxl_pmu_event_attrs[] = {
>         CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_curblk,                CXL_PMU_GID_S2M_BISNP, BIT(4)),
>         CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_datblk,                CXL_PMU_GID_S2M_BISNP, BIT(5)),
>         CXL_PMU_EVENT_CXL_ATTR(s2m_bisnp_invblk,                CXL_PMU_GID_S2M_BISNP, BIT(6)),
> -       /* CXL rev 3.0 Table 3-43 S2M NDR Opcopdes */
> +       /* CXL rev 3.1 Table 3-50 S2M NDR Opcopdes */
>         CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmp,                     CXL_PMU_GID_S2M_NDR, BIT(0)),
>         CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmps,                    CXL_PMU_GID_S2M_NDR, BIT(1)),
>         CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmpe,                    CXL_PMU_GID_S2M_NDR, BIT(2)),
> -       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_biconflictack,           CXL_PMU_GID_S2M_NDR, BIT(3)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_cmpm,                    CXL_PMU_GID_S2M_NDR, BIT(3)),
> +       CXL_PMU_EVENT_CXL_ATTR(s2m_ndr_biconflictack,           CXL_PMU_GID_S2M_NDR, BIT(4)),
>         /* CXL rev 3.0 Table 3-46 S2M DRS opcodes */
>         CXL_PMU_EVENT_CXL_ATTR(s2m_drs_memdata,                 CXL_PMU_GID_S2M_DRS, BIT(0)),
>         CXL_PMU_EVENT_CXL_ATTR(s2m_drs_memdatanxm,              CXL_PMU_GID_S2M_DRS, BIT(1)),
> --
> 2.34.1