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authorReinette Chatre <reinette.chatre@intel.com>2018-12-10 13:21:54 -0800
committerBorislav Petkov <bp@suse.de>2018-12-11 21:59:01 +0100
commit80b71c340f17705ec145911b9a193ea781811b16 (patch)
tree7c581fbeb3f992693642db5acddaf25c10e0038b /arch
parent254eb5505ca0ca749d3a491fc6668b6c16647a99 (diff)
x86/intel_rdt: Ensure a CPU remains online for the region's pseudo-locking sequence
The user triggers the creation of a pseudo-locked region when writing the requested schemata to the schemata resctrl file. The pseudo-locking of a region is required to be done on a CPU that is associated with the cache on which the pseudo-locked region will reside. In order to run the locking code on a specific CPU, the needed CPU has to be selected and ensured to remain online during the entire locking sequence. At this time, the cpu_hotplug_lock is not taken during the pseudo-lock region creation and it is thus possible for a CPU to be selected to run the pseudo-locking code and then that CPU to go offline before the thread is able to run on it. Fix this by ensuring that the cpu_hotplug_lock is taken while the CPU on which code has to run needs to be controlled. Since the cpu_hotplug_lock is always taken before rdtgroup_mutex the lock order is maintained. Fixes: e0bdfe8e36f3 ("x86/intel_rdt: Support creation/removal of pseudo-locked region") Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: gavin.hindman@intel.com Cc: jithu.joseph@intel.com Cc: stable <stable@vger.kernel.org> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/b7b17432a80f95a1fa21a1698ba643014f58ad31.1544476425.git.reinette.chatre@intel.com
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
index 27937458c231..efa4a519f5e5 100644
--- a/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
+++ b/arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c
@@ -23,6 +23,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/cpu.h>
#include <linux/kernfs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
@@ -310,9 +311,11 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
return -EINVAL;
buf[nbytes - 1] = '\0';
+ cpus_read_lock();
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
rdtgroup_kn_unlock(of->kn);
+ cpus_read_unlock();
return -ENOENT;
}
rdt_last_cmd_clear();
@@ -367,6 +370,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
out:
rdtgroup_kn_unlock(of->kn);
+ cpus_read_unlock();
return ret ?: nbytes;
}