RE: [PATCH v13 08/12] KVM: x86: Add Intel PT context switch for each vcpu

[Kang, Luwei]

> > +static void pt_guest_enter(struct vcpu_vmx *vmx) {
> > +	if (pt_mode == PT_MODE_SYSTEM)
> > +		return;
> > +
> > +	/* Save host state before VM entry */
> > +	rdmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl);
> > +
> > +	/*
> > +	 * Set guest state of MSR_IA32_RTIT_CTL MSR (PT will be disabled
> > +	 * on VM entry when it has been disabled in guest before).
> > +	 */
> > +	vmcs_write64(GUEST_IA32_RTIT_CTL, vmx->pt_desc.guest.ctl);
> > +
> > +	if (vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) {
> > +		wrmsrl(MSR_IA32_RTIT_CTL, 0);
> > +		pt_save_msr(&vmx->pt_desc.host, vmx->pt_desc.addr_range);
> > +		pt_load_msr(&vmx->pt_desc.guest, vmx->pt_desc.addr_range);
> > +	}
> > +}
> 
> From my side this is still a NAK, because [1].
> 
> [1] https://marc.info/?l=kvm&m=153847567226248&w=2
> 

This place is save the host PT status and load the guest PT status before VM-entry when working in Host-Guest mode.

Thanks,
Luwei Kang