Commit dc6416f1d711eb4c1726e845d653235dcaae12e1 ("xen/x86: Call
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE) from xen_play_dead()")
introduced an error leading to a stack overflow of the idle task when
a cpu was brought offline/online many times: by calling
cpu_startup_entry() instead of returning at the end of xen_play_dead()
do_idle() would be entered again and again.

Don't use cpu_startup_entry(), but cpuhp_online_idle() instead allowing
to return from xen_play_dead().

Cc: <stable@vger.kernel.org> # 4.12
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

CONFIG_BOOTPARAM_HOTPLUG_CPU0 allows to offline CPU0 but Xen HVM guests
BUG() in xen_teardown_timer(). Remove the BUG_ON(), this is probably a
leftover from ancient times when CPU0 hotplug was impossible, it works
just fine for HVM.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

Pull tty/serial fixes from Greg KH:
 "Here are some small tty and serial driver fixes for 4.13-rc2. Nothing
  huge at all, a revert of a patch that turned out to break things, a
  fix up for a new tty ioctl we added in 4.13-rc1 to get the uapi
  definition correct, and a few minor serial driver fixes for reported
  issues.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: Fix TIOCGPTPEER ioctl definition
  tty: hide unused pty_get_peer function
  tty: serial: lpuart: Fix the logic for detecting the 32-bit type UART
  serial: imx: Prevent TX buffer PIO write when a DMA has been started
  Revert "serial: imx-serial - move DMA buffer configuration to DT"
  serial: sh-sci: Uninitialized variables in sysfs files
  serial: st-asc: Potential error pointer dereference

Pull KVM fixes from Radim Krčmář:
 "A bunch of small fixes for x86"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: x86: hyperv: avoid livelock in oneshot SynIC timers
  KVM: VMX: Fix invalid guest state detection after task-switch emulation
  x86: add MULTIUSER dependency for KVM
  KVM: nVMX: Disallow VM-entry in MOV-SS shadow
  KVM: nVMX: track NMI blocking state separately for each VMCS
  KVM: x86: masking out upper bits

Pull powerpc fixes from Michael Ellerman:
 "A handful of fixes, mostly for new code:

   - some reworking of the new STRICT_KERNEL_RWX support to make sure we
     also remove executable permission from __init memory before it's
     freed.

   - a fix to some recent optimisations to the hypercall entry where we
     were clobbering r12, this was breaking nested guests (PR KVM).

   - a fix for the recent patch to opal_configure_cores(). This could
     break booting on bare metal Power8 boxes if the kernel was built
     without CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG.

   - .. and finally a workaround for spurious PMU interrupts on Power9
     DD2.

  Thanks to: Nicholas Piggin, Anton Blanchard, Balbir Singh"

* tag 'powerpc-4.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm: Mark __init memory no-execute when STRICT_KERNEL_RWX=y
  powerpc/mm/hash: Refactor hash__mark_rodata_ro()
  powerpc/mm/radix: Refactor radix__mark_rodata_ro()
  powerpc/64s: Fix hypercall entry clobbering r12 input
  powerpc/perf: Avoid spurious PMU interrupts after idle
  powerpc/powernv: Fix boot on Power8 bare metal due to opal_configure_cores()

Pull x86 fixes from Ingo Molnar:
 "Half of the fixes are for various build time warnings triggered by
  randconfig builds. Most (but not all...) were harmless.

  There's also:

