linux-kernel - Re: [PATCH v4 06/31] x86/rectrl: Fake OOBMSM interface

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Message-ID: <7fa19421-9093-411b-b8e2-da56156a9971@intel.com>
Date: Wed, 7 May 2025 20:33:26 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.com>, "Maciej
 Wieczor-Retman" <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>, Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v4 06/31] x86/rectrl: Fake OOBMSM interface

Hi Tony,

On 4/28/25 5:33 PM, Tony Luck wrote:


> diff --git a/arch/x86/kernel/cpu/resctrl/fake_intel_aet_features.c b/arch/x86/kernel/cpu/resctrl/fake_intel_aet_features.c
> new file mode 100644
> index 000000000000..22b7c02a538c
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/resctrl/fake_intel_aet_features.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/cleanup.h>
> +#include <linux/minmax.h>
> +#include <linux/slab.h>
> +#include "fake_intel_aet_features.h"
> +#include <linux/intel_vsec.h>
> +#include <linux/resctrl.h>
> +
> +#include "internal.h"
> +
> +/*
> + * Amount of memory for each fake MMIO space
> + * Magic numbers here match values for XML ID 0x26696143 and 0x26557651
> + * 576: Number of RMIDs
> + * 2: Energy events in 0x26557651
> + * 7: Perf events in 0x26696143
> + * 3: Qwords for status counters after the event counters
> + * 8: Bytes for each counter
> + */

Thanks for adding the explanations. This does not answer the question from 
https://lore.kernel.org/lkml/2897fc2a-8977-4415-ae6d-bd0002874b3a@intel.com/
though.

It looks like this sample interface is created to present the scenario where
the energy events do not have sufficient "counters" to support the number of
RMIDs in the MMIO space? It would make this work much easier to review if
these quirks are documented or at least answer the questions during review.  

Reinette