Commit 2a5d76a4 authored by Reinette Chatre's avatar Reinette Chatre Committed by Thomas Gleixner
Browse files

x86/intel_rdt: Utilities to restrict/restore access to specific files 



In support of Cache Pseudo-Locking we need to restrict access to specific
resctrl files to protect the state of a resource group used for
pseudo-locking from being changed in unsupported ways.

Introduce two utilities that can be used to either restrict or restore the
access to all files irrelevant to cache pseudo-locking when pseudo-locking
in progress for the resource group.

At this time introduce a new source file, intel_rdt_pseudo_lock.c, that
will contain most of the code related to cache pseudo-locking.

Temporarily mark these new functions as unused to silence compile warnings
until they are used.

Signed-off-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: fenghua.yu@intel.com
Cc: tony.luck@intel.com
Cc: vikas.shivappa@linux.intel.com
Cc: gavin.hindman@intel.com
Cc: jithu.joseph@intel.com
Cc: dave.hansen@intel.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/ab6319d1244366be3f9b7f9fba1c3da4810a274b.1529706536.git.reinette.chatre@intel.com
parent c966dac8

arch/x86/kernel/cpu/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -35,7 +35,8 @@ obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o 
obj-$(CONFIG_CPU_SUP_TRANSMETA_32)	+= transmeta.o

obj-$(CONFIG_CPU_SUP_UMC_32)		+= umc.o



obj-$(CONFIG_INTEL_RDT)	+= intel_rdt.o intel_rdt_rdtgroup.o intel_rdt_monitor.o intel_rdt_ctrlmondata.o

obj-$(CONFIG_INTEL_RDT)	+= intel_rdt.o intel_rdt_rdtgroup.o intel_rdt_monitor.o

obj-$(CONFIG_INTEL_RDT)	+= intel_rdt_ctrlmondata.o intel_rdt_pseudo_lock.o



obj-$(CONFIG_X86_MCE)			+= mcheck/

obj-$(CONFIG_MTRR)			+= mtrr/

arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c

0 → 100644
+113 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Resource Director Technology (RDT)

 *

 * Pseudo-locking support built on top of Cache Allocation Technology (CAT)

 *

 * Copyright (C) 2018 Intel Corporation

 *

 * Author: Reinette Chatre <reinette.chatre@intel.com>

 */



#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt



#include "intel_rdt.h"



/**

 * rdtgroup_locksetup_user_restrict - Restrict user access to group

 * @rdtgrp: resource group needing access restricted

 *

 * A resource group used for cache pseudo-locking cannot have cpus or tasks

 * assigned to it. This is communicated to the user by restricting access

 * to all the files that can be used to make such changes.

 *

 * Permissions restored with rdtgroup_locksetup_user_restore()

 *

 * Return: 0 on success, <0 on failure. If a failure occurs during the

 * restriction of access an attempt will be made to restore permissions but

 * the state of the mode of these files will be uncertain when a failure

 * occurs.

 */

static int __attribute__ ((unused))

rdtgroup_locksetup_user_restrict(struct rdtgroup *rdtgrp)

{

	int ret;



	ret = rdtgroup_kn_mode_restrict(rdtgrp, "tasks");

	if (ret)

		return ret;



	ret = rdtgroup_kn_mode_restrict(rdtgrp, "cpus");

	if (ret)

		goto err_tasks;



	ret = rdtgroup_kn_mode_restrict(rdtgrp, "cpus_list");

	if (ret)

		goto err_cpus;



	if (rdt_mon_capable) {

		ret = rdtgroup_kn_mode_restrict(rdtgrp, "mon_groups");

		if (ret)

			goto err_cpus_list;

	}



	ret = 0;

	goto out;



err_cpus_list:

	rdtgroup_kn_mode_restore(rdtgrp, "cpus_list");

err_cpus:

	rdtgroup_kn_mode_restore(rdtgrp, "cpus");

err_tasks:

	rdtgroup_kn_mode_restore(rdtgrp, "tasks");

out:

	return ret;

}



/**

 * rdtgroup_locksetup_user_restore - Restore user access to group

 * @rdtgrp: resource group needing access restored

 *

 * Restore all file access previously removed using

 * rdtgroup_locksetup_user_restrict()

 *

 * Return: 0 on success, <0 on failure.  If a failure occurs during the

 * restoration of access an attempt will be made to restrict permissions

 * again but the state of the mode of these files will be uncertain when

 * a failure occurs.

 */

static int __attribute__ ((unused))

rdtgroup_locksetup_user_restore(struct rdtgroup *rdtgrp)

{

	int ret;



	ret = rdtgroup_kn_mode_restore(rdtgrp, "tasks");

	if (ret)

		return ret;



	ret = rdtgroup_kn_mode_restore(rdtgrp, "cpus");

	if (ret)

		goto err_tasks;



	ret = rdtgroup_kn_mode_restore(rdtgrp, "cpus_list");

	if (ret)

		goto err_cpus;



	if (rdt_mon_capable) {

		ret = rdtgroup_kn_mode_restore(rdtgrp, "mon_groups");

		if (ret)

			goto err_cpus_list;

	}



	ret = 0;

	goto out;



err_cpus_list:

	rdtgroup_kn_mode_restrict(rdtgrp, "cpus_list");

err_cpus:

	rdtgroup_kn_mode_restrict(rdtgrp, "cpus");

err_tasks:

	rdtgroup_kn_mode_restrict(rdtgrp, "tasks");

out:

	return ret;

}

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