- Use the more current logging style pr_<level>(...) instead of the old
   printk(KERN_<LEVEL> ...).

 - Convert pr_warning() to pr_warn().
Signed-off-by: NChen Yucong <slaoub@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1454384702-21707-1-git-send-email-slaoub@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The caller of force_ibs_eilvt_setup() is ibs_eilvt_setup()
which does not care about the return values.

So mark it void and clean up the return statements.
Signed-off-by: NAravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: <hpa@zytor.com>
Cc: <paulus@samba.org>
Cc: <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1422037175-20957-1-git-send-email-aravind.gopalakrishnan@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

New Fam15h models carry extra feature bits and extend
the MSR register space for IBS ops. Adding them here.

While at it, add functionality to read IbsBrTarget and
OpData4 depending on their availability if user wants a
PERF_SAMPLE_RAW.
Signed-off-by: NAravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Acked-by: NBorislav Petkov <bp@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <paulus@samba.org>
Cc: <acme@kernel.org>
Link: http://lkml.kernel.org/r/1415651066-13523-1-git-send-email-Aravind.Gopalakrishnan@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Use NOKPROBE_SYMBOL macro for protecting functions
from kprobes instead of __kprobes annotation under
arch/x86.

This applies nokprobe_inline annotation for some cases,
because NOKPROBE_SYMBOL() will inhibit inlining by
referring the symbol address.

This just folds a bunch of previous NOKPROBE_SYMBOL()
cleanup patches for x86 to one patch.
Signed-off-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/20140417081814.26341.51656.stgit@ltc230.yrl.intra.hitachi.co.jp
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fernando Luis Vázquez Cao <fernando_b1@lab.ntt.co.jp>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Lebon <jlebon@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

Instead, the correct and race-free way of performing the callback
registration is:

	cpu_notifier_register_begin();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	/* Note the use of the double underscored version of the API */
	__register_cpu_notifier(&foobar_cpu_notifier);

	cpu_notifier_register_done();

Fix the amd-ibs code in x86 by using this latter form of callback
registration.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

On AMD family 10h we see following error messages while waking up from
S3 for all non-boot CPUs leading to a failed IBS initialization:

 Enabling non-boot CPUs ...
 smpboot: Booting Node 0 Processor 1 APIC 0x1
 [Firmware Bug]: cpu 1, try to use APIC500 (LVT offset 0) for vector 0x400, but the register is already in use for vector 0xf9 on another cpu
 perf: IBS APIC setup failed on cpu #1
 process: Switch to broadcast mode on CPU1
 CPU1 is up
 ...
 ACPI: Waking up from system sleep state S3

Reason for this is that during suspend the LVT offset for the IBS
vector gets lost and needs to be reinialized while resuming.

The offset is read from the IBSCTL msr. On family 10h the offset needs
to be 1 as offset 0 is used for the MCE threshold interrupt, but
firmware assings it for IBS to 0 too. The kernel needs to reprogram
the vector. The msr is a readonly node msr, but a new value can be
written via pci config space access. The reinitialization is
implemented for family 10h in setup_ibs_ctl() which is forced during
IBS setup.

This patch fixes IBS setup after waking up from S3 by adding
resume/supend hooks for the boot cpu which does the offset
reinitialization.

Marking it as stable to let distros pick up this fix.
Signed-off-by: NRobert Richter <rric@kernel.org>
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> v3.2..
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1389797849-5565-1-git-send-email-rric.net@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/x86 uses of the __cpuinit macros from
all C files.  x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NH. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Signed-off-by: NJorrit Schippers <jorrit@ncode.nl>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Add sysfs format entries for AMD IBS PMUs:

 # find /sys/bus/event_source/devices/ibs_*/format
 /sys/bus/event_source/devices/ibs_fetch/format
 /sys/bus/event_source/devices/ibs_fetch/format/rand_en
 /sys/bus/event_source/devices/ibs_op/format
 /sys/bus/event_source/devices/ibs_op/format/cnt_ctl

This allows to specify following IBS options:

 $ perf record -e ibs_fetch/rand_en=1/GH ...
 $ perf record -e ibs_op/cnt_ctl=1/GH ...

