[PATCH v2 0/2] i8253: Fix PIT shutdown quirk on Hyper-V

[Michael Kelley <mikelley@microsoft.com>]

pit_shutdown() doesn't work on Hyper-V because of a quirk in the
PIT emulation. This problem exists in all versions of Hyper-V and
had not been noticed previously. When the counter register is set
to zero, the emulated PIT continues to interrupt @18.2 HZ.

Account for this quirk by adding a global variable in the i8253
code that controls whether the counter register is zero'ed. Then
in Hyper-V initialization code, override the default setting so
the counter register is not zero'ed.

Changes in v2:
* Instead of a function call to check if running on Hyper-V,
use a global variable to control whether the counter register
is zero'ed. [Juergen Gross & Thomas Gleixner]

Michael Kelley (2):
  i8253: Add support for PIT shutdown quirk
  x86/hyper-v: Enable PIT shutdown quirk

 arch/x86/kernel/cpu/mshyperv.c | 11 +++++++++++
 drivers/clocksource/i8253.c    | 14 ++++++++++++--
 include/linux/i8253.h          |  1 +
 3 files changed, 24 insertions(+), 2 deletions(-)

-- 
1.8.3.1