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Merge branch 'x86/hyperv' of git://git.kernel.org/pub/scm/linux/kerne…
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Topic branch for stable KVM clockource under Hyper-V.

Thanks to Christoffer Dall for resolving the ARM conflict.
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@rkrcmar
rkrcmar committed Feb 1, 2018
2 parents 87cedc6 + 5fa4ec9 commit 7bf14c2
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1 change: 1 addition & 0 deletions .mailmap
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Expand Up @@ -107,6 +107,7 @@ Linus Lüssing <linus.luessing@c0d3.blue> <linus.luessing@ascom.ch>
Maciej W. Rozycki <macro@mips.com> <macro@imgtec.com>
Marcin Nowakowski <marcin.nowakowski@mips.com> <marcin.nowakowski@imgtec.com>
Mark Brown <broonie@sirena.org.uk>
Mark Yao <markyao0591@gmail.com> <mark.yao@rock-chips.com>
Martin Kepplinger <martink@posteo.de> <martin.kepplinger@theobroma-systems.com>
Martin Kepplinger <martink@posteo.de> <martin.kepplinger@ginzinger.com>
Matthieu CASTET <castet.matthieu@free.fr>
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16 changes: 16 additions & 0 deletions Documentation/ABI/testing/sysfs-bus-iio-dfsdm-adc-stm32
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@@ -0,0 +1,16 @@
What: /sys/bus/iio/devices/iio:deviceX/in_voltage_spi_clk_freq
KernelVersion: 4.14
Contact: arnaud.pouliquen@st.com
Description:
For audio purpose only.
Used by audio driver to set/get the spi input frequency.
This is mandatory if DFSDM is slave on SPI bus, to
provide information on the SPI clock frequency during runtime
Notice that the SPI frequency should be a multiple of sample
frequency to ensure the precision.
if DFSDM input is SPI master
Reading SPI clkout frequency,
error on writing
If DFSDM input is SPI Slave:
Reading returns value previously set.
Writing value before starting conversions.
16 changes: 16 additions & 0 deletions Documentation/ABI/testing/sysfs-devices-system-cpu
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Expand Up @@ -375,3 +375,19 @@ Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: information about CPUs heterogeneity.

cpu_capacity: capacity of cpu#.

What: /sys/devices/system/cpu/vulnerabilities
/sys/devices/system/cpu/vulnerabilities/meltdown
/sys/devices/system/cpu/vulnerabilities/spectre_v1
/sys/devices/system/cpu/vulnerabilities/spectre_v2
Date: January 2018
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Information about CPU vulnerabilities

The files are named after the code names of CPU
vulnerabilities. The output of those files reflects the
state of the CPUs in the system. Possible output values:

"Not affected" CPU is not affected by the vulnerability
"Vulnerable" CPU is affected and no mitigation in effect
"Mitigation: $M" CPU is affected and mitigation $M is in effect
36 changes: 2 additions & 34 deletions Documentation/IRQ-domain.txt
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Expand Up @@ -265,37 +265,5 @@ support other architectures, such as ARM, ARM64 etc.

=== Debugging ===

If you switch on CONFIG_IRQ_DOMAIN_DEBUG (which depends on
CONFIG_IRQ_DOMAIN and CONFIG_DEBUG_FS), you will find a new file in
your debugfs mount point, called irq_domain_mapping. This file
contains a live snapshot of all the IRQ domains in the system:

name mapped linear-max direct-max devtree-node
pl061 8 8 0 /smb/gpio@e0080000
pl061 8 8 0 /smb/gpio@e1050000
pMSI 0 0 0 /interrupt-controller@e1101000/v2m@e0080000
MSI 37 0 0 /interrupt-controller@e1101000/v2m@e0080000
GICv2m 37 0 0 /interrupt-controller@e1101000/v2m@e0080000
GICv2 448 448 0 /interrupt-controller@e1101000

it also iterates over the interrupts to display their mapping in the
domains, and makes the domain stacking visible:


irq hwirq chip name chip data active type domain
1 0x00019 GICv2 0xffff00000916bfd8 * LINEAR GICv2
2 0x0001d GICv2 0xffff00000916bfd8 LINEAR GICv2
3 0x0001e GICv2 0xffff00000916bfd8 * LINEAR GICv2
4 0x0001b GICv2 0xffff00000916bfd8 * LINEAR GICv2
5 0x0001a GICv2 0xffff00000916bfd8 LINEAR GICv2
[...]
96 0x81808 MSI 0x (null) RADIX MSI
96+ 0x00063 GICv2m 0xffff8003ee116980 RADIX GICv2m
96+ 0x00063 GICv2 0xffff00000916bfd8 LINEAR GICv2
97 0x08800 MSI 0x (null) * RADIX MSI
97+ 0x00064 GICv2m 0xffff8003ee116980 * RADIX GICv2m
97+ 0x00064 GICv2 0xffff00000916bfd8 * LINEAR GICv2

