linux-kernel - [PATCH 0/2] x86/intel_rdt: Display CPUs associated with pseudo-locked region

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Date:   Sat, 30 Jun 2018 22:17:31 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     tglx@...utronix.de, fenghua.yu@...el.com, tony.luck@...el.com,
        vikas.shivappa@...ux.intel.com
Cc:     gavin.hindman@...el.com, jithu.joseph@...el.com,
        dave.hansen@...el.com, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Reinette Chatre <reinette.chatre@...el.com>
Subject: [PATCH 0/2] x86/intel_rdt: Display CPUs associated with pseudo-locked region

Dear Maintainers,

The cpus and cpus_list resctrl files are locked down when the resource
group enters pseudo-locksetup mode and remains locked down when the
resource group transitions to pseudo-locked mode. This was done to ensure a
resource group in pseudo-locksetup mode is and remain unused until it
transitions to pseudo-locked mode.

With this series read (but not write) access is restored to the cpus and
cpus_list files after a resource group enters pseudo-locked mode. The
information displayed is also adjusted appropriately. It is now possible
for users to view which cpus are associated with a pseudo-locked region
through the existing cpus and cpus_list resctrl files. Only the tasks file
remains locked down.

For example:
# mount -t resctrl resctrl /sys/fs/resctrl
# cd /sys/fs/resctrl
# echo 'L2:1=0xfc' > schemata
# mkdir p1
# ls -l p1/cpus* p1/tasks
-rw-r--r-- 1 root root 0 Jun 30 06:30 p1/cpus
-rw-r--r-- 1 root root 0 Jun 30 06:30 p1/cpus_list
-rw-r--r-- 1 root root 0 Jun 30 06:30 p1/tasks
# echo pseudo-locksetup > p1/mode
# ls -l p1/cpus* p1/tasks
---------- 1 root root 0 Jun 30 06:30 p1/cpus
---------- 1 root root 0 Jun 30 06:30 p1/cpus_list
---------- 1 root root 0 Jun 30 06:30 p1/tasks
# echo 'L2:1=0x3' > p1/schemata
# ls -l p1/cpus* p1/tasks
-r--r--r-- 1 root root 0 Jun 30 06:30 p1/cpus
-r--r--r-- 1 root root 0 Jun 30 06:30 p1/cpus_list
---------- 1 root root 0 Jun 30 06:30 p1/tasks
# grep . p1/*
p1/cpus:c
p1/cpus_list:2-3
p1/mode:pseudo-locked
p1/schemata:L2:1=3
p1/size:L2:1=262144
grep: p1/tasks: Permission denied

Reinette Chatre (2):
  x86/intel_rdt: Support restoration of subset of permissions
  x86/intel_rdt: cpu information accessible for pseudo-locked regions

 Documentation/x86/intel_rdt_ui.txt          |  3 +++
 arch/x86/kernel/cpu/intel_rdt.h             |  3 ++-
 arch/x86/kernel/cpu/intel_rdt_pseudo_lock.c | 17 ++++++++++-------
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c    | 14 ++++++++++----
 4 files changed, 25 insertions(+), 12 deletions(-)

-- 
2.17.0