RE: [patch v2 3/8] KVM: x86: add Intel processor trace virtualization mode

[Kang, Luwei]

> > +	if (!(_cpu_based_2nd_exec_control & SECONDARY_EXEC_PT_USE_GPA) ||
> > +		!(_vmexit_control & VM_EXIT_CLEAR_IA32_RTIT_CTL) ||
> > +		!(_vmentry_control & VM_ENTRY_LOAD_IA32_RTIT_CTL)) {
> > +		_cpu_based_2nd_exec_control &= ~SECONDARY_EXEC_PT_USE_GPA;
> 
> Also, you are not checking anywhere if the SUPPRESS_PIP controls are available.  This is probably the best place.

SUPPRESS_PIP(should be "CONCEAL", will fix it.) is use for control of  processor trace packet. 
I think we should clear it when in SYSTEM mode (For example, PIPs are generated on VM exit, with NonRoot=0. On VM exit to SMM, VMCS packets are additionally generated). Why need check this here?

> 
> > +		_vmexit_control &= ~VM_EXIT_CLEAR_IA32_RTIT_CTL;
> > +		_vmentry_control &= ~VM_ENTRY_LOAD_IA32_RTIT_CTL;
> 
> These two are not needed; disabling SECONDARY_EXEC_PT_USE_GPA is enough.
> The tracing mode will revert to PT_SYSTEM, which does not use the load/clear RTIT_CTL controls.
> 

The status of *_RTIT_CTL should be same with SECONDARY_EXEC_PT_USE_GPA or would cause VM-entry failed. (architecture-instruction-set-extensions-programming-reference  5.2.3)