Re: Migration failure when running nested VMs

[Jintack Lim]

On Mon, Sep 23, 2019 at 4:48 AM Paolo Bonzini <address@hidden> wrote:
>
> On 23/09/19 12:42, Dr. David Alan Gilbert wrote:
> >
> > With those two clues, I guess maybe some dirty pages made by L2 are
> > not transferred to the destination correctly, but I'm not really sure.
> >
> > 3) It happens on Intel(R) Xeon(R) Silver 4114 CPU, but it does not on
> > Intel(R) Xeon(R) CPU E5-2630 v3 CPU.
>
> Hmm, try disabling pml (kvm_intel.pml=0).  This would be the main
> difference, memory-management wise, between those two machines.
>

Thank you, Paolo.

This makes migration work successfully over 20 times in a row on
Intel(R) Xeon(R) Silver 4114 CPU where migration failed almost always
without disabling pml.

I guess there's a problem in KVM pml code? I'm fine with disabling
pml. But if you have patches to fix the issue, I'm willing to test it
on the CPU.

Thanks,
Jintack

> Paolo