Option cnt_ctl is only enabled if the IBS_CAPS_OPCNT bit is set in IBS
cpuid feature flags (AMD family 10h RevC and above).
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347447584-28405-1-git-send-email-robert.richter@amd.com
[ Added small readability improvements. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Current implementation simply ignores attribute flags. Thus, there is
no notification to userland of unsupported features. Check syscall's
attribute flags to let userland know if a feature is supported by the
kernel. This is also needed to distinguish between future kernels what
might support a feature.

Cc: <stable@vger.kernel.org> v3.5..
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120910093018.GO8285@erda.amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Some PMUs don't provide a full register set for their sample,
specifically 'advanced' PMUs like AMD IBS and Intel PEBS which provide
'better' than regular interrupt accuracy.

In this case we use the interrupt regs as basis and over-write some
fields (typically IP) with different information.

The perf core however uses user_mode() to distinguish user/kernel
samples, user_mode() relies on regs->cs. If the interrupt skid pushed
us over a boundary the new IP might not be in the same domain as the
interrupt.

Commit ce5c1fe9 ("perf/x86: Fix USER/KERNEL tagging of samples")
tried to fix this by making the perf core use kernel_ip(). This
however is wrong (TM), as pointed out by Linus, since it doesn't allow
for VM86 and non-zero based segments in IA32 mode.

Therefore, provide a new helper to set the regs->ip field,
set_linear_ip(), which massages the regs into a suitable state
assuming the provided IP is in fact a linear address.

Also modify perf_instruction_pointer() and perf_callchain_user() to
deal with segments base offsets.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1341910954.3462.102.camel@twinsSigned-off-by: NIngo Molnar <mingo@kernel.org>

The value of IbsOpCurCnt rolls over when it reaches IbsOpMaxCnt. Thus,
it is reset to zero by hardware. To get the correct count we need to
add the max count to it in case we received an ibs sample (valid bit
set).
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-13-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

After disabling IBS there could be still incomming NMIs with samples
that even have the valid bit cleared. Mark all this NMIs as handled to
avoid spurious interrupt messages.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-12-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

When disabling ibs there might be the case where hardware continuously
generates interrupts. This is described in erratum #420 (Instruction-
Based Sampling Engine May Generate Interrupt that Cannot Be Cleared).
To avoid this we must clear the counter mask first and then clear the
enable bit. This patch implements this.

See Revision Guide for AMD Family 10h Processors, Publication #41322.

Note: We now keep track of the last read ibs config value which is
then used to disable ibs. To update the config value we pass now a
pointer to the functions reading it.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-11-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

If the last hw period is too short we might hit the irq handler which
biases the results. Thus try to have a max last period that triggers
the sw overflow.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-10-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

There are cases where the remaining period is smaller than the minimal
possible value. In this case the counter is restarted with the minimal
period. This is of no use as the interrupt handler will trigger
immediately again and most likely hits itself. This biases the
results.

So, if the remaining period is within the min range, we better do not
restart the counter and instead trigger the overflow.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-9-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Simple patch that just renames some variables for better
understanding.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-8-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch adds support for precise event sampling with IBS. There are
two counting modes to count either cycles or micro-ops. If the
corresponding performance counter events (hw events) are setup with
the precise flag set, the request is redirected to the ibs pmu:

 perf record -a -e cpu-cycles:p ...    # use ibs op counting cycle count
 perf record -a -e r076:p ...          # same as -e cpu-cycles:p
 perf record -a -e r0C1:p ...          # use ibs op counting micro-ops

Each ibs sample contains a linear address that points to the
instruction that was causing the sample to trigger. With ibs we have
skid 0. Thus, ibs supports precise levels 1 and 2. Samples are marked
with the PERF_EFLAGS_EXACT flag set. In rare cases the rip is invalid
when IBS was not able to record the rip correctly. Then the
PERF_EFLAGS_EXACT flag is cleared and the rip is taken from pt_regs.

V2:
* don't drop samples in precise level 2 if rip is invalid, instead
  support the PERF_EFLAGS_EXACT flag
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120502103309.GP18810@erda.amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Each IBS sample contains a linear address of the instruction that
caused the sample to trigger. This address is more precise than the
rip that was taken from the interrupt handler's stack. Update the rip
with that address. We use this in the next patch to implement
precise-event sampling on AMD systems using IBS.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-6-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Fixing profiling at a fixed frequency, in this case the freq value and
sample period was setup incorrectly. Since sampling periods are
adjusted we also allow periods that have lower 4 bits set.

