bitkeeper revision 1.1159.1.556 (420951de12d7YPCDmxFldoqZYbe2cw)

bitkeeper revision 1.1159.1.556 (420951de12d7YPCDmxFldoqZYbe2cw)

Subject: [PATCH] pit-in-hv.patch

- Use ac_timer for PIT interrupt injection (more accurate time keeping)
- Accelerate some critical PIT I/O operations in the hypervisor
  (saves 15us per op). Cuts down guest timer interrupt handler execution time
  by a third.
- If the domain is scheduled out, make sure that interrupts are not lost
- Add a generic framework for device I/O interception

Signed-off-by: Edwin Zhai <edwin.zhai@intel.com>
Signed-off-by: Arun Sharma <arun.sharma@intel.com>
Signed-off-by: ian@xensource.com