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

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Message-ID: <20240215080906epcms2p2c49c6b9bfe271e1d089ad35ab527b958@epcms2p2>
Date: Thu, 15 Feb 2024 17:09:06 +0900
From: Hojin Nam <hj96.nam@...sung.com>
To: "linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>,
	"jonathan.cameron@...wei.com" <jonathan.cameron@...wei.com>
CC: 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: [PATCH v2] perf: CXL: fix CPMU filter value mask length

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>
---

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