   - ACPI boundary condition fixes

   - UV platform fixes

   - defconfig updates

   - an AMD K6 CPU init fix

   - a %pOF printk format related preparatory change

   - .. and a warning fix related to the tlb/PCID changes"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/devicetree: Convert to using %pOF instead of ->full_name
  x86/platform/uv/BAU: Disable BAU on single hub configurations
  x86/platform/intel-mid: Fix a format string overflow warning
  x86/platform: Add PCI dependency for PUNIT_ATOM_DEBUG
  x86/build: Silence the build with "make -s"
  x86/io: Add "memory" clobber to insb/insw/insl/outsb/outsw/outsl
  x86/fpu/math-emu: Avoid bogus -Wint-in-bool-context warning
  x86/fpu/math-emu: Fix possible uninitialized variable use
  perf/x86: Shut up false-positive -Wmaybe-uninitialized warning
  x86/defconfig: Remove stale, old Kconfig options
  x86/ioapic: Pass the correct data to unmask_ioapic_irq()
  x86/acpi: Prevent out of bound access caused by broken ACPI tables
  x86/mm, KVM: Fix warning when !CONFIG_PREEMPT_COUNT
  x86/platform/uv/BAU: Fix congested_response_us not taking effect
  x86/cpu: Use indirect call to measure performance in init_amd_k6()

Pull perf fixes from Ingo Molnar:
 "Two hw-enablement patches, two race fixes, three fixes for regressions
  of semantics, plus a number of tooling fixes"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Add proper condition to run sched_task callbacks
  perf/core: Fix locking for children siblings group read
  perf/core: Fix scheduling regression of pinned groups
  perf/x86/intel: Fix debug_store reset field for freq events
  perf/x86/intel: Add Goldmont Plus CPU PMU support
  perf/x86/intel: Enable C-state residency events for Apollo Lake
  perf symbols: Accept zero as the kernel base address
  Revert "perf/core: Drop kernel samples even though :u is specified"
  perf annotate: Fix broken arrow at row 0 connecting jmp instruction to its target
  perf evsel: State in the default event name if attr.exclude_kernel is set
  perf evsel: Fix attr.exclude_kernel setting for default cycles:p

Pull core fixes from Ingo Molnar:
 "A fix to WARN_ON_ONCE() done by modules, plus a MAINTAINERS update"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debug: Fix WARN_ON_ONCE() for modules
  MAINTAINERS: Update the PTRACE entry

Now that we have a custom printf format specifier, convert users of
full_name to use %pOF instead. This is preparation to remove storing
of the full path string for each device node.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: devicetree@vger.kernel.org
Link: http://lkml.kernel.org/r/20170718214339.7774-7-robh@kernel.org
[ Clarify the error message while at it, as 'node' is ambiguous. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

We have 2 functions using the same sched_task callback:

  - PEBS drain for free running counters
  - LBR save/store

Both of them are called from intel_pmu_sched_task() and
either of them can be unwillingly triggered when the
other one is configured to run.

Let's say there's PEBS drain configured in sched_task
callback for the event, but in the callback itself
(intel_pmu_sched_task()) we will also run the code for
LBR save/restore, which we did not ask for, but the
code in intel_pmu_sched_task() does not check for that.

This can lead to extra cycles in some perf monitoring,
like when we monitor PEBS event without LBR data.

  # perf record --no-timestamp -c 10000 -e cycles:p ./perf bench sched pipe -l 1000000

  (We need PEBS, non freq/non timestamp event to enable
   the sched_task callback)

The perf stat of cycles and msr:write_msr for above
command before the change:
  ...
  Performance counter stats for './perf record --no-timestamp -c 10000 -e cycles:p \
                                 ./perf bench sched pipe -l 1000000' (5 runs):

    18,519,557,441      cycles:k
        91,195,527      msr:write_msr

      29.334476406 seconds time elapsed

And after the change:
  ...
  Performance counter stats for './perf record --no-timestamp -c 10000 -e cycles:p \
                                 ./perf bench sched pipe -l 1000000' (5 runs):

    18,704,973,540      cycles:k
        27,184,720      msr:write_msr

      16.977875900 seconds time elapsed

There's no affect on cycles:k because the sched_task happens
with events switched off, however the msr:write_msr tracepoint
counter together with almost 50% of time speedup show the
improvement.

Monitoring LBR event and having extra PEBS drain processing
in sched_task callback showed just a little speedup, because
the drain function does not do much extra work in case there
is no PEBS data.

Adding conditions to recognize the configured work that needs
to be done in the x86_pmu's sched_task callback.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170719075247.GA27506@krava
Signed-off-by: Ingo Molnar <mingo@kernel.org>