linux.git/arch/x86/kernel/cpu/intel.c, branch v4.12

x86/arch_prctl: Add ARCH_[GET|SET]_CPUID

2017-03-20T15:10:34+00:00

Intel supports faulting on the CPUID instruction beginning with Ivy Bridge.
When enabled, the processor will fault on attempts to execute the CPUID
instruction with CPL>0. Exposing this feature to userspace will allow a
ptracer to trap and emulate the CPUID instruction.

When supported, this feature is controlled by toggling bit 0 of
MSR_MISC_FEATURES_ENABLES. It is documented in detail in Section 2.3.2 of
https://bugzilla.kernel.org/attachment.cgi?id=243991

Implement a new pair of arch_prctls, available on both x86-32 and x86-64.

ARCH_GET_CPUID: Returns the current CPUID state, either 0 if CPUID faulting
    is enabled (and thus the CPUID instruction is not available) or 1 if
    CPUID faulting is not enabled.

ARCH_SET_CPUID: Set the CPUID state to the second argument. If
    cpuid_enabled is 0 CPUID faulting will be activated, otherwise it will
    be deactivated. Returns ENODEV if CPUID faulting is not supported on
    this system.

The state of the CPUID faulting flag is propagated across forks, but reset
upon exec.

Signed-off-by: Kyle Huey 
Cc: Grzegorz Andrejczuk 
Cc: kvm@vger.kernel.org
Cc: Radim Krčmář 
Cc: Peter Zijlstra 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: linux-kselftest@vger.kernel.org
Cc: Nadav Amit 
Cc: Robert O'Callahan 
Cc: Richard Weinberger 
Cc: "Rafael J. Wysocki" 
Cc: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Len Brown 
Cc: Shuah Khan 
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: Jeff Dike 
Cc: Alexander Viro 
Cc: user-mode-linux-user@lists.sourceforge.net
Cc: David Matlack 
Cc: Boris Ostrovsky 
Cc: Dmitry Safonov 
Cc: linux-fsdevel@vger.kernel.org
Cc: Paolo Bonzini 
Link: http://lkml.kernel.org/r/20170320081628.18952-9-khuey@kylehuey.com
Signed-off-by: Thomas Gleixner

x86/cpufeature: Detect CPUID faulting support

2017-03-20T15:10:34+00:00

Intel supports faulting on the CPUID instruction beginning with Ivy Bridge.
When enabled, the processor will fault on attempts to execute the CPUID
instruction with CPL>0. This will allow a ptracer to emulate the CPUID
instruction.

Bit 31 of MSR_PLATFORM_INFO advertises support for this feature. It is
documented in detail in Section 2.3.2 of
https://bugzilla.kernel.org/attachment.cgi?id=243991

Detect support for this feature and expose it as X86_FEATURE_CPUID_FAULT.

Signed-off-by: Kyle Huey 
Reviewed-by: Borislav Petkov 
Cc: Grzegorz Andrejczuk 
Cc: kvm@vger.kernel.org
Cc: Radim Krčmář 
Cc: Peter Zijlstra 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: linux-kselftest@vger.kernel.org
Cc: Nadav Amit 
Cc: Robert O'Callahan 
Cc: Richard Weinberger 
Cc: "Rafael J. Wysocki" 
Cc: Andy Lutomirski 
Cc: Len Brown 
Cc: Shuah Khan 
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: Jeff Dike 
Cc: Alexander Viro 
Cc: user-mode-linux-user@lists.sourceforge.net
Cc: David Matlack 
Cc: Boris Ostrovsky 
Cc: Dmitry Safonov 
Cc: linux-fsdevel@vger.kernel.org
Cc: Paolo Bonzini 
Link: http://lkml.kernel.org/r/20170320081628.18952-8-khuey@kylehuey.com
Signed-off-by: Thomas Gleixner

x86/msr: Rename MISC_FEATURE_ENABLES to MISC_FEATURES_ENABLES

2017-03-20T15:10:32+00:00

This matches the only public Intel documentation of this MSR, in the
"Virtualization Technology FlexMigration Application Note"
(preserved at https://bugzilla.kernel.org/attachment.cgi?id=243991)