Here, interrupts 1-5 are only using a single domain, while 96 and 97
are build out of a stack of three domain, each level performing a
particular function.
Most of the internals of the IRQ subsystem are exposed in debugfs by
turning CONFIG_GENERIC_IRQ_DEBUGFS on.
49 changes: 34 additions & 15 deletions Documentation/RCU/Design/Data-Structures/Data-Structures.html
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Expand Up @@ -1097,7 +1097,8 @@ <h5>Quiescent-State and Grace-Period Tracking</h5>
its next exit from idle.
Finally, the <tt>rcu_qs_ctr_snap</tt> field is used to detect
cases where a given operation has resulted in a quiescent state
for all flavors of RCU, for example, <tt>cond_resched_rcu_qs()</tt>.
for all flavors of RCU, for example, <tt>cond_resched()</tt>
when RCU has indicated a need for quiescent states.

<h5>RCU Callback Handling</h5>

Expand Down Expand Up @@ -1182,24 +1183,40 @@ <h3><a name="The rcu_dynticks Structure">
Its fields are as follows:

<pre>
1 int dynticks_nesting;
2 int dynticks_nmi_nesting;
1 long dynticks_nesting;
2 long dynticks_nmi_nesting;
3 atomic_t dynticks;
4 bool rcu_need_heavy_qs;
5 unsigned long rcu_qs_ctr;
6 bool rcu_urgent_qs;
</pre>

<p>The <tt>-&gt;dynticks_nesting</tt> field counts the
nesting depth of normal interrupts.
In addition, this counter is incremented when exiting dyntick-idle
mode and decremented when entering it.
nesting depth of process execution, so that in normal circumstances
this counter has value zero or one.
NMIs, irqs, and tracers are counted by the <tt>-&gt;dynticks_nmi_nesting</tt>
field.
Because NMIs cannot be masked, changes to this variable have to be
undertaken carefully using an algorithm provided by Andy Lutomirski.
The initial transition from idle adds one, and nested transitions
add two, so that a nesting level of five is represented by a
<tt>-&gt;dynticks_nmi_nesting</tt> value of nine.
This counter can therefore be thought of as counting the number
of reasons why this CPU cannot be permitted to enter dyntick-idle
mode, aside from non-maskable interrupts (NMIs).
NMIs are counted by the <tt>-&gt;dynticks_nmi_nesting</tt>
field, except that NMIs that interrupt non-dyntick-idle execution
are not counted.
mode, aside from process-level transitions.

<p>However, it turns out that when running in non-idle kernel context,
the Linux kernel is fully capable of entering interrupt handlers that
never exit and perhaps also vice versa.
Therefore, whenever the <tt>-&gt;dynticks_nesting</tt> field is
incremented up from zero, the <tt>-&gt;dynticks_nmi_nesting</tt> field
is set to a large positive number, and whenever the
<tt>-&gt;dynticks_nesting</tt> field is decremented down to zero,
the the <tt>-&gt;dynticks_nmi_nesting</tt> field is set to zero.
Assuming that the number of misnested interrupts is not sufficient
to overflow the counter, this approach corrects the
<tt>-&gt;dynticks_nmi_nesting</tt> field every time the corresponding
CPU enters the idle loop from process context.

