linux-kernel - Re: [RFC PATCH 09/36] arm64: kconfig: Add Kconfig entry for MPAM

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Message-ID: <20250716172652.00005a76@huawei.com>
Date: Wed, 16 Jul 2025 17:26:52 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: James Morse <james.morse@....com>
CC: <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	"Rob Herring" <robh@...nel.org>, Ben Horgan <ben.horgan@....com>, Rohit
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Subject: Re: [RFC PATCH 09/36] arm64: kconfig: Add Kconfig entry for MPAM

On Fri, 11 Jul 2025 18:36:21 +0000
James Morse <james.morse@....com> wrote:

> 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, that is where the Kconfig option makes the most sense.
> 
> This Kconfig option will later be used by the arch code to enable
> or disable the MPAM context-switch code, and registering the CPUs
> properties with the MPAM driver.
> 
> Signed-off-by: James Morse <james.morse@....com>

Seems like a reasonable help test so FWIW

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

> ---
>  arch/arm64/Kconfig | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 55fc331af337..5f08214537d0 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -2058,6 +2058,23 @@ 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 Partitioning and Monitoring is an optional extension
> +	  that allows the CPUs to mark load and store transactions with
> +	  labels for partition-id and performance-monitoring-group.
> +	  System components, such as the caches, can use the partition-id
> +	  to apply a performance policy. MPAM monitors can use the
> +	  partition-id and performance-monitoring-group to measure the
> +	  cache occupancy or data throughput.
> +
> +	  Use of this extension requires CPU support, support in the
> +	  memory system components (MSC), and a description from firmware
> +	  of where the MSC 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"