linux-kernel - Re: [PATCH v3 09/29] arm_mpam: Add MPAM MSC register layout definitions

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Message-ID: <20251024183228.00005a64@huawei.com>
Date: Fri, 24 Oct 2025 18:32:28 +0100
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: James Morse <james.morse@....com>
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Subject: Re: [PATCH v3 09/29] arm_mpam: Add MPAM MSC register layout
 definitions

On Fri, 17 Oct 2025 18:56:25 +0000
James Morse <james.morse@....com> wrote:

> Memory Partitioning and Monitoring (MPAM) has memory mapped devices
> (MSCs) with an identity/configuration page.
> 
> Add the definitions for these registers as offset within the page(s).
> 
> Link: https://developer.arm.com/documentation/ihi0099/latest/

I can't figure out how to get a stable link when there is only
one version.  If possible would be good to use one.

I guess it probably doesn't matter unless someone renames things as
you only have as subset of the fields currently there for some registers.

> Signed-off-by: James Morse <james.morse@....com>
> Reviewed-by: Ben Horgan <ben.horgan@....com>
> Reviewed-by: Fenghua Yu <fenghuay@...dia.com>
> Tested-by: Fenghua Yu <fenghuay@...dia.com>
A few tiny things inline.

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


> ---
>  drivers/resctrl/mpam_internal.h | 268 ++++++++++++++++++++++++++++++++
>  1 file changed, 268 insertions(+)
> 
> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
> index 1a5d96660382..1ef3e8e1d056 100644
> --- a/drivers/resctrl/mpam_internal.h
> +++ b/drivers/resctrl/mpam_internal.h
> @@ -142,4 +142,272 @@ extern struct list_head mpam_classes;
>  int mpam_get_cpumask_from_cache_id(unsigned long cache_id, u32 cache_level,
>  				   cpumask_t *affinity);
>  
> +/*
> + * MPAM MSCs have the following register layout. See:
> + * Arm Memory System Resource Partitioning and Monitoring (MPAM) System
> + * Component Specification.
> + * https://developer.arm.com/documentation/ihi0099/latest/
> + */
> +#define MPAM_ARCHITECTURE_V1    0x10

> +#define MSMON_MBWU_L		0x0880  /* current long mem-bw usage value */
> +#define MSMON_MBWU_CAPTURE_L	0x0890  /* last long mem-bw value captured */
Spec name I'm seeing is
MSMON_MBWU_L_CAPTURE.  Maybe a good idea to match?

> + */
> +#define MSMON_CFG_x_CTL_TYPE			GENMASK(7, 0)
> +#define MSMON_CFG_MBWU_CTL_OFLOW_STATUS_L	BIT(15)
> +#define MSMON_CFG_x_CTL_MATCH_PARTID		BIT(16)
> +#define MSMON_CFG_x_CTL_MATCH_PMG		BIT(17)
> +#define MSMON_CFG_x_CTL_SUBTYPE			GENMASK(22, 20)
> +#define MSMON_CFG_x_CTL_OFLOW_FRZ		BIT(24)
> +#define MSMON_CFG_x_CTL_OFLOW_INTR		BIT(25)
> +#define MSMON_CFG_x_CTL_OFLOW_STATUS		BIT(26)
> +#define MSMON_CFG_x_CTL_CAPT_RESET		BIT(27)
> +#define MSMON_CFG_x_CTL_CAPT_EVNT		GENMASK(30, 28)
> +#define MSMON_CFG_x_CTL_EN			BIT(31)
> +
> +#define MSMON_CFG_MBWU_CTL_TYPE_MBWU		0x42
> +#define MSMON_CFG_CSU_CTL_TYPE_CSU		0x43
> +
> +#define MSMON_CFG_MBWU_CTL_SCLEN		BIT(19)

Why is this one down here, but OFLOW_STATUS_L is in middle of the shared
block of definitions? I don't mind which approach you use, but not a mix.

> +
> +/*
> + * MSMON_CSU - Memory system performance monitor cache storage usage monitor
> + *            register
> + * MSMON_CSU_CAPTURE -  Memory system performance monitor cache storage usage
> + *                     capture register
> + * MSMON_MBWU  - Memory system performance monitor memory bandwidth usage
> + *               monitor register
> + * MSMON_MBWU_CAPTURE - Memory system performance monitor memory bandwidth usage
> + *                     capture register
> + */
> +#define MSMON___VALUE		GENMASK(30, 0)
> +#define MSMON___NRDY		BIT(31)
> +#define MSMON___NRDY_L		BIT(63)
> +#define MSMON___L_VALUE		GENMASK(43, 0)
Positioning of L in these seems a little inconsistent?

> +#define MSMON___LWD_VALUE	GENMASK(62, 0)

>  #endif /* MPAM_INTERNAL_H */