Signed-off-by: Kyle Huey 
Cc: Grzegorz Andrejczuk 
Cc: kvm@vger.kernel.org
Cc: Radim Krčmář 
Cc: Peter Zijlstra 
Cc: Dave Hansen 
Cc: Andi Kleen 
Cc: linux-kselftest@vger.kernel.org
Cc: Nadav Amit 
Cc: Robert O'Callahan 
Cc: Richard Weinberger 
Cc: "Rafael J. Wysocki" 
Cc: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Len Brown 
Cc: Shuah Khan 
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: Jeff Dike 
Cc: Alexander Viro 
Cc: user-mode-linux-user@lists.sourceforge.net
Cc: David Matlack 
Cc: Boris Ostrovsky 
Cc: Dmitry Safonov 
Cc: linux-fsdevel@vger.kernel.org
Cc: Paolo Bonzini 
Link: http://lkml.kernel.org/r/20170320081628.18952-2-khuey@kylehuey.com
Signed-off-by: Thomas Gleixner

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-03-07T22:42:34+00:00

Pull scheduler fixes from Ingo Molnar:
 "A fix for KVM's scheduler clock which (erroneously) was always marked
  unstable, a fix for RT/DL load balancing, plus latency fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface
  sched/core: Fix pick_next_task() for RT,DL
  sched/fair: Make select_idle_cpu() more aggressive

sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface

2017-03-02T07:50:49+00:00

Wanpeng Li reported that since the following commit:

  acb04058de49 ("sched/clock: Fix hotplug crash")

... KVM always runs with unstable sched-clock even though KVM's
kvm_clock _is_ stable.

The problem is that we've tied clear_sched_clock_stable() to the TSC
state, and overlooked that sched_clock() is a paravirt function.

Solve this by doing two things:

 - tie the sched_clock() stable state more clearly to the TSC stable
   state for the normal (!paravirt) case.

 - only call clear_sched_clock_stable() when we mark TSC unstable
   when we use native_sched_clock().

The first means we can actually run with stable sched_clock in more
situations then before, which is good. And since commit:

  12907fbb1a69 ("sched/clock, clocksource: Add optional cs::mark_unstable() method")

... this should be reliable. Since any detection of TSC fail now results
in marking the TSC unstable.

Reported-by: Wanpeng Li 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Paolo Bonzini 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Fixes: acb04058de49 ("sched/clock: Fix hotplug crash")
Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27+00:00

We are going to split  out of , which
will have to be picked up from other headers and .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

Merge branch 'x86-cpufeature-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-02-20T22:37:08+00:00

Pull x86 cpufeature updates from Ingo Molnar:
 "The main changes in this cycle were related to enable ring-3
  MONITOR/MWAIT instructions support on supported CPUs, by Grzegorz
  Andrejczuk and Piotr Luc"

* 'x86-cpufeature-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpufeature: Move RING3MWAIT feature to avoid conflicts
  x86/cpufeature: Enable RING3MWAIT for Knights Mill
  x86/cpufeature: Enable RING3MWAIT for Knights Landing
  x86/cpufeature: Add RING3MWAIT to CPU features
  x86/elf: Add HWCAP2 to expose ring 3 MONITOR/MWAIT
  x86/msr: Add MSR_MISC_FEATURE_ENABLES and RING3MWAIT bit
  x86/cpufeature: Add AVX512_VPOPCNTDQ feature

x86/cpufeature: Enable RING3MWAIT for Knights Mill

2017-02-04T23:19:52+00:00

Enable ring 3 MONITOR/MWAIT for Intel Xeon Phi codenamed Knights Mill. We
can't guarantee that this (KNM) will be the last CPU model that needs this
hack.  But, we do recognize that this is far from optimal, and there is an
effort to ensure we don't keep doing extending this hack forever.

Signed-off-by: Piotr Luc 
Cc: Piotr.Luc@intel.com
Cc: dave.hansen@linux.intel.com
Link: http://lkml.kernel.org/r/1484918557-15481-6-git-send-email-grzegorz.andrejczuk@intel.com
Signed-off-by: Thomas Gleixner

x86/cpufeature: Enable RING3MWAIT for Knights Landing

2017-02-04T07:51:09+00:00

Enable ring 3 MONITOR/MWAIT for Intel Xeon Phi x200 codenamed Knights
Landing.

Presence of this feature cannot be detected automatically (by reading any
other MSR) therefore it is required to explicitly check for the family and
model of the CPU before attempting to enable it.

Signed-off-by: Grzegorz Andrejczuk 
Cc: Piotr.Luc@intel.com
Cc: dave.hansen@linux.intel.com
Link: http://lkml.kernel.org/r/1484918557-15481-5-git-send-email-grzegorz.andrejczuk@intel.com
Signed-off-by: Thomas Gleixner

Merge branch 'linus' into sched/core, to pick up fixes and refresh the branch

2017-02-01T08:12:25+00:00

Signed-off-by: Ingo Molnar