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

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
...@@ -35,7 +35,8 @@ obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o ...@@ -35,7 +35,8 @@ obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o
obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o
obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o obj-$(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-$(CONFIG_X86_MCE) += mcheck/
obj-$(CONFIG_MTRR) += mtrr/ obj-$(CONFIG_MTRR) += mtrr/
......
// 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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