linux-kernel - Re: [PATCH v1 04/31] x86/resctrl: Add helper for setting CPU default properties

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Date: Mon, 8 Apr 2024 20:15:03 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Fenghua Yu <fenghua.yu@...el.com>, 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>
Subject: Re: [PATCH v1 04/31] x86/resctrl: Add helper for setting CPU default
 properties

Hi James,

On 3/21/2024 9:50 AM, James Morse wrote:

> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -3623,14 +3623,18 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
>  static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
>  {
>  	struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
> +	u32 closid, rmid;
>  	int cpu;
>  
>  	/* Give any tasks back to the parent group */
>  	rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
>  
>  	/* Update per cpu rmid of the moved CPUs first */
> +	closid = rdtgrp->closid;
> +	rmid = prdtgrp->mon.rmid;
>  	for_each_cpu(cpu, &rdtgrp->cpu_mask)
> -		per_cpu(pqr_state.default_rmid, cpu) = prdtgrp->mon.rmid;
> +		resctrl_arch_set_cpu_default_closid_rmid(cpu, closid, rmid);
> +

While I understand that the CLOSIDs are the same, I do think it looks unexpected
for the CLOSID to be set to the CLOSID of the group being removed. Could this
be set to CLOSID of parent group instead?

Reinette