Re: [PATCH] KVM: VMX: switch to hrtimer for TSC deadline timer when L2 guest is running

[Paolo Bonzini]

On 06/07/2016 07:37, Wanpeng Li wrote:
> Cc Jan,
> 2016-07-06 13:10 GMT+08:00 Haozhong Zhang <haozhong.zhang@xxxxxxxxx>:
>> A different VMCS is loaded when L2 guest is running, so it's incorrect
>> to use the VMX preemption timer for L1 TSC deadline timer. This patch
>> switches to hrtimer for L1 TSC deadline timer when entering L2 guest,
>> and switches back to VMX preemption timer when nested VMEXIT from L2 to
>> L1.
> 
> Nested preemption timer is emulated by hrtimer, so it doesn't
> influence vmcs02, why this is needed?

I agree (and nested APIC timer is emulated by L1).  Because the L1 APIC
timer is set in the preemption timer before vmentry, this should not be
necessary.

Paolo