Another fix is the setup of the hw counter: If we modify
hwc->sample_period, we also need to update hwc->last_period and
hwc->period_left.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-5-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Allow enabling ibs op micro-ops counting mode.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-4-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

We always need to pass the last sample period to
perf_sample_data_init(), otherwise the event distribution will be
wrong. Thus, modifiyng the function interface with the required period
as argument. So basically a pattern like this:

        perf_sample_data_init(&data, ~0ULL);
        data.period = event->hw.last_period;

will now be like that:

        perf_sample_data_init(&data, ~0ULL, event->hw.last_period);

Avoids unininitialized data.period and simplifies code.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-3-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The last sw period was not correctly updated on overflow and thus led
to wrong distribution of events. We always need to properly initialize
data.period in struct perf_sample_data.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1333390758-10893-2-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

A function name represents the pointer to it - no need to take the
address of it. (Fixing this helps us introduce some macro magic
around register_nmi_handler() in the future.)

Cc: Robert Richter <robert.richter@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

This patch implements 64 bit counter support for IBS. The
sampling period is no longer limited to the hw counter width.

The functions perf_event_set_period() and
perf_event_try_update() can be used as generic functions. They
can replace similar code that is duplicate across architectures.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-5-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Add code to control the IBS pmu. We need to maintain per-cpu
states. Since some states are used and changed by the nmi
handler, access to these states must be atomic.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-4-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

This patch implements code to handle ibs interrupts. If ibs data
is available a raw perf_event data sample is created and sent
back to the userland. This patch only implements the storage of
ibs data in the raw sample, but this could be extended in a
later patch by generating generic event data such as the rip
from the ibs sampling data.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-3-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

This patch implements perf configuration for AMD IBS. The IBS
pmu is selected using the type attribute in sysfs. There are two
types of ibs pmus, for instruction fetch (IBS_FETCH) and for
instruction execution (IBS_OP):

 /sys/bus/event_source/devices/ibs_fetch/type
 /sys/bus/event_source/devices/ibs_op/type

Except for the sample period IBS can only be set up with raw
config values and raw data samples. The event attributes for the
syscall should be programmed like this (IBS_FETCH):

        type = get_pmu_type("/sys/bus/event_source/devices/ibs_fetch/type");

        memset(&attr, 0, sizeof(attr));
        attr.type        = type;
        attr.sample_type = PERF_SAMPLE_CPU | PERF_SAMPLE_RAW;
        attr.config      = IBS_FETCH_CONFIG_DEFAULT;

This implementation does not yet support 64 bit counters. It is
limited to the hardware counter bit width which is 20 bits. 64
bit support can be added later.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1323968199-9326-2-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

On AMD family 10h we see firmware bug messages like the following:

 [Firmware Bug]: cpu 6, try to use APIC500 (LVT offset 0) for vector 0x10400, but the register is already in use for vector 0xf9 on another cpu
 [Firmware Bug]: cpu 6, IBS interrupt offset 0 not available (MSRC001103A=0x0000000000000100)
 [Firmware Bug]: using offset 1 for IBS interrupts
 [Firmware Bug]: workaround enabled for IBS LVT offset
 perf: AMD IBS detected (0x00000007)

We always see this, since the offsets are not assigned by the BIOS for
this family. Force LVT offset assignment in this case. If the OS
assignment fails, fallback to BIOS settings and try to setup this.

The fallback to BIOS settings weakens the family check since
force_ibs_eilvt_setup() may fail e.g. in case of virtual machines.
But setup may still succeed if BIOS offsets are correct.

Other families don't have a workaround implemented that assigns LVT
offsets. It's ok, to drop calling force_ibs_eilvt_setup() for that
families.

With the patch the [Firmware Bug] messages vanish. We see now:

 IBS: LVT offset 1 assigned
 perf: AMD IBS detected (0x00000007)
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20111109162225.GO12451@erda.amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

This patch implements IBS feature detection and initialzation. The
code is shared between perf and oprofile. If IBS is available on the
system for perf, a pmu is setup.
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1316597423-25723-3-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>