linux-kernel - Re: [PATCH v6 13/42] x86/resctrl: Move resctrl types to a separate header

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Message-ID: <8ff43700-25f4-4606-ba99-3ed71721d9fe@intel.com>
Date: Wed, 19 Feb 2025 15:29:45 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>, H Peter Anvin <hpa@...or.com>, Babu Moger
	<Babu.Moger@....com>, <shameerali.kolothum.thodi@...wei.com>, "D Scott
 Phillips OS" <scott@...amperecomputing.com>, <carl@...amperecomputing.com>,
	<lcherian@...vell.com>, <bobo.shaobowang@...wei.com>,
	<tan.shaopeng@...itsu.com>, <baolin.wang@...ux.alibaba.com>, Jamie Iles
	<quic_jiles@...cinc.com>, Xin Hao <xhao@...ux.alibaba.com>,
	<peternewman@...gle.com>, <dfustini@...libre.com>, <amitsinght@...vell.com>,
	David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
	"Dave Martin" <dave.martin@....com>, Koba Ko <kobak@...dia.com>, Shanker
 Donthineni <sdonthineni@...dia.com>, Shaopeng Tan
	<tan.shaopeng@...fujitsu.com>, "Tony Luck" <tony.luck@...el.com>
Subject: Re: [PATCH v6 13/42] x86/resctrl: Move resctrl types to a separate
 header

Hi James,

On 2/7/25 10:17 AM, James Morse wrote:
> When resctrl is fully factored into core and per-arch code, each arch
> will need to use some resctrl common definitions in order to define its
> own specializations and helpers.  Following conventional practice, it
> would be desirable to put the dependent arch definitions in an
> <asm/resctrl.h> header that is included by the common <linux/resctrl.h>
> header.  However, this can make it awkward to avoid a circular
> dependency between <linux/resctrl.h> and the arch header.
> 
> To avoid such dependencies, move the affected common types and
> constants into a new header that does not need to depend on
> <linux/resctrl.h> or on the arch headers.
> 
> The same logic applies to the monitor-configuration defines, move these
> too.
> 
> Some kind of enumeration for events is needed between the filesystem
> and architecture code. Take the x86 definition as its convenient for
> x86.
> 
> The definition of enum resctrl_event_id is needed to allow the
> architecture code to define resctrl_arch_mon_ctx_alloc() and
> resctrl_arch_mon_ctx_free().
> 
> The definition of enum resctrl_res_level is needed to allow the
> architecture code to define resctrl_arch_set_cdp_enabled() and
> resctrl_arch_get_cdp_enabled().
> 
> The bits for mbm_local_bytes_config et al are ABI, and must be the same
> on all architectures. These are documented in
> Documentation/arch/x86/resctrl.rst
> 
> The maintainers entry for these headers was missed when resctrl.h was
> created. Add a wildcard entry to match both resctrl.h and
> resctrl_types.h.
> 
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Carl Worth <carl@...amperecomputing.com> # arm64
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> ---

...


> diff --git a/include/linux/resctrl_types.h b/include/linux/resctrl_types.h
> new file mode 100644
> index 000000000000..51c51a1aabfb
> --- /dev/null
> +++ b/include/linux/resctrl_types.h
> @@ -0,0 +1,54 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2024 Arm Ltd.

Please note year.

> + * Based on arch/x86/kernel/cpu/resctrl/internal.h
> + */
> +
> +#ifndef __LINUX_RESCTRL_TYPES_H
> +#define __LINUX_RESCTRL_TYPES_H
> +
> +/* Reads to Local DRAM Memory */
> +#define READS_TO_LOCAL_MEM		BIT(0)
> +
> +/* Reads to Remote DRAM Memory */
> +#define READS_TO_REMOTE_MEM		BIT(1)
> +
> +/* Non-Temporal Writes to Local Memory */
> +#define NON_TEMP_WRITE_TO_LOCAL_MEM	BIT(2)
> +
> +/* Non-Temporal Writes to Remote Memory */
> +#define NON_TEMP_WRITE_TO_REMOTE_MEM	BIT(3)
> +
> +/* Reads to Local Memory the system identifies as "Slow Memory" */
> +#define READS_TO_LOCAL_S_MEM		BIT(4)
> +
> +/* Reads to Remote Memory the system identifies as "Slow Memory" */
> +#define READS_TO_REMOTE_S_MEM		BIT(5)
> +
> +/* Dirty Victims to All Types of Memory */
> +#define DIRTY_VICTIMS_TO_ALL_MEM	BIT(6)
> +
> +/* Max event bits supported */
> +#define MAX_EVT_CONFIG_BITS		GENMASK(6, 0)
> +
> +enum resctrl_res_level {
> +	RDT_RESOURCE_L3,
> +	RDT_RESOURCE_L2,
> +	RDT_RESOURCE_MBA,
> +	RDT_RESOURCE_SMBA,
> +
> +	/* Must be the last */
> +	RDT_NUM_RESOURCES,
> +};
> +
> +/*
> + * Event IDs, the values match those used to program IA32_QM_EVTSEL before
> + * reading IA32_QM_CTR on RDT systems.
> + */
> +enum resctrl_event_id {
> +	QOS_L3_OCCUP_EVENT_ID		= 0x01,
> +	QOS_L3_MBM_TOTAL_EVENT_ID	= 0x02,
> +	QOS_L3_MBM_LOCAL_EVENT_ID	= 0x03,
> +};
> +
> +#endif /* __LINUX_RESCTRL_TYPES_H */

Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette