Re: [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE

[Paolo Bonzini]

On 10/12/20 13:14, Peter Zijlstra wrote:
> On Thu, Dec 10, 2020 at 12:42:36PM +0100, Paolo Bonzini wrote:
> > On 07/12/20 18:41, Thomas Gleixner wrote:
> > > Right this happens still occasionally, but for quite some time this is
> > > 100% firmware sillyness and not a fundamental property of the hardware
> > > anymore.
> >
> > It's still a fundamental property of old hardware.  Last time I tried to
> > kill support for processors earlier than Core 2, I had to revert it. That's
> > older than Nehalem.
>
> Core2 doesn't use TSC for timekeeping anyway. KVM shouldn't either.

On Core2, KVM guests pass TSC through kvmclock in order to get something 
usable and not incredibly slow.

Paolo