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

[Roman Bolshakov]

On Mon, Jun 29, 2020 at 03:35:16PM +0200, Paolo Bonzini wrote:
> On 29/06/20 15:29, Roman Bolshakov wrote:
> >>> 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.
> >>
> > Well, I've got new VM-exits (caused by zero preemption timer) on either
> > of my laptops.
> 
> If you have already tried 11.0 that's great.  I was worried that it
> would forcibly clear the preemption timer bit when passed
> HV_DEADLINE_FOREVER.
> 

I did not but I can check how it works on it then, note that I'm not
using hv_vcpu_run_until() because it doesn't have HV_DEADLINE_FOREVER
and it performs poorly on macOS 10.15. My approach is based
hv_vcpu_run() and should hopefully work almost anywhere where
Hypervisor.framework is available because Hypervisor framework exposes
timer value
(https://developer.apple.com/documentation/hypervisor/vmcs_guest_vmx_timer_value)
since macOS 10.10.3+.

I can also test how hv_vcpu_run_until() performs with HV_DEADLINE_FOREVER
on the Beta. And if the performance issues with VMX-preemption timer and
hv_vcpu_run_until() are fixed there.

-Roman