linux-kernel - RE: [PATCH v3 00/29] arm_mpam: Add basic mpam driver

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Message-ID:
 <OSZPR01MB87983EC9DDD46653231A6C7A8BF0A@OSZPR01MB8798.jpnprd01.prod.outlook.com>
Date: Thu, 23 Oct 2025 08:15:11 +0000
From: "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>
To: 'James Morse' <james.morse@....com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-acpi@...r.kernel.org"
	<linux-acpi@...r.kernel.org>
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 Linton <jeremy.linton@....com>, Gavin Shan <gshan@...hat.com>
Subject: RE: [PATCH v3 00/29] arm_mpam: Add basic mpam driver

Hello James,

> This series is based on v6.18-rc4, and can be retrieved from:
> https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git
> mpam/driver/v3
> 
> The rest of the driver can be found here:
> https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git
> mpam/snapshot/v6.18-rc1

This series(mpam/driver/v3) based on v6.18-rc1 and mpam driver(mpam/snapshot/v6.18-rc1) can not run on my machine(The cause is still unknown),
But I applied this series and mpam driver on v6.18-rc2, they are run successfully.

Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>

However, I make a few minor fixes as follows:

1)
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index f890d1381af6..dd6041ae7cc9 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -645,6 +645,13 @@ static inline void mpam_resctrl_teardown_class(struct mpam_class *class) { }
 #define MPAMF_IIDR_VARIANT     GENMASK(19, 16)
 #define MPAMF_IIDR_PRODUCTID   GENMASK(31, 20)
+#define MPAMF_IIDR_REVISON_SHIFT       12
+//#define MPAMF_IIDR_REVISION_SHIFT    12
+#define MPAMF_IIDR_IMPLEMENTER_SHIFT    0
+#define MPAMF_IIDR_VARIANT_SHIFT    16
+#define MPAMF_IIDR_PRODUCTID_SHIFT    20

or
#define IIDR_REV(x)     ((x) << MPAMF_IIDR_REVISON_SHIFT)
s/MPAMF_IIDR_REVISON_SHIFT/MPAMF_IIDR_REVISION_SHIFT/


2)
diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
index 0ea76b7783b6..99b2bbb80a5a 100644
--- a/drivers/resctrl/mpam_resctrl.c
+++ b/drivers/resctrl/mpam_resctrl.c
@@ -1113,9 +1118,9 @@ static void mpam_resctrl_pick_counters(void)
                                        update_rmid_limits(cache_size);

                                counter_update_class(QOS_L3_OCCUP_EVENT_ID, class);
-                               return;
+                               break;
                        default:
-                               return;
+                               break;
                        }
                }


3)
when building this series(mpam/driver/v3),the `EXPERT` Kconfig option needs to be explicitly enabled.
This aligns with Ben's observation in the following patch:
https://lore.kernel.org/lkml/146ad8f4-ef6c-48cb-aed8-db619c8258a8@arm.com/


Best regards,
Shaopeng TAN