[PATCH v5 0/6] Support calling functions on dedicated physical cpu

[Juergen Gross]

Some hardware (e.g. Dell Studio laptops) require special functions to
be called on physical cpu 0 in order to avoid occasional hangs. When
running as dom0 under Xen this could be achieved only via special boot
parameters (vcpu pinning) limiting the hypervisor in it's scheduling
decisions.

This patch series is adding a generic function to be able to temporarily
pin a (virtual) cpu to a dedicated physical cpu for executing above
mentioned functions on that specific cpu. The drivers (dcdbas and i8k)
requiring this functionality are modified accordingly.

Changes in V5:
- patch 3: rename and reshuffle parameters of smp_call_on_cpu() as requested
  by Peter Zijlstra
- patch 3: test target cpu to be online as requested by Peter Zijlstra
- patch 4: less wordy messages as requested by David Vrabel

Changes in V4:
- move patches 5 and 6 further up in the series
- patch 2 (was 5): WARN_ONCE in case platform doesn't support pinning
  as requested by Peter Zijlstra
- patch 3 (was 2): change return value in case of illegal cpu as
  requested by Peter Zijlstra
- patch 3 (was 2): make pinning of vcpu an option as suggested by
  Peter Zijlstra
- patches 5 and 6 (were 3 and 4): add call to get_online_cpus()

Changes in V3:
- use get_cpu()/put_cpu() as suggested by David Vrabel

Changes in V2:
- instead of manipulating the allowed set of cpus use cpu specific
  workqueue as requested by Peter Zijlstra
- add include/linux/hypervisor.h to hide architecture specific stuff
  from generic kernel code

Juergen Gross (6):
  xen: sync xen header
  virt, sched: add generic vcpu pinning support
  smp: add function to execute a function synchronously on a cpu
  xen: add xen_pin_vcpu() to support calling functions on a dedicated
    pcpu
  dcdbas: make use of smp_call_on_cpu()
  hwmon: use smp_call_on_cpu() for dell-smm i8k

 MAINTAINERS                       |   1 +
 arch/x86/include/asm/hypervisor.h |   4 ++
 arch/x86/kernel/cpu/hypervisor.c  |  11 +++++
 arch/x86/xen/enlighten.c          |  40 +++++++++++++++
 drivers/firmware/dcdbas.c         |  51 +++++++++----------
 drivers/hwmon/dell-smm-hwmon.c    |  35 +++++++------
 include/linux/hypervisor.h        |  17 +++++++
 include/linux/smp.h               |   3 ++
 include/xen/interface/sched.h     | 100 +++++++++++++++++++++++++++++++-------
 kernel/smp.c                      |  51 +++++++++++++++++++
 kernel/up.c                       |  18 +++++++
 11 files changed, 273 insertions(+), 58 deletions(-)
 create mode 100644 include/linux/hypervisor.h

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2.6.6