</p><p>The <tt>-&gt;dynticks</tt> field counts the corresponding
CPU's transitions to and from dyntick-idle mode, so that this counter
Expand Down Expand Up @@ -1231,14 +1248,16 @@ <h3><a name="The rcu_dynticks Structure">
<tr><th>&nbsp;</th></tr>
<tr><th align="left">Quick Quiz:</th></tr>
<tr><td>
Why not just count all NMIs?
Wouldn't that be simpler and less error prone?
Why not simply combine the <tt>-&gt;dynticks_nesting</tt>
and <tt>-&gt;dynticks_nmi_nesting</tt> counters into a
single counter that just counts the number of reasons that
the corresponding CPU is non-idle?
</td></tr>
<tr><th align="left">Answer:</th></tr>
<tr><td bgcolor="#ffffff"><font color="ffffff">
It seems simpler only until you think hard about how to go about
updating the <tt>rcu_dynticks</tt> structure's
<tt>-&gt;dynticks</tt> field.
Because this would fail in the presence of interrupts whose
handlers never return and of handlers that manage to return
from a made-up interrupt.
</font></td></tr>
<tr><td>&nbsp;</td></tr>
</table>
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7 changes: 4 additions & 3 deletions Documentation/RCU/Design/Requirements/Requirements.html
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Expand Up @@ -581,7 +581,8 @@ <h3><a name="Publish-Subscribe Guarantee">Publish/Subscribe Guarantee</a></h3>
DYNIX/ptx used an explicit memory barrier for publication, but had nothing
resembling <tt>rcu_dereference()</tt> for subscription, nor did it
have anything resembling the <tt>smp_read_barrier_depends()</tt>
that was later subsumed into <tt>rcu_dereference()</tt>.
that was later subsumed into <tt>rcu_dereference()</tt> and later
still into <tt>READ_ONCE()</tt>.
The need for these operations made itself known quite suddenly at a
late-1990s meeting with the DEC Alpha architects, back in the days when
DEC was still a free-standing company.
Expand Down Expand Up @@ -2797,7 +2798,7 @@ <h3><a name="Performance, Scalability, Response Time, and Reliability">
executing in usermode (which is one use case for
<tt>CONFIG_NO_HZ_FULL=y</tt>) or in the kernel.
That said, CPU-bound loops in the kernel must execute
<tt>cond_resched_rcu_qs()</tt> at least once per few tens of milliseconds
<tt>cond_resched()</tt> at least once per few tens of milliseconds
in order to avoid receiving an IPI from RCU.

<p>
Expand Down Expand Up @@ -3128,7 +3129,7 @@ <h3><a name="Tasks RCU">Tasks RCU</a></h3>
is to have implicit
read-side critical sections that are delimited by voluntary context
switches, that is, calls to <tt>schedule()</tt>,
<tt>cond_resched_rcu_qs()</tt>, and
<tt>cond_resched()</tt>, and
<tt>synchronize_rcu_tasks()</tt>.
In addition, transitions to and from userspace execution also delimit
tasks-RCU read-side critical sections.
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6 changes: 1 addition & 5 deletions Documentation/RCU/rcu_dereference.txt
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Expand Up @@ -122,11 +122,7 @@ o Be very careful about comparing pointers obtained from
Note that if checks for being within an RCU read-side
critical section are not required and the pointer is never
dereferenced, rcu_access_pointer() should be used in place
of rcu_dereference(). The rcu_access_pointer() primitive
does not require an enclosing read-side critical section,
and also omits the smp_read_barrier_depends() included in
rcu_dereference(), which in turn should provide a small
performance gain in some CPUs (e.g., the DEC Alpha).
of rcu_dereference().

o The comparison is against a pointer that references memory
that was initialized "a long time ago." The reason
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10 changes: 4 additions & 6 deletions Documentation/RCU/stallwarn.txt
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Expand Up @@ -23,12 +23,10 @@ o A CPU looping with preemption disabled. This condition can
o A CPU looping with bottom halves disabled. This condition can
result in RCU-sched and RCU-bh stalls.

o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the
kernel without invoking schedule(). Note that cond_resched()
does not necessarily prevent RCU CPU stall warnings. Therefore,
if the looping in the kernel is really expected and desirable
behavior, you might need to replace some of the cond_resched()
calls with calls to cond_resched_rcu_qs().
o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the kernel
without invoking schedule(). If the looping in the kernel is
really expected and desirable behavior, you might need to add
some calls to cond_resched().

o Booting Linux using a console connection that is too slow to
keep up with the boot-time console-message rate. For example,
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3 changes: 1 addition & 2 deletions Documentation/RCU/whatisRCU.txt
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Expand Up @@ -600,8 +600,7 @@ don't forget about them when submitting patches making use of RCU!]

#define rcu_dereference(p) \
({ \
typeof(p) _________p1 = p; \
smp_read_barrier_depends(); \
typeof(p) _________p1 = READ_ONCE(p); \
(_________p1); \
})

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1 change: 1 addition & 0 deletions Documentation/admin-guide/kernel-parameters.rst
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Expand Up @@ -109,6 +109,7 @@ parameter is applicable::
IPV6 IPv6 support is enabled.
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
ISOL CPU Isolation is enabled.
JOY Appropriate joystick support is enabled.
KGDB Kernel debugger support is enabled.
KVM Kernel Virtual Machine support is enabled.
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