linux-kernel - [PATCH v2 05/29] arm64: kconfig: Add Kconfig entry for MPAM

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Message-Id: <20250910204309.20751-6-james.morse@arm.com>
Date: Wed, 10 Sep 2025 20:42:45 +0000
From: James Morse <james.morse@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-acpi@...r.kernel.org
Cc: James Morse <james.morse@....com>,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com,
	lcherian@...vell.com,
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	David Hildenbrand <david@...hat.com>,
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Subject: [PATCH v2 05/29] arm64: kconfig: Add Kconfig entry for MPAM

The bulk of the MPAM driver lives outside the arch code because it
largely manages MMIO devices that generate interrupts. The driver
needs a Kconfig symbol to enable it. As MPAM is only found on arm64
platforms, the arm64 tree is the most natural home for the Kconfig
option.

This Kconfig option will later be used by the arch code to enable
or disable the MPAM context-switch code, and to register properties
of CPUs with the MPAM driver.

Signed-off-by: James Morse <james.morse@....com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
CC: Dave Martin <dave.martin@....com>
---
Changes since v1:
 * Help text rewritten by Dave.
---
 arch/arm64/Kconfig | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e9bbfacc35a6..4be8a13505bf 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2060,6 +2060,29 @@ config ARM64_TLB_RANGE
 	  ARMv8.4-TLBI provides TLBI invalidation instruction that apply to a
 	  range of input addresses.
 
+config ARM64_MPAM
+	bool "Enable support for MPAM"
+	help
+	  Memory System Resource Partitioning and Monitoring (MPAM) is an
+	  optional extension to the Arm architecture that allows each
+	  transaction issued to the memory system to be labelled with a
+	  Partition identifier (PARTID) and Performance Monitoring Group
+	  identifier (PMG).
+
+	  Memory system components, such as the caches, can be configured with
+	  policies to control how much of various physical resources (such as
+	  memory bandwidth or cache memory) the transactions labelled with each
+	  PARTID can consume.  Depending on the capabilities of the hardware,
+	  the PARTID and PMG can also be used as filtering criteria to measure
+	  the memory system resource consumption of different parts of a
+	  workload.
+
+	  Use of this extension requires CPU support, support in the
+	  Memory System Components (MSC), and a description from firmware
+	  of where the MSCs are in the address space.
+
+	  MPAM is exposed to user-space via the resctrl pseudo filesystem.
+
 endmenu # "ARMv8.4 architectural features"
 
 menu "ARMv8.5 architectural features"
-- 
2.39.5