Xen devel - Sep 2012 - [PATCH 0/3] tsc adjust support for hvm guest

Intel recently release a new tsc adjust feature at latest SDM 17.13.3.
CPUID.7.0.EBX[1]=1 indicates TSC_ADJUST MSR 0x3b is supported.

Basically it is used to simplify TSC synchronization, operation of
IA32_TSC_ADJUST MSR is as follows:
1). On RESET, the value of the IA32_TSC_ADJUST MSR is 0;
2). If an execution of WRMSR to the IA32_TIME_STAMP_COUNTER MSR adds (or
subtracts)
    value X from the TSC, the logical processor also adds (or subtracts) value X
    from the IA32_TSC_ADJUST MSR;
3). If an execution of WRMSR to the IA32_TSC_ADJUST MSR adds (or subtracts)
    value X from that MSR, the logical processor also adds (or subtracts) value
X
    from the TSC;

This patch provides tsc adjust support for hvm guest, with it hvm guest would be
happy when sync tsc.

Thanks,
Jinsong