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Date: Tue, 19 Jun 2018 17:23:51 -0700
From: tip-bot for Reinette Chatre <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: reinette.chatre@...el.com, mingo@...nel.org,
linux-kernel@...r.kernel.org, tglx@...utronix.de, hpa@...or.com
Subject: [tip:x86/cache] x86/intel_rdt: Utilities to restrict/restore access
to specific files
Commit-ID: 59abca1db18cef53bc0cfad1f538b3c9a0495bc6
Gitweb: https://git.kernel.org/tip/59abca1db18cef53bc0cfad1f538b3c9a0495bc6
Author: Reinette Chatre <reinette.chatre@...el.com>
AuthorDate: Tue, 29 May 2018 05:57:46 -0700
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 20 Jun 2018 00:56:34 +0200
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: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: fenghua.yu@...el.com
Cc: tony.luck@...el.com
Cc: vikas.shivappa@...ux.intel.com
Cc: gavin.hindman@...el.com
Cc: jithu.joseph@...el.com
Cc: dave.hansen@...el.com
Cc: hpa@...or.com
Link: https://lkml.kernel.org/r/398e0fc7313bee62db55215fe9fd87df67f1b366.1527593971.git.reinette.chatre@intel.com
---
arch/x86/kernel/cpu/Makefile | 3 +-
arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c | 113 ++++++++++++++++++++++++++++
2 files changed, 115 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 7a40196967cb..c4e02555563a 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -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/
diff --git a/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
new file mode 100644
index 000000000000..dc79b3090ac5
--- /dev/null
+++ b/arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c
@@ -0,0 +1,113 @@
+// 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@...el.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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