Re: [PATCH 4/8] i386: hvf: Implement CPU kick

[Paolo Bonzini]

On 29/06/20 13:31, Roman Bolshakov wrote:
> I implemented what you proposed using VMX-preemption timer in Pin-based
> controls and regular hv_vcpu_run(). It works fine without noticable
> regressions, I'll send that in v2.
> 
> hv_vcpu_run_until() was also evaluated on macOS 10.15.5 but it degrades
> VM performance significantly compared to explicit setting of
> VMX-preepmtion timer value and hv_vcpu_run(). The performance issue was
> observed on Broadwell-based MacBook Air and Ivy Bridge-based MacBook
> Pro.
> 
> macOS 11.0 Beta deprecated hv_vcpu_run() and introduced a special
> declaration for hv_vcpu_run_until(), that's not available 10.15 -
> HV_DEADLINE_FOREVER (UINT64_MAX, which is bigger than maximum value of
> VMX-preeemption counter). Perhaps the performance issue is addressed
> there.

Possibly.  I'm worried that the preemption-timer trick will fail to run
there, but we'll see.